Preparation of Special Solutions and Reagents

α-Naphthol (Molisch´s reagent for wool). Dissolve 15 g of a-naphthol in 100 ml of alcohol or chloroform.

α-Nitroso-b-naphthol. Make a saturated solution in 50 % acetic acid (1 part of glacial acetic acid with 1 part of water). Does not keep well.

Aluminon (qualitative test for aluminum). Aluminon is a trade name for the ammonium salt of aurin tricarboxylic acid. Dissolve 1 g of the salt in 1 liter of distilled water. Shake the solution well to insure thorough mixing.

Bang΄s reagent (for glucose estimation). Dissolve 100 g of K₂CO₃, 66 g of KCl and 160 of KHCO₃ in the order given in about 700 ml of water at 30° C. Add 4.4 g of CuSO₄ and dilute to 1 liter after the CO₂ is evolved. This solution should be shaken only in such a manner as not to allow entry of air. After 24 hours 300 ml are diluted to 1 liter with saturated KCl solution, shaken gently and used after 24 hours; 50 ml equivalent to 10 mg glucose.

Barfoed΄s reagent (test for glucose). See Cupric acetate.

Baudisch΄s reagent. See Cupferron.

Benedict΄s solution (qualitative reagent for glucose). With the aid of heat, dissolve 173 g of sodium citrate and 100 g of Na₂CO₃ in 800 ml of water. Filter, if necessary, and dilute to 850 ml. Dissolve 17.3 gof CuSO₄.5H₂O in 100 ml of water. Pour the latter solution, with constant stirring, into the carbonate-citrate solution, and make up to 1 liter.

Benzidine hydrochloride solution (for sulfate determination). Make a paste of 8 g of benzidine hydrochloride (C₁₂H₈(NH₂)₂.2HCl) and 20 ml of water, add 20 ml of HCl (sp. gr. 1.12) and dilute to 1 liter with water. Each ml of this solution is equivalent to 0.00357 g of H₂SO₄.

Bertrand΄s reagent (glucose estimation). Consists of the following solutions:
(a) Dissolve 200 g of Rochelle salts and 150 g of NaOH in sufficient water to make 1 liter of solution.
(b) Dissolve 40 g of CuSO₄ in enough water to make 1 liter of solution.
(c) Dissolve 50 g of Fe₂(SO₄)₃ and 200 g of H₂SO₄ (sