Photographic Chemical Descriptions

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Please note: All medical suggestions are for information and advice only. On all occasions please seek medical help, from a Doctor, immediately. Remember to take any packaging, bottles, descriptions etc to the hospital

ACETIC ACID, GLACIAL

Other names: Methanecabboxylic acid; ethanoic acid.
Description: Colourless, water like liquid with a pungent vinegary odour.
Precautions: Causes severe burns so avoid contact with liquid or vapour in the eyes, on the skin, by breathing, or on clothing. Keep bottle in a cool place and remove cap very carefully to avoid liquid or vapour contact. May be fatal if swallowed. Keep away from heat and open flame.

First Aid: In case of contact with eyes, flush with plenty of water for at least 15 minutes, then get medical attention. For external contact, flush with water, then water containing sodium bicarbonate. If taken internally, give tap water, milk, or milk of magnesia. Give whites of eggs beaten with water. Do not give emetics. See a doctor immediately.

Note: Glacial acetic acid contains at least 99.5% acetic acid; acetic acid contains 36 to 37%, by weight. Photographic grade acetic acid is 28% because glacial acetic acid cannot be added to sodium sulphite without decomposing the sulphite to form sulphur dioxide gas. Do not add glacial acetic acid to sodium-thiosulphate solutions without sodium sulphite being present as the thiosulfate will sulfurize. White vinegar is a dilute solution of acetic acid, usually 3 to 6% acetic acid, although distilled vinegar may have a higher acid content. Glacial acetic acid may be diluted to 28 percent by mixing 3 parts of Glacial acetic acid with 8 parts of water.

Photographic Formulas: Blue Toner (GT-14), Fixer 6a, Stop Bath SB-1, Uranium Toner.

AMMONIUM ALUM

Other names: Ammonium alum; ammonium aluminium sulphate; aluminium ammonium sulphate dodecahydrate.
Description: Colourless crystals, white granules, or powder with a strong, astringent taste melt at 94.5°C, lose 20 H2O at 120°C, and dehydrate completely at about 250°C. Solubility is 15.1 grams in 100ml water at 20°C with greater solubility in hot water (66.6 grams at 60°C). Freely soluble in glycerol and dilute acid but almost insoluble in alcohol. The pH of an aqueous solution (0.05 molecular weight in 1000 ml solution) is 4.6

Precautions: Ammonium alum is considered only moderately toxic but may cause dermatitis by skin irritation because of the release of sulphuric acid. Inhalation and ingestion of large quantities cause serious upset. Keep in closed container and avoid breathing dust. Use only with adequate ventilation. Avoid contact with eyes, skin, and clothing. Wear safety glasses and rubber, or similar gloves when handling. Wash after handling. Do not swallow.

First Aid: If contact is made with the skin, flush thoroughly with plenty of water, using soap, if available. If contact is made with eyes, flush with plenty of water for 15 minutes. Call a doctor. If inhaled or ingested, dilute by drinking a large volume of water, then call a doctor immediately for further treatment. Get medical help if skin dermatitis develops.

Uses: As a hardener in acid fixing baths or sometimes as a separate hardener for gelatin.
Photographic Formulas: Uranium Toner (Kodak T-9).

AMMONIUM CARBONATE

Other names: Ammonium sesquicarbonate; crystal ammonia; hartshorn; rock ammonia; sal volatile.
Description: The double salt of ammonium bicarbonate and ammonium carbonate, consists of colourless, translucent plates or masses, or white powder, with a strong odour of ammonia (ingredient of smelling salts). The solid is unstable in air, evolving ammonia and carbon dioxide to leave ammonium bicarbonate, becoming white and powdery on the outside to form a solid of uncertain composition.

Precautions: Keep container tightly closed and store in a cool place. Do not heat as irritating fumes will be evolved. Use with adequate ventilation and do not breathe the fumes. Avoid contact with eyes, skin, and clothing. Avoid breathing fumes from solid or solutions as irritation may result.

First Aid: In case of contact, immediately flush eyes or skin with plenty of water for at least 15 minutes. Remove contaminated clothing and shoes. Wash clothing before re-use. Call a doctor, especially an eye specialist, about eye contamination. If inhaled, remove at once to an area of uncontaminated air. If swallowed, have the person drink large quantities of water followed by dilute vinegar, lemon juice, cider, or other weak acid fruit juices. Call a doctor about further treatment.

Photographic Formulas: Two Bath Redevelopment Toners.

AMMONIUM THIOCYANATE

Other names: Ammonium sulfocyanate; ammonium sulphocyanate; ammonium sulphocyanate; ammonium sulphocyanide; ammonium rhodanide.
Description: The colourless crystals are stable but readily absorb enough water from the air to become wet. The compound is available as a solid of 98 to 99% purity but often sold as a 55 to 60% solution in water to avoid the uncertainties of the absorption of water.

Precautions: Keep container tightly closed and store in a cool, dry place. Avoid contact with the eyes, skin, and respiratory system. Wear safety glasses and rubber gloves. Wash thoroughly after handling as the compound may cause skin eruptions. May be harmful if inhaled or swallowed.

First Aid: If contact is made with eyes or skin, flush immediately with plenty of water. Call a doctor about eye and skin irritations. If swallowed call a doctor at once.

Photographic Formulas: Gold Toner (GAF-231), Gold Toner (Ilford IT-4).

AMMONIUM THIOSULPHATE

Other names: Ammonium hyposulphite; ammonium hypo.
Description: Ammonium thiosulphate occurs as anhydrous, colourless, or white crystals that are very water soluble in water (173 grams in 100 ml water at 20°C or 205 grams at 40°C). Two forms are available for photographic use; crystal solid (at least 97% by weight) and an aqueous solution (60% by weight).

Precautions: Keep container tightly closed and store in a cool dry place; avoid breathing dust.

First Aid: If contact is made with eyes or skin, flush immediately with plenty of water. Call a doctor about eye and skin irritations. If large quantities are swallowed call a doctor at once.

Photographic Formulas: TF-3 Alkaline Film Fixer, TF-4 Archival Rapid Fixer.

ASCORBIC ACID

Other names: Vitamin C, cevitamic acid, and many trademarked names.
Description: White crystals or powder. Reasonably stable in air when compound is dry but darkens gradually on exposure to light. Water solutions are oxidized rapidly by air, especially in the presence of alkali, copper, or iron.

Precautions: Protect from air, light, and heat. No other special treatment is necessary.
Note: (iso-Ascorbic acid [D-(-)-Araboascorbic acid], has very low anti scorbutic activity but may be substituted for ascorbic acid for some photographic uses. Sodium ascorbate, the sodium salt of Vitamin C, may also be used in place of ascorbic acid. One gram of this crystalline compound is equivalent to 0.8890 gram ascorbic acid, or 1 gram of the acid is equivalent to 1.1248 grams of sodium ascorbate. Sodium ascorbate is very soluble in water (62 grams dissolve in 100 ml water at 23°C) but the solution is unstable in air.

Photographic Formulas: Chris Patton's E-76, Mytol Film Developer (Xtol Substitute), Chris Patton's E-72 Print Developer,

BENZOTRIAZOLE

Other names: 1,2,3-Benzotriazole; 1-H-benzotriazole; azimidobenzene; benzene azimide; benzisotriazole.
Description: The white, odourless, crystalline powder, melting point 98.5°C, is only slightly soluble in water but soluble in alcohol, benzene, chloroform, dimethylformamide, and toluene.

Precautions: Keep container closed. Use with adequate ventilation. Do not inhale dust or vapour from solutions. Benzotriazole may cause irritation so avoid contact with eyes, skin, or clothing. Wear safety glasses or goggles and rubber or similar gloves when handling. Do not swallow as benzotriazole is believed to be moderately toxic.

First Aid: If inhaled, remove from exposure. If contact is made with eyes or skin, flush with plenty of water to remove traces of compound. Irrigate eyes thoroughly, then call a doctor or an eye specialist. Remove contaminated clothing and reuse only after washing. If swallowed, induce vomiting by giving a glass of lukewarm, salty water (one tablespoonful of common table salt per glass). Call a doctor at once.

Uses: Benzotriazole has been primarily used as anti-foggant in photographic developers; as a fog restrainer for developers used to process outdated (foggy) photographic paper; as an addition to developers to produce blue-black developed image tones.
Photographic Formulas: FX 37 Film Developer, Divided D-76 Film Developer (Variations), Print Developer 130 Adams Version,

BORIC ACID

Other names: Orthoboric acid; boracic.
Description: Boric acid is available as colourless, odourless, transparent, waxy crystals or white granules or powder which lose 1 H2O upon slow heating to form metaboric acid.

Precautions: The handling of boric acid is generally not considered hazardous. Ingestion or absorption of boric acid through burned or abraded skin can result in poisoning, even death. Protect the eyes and skin from contact with the acid. Wear safety glasses and protective rubber gloves.

First Aid: If contact occurs with the eyes or the skin, flush with copious amounts of water for about 15 minutes. If swallowed or if contact with open wounds is made, call a doctor immediately.

Photographic Formulas: Burton 195 Film Developer.

CATECHOL

Other names: Pyrocatechol; pyrocatechin; 1,2-benzenediol; 1,2-dihy-drpxybenzene; o-dihydroxybenzene; 1,2-phendiol; Kachin (trade name).
Description: Colourless or white crystalline compound that has a slight phenolic odour and sublimes or volatilises with steam. The solid discolours upon exposure to air and light. Alkaline solutions rapidly turn brown or black.

Precautions: Catechol is considered more toxic than hydroquinone. It should be handled with care, and contact with the skin, eyes, and inhalation of the dust should be avoided. Wear safety glasses and rubber gloves when handling the solid or solutions. Wash thoroughly after handling. Do not swallow.

First Aid: In case of contact, immediately flush eyes or skin with plenty of water for at least 15 minutes. If swallowed, induce vomiting by giving a glass of water containing two teaspoonfuls of table salt. Call a doctor at once.

Photographic Formulas: Modified Windisch Catechol Film Developer, Pyrocat-HD Film Developer, Warm-Tone Redeveloper.

CITRIC ACID

Other names: 2-Hydroxy-1,2,3,-propanetncarboxylic acid; 8-hydroxy-tricarballylic acid.
Description: Anhydrous citric acid crystallizes from hot concentrated aqueous solutions in the form of odourless, colourless, and translucent crystals.

Precautions: Citric acid is completely metabolised in the human body, and is not considered a hazard for darkroom or laboratory use. It is a relatively strong organic acid, however, and the eyes and hands should be protected from liquid splashes or mists. Keep container tightly closed. Aqueous solutions of citric acid are mildly corrosive to carbon steels but not to stainless steels.

First Aid: Flush skin or eyes with plenty of water if the liquid is splashed into contact. If considerable quantities are swallowed, consult a doctor.

Photographic Formulas: Modified Windisch Catechol Film Developer, Gold-Thiocarbamide Toner (Ilford IT-5), Fixer 24.

COPPER SULPHATE

Other names: Copper sulphate pentahydrate; copper (It) sulphate pentahydrate; cupric sulphate; cupric sulphate; blue vitriol; Roman vitriol; bluestone; blue copperas.
Description: The pentahydrate, sometimes as pure as 99.999%, consists of large blue crystals, blue granules, or light blue powder, that slowly lose water of crystallisation when exposed to air.

Precautions: Keep container tightly closed. Use with adequate ventilation and do not breathe dust or mists. Avoid contact with the skin or eyes because severe irritation may result. Wear safety glasses or goggles and rubber or similar impervious gloves. Wash thoroughly after handling. Do not swallow as the poisonous compound will cause serious internal irritation and may induce vomiting (300 mg of the sulphate salt is an emetic dose for an adult).

First Aid: If inhaled, remove from exposure, rest, and keep warm. If contact is made with the skin or eyes, flush with plenty of water, irrigating the eyes thoroughly. If serious irritation results, call a doctor. If swallowed, wash out mouth with plenty of water, then, if vomiting has not occurred, give a glass of lukewarm, salty water to produce vomiting. Call a doctor at once.

Note: Do not confuse copper sulphate with tri basic copper sulphate

Photographic Formulas: Copper Print Toner, Red Toner, Two Bath Redevelopment Toners.

DIETHYLENE GLYCOL

Other names:Oxydiethanol.
Description: Diethylene glycol is a colourless, almost odourless, viscous liquid that absorbs water from the air.

Precautions: The liquid is a stable chemical, not flammable, and neither appreciably irritating to the eyes or skin nor absorbed through the skin in significant amounts unless extensive and prolonged skin contact occurs. Inhalation of toxic concentrations at room temperature is impossible but hazardous prolonged inhalation can occur from heated or misted solutions. Ingestion of substantial amounts can result in fatal poisoning. Keep containers closed and clearly labeled as to contents; use adequate ventilation when using, especially if the liquid is heated or in a mist or fog.

First Aid: Only the normal safe practices are necessary for the darkroom or laboratory. Flush eyes or skin with plenty of water if contact is made. If ingested, get medical attention at once.

Photographic Formulas: Raphaelson GPQ Liquid Concentrate.

FERRIC CHLORIDE

Other names: Iron tri chloride; ferric tri chloride; ferric perchloride; iron perchloride; iron chloride; iron (III) chloride; ferric chloride hydrate; ferric chloride hexahydrate.
Description: Anhydrous ferric chloride, occurs as brownish black crystals, red by transmitted light and green by reflected light, readily absorbs water from the air to form hexahydrate. The anhydrous salt is soluble in water, ethyl and methyl alcohols, acetone, and ether, but insoluble in glycerol and ethyl acetate. The anhydrous FeCl3 on exposure to air forms the yellowish brown to orange-yellow, crystalline hexahydrate. The hexahydrate takes up water from moist air and decomposes to give hydrochloric acid which can be detected by slight smell of HCl. The melting point is 37°C. The hexahydrate is very soluble in water (191 grams per litre of water at 20°C and much more soluble in hot water), and soluble in acetone, alcohol, and ether. An aqueous solution has a pH of 2.0 (0.1 molecular weight in 1000 ml solution).

Precautions: Keep container tightly closed. Use with adequate ventilation. Do not inhale as the anhydrous form is corrosive when moist, causing burns of the mucous membranes, as well as of eyes, skin, or mouth. Avoid contact of the eyes, skin, and respiratory system. Wear safety glasses or goggles and rubber or similar impervious gloves. Do not swallow.

First Aid: If inhaled, remove from exposure, rest, and keep warm. If contact is made with eyes, flush with plenty of waters, irrigating thoroughly, then call a doctor for further medical attention. For skin contact flush with plenty of water. Call a doctor if any irritation persists. If swallowed, wash out mouth with water and have the person drink a large quantity of water, the follow with milk of magnesia. Call a doctor at once for further treatment.

Uses: As an ingredient in reducing and toning solutions; in photo etching processes on metal plates; as the light sensitive element in the cyanotype process.
Photographic Formulas: Vandium Print Toner.

FERRIC AMMONIUM CITRATE

Other names: Iron ammonium citrate; iron (Ill) ammonium citrate; ferric ammonio-citrate, ammonium ferric citrate.
Description: Ferric ammonium citrate, brown form, is commercially available as red transparent scales, reddish-brown granules, or a brownish yellow powder. The brown form is odourless or with a slight ammonia odour and very readily absorbs water from moist air. The compound is light sensitive, being reduced to the ferrous salt by the light.

Precautions: Keep container tightly closed and well protected from light. Use good laboratory procedures with this compound. Wear safety glasses to protect eyes.

First Aid: If contact is made, flush from skin or eyes with plenty of water. If considerable quantity is swallowed, especially by a child, call a doctor.

Photographic Formulas: Blue Toner (GT-14), Iron Blue Toner, Iron Green/Blue Toner, Ferricyanide-Iron Blue Toner (Ilford IT-6),

GLYCIN

Other names: p-Hydroxyphenylaminoacetic acid; p-hydroxyanilinoacetic acid; para-oxyphenyl glycin; para-oxyphenyl glycol; and a number of trade names (Athenon, Glycin, Iconyl, and Monazol).
Description: The very small thin plates, occurring as a white powder, are almost insoluble in water, acetone, alcohol, benzene, chloroform, ether, ethyl acetate, and glacial acetic acid. A 3% sodium sulphite solution at 60°F will dissolve almost 13% by weight of Glycin, thus the recommendation to add the sodium sulphite before the Glycin when making developer solutions.

Precautions: Avoid repeated or prolonged contact with this compound as kidney damage has been reported from persistent contact. Keep container closed and use with adequate ventilation. Do not breathe dust or swallow, Wear safety glasses or rubber gloves when handling and wash thoroughly after handling.

First Aid: In case of contact, flush the eyes or skin with plenty of water. If swallowed, induce vomiting by giving a glass of lukewarm salty water (2 teaspoonfuls of table salt to one glass of water). Call a doctor.

Photographic Formulas: FX-2 Film Developer, FX-11 Film Developer, Raphaelson GPQ Liquid Concentrate, Print Developer 106, Print Developer 130 Adams Version, Kodak D-155 Print Developer, WW-1 Print Developer.

GOLD CHLORIDE

Other names: Chloroauric acid; chlora-auric acid; hydro chloroauric acid; gold tri chloride, acid; tetra chloroauric acid.
Description: The bright golden-yellow to reddish yellow crystals readily absorb water from the air and are sensitive to sunlight.

Precautions: Keep container closed, or tube unbroken, until ready for use. Protect from light. Avoid contact with eyes and skin as irritation or allergic dermatitis may result. Wear safety glasses or goggles and rubber or similar impervious gloves. Do not swallow.

First Aid: If contact is made with eyes or skin, flush with plenty of water. Call a doctor for the eyes. If swallowed, induce vomiting by having the person drink a glass of lukewarm, salty water (one tablespoon of table salt in glass of water). Call a doctor.

Photographic Formulas: Gold Toner (Ilford IT-4), Gold-Thiocarbamide Toner (Ilford IT-5), Nelson Gold Print Toner, Gold Toner (Kodak T-26),

HYDROQUINONE

Other names: Hydrochinon; hydrokinone; hydroquinol; quinol; p-dihydroxybenzene; 1,4-dihydroxybenzene; 1,4-benzenediol; Tecquinol.
Description: The white crystalline solid (needles or prisms) is very stable if kept dry and tightly closed in a container.

Precautions: Under normal conditions of darkroom and laboratory use, hydroquinone is not a serious hazard but prolonged or repeated exposure or ingestion can result in skin dermatitis, intestinal irritation or death (from ingesting 3 to 12 grams), and discoloration and opacification of the cornea of the eye. Keep container tightly closed and protected from light. Use with adequate ventilation. Avoid breathing dust. Wash thoroughly after handling. Avoid contact with eyes, skin, and clothing. Wear safety glasses and rubber gloves. May be harmful if swallowed.

First Aid: In case of contact, immediately flush skin or eyes with plenty of water for at least 15 minutes. Get medical attention for eyes. If swallowed, induce vomiting by giving lukewarm water containing table salt, Call a doctor at once.

Photographic Formulas: D-76 Film Developer, Divided D-76 Film Developer (Variations), FX-11 Film Developer, FX-19 Film Developer, FX 37 Film Developer, Raphaelson GPQ Liquid Concentrate, GAF-125 Print Developer, Divided D-76 Film Developer (Variations), Print Developer 106, Brown Tone Print Developer (Agfa 120), Print Developer 130 Adams Version, Kodak D-72 Print Developer, Kodak D-155 Print Developer, WW-1 Print Developer, Two Bath Redevelopment Toners.

LIVER OF SULPHUR

Other names: Potash sulphurated; sulphurated potassa; hepar sulfuris; liver of sulphur.

Precautions: Keep container tightly closed as liver of sulphur absorbs water and carbon dioxide from the air, resulting in the decomposition of the compound. Use with adequate ventilation. Do not breathe fumes or vapours as hydrogen sulphide is a poisonous gas. Avoid touching the solid with metal spatulas or spoons and avoid contacting with acid or acid salts, alcohol, or water containing much carbon dioxide, Avoid contact with eyes and skin. Wear safety glasses or goggles and rubber or similar gloves. Keep away from heat, sparks, and open flame as hydrogen sulphide is an explosive and flammable gas.

First Aid: If hydrogen sulphide is inhaled, move to fresh air. In case of skin contact, flush with plenty of water. If eye contact is made, flush with plenty of water for at least 15 minutes, then call a doctor or an eye specialist. If swallowed, get immediate aid from a doctor.

Photographic Formulas: Polysulphide Toner (T-8).

p-METHYLAMINOPHENOL SULPHATE (METOL)

Other names: Monomethyl-p-aminophenol sulphate; ji-hydroxymethylaniline sulphate; 4-methylaminophenol sulphate; and a large number of trade names (Enol, LIon, Genol, Graphol, Metol, Photo-Rex, Pictol, Planetol, Rhodol, Satrapol, Scalol, Verol, and Viterol, to mention only a few).

Description: The free base, 4-methylaminophenol, is a crystalline compound, melting point 87°C, that is unstable in air and light, so that the compound is handled as a hydrochloride or sulphate salt. The white, odourless crystals of the sulphate salt (such as the commonly available EIon, Metol, and Pictol products) are fairly stable but may discolour in air in time,

Precautions: Repeated and prolonged contact can cause skin irritation and allergic skin reactions, reported to be not an inherent property of the compound but due to the presence of an impurity (N,N-dimethyl-p-phenylenediamine) that occurs in some preparations. Use with adequate ventilation and avoid breathing the dust. Keep container tightly closed and protected from the light. Avoid contact with the eyes, skin, and clothing. May be harmful if swallowed. Wear safety glasses or goggles and rubber or similar impervious gloves when handling the compound or its solutions. Wash thoroughly after use.

First Aid: If contact is made with the skin or eyes, flush with plenty of water. Get medical attention for skin irritation or dermatitis. If swallowed, induce vomiting by giving a glass of lukewarm salty water (2 teaspoonfuls of table salt per glass). Call a doctor at once for further treatment.

Photographic Formulas: D-76 Film Developer, Divided D-76 Film Developer (Variations), Film Developer 25, Buetler High Acutance Film Developer, FX-1 Film Developer, FX-2 Film Developer, Burton 195 Film Developer, Divided D-76 Film Developer (Variations), PMK Film Developer, Gevaert Warm Tone Developer (GD-67), GAF 120 Soft Working Paper Developer, GAF-125 Print Developer, Print Developer 130 Adams Version, Kodak D-72 Print Developer, Kodak D-155 Print Developer, WW-1 Print Developer, Two Bath Redevelopment Toners.

NITRIC ACID

Other names: Aqua foftis; hydrogen nitrate.
Description: Nitric acid is a colourless liquid, fuming in moist air, with an acrid, choking odour The concentrated acid contains about 69 to 71% NO2. Acid may become light brown in colour in presence of light because of the release of NO2. The corrosive liquid attacks all base metals except aluminium and chromium steels.

Precautions: Avoid contact of nitric acid with the eyes, skin, or clothing as the acid causes severe burns. Avoid inhalation of the vapours or gaseous nitrous oxides as severe injury to the respiratory system or lungs may occur. Nitric acid is corrosive to most metals and may cause spontaneous ignition with wood or wood products, cotton and cotton waste, and similar organic products. Keep container closed except when in use; avoid breathing the vapour; and use with adequate ventilation.

First Aid: If vapours are inhaled, carry patient to uncontaminated area and get medical attention. Symptoms following inhalation may be delayed for several hours. If contact with skin or clothing has been made, flush skin with plenty of water for at least 15 minutes. Immediately remove contaminated clothing, shoes and socks. If the acid contacts the eyes, immediately irrigate with large amounts of water for at least 15 minutes. If pain persists, irrigate another 15 minutes. Consult a doctor, especially an eye specialist. If swallowed, the person should immediately drink large amounts of water to dilute the acid. Do not use carbonated alkalis as an antidote. Get medical attention.

Photographic Formulas: Vandium Print Toner,

OXALIC ACID

Description: The anhydrous acid is an odourless, crystalline solid, whitish in colour, that absorbs moisture from the air. The odourless, whitish crystals of the dihydrate are a different form than those of the anhydrous acid, giving off water of crystallization when heated to 101.5°C, the melting point.

Precautions: Oxalic acid is an irritant to the eyes, mucous membranes, and skin; swallowing as little as 5 grams has been reported to cause death. Avoid contact with the liquid, dust, or mist (from hot solutions). Protect the eyes with safety glasses and wear rubber gloves for hand protection. Do not inhale dust or mist. Avoid contact with eyes. Avoid prolonged or repeated contact with the skin. Do not swallow. Keep container closed and use with adequate ventilation.

First Aid: If contact is made with the liquid, flush eyes or skin with plenty of water. If swallowed, give copious quantities of milk, milk of magnesia, calcium lactate, or a dilute solution of any calcium or magnesium salt. Call a doctor immediately.

Photographic Formulas: Uranium Print Toner, Vandium Print Toner.

I-PHENYL-3-PYRAZOLIDONE

Other names: l-Phenyl-3-pyrazolidinone; trade names: Phenidone and Graphidone.
Description: Odourless leaflets or needles are obtained from benzene but usually supplied as a fine, white powder.

Precautions: Compound has low oral toxicity and has not caused dermatitis. Keep container closed and avoid breathing dust. Use with adequate ventilation. Wear safety glasses and gloves for protection against solutions which are usually alkaline.

First Aid: If contact of the solutions is made with the eyes or skin, flush with plenty of water. Call a doctor if there is eye irritation or if swallowed.

Photographic Formulas: Chris Patton's E-76, FX-19 Film Developer, FX 37 Film Developer, Raphaelson GPQ Liquid Concentrate, Divided D-76 Film Developer (Variations), Mytol Film Developer (Xtol Substitute), Pyrocat-HD Film Developer, Chris Patton's E-72 Print Developer,

POTASSIUM ALUM

Other names: Alum; potash alum; common alum; white alum; potassium aluminium sulphate; aluminium potassium sulphate dodecahydrate.
Description: The colourless, odourless, large transparent crystals or white crystalline powder have a sweet, astringent taste and are stable at ordinary temperatures but lose 18 H2O at 64.5°C (melting at 92.5°C).

Precautions: The compound is stable in air and not considered toxic. Avoid breathing dust. Avoid contact with eyes, skin, and clothing. Wear safety glasses and rubber gloves when handling. Do not inhale or swallow. Wash after handling.

First Aid: If contact is made with the skin or eyes, flush thoroughly with plenty of water to remove the acidic compound. Call a doctor for the irritation of the skin or eyes. If inhaled or swallowed, call a doctor.

Photographic Formulas: Divided D-76 Film Developer (Variations), Fixer 6a, Hypo-Alum Sepia Toner, Thiourea Toner, Thiourea Carbonate Toner,

POTASSIUM BROMIDE

Other names: Bromide of potassium or potash.
Description: Colourless crystals or white granules or powder that give an aqueous solution with a strong, bitter salty taste. The solid has a slight tendency to take up moisture from the air and is very soluble in water: one gram dissolves in 1.0 ml water or 1.0 ml boiling water.

Precautions: Potassium bromide is moderately toxic if large amounts are inhaled or swallowed. Keep container tightly closed; use with adequate ventilation. Do not breathe dust.

First Aid: If potassium bromide is inhaled or swallowed in considerable quantity, consult a doctor.

Photographic Formulas: Divided D-76 Film Developer (Variations), FX-11 Film Developer, GAF-125 Print Developer, FX 37 Film Developer, Divided D-76 Film Developer (Variations), Gevaert Warm Tone Developer (GD-67), Print Developer 106, GAF 120 Soft Working Paper Developer, Print Developer 130 Adams Version, Chris Patton's E-72 Print Developer, Kodak D-72 Print Developer, Kodak D-155 Print Developer, Pyrocat-HD Film Developer, Sepia Sulphide 221 Toner, Tin Print Toner, Thiourea Toner, Thiourea Carbonate Toner, WW-1 Print Developer, Warm-Tone Redeveloper.

POTASSIUM CARBONATE

Other names: Potash; pearl ash; salt of tartar; salt of wormwood.
Description: Before 1870 potassium carbonate was obtained from ashes (potash) which, after re crystallisation, were called pearl ash. The anhydrous potassium carbonate consists of odourless, white, translucent granules or powder which absorb water from the air.

Precautions: Keep container tightly closed. Use with adequate ventilation. Do not inhale dust. Avoid contact with eyes and skin. Wear safety glasses or goggles and rubber or similar impervious gloves. Wash after handling. Do not swallow. Solutions are irritating to tissue but less severe than potassium hydroxide.

First Aid: In case of contact, immediately flush eyes or skin with plenty of water for at least 15 minutes. If a doctor is not immediately available, irrigate eyes for an additional 15 minutes, then get medical help. Remove contaminated clothing and wash before re-use. If swallowed, dilute the chemical by drinking large quantities of water or milk, followed by dilute vinegar or fruit juice to neutralize the alkali. Do not induce vomiting.

Photographic Formulas: FX-2 Film Developer, Pyrocat-HD Film Developer.

POTASSIUM CITRATE

Other name: Tri basic citrate of potash.
Description: The odourless, colourless or white crystals, granules, or powder with a cooling, saline taste absorb water from the air but lose all water at 180°C.
Precautions: Keep container tightly closed. Do not make up water solutions before needed and use promptly. Follow good darkroom or laboratory practices in handling this nontoxic compound.

First Aid: Potassium citrate is widely used for food and medicinal preparations and it would not be expected that first aid measures would be needed with this edible compound.

Photographic Formulas: Copper Print Toner, Red Toner.

POTASSIUM DICHROMATE

Other names: Potassium bichromate; red potassium chromate.
Description: Potassium dichromate is available as odourless, non-combustible, bright orange-red crystals in granular and powdered forms that do not absorb water from the air (unlike sodium dichromate that does take up moisture).

Precautions: As dust, solution mist, or solution, potassium dichromate can irritate the eyes, mucous membranes, and skin, causing ulceration of skin wounds, but if ingested tends to be self-purging from the system. Keep container closed; use with adequate ventilation; avoid breathing dust or solution spray. Wash thoroughly after handling. Wear safely glasses to protect the eyes. Wear rubber or similar impervious gloves to protect the hands.

First Aid: Give first aid at once to decrease the severity of any effect. Immediately after contact flush eyes or skin with plenty of water for at least 15 minutes. For the eyes consult a doctor, preferably an eye specialist, without delay. Swallowing potassium dichromate will usually induce vomiting and purging. Even so, given an emetic such as soapy water followed by drinking as much water as possible. Persistent dermatitis or "chrome sores" (hard, discoloured ulcers) should be treated by a doctor.

Photographic Formulas: Two Bath Redevelopment Toners.

POTASSIUM FERRICYANIDE

Other names: Potassium hexacyanoferrate; red prussiate of potash; red potassium prussiate; red prussiate.
Description: The bright red crystals or powder should be free from any yellow powdery coating.

Precautions: Store the compound in a cool, dry place, and protect from the light and air. Keep the container tightly closed and do not heat strongly solid or solutions. Use with adequate ventilation. Protect solution from light and air. Purchase fresh and pure compound for photographic use. Wear safety glasses and rubber gloves to avoid contact with the compound. Although ferricyanide is considered to have low toxicity, avoid inhaling dust or swallowing.

First Aid: In case of contact with eyes or skirt, flush with plenty of water. If the dust is inhaled or the compound swallowed, call a doctor.

Photographic Formulas: Blue Toner (GT-14), Copper Print Toner, Iron Blue Toner, Iron Green/Blue Toner, Ferricyanide-Iron Blue, Red Toner, Sepia Sulphide 221 Toner, Thiourea Toner, Thiourea Carbonate Toner, Tin Print Toner, Uranium Toner, Uranium Print Toner, Uranium Toner (Kodak T-9), Vandium Print Toner, Warm-Tone Redeveloper, Two Bath Redevelopment Toners.

POTASSIUM HYDROXIDE

Other names: Caustic potash; potassa; potassium hydrate.
Description: Potassium hydroxide is available as white lumps, pellets, sticks, or cake. Rapidly absorbs water vapour and carbon dioxide from the air, forming carbonate which changes its alkalinity. Aqueous solutions attack wool, leather, and some metals, such as aluminium, lead, tin, and zinc.

Precautions: Keep container closed except when in use; do not handle with bare hands; wash thoroughly after handling. The solid or liquid causes burns on contact with body tissues, often with deep ulceration and ultimate scarring, so avoid contact with eyes, face, neck, skin, or inhalation of the dust or mist. Wear eye, face, skin, and hand protection. Chemical safety goggles for the eyes and gloves (neoprene, rubber, or vinyl) for the hands should always be worn.

First Aid: In case of contact, immediately flush eyes or skin with plenty of water for at least 15 minutes. If a doctor is not immediately available, wash eyes for another 15 minutes and skin for additional one to two hours. Get medical attention, especially an eye specialist for the eyes. Remove contaminated clothing and shoes, and wash before re-use. If taken internally, dilute the chemical by drinking large quantities of water or milk, followed by dilute vinegar or fruit juice to accomplish neutralization of the alkali. Do not induce vomiting.
Note: When making solutions, add compound slowly with agitation to the surface of the solution to avoid violent spattering. Hot water should not be used.

Photographic Formulas: Paraminophenolate (Rodinal Type) Film Developer, Tin Print Toner.

POTASSIUM IODIDE

Other name: Iodide of potash.
Description: Colourless or white crystals, white granules or powder absorb water from moist air. Long exposure to moist air and light cause solid to yellow because of liberation of iodine and iodate.

Precautions: Potassium iodide is incompatible with calomel, potassium chlorate, metallic salts, and tartaric and other acids. Store solid in a cool, dark place and keep container tightly closed. Use with adequate ventilation. Do not breathe dust or swallow.

First Aid: The compound is considered to have low toxicity but if considerable amounts are swallowed, consult a doctor.

Photographic Formulas: FX-1 Film Developer, Divided D-76 Film Developer (Variations), Hypo-Alum Sepia Toner.

POTASSIUM METABISULPHITE

Other names: Potassium pyrosulphite.
Description: The white crystals or crystalline powder have an odour of sulphur dioxide and oxidize in air, especially moist air, to sulphate

Precautions: Keep container closed and store in a cool, dry place. Use with adequate ventilation. Do not inhale dust or fumes. Keep away from acids, either during storage or in use. Avoid contact with skin and eyes. Do not swallow.

First Aid: If inhaled, remove to fresh air. If contact is made, flush eyes and skin with plenty of water. If swallowed, immediately call a doctor.

Photographic Formulas: Two Bath Redevelopment Toners.

POTASSIUM OXALATE

Other names: Neutral oxalate of potash; oxalic acid, dipotassium salt.
Description: The colourless, odourless, transparent crystals slowly lose water in warm, dry air, losing all water at about 160°C. Decomposes into carbonate when heated.

Precautions: Keep container tightly closed and store in a cool place. Use with adequate ventilation and do not breathe dust or hot vapours Oxalate salts are an irritant to the eyes, skin, and mucous membranes, as well as being toxic if ingested. Avoid contact with eyes, skin, and clothing. Wear safety glasses or goggles and rubber or similar impervious gloves. Wash thoroughly after handling. Do not swallow.

First Aid: If inhaled, remove from exposure. Flush contaminated skin with plenty of water. Remove contaminated clothing and wash before re-use. If contact is made with eyes, irrigate thoroughly with plenty of water for about 15 minutes, then call a doctor or eye specialist. If swallowed, immediately contact a doctor for treatment, as convulsions, shock, and kidney damage often result. Ingesting an oxalate should be considered an emergency.

Photographic Formulas: Uranium Toner (Kodak T-9).

POTASSIUM PERSULPHATE

Other names: Potassium persulphate; potassium peroxydisulfate; persulphate of potash; trade name: Anthion.
Description: The odourless, colourless or white crystals have been reported to have excellent storage stability and to be practically unaffected by exposure to the atmosphere. The commercial product, containing about 93 to 97% K2S2O8, is said to decompose slowly, losing available oxygen, and more rapidly at higher temperatures, completely at about 100°C.

Precautions: Keep container tightly closed and store in a cool, dry place. Do not contaminate with, or store near combustible materials. The compound is an irritant and moderately toxic. Avoid contact with eyes, skin or mucous membranes. Wear safety glasses and rubber gloves when handling. Do not inhale dust or swallow.

First Aid: In case of contact with skin or eyes, flush with plenty of water for about 15 minutes. For serious skin irritation or contact of any kind with eyes, call a doctor. If swallowed, get medical attention.

Photographic Formulas: Nelson Gold Print Toner.

POTASSIUM THIOCYANATE

Other names: Potassium sulfocyanate; potassium sulphocyanate; potassium sulphocyanide; potassium rhodanide.
Description: The colourless or white crystals are soluble in water (217 grams in 100 grams of water at 20°C), taking up moisture very easily from the air. Purity of the solid is often a minimum of 99%.

Precautions: Keep container tightly closed and store in a cool, dry place. Avoid contact with the eyes, skin, and respiratory system. Wear safety glasses and rubber gloves. Wash thoroughly after handling as the compound may cause skin eruptions. May be harmful if inhaled or swallowed.

First Aid: If contact is made with eyes or skin, flush immediately with plenty of water. Call a doctor about eye and skin irritations. If swallowed call a doctor at once.

Photographic Formulas: Gold Toner (GAF-231).

PYROGALLOL

Other names: Pyro; pyrogallic acid; 1,2,3-trihydroxybenzene; 1,2,3-beazene-triol; Piral (trade name for crystallized pyrogallol).
Description: The pure compound is an extremely light, fine white powder of very fine crystals. Because the fine crystals tend to float into the air at the slightest movement of the air, a crystallized form (large colourless crystals) is available, causing less trouble to weigh and mix than the finer crystalline, fluffy needles. Fairly stable in tightly closed containers but turns gray on exposure to air and light.

Precautions: Pyrogallol is considered poisonous because it is harmful if absorbed through the skin or swallowed. Avoid contact with eyes, skin, or clothing. Wear safety glasses to protect eyes and rubber gloves for hand protection. Keep container tightly closed and protected from light. Use with adequate ventilation, and use, if possible, the crystallized form to minimize danger of inhalation and skin contact. Wash thoroughly after handling. Avoid contact with low-sulphite alkaline solutions of pyro, such as a developing solution, as such solutions stain the skin brown and risk poisoning through absorption through the skin.

First Aid: If contact is made, flush the skin and eyes with plenty of water for about 15 minutes. If extensive areas of the skin have been contacted or for the eyes, consult a doctor. If inhaled or ingested, get medical attention immediately, as pyrogallol can cause degeneration of the kidneys and liver as well as removing the oxygen from the blood (resulting in death).

Photographic Formulas: PMK Film Developer.

SELENIUM

Other name: None.
Description: This nonmetallic element exists in different forms: (1) amorphous, (2) crystalline or red, and (3) gray or metallic.
Amorphous: The dark red to black powder softens at 40 to 60°C, producing a vitreous mass upon cooling.
Crystalline or red: Cooling molten selenium produces dark red transparent crystals, melting at 144° to form a brownish red liquid, and changing into the gray or metallic form upon heating. The dark red crystals are soluble in dilute water solutions of caustic alkali or in potassium sulphite solution.
Gray or metallic: The gray to black crystals with a metallic lustre are the most stable form of elemental selenium and are insoluble in alcohol or water but soluble in ether.

Precautions: Keep container tightly closed. Use only with adequate ventilation. Do not inhale the dust, gasses, vapours, or fumes of the element or its compounds. Avoid contact with eyes or skin as irritation may result. Wear safety goggles and rubber or similar gloves. Change gloves frequently as they may become saturated with selenium or its salts. Do not eat or smoke while working. Do not swallow.

First Aid: If dust or vapour is inhaled, remove from exposure, rest, and keep warm. If contact is made with eyes, flush thoroughly with plenty of water (10% sodium thiosulfate in water) and call a doctor at once. Wash contaminated skin areas with plenty of soap and water (or 10% aqueous sodium thiosulfate solution). Wash contaminated clothing before re-use. If swallowed, wash out mouth with water, then induce vomiting by giving a glass of lukewarm salty water (one tablespoon of salt in a glass of water). Call a doctor at once.

Uses: As a toning agent for photographic silver prints.

SILVER NITRATE

Other name: Lunar caustic (fused salt).
Description: The odourless, colourless, transparent, large crystals or small white crystals, reported to have a bitter and caustic taste, are available in exceptional purity, such as 99.9999% from a commercial source. The pure crystals are stable in pure air and do not darken on exposure to light unless organic matter is present. For example, the presence of human skin, gelatin or paper will cause pure silver nitrate to turn gray or greyish-black on exposure to light.

Precautions: Store in tightly closed, light-resistant containers. Use with adequate ventilation and avoid breathing dust or vapour over heated solutions. Avoid contact with eyes and skin as eye irritation and skin burns result. Silver may impregnate skin, eyes, and mucous membranes, producing gray-blue patches of pigmentation (argyria), said to require the accumulated intake of from 1 to 5 grams of silver. Wear safety glasses and rubber gloves. Avoid contamination of clothing or use of contaminated gloves. Do not swallow. Silver nitrate is a poisonous compound.

First Aid: If inhaled, remove from exposure, rest, and keep warm. If contact is made with eyes or skin, flush immediately with plenty of water, making sure that the irrigation of the eyes is thorough. Call a doctor or eye specialist at once as damage to eyes can be permanent. If swallowed, have the person drink salt water (sodium chloride) to precipitate insoluble silver chloride, then lukewarm salty water to cause vomiting to remove the silver salt.

Photographic Formulas: Hypo-Alum Sepia Toner, Nelson Gold Print Toner.

SODIUM ASCORBATE

Other names: Soda ascorbate, Sodium Isoascorbate, Vitamin C sodium.
Description: White crystals.

Precautions: Protect from air, light, and heat. No other special treatment is necessary.
Note: Sodium ascorbate, the sodium salt of Vitamin C, may be used in place of ascorbic acid. One gram of this crystalline compound is equivalent to 0.8890 gram ascorbic acid, or 1 gram of the acid is equivalent to 1.1248 grams of sodium ascorbate. Sodium ascorbate is very soluble in water (62 grams dissolve in 100 ml water at 23°C) but the solution is unstable in air.

Photographic Formulas: Chris Patton's E-76, Mytol Film Developer (Xtol Substitute).

SODIUM BICARBONATE

Other names: Sodium hydrogen carbonate; Sodium acid carbonate; baking soda.
Description: Sodium bicarbonate is a white, crystalline powder or granules that is often supplied as 99.7% or better purity. Compound is stable in dry air but slowly decomposes in moist air.

Precautions: Sodium bicarbonate requires only the good safe working conditions and precautions of normal darkroom and laboratory practice. Keep container tightly closed.

Photographic Formulas: Mytol Film Developer (Xtol Substitute).

SODIUM BISULPHATE

Other names: Sodium acid sulphate; sodium hydrogen sulphate; sodium bisulphate; acid sulphate; sodium pyrosulphate; niter cake (impure).
Description: Sodium bisulphate is available as colourless, free-flowing crystals or as white, fused lumps; One part of the anhydrous bisulphate is soluble in 2 parts water or 1 part boiling water, but alcohol decomposes it into sodium sulphate and sulphuric acid.

Precautions: Keep container tightly closed. Use with adequate ventilation. Do not inhale dust as contact with sodium bisulphate causes burns. Avoid contact with eyes, skin, and clothing. Always wear safety glasses or goggles and rubber or similar impervious gloves. Do not swallow.

First Aid: For eye contact irrigate the eyes thoroughly with plenty of water, then contact a doctor or an eye specialist. Thoroughly flush contacted skin with plenty of water. Remove contaminated clothing at once and wash clothing before re-use. If swallowed, wash out mouth thoroughly with plenty of water; give much water to drink, then give milk of magnesia. Call a doctor at once.

Photographic Formulas: Iron Green/Blue Toner.

SODIUM BISULPHITE (SODIUM BISULFITE)

Other name: Sodium acid sulphite
Description: The colourless or white crystals or powder have a faint sulphur dioxide odour

Precautions: Keep container tightly closed and store in a cool dry place. Do not store near, and avoid contact with, acids or oxidizing agents. Emits toxic fumes when heated so do not inhale vapour Use with adequate ventilation. Concentrated solutions can be irritating to the skin, eyes, or mucous membranes, so protect eyes with safety glasses and wear rubber or other impervious gloves for hand protection.

Photographic Formulas: Divided D-76 Film Developer (Variations), PMK Film Developer, Print Developer 130 Adams Version, Pyrocat-HD Film Developer.

SODIUM BORATE (BORAX)

Other names: Sodium tetraborate; sodium pyroborate; sodium biborate.
Two of the common forms of sodium borate are:
Disodlum tetraborate (anhydrous borax, fused borax, borax glass, or fused sodium borate)
Disodium tetraborate decahydrate (borax decahydrate, borax, sodium borate decahydrate)
Description: Anhydrous sodium borate (anhydrous borax) consists of glassy plates or crystalline powder that take up water on exposure to air and are only slowly soluble in water. Sodium borate decahydrate (borax) is available as colourless, odourless, hard crystals or fine white granules or powder that slowly lose some of their water of crystallization in air.

Precautions: The handling of borax is not considered hazardous under normal safe darkroom and laboratory practice. Do not swallow and keep out of the reach of children who might.

First Aid: If contact is made with skin or eyes, flush with water to remove the compound. In case borax is swallowed, especially by a young child, contact a doctor immediately.

Photographic Formulas: Burton 195 Film Developer, D-76 Film Developer, Chris Patton's E-76, Divided D-76 Film Developer (Variations), FX-11 Film Developer, FX 37 Film Developer, Iron Blue Toner.

SODIUM CARBONATE

Other names: Soda ash, soda, calcined soda, ash.
Description: Anhydrous sodium carbonate is a white, crystalline, odourless powder that absorbs water vapour from the air, gradually forming sodium carbonate monohydrate.

Precautions: Sodium carbonate is a skin irritant, and dusts and mists are irritating to the eyes and the respiratory system. Keep container closed; use with adequate ventilation; store in a cool dry place. Do not breathe dust. Avoid prolonged or repeated contact with the skin. Do not take internally. Wear safety glasses for the eyes and rubber or other impervious gloves on the hands.

First Aid: In case of contact, use plenty of water to flush eyes or skin for at least 15 minutes. For eyes, consult a doctor. If swallowed, get medical attention.

Photographic Formulas: Buetler High Acutance Film Developer, FX-1 Film Developer, FX-11 Film Developer, FX 37 Film Developer, Raphaelson GPQ Liquid Concentrate, Divided D-76 Film Developer (Variations), Gevaert Warm Tone Developer (GD-67), GAF-125 Print Developer, Print Developer 106, Brown Tone Print Developer (Agfa 120), GAF 120 Soft Working Paper Developer, Print Developer 130 Adams Version, Chris Patton's E-72 Print Developer, Kodak D-72 Print Developer, Kodak D-155 Print Developer, WW-1 Print Developer, Polysulphide Toner (T-8), Sepia Sulphide 221 Toner, Thiourea Toner, Thiourea Carbonate Toner, Uranium Print Toner, Uranium Toner (Kodak T-9), Two Bath Redevelopment Toners, Warm-Tone Redeveloper.

SODIUM CHLORIDE

Other names: Salt; common salt; muriate or chloride of soda.
Description: Sodium chloride is available as white crystals, granules, or powder; large, pure crystals are colourless and transparent.

Precautions: Salt is noncombustible and has very low toxicity. In fact, salt is an essential ingredient of the human diet to maintain chloride balance in the body. In the presence of moisture and carbon dioxide of the air, salt increases the rate of the rusting of iron and steel, and is corrosive on other metals, especially zinc. Certain stainless steels and monel metal are almost resistant to salt corrosion. Brass, bronze, and tin are somewhat resistant to attack.

First Aid: Salt is not considered poisonous but if large amounts are swallowed, especially by infants, a doctor should be consulted.
Uses: As an ingredient in the precipitation of photographic emulsions; as a silver halide solvent in fine grain developers; as an ingredient in reducing and toning solutions; as a washing aid to eliminate residual thiosulfate from silver images.
Note: There are a number of compounds called salt that are not pure sodium chloride. Rock salt is mined from the earth and contains 1 to 3% impurities (especially calcium sulphate). Sea salt or solar salt is obtained by evaporation of salt lakes or ocean water and contains a variety of impurities. Table salt is sodium chloride to which has been added a free-flowing agent (about 1% calcium silicate or magnesium carbonate), an anti-caking agent (sodium ferro cyanide), an iodising salt (about 0.01% potassium iodide or sodium iodide), and a stabilizer for the iodine (often 0.1% sodium carbonate and 0.1% sodium thiosulfate).

Photographic Formulas: Nelson Gold Print Toner, Two Bath Redevelopment Toners, Warm-Tone Redeveloper.

SODIUM HYDROXIDE

Other names: Caustic; caustic soda; lye; soda lye; sodium hydrate.
Description: Sodium hydroxide is sold as white deliquescent flakes, lumps, pellets, sticks, cake, or in solutions of various concentration of sodium hydroxide in water. Solid forms usually contain 97 to 98% sodium hydroxide but rapidly absorb carbon dioxide and water from the air. Caustic solutions attack wool and leather clothing, and certain metals, such as aluminium, tin, and zinc, as well as their alloys.

Precautions: Keep container closed unless in use. Sodium hydroxide absorbs both water and carbon dioxide from the air, forming carbonate which lowers the alkalinity. The heat generated when water is added to caustic solution may be sufficient to cause boiling and spattering of the hot solution. Sodium hydroxide causes severe burns or corrosive attack on all tissues of the human body. Protect the eyes, face, neck, hands, and respiratory passages from contact with the solid, solutions, dust, or mist. When handling, wear safety goggles or face shield, gloves, and protective clothing.

First Aid: Speed in removing caustic soda is of primary importance if contact has been made with this chemical, Immediately flush skin with plenty of water for up to two hours or until medical help arrives for serious cases. For eyes, flush with plenty of water for at least 15 minutes. If a doctor is not available then, continue flushing for another 15 minutes, then get medical attention, preferably a eye specialist. If taken internally, have the patient drink large amounts of water or milk. Dilute vinegar or fruit juice may then be given to attempt neutralization of the alkali. Do not induce vomiting. Remove contaminated clothing and shoes. Decontaminate before re-use.

Photographic Formulas: Modified Windisch Catechol Film Developer, Thiourea Carbonate Toner, Two Bath Redevelopment Toners.

SODIUM METABISULFITE

Other names: Sodium pyrosulphite; sodium metabisuiphite.
Description: Sodium metabisuiphite is the commercial name for the sodium salt of pyrosulphurous acid, an acid that is known only through its salts,

Precautions: Keep container tightly closed and store under cool, dry conditions as moisture causes caking and oxidation with liberation of sulphur dioxide. Use with adequate ventilation. Do not inhale dust or fumes, Keep away from acids because sulphur dioxide may be released, Avoid contact with eyes or skin. Do not swallow.

First Aid: If inhaled, remove to fresh air. If contact is made with eyes or skin, flush with plenty of water, being certain to irrigate the eyes thoroughly. If swallowed, call a doctor immediately.

Photographic Formulas: Film Developer 25, Paraminophenolate (Rodinal Type) Film Developer, Mytol Film Developer (Xtol Substitute), Fixer 24, TF-3 Alkaline Film Fixer.

SODIUM METABORATE

Other names: Sodium metaborate tetrahydrate; trade name: Kodalk balanced alkali.
Description: When a solution containing borax and an amount of sodium hydroxide just in excess of the theoretical value is cooled, the tetrahydrate is the stable phase in contact with the saturated liquid between 11.3 and 33.6°C; the dihydrate is the stable form between 33.6 and 103°C. Anhydrous sodium metaborate is obtained by fusing borax and sodium carbonate. The tetrahydrate, is a white, odourless, crystalline compound soluble in water and methanol.

Precautions: Keep container tightly closed as exposure to the atmosphere may considerably reduce the activity of the compound. Use with adequate ventilation and do not inhale the dust. Avoid contact with eyes, skin, and clothing. Wear safety glasses or goggles and rubber or similar impervious gloves. Do not swallow.

First Aid: If inhaled, remove from exposure. Immediately flush with plenty of water if contact is made with eyes or skin. After irrigating the eyes thoroughly, call a doctor or eye specialist. If swallowed, induce vomiting by having the person drink a glass of lukewarm, salty water (one tablespoonful of table salt to a glass of water). Call a doctor at once.

Photographic Formulas: PMK Film Developer, D-76 Film Developer, Divided D-76 Film Developer (Variations), Film Developer 25, FX-2K Film Developer, Mytol Film Developer (Xtol Substitute), Print Developer 106, Print Developer 130 Adams Version, Fixer 6a, Fixer 24, TF-2 Alkaline Sodium Thiosulfate Fixer.

SODIUM SULPHATE

Description: Anhydrous sodium sulphate is available as colourless crystals or a white powder that reaches maximum solubility in water at 34.4°C, the transition point from the decahydrate to the anhydrous salt.
The decahydrate or Glauber's salt, named after the man who first prepared it by decomposing sodium chloride with sulphuric acid, has the form of odourless crystals or granules that slowly lose the water of crystallization. All the water is lost at 100°C.

Precautions: Keep the decahydrate (Glauber's salt) in a tightly closed container to prevent the loss of the water of crystallization.
First Aid: Sodium sulphate is used as a diuretic and cathartic.

Photographic Formulas: Gold Toner (Kodak T-26).

SODIUM SULPHIDE (SODIUM SULFIDE)

Other names: Sodium monosulphide; sodium sulfuret.
Description: Sodium sulphide (anhydrous): The crystals or granules readily take up moisture from the air and discolour The pure monosulphide is a white microcrystalline powder but the commercial product is often yellow-to-red lumps or fused flakes. The solid is unstable and may explode upon rapid heating or percussion. In contact with air aqueous solutions are converted slowly to sodium thiosulfate and sodium hydroxide.

Precautions: Keep containers well closed and in a cool place. Keep away from acid. Clean up any spillage and do not flush into sewer which may contain acid. Wear safety glasses to protect eyes from contact as the solution can cause severe burns. Wear rubber or other impervious gloves and do not handle with bare hands. Avoid prolonged or repeated breathing of vapour, such as from heated solutions. Use only in well ventilated areas, and keep away from heat, sparks, and open flame (hydrogen sulphide is extremely flammable). Do not depend upon the obnoxious odour of the gas as a warning signal, as the gas deadens the sense of smell.

First Aid: If small amounts of the gas are inhaled, move to fresh air immediately. In case of skin contact, flush with plenty of water. In case of eye contact, flush with plenty of water for at least 15 minutes. Call a doctor or an eye specialist. If liquid is swallowed accidentally, get immediate aid from a doctor.

Photographic Formulas: Sepia Sulphide 221 Toner.

SODIUM SULPHITE (SODIUM SULFITE)

Two forms are commonly found: Sodium sulphite, anhydrous or desiccated, and Sodium sulphite, crystal or heptahydrate.
Description: Anhydrous sodium sulphite: The white crystalline powder or granules can exist for long periods as a free-flowing powder of constant composition, unlike the hydrated form.

Precautions: Keep containers well closed and in a cool place. Emits toxic fumes when heated. Do not store near, and avoid contact with, oxidizing agents.

First Aid: Sodium sulphite is harmful if swallowed. Call a doctor if any quantity is swallowed or if the fumes from heated solid are inhaled.
Note: Twice as much sodium sulphite heptahydrate is required as anhydrous sodium sulphite Do not confuse sodium SULFITE with sodium SULFIDE or sodium SULFATE.

Photographic Formulas: D-76 Film Developer, Divided D-76 Film Developer (Variations), Chris Patton's E-76, Film Developer 25, Buetler High Acutance Film Developer, FX-1 Film Developer, FX-2 Film Developer, FX-11 Film Developer, FX-19 Film Developer, FX 37 Film Developer, Raphaelson GPQ Liquid Concentrate, Modified Windisch Catechol Film Developer, Divided D-76 Film Developer (Variations), Burton 195 Film Developer, Mytol Film Developer (Xtol Substitute), Gevaert Warm Tone Developer (GD-67), GAF-125 Print Developer, Print Developer 106, Brown Tone Print Developer (Agfa 120), GAF 120 Soft Working Paper Developer, Print Developer 130 Adams Version, Chris Patton's E-72 Print Developer, Kodak D-72 Print Developer, Kodak D-155 Print Developer, Fixer 6a, Fixer 24, TF-2 Alkaline Sodium Thiosulfate Fixer, TF-3 Alkaline Film Fixer, Thiourea Toner, Thiourea Carbonate Toner, WW-1 Print Developer, Two Bath Redevelopment Toners.

SODIUM THIOCYANATE

Other names: Sodium sulfocyanate; sodium sulphocyanate; sodium sulphocyanide; sodium rhodanide.
Description: The colourless or white crystals readily take up moisture from the air.

Precautions: Keep container tightly closed and store in a cool, dry place. Avoid contact with the eyes, skin, and respiratory system. Wear safety glasses and rubber gloves. Wash thoroughly after handling as the compound may cause skin eruptions. May be harmful if inhaled or swallowed.

First Aid: If contact is made with eyes or skin, flush immediately with plenty of water. Call a doctor about eye and skin irritations. If swallowed call a doctor at once.

Photographic Formulas: Gold Toner (GAF-231), Gold Toner (Ilford IT-4).

SODIUM THIOSULPHATE

Other names: Sodium hydrosulphite; sodium sub-sulphite; hypo; antichlor.
Description: Large, colourless or white, odourless crystals or a coarse crystalline powder are common forms of the pentahydrate of sodium thiosulfate that are available. In warm dry air the crystals give up some of the water of crystallization (above 33°C); in moist air the crystals absorb water vapour from the air.

Precautions: Sodium thiosulfate has low toxicity and swallowing large amounts cause purging. In fact, thiosulfate is an antidote for cyanide poisoning. Keep container tightly closed; use adequate ventilation to prevent breathing dust; store in a cool dry place. Use the normal safe practices of darkroom and laboratory procedures.

First Aid: If contact is made, flush the eyes and skin with water. If irritation occurs, or large quantities are swallowed, consult a doctor.
Note: The anhydrous form of sodium thiosulfate (anhydrous hypo) is also commercially available. The white powder is soluble in water but insoluble in alcohol. The solid takes up water vapour from the air. The anhydrous form saves about 36% by weight in place of the pentahydrate and has a better shelf life in mixed photographic preparations.

Photographic Formulas: Fixer 6a, Fixer 24, TF-2 Alkaline Sodium Thiosulfate Fixer, Nelson Gold Print Toner.

STANNOUS CHLORIDE

Other names: Tin chloride; tin dichloride; tin salt; tin proto chloride.
Description: The white, crystalline solid, which changes into oxy chloride by absorbing oxygen from the air, is soluble in water, acetone, alcohol, alkali, glacial acetic acid, tartaric acid, and many organic solvents. Dilute aqueous solutions tend to hydrolyze and oxidize in the presence of air but concentrated solutions are stable to both of these tendencies. A 33% solution of stannous chloride has been reported to have shown no oxidation after 5 years. Even dilute solutions have shown remarkable stability if the pH value (1 or 2) are very low, such as by the addition of 0.25 to 1% hydrochloric acid. A monohydrate of stannous chloride is also available commercially and is used interchangeably with the anhydrous salt. It has the disadvantage of being oxidized in storage, losing up to 15% of its reductive activity in 3 months. Its solutions undergo hydrolysis and oxidation.

Precautions: There is no evidence that tin compounds, as ingested in food, have any effect on man. Stannous chloride, however, should be considered as a strong acid. Keep the container tightly closed. Use with adequate ventilation. Do not breathe dust or vapours Avoid contact with eyes, skin, and clothing. Wear safety glasses or goggles and rubber or similar impervious gloves. Do not swallow.

First Aid: If inhaled, remove from exposure, rest, and keep warm. If eyes are affected, irrigate thoroughly with plenty of water; obtain prompt medical attention if warranted. If contact is made with skin, flush thoroughly with plenty of water. Remove contaminated clothing and wash before re-use. If swallowed, wash out mouth thoroughly with water, then give plenty of water followed by milk of magnesia. Call a doctor immediately.

Uses: Stannous chloride has been used as a blackening agent for intensification and for fogging silver halides during reversal processing.
Photographic Formulas: Tin Print Toner.

SULPHURIC ACID

Other names: Oil of vitriol; fuming sulphuric acid; oleum (sulphuric acid with dissolved sulphur trioxide).
Description: Sulphuric acid is a colourless, odourless, oily liquid of a corrosive character available in many grades and concentrations. Miscible with water or alcohol, evolving heat. Fuming sulphuric acid (oleum) has a sharp penetrating odour because of the release of S02 gas. Sulphuric acid has a great affinity for water, removing it from air or from many substances (charring wood, clothing, sugars, etc.) Highly corrosive in water dilution to most metals, evolving hydrogen gas. Concentrated sulphuric acid is a strong oxidizing agent, causing possible ignition on contact with organic materials, carbides, chlorates, nitrates, and other substances.

Precautions: Because of its corrosive and oxidizing properties, sulphuric acid causes severe burns and destroys human tissue of any kind upon contact. Do not breathe evolved gas. Although the acid itself is not flammable, the higher concentrations may cause ignition of combustible materials. The acid attacks most metals, evolving hydrogen that is flammable and explosive. Keep containers closed except when in use. Use with adequate ventilation. Protect eyes, skin, respiratory tract, and clothing from contact at all times.

First Aid: In case of contact, immediately flush skin with plenty of water for 15 minutes. Remove all contaminated clothing, including socks and shoes. If small amounts of sulphuric acid enters the eyes, immediately flush the eyes with large amounts of water for at least 15 minutes and, if necessary, continue for another 15 minutes. Then consult a doctor, preferably an eye specialist. If swallowed, give large amounts of water to dilute the concentration of the acid. If inhaled, remove to an uncontaminated area. In all cases, get medical attention as soon as possible.
Note: Sulphuric acid is extremely dangerous when improperly handled. When diluting always add the acid to the water, never the water to the acid. Severe burns, loss of sight, or damage of the respiratory or lung tissues can result from careless handling of this acid.

Photographic Formulas: Ferricyanide-Iron Blue Toner (Ilford IT-6), Two Bath Redevelopment Toners.

TARTARIC (SUCCINIC) ACID

Other names: L-Tartaric acid; natural tartaric acid; ordinary tartaric acid; d-tartaric acid; (+)-tartaric acid; dextrotartaric acid; d-a,(3-dihydroxysuccinic acid; t-2,3-dihydroxybutancdiodic acid.
Description: The odourless, colourless, transparent crystals or white crystalline powder are stable to light and air, having a strong acid taste in water but pleasant in dilute solution.

Precautions: Tartaric acid is non-toxic but is a very strong organic acid, causing local irritation. Do not allow contact with the eyes, skin, or teeth (erodes tooth surfaces). Wear safety glasses or goggles to protect eyes from irritation. Do not breathe the vapour from hot solutions. Wear rubber or other protective gloves.

First Aid: In case of contact, wash eyes or skin flush with plenty of water until the acid is flushed away. In case of skin ulcers from repeated and prolonged contact or gastric disturbances because of inhalation or ingestion, call a doctor for treatment.

Photographic Formulas: Iron Blue Toner, Gold Toner (Kodak T-26).

THIOUREA

Other names: Thiocarbamide; sulphur-carbamide; sulfouren.
Description: The colourless or white crystals are soluble in water or alcohol but only sparingly soluble in ether. Thiourea solutions dissolve salts of silver, gold, and platinum. Gelatin is softened and may be made soluble.

Precautions: Do not inhale dust. Use with adequate ventilation. Wear safety glasses or goggles and gloves when preparing or using thiourea solutions. Avoid contact with the eyes and skin. Make sure gloves are decontaminated after use by rinsing the outer surface with a dilute solution of sodium hypochlorite (30 ml of Clorox or similar liquid household bleach to 1 litre of water). Then use warm water to wash the gloves thoroughly after the hypochlorite treatment. Do not ingest thiourea. Use good laboratory or darkroom practices when handling thiourea as it has carcinogenic properties.

First Aid: If inhaled, remove from exposure. If contact is made with eyes or skin, flush with plenty of water for about 15 minutes. If swallowed, call a doctor at once for treatment.
Note: Thiourea is a powerful fogging agent for silver-sensitized photographic materials. Do not contaminate darkrooms by mixing and using thiourea solutions in the same area where photographic processing is to be done.

Photographic Formulas: Gold-Thiocarbamide Toner (Ilford-IT5), Gold Toner (Kodak T-26), Iron Blue Toner, Thiourea Toner, Thiourea Carbonate Toner.

URANYL NITRATE

Other name: Uranium nitrate; uranic nitrate; uranium oxy nitrate; uranium nitrate hexahydrate.
Description: The yellow crystals with a greenish lustre by reflected light, melting at 60.2°C, are soluble in water (8 grams/litre at 14° and 33 grams/litre at 100°C), alcohol, and ether.

Precautions: Uranyl nitrate is a highly toxic compound that causes serious kidney damage. It also represents a severe fire and explosion risk when heated or subjected to shock in contact with oxidisable substances. Keep in a tightly closed containers to and protect against physical damage. Store in a cool, dry place. Use with adequate ventilation. Do not inhale dust, vapour or fumes. Avoid contact with eyes, skin, and respiratory system. Prolonged skin contact should be avoided because of potential radiation damage. Do not swallow. Wear safety glasses or goggles and rubber or similar impervious gloves. Wash thoroughly after handling and before eating or smoking.

First Aid: If contact is made with eyes, immediately irrigate thoroughly with plenty of water, then call a doctor or an eye specialist. Wash contaminated areas of skin with plenty of soap and water. If swallowed, induce vomiting by having the person drink a glass of lukewarm, salty water (one tablespoonful of table salt in a glass of water). Call a doctor at once. Treat as a emergency.

Photographic Formulas: Uranium Toner, Uranium Print Toner, Uranium Toner (Kodak T-9).

WATER

Other name: Hydrogen oxide.
Description: Water is a colourless, odourless, tasteless liquid at room temperatures but under other conditions exists as a solid (ice) or a vapour (steam). Ice forms at the freezing point, 32°F or 0°C, expanding about 10% in volume, but the maximum density of 1.00(100 gram/ml is reached at 4.08°C (ice 0.915). Steam is produced at 100°C at 760 mm mercury pressure; superheated steam may be made by enclosing water in an autoclave and increasing pressure. Water requires one calorie per gram to raise the temperature 1°C. Ice needs 80 calories/gram to change from ice to water; steam gives up 540 calories/gram when it condenses to form water. Water has been called the most universal solvent known and this property is exhibited by natural waters, which rapidly become contaminated by gases and solids. Hard water contains calcium and magnesium salts that are difficult to remove but water can be purified by distillation and re distillation, that is, by evaporation and steam and then condensation as water two or more times. Care must be taken in the selection of containers for distilled water as the solvent power of water may dissolve parts of the containers, especially free alkali in glass.

Precautions: Keep purified water in tightly closed containers to prevent atmospheric contamination or loss by evaporation. Do not allow water to freeze in containers that may be ruptured by the expansion of ice. Do not allow boiling water to contact eyes or skin. Do not inhale steam.

First Aid: Water is an essential nutrient for human life but protect against exposure to boiling water and steam. Wear safety glasses or goggles and rubber or protective gloves when handling heated water.

Photographic Formulas: Film Developers, Paper Developers, Fixers, Paper Toners, Washes.

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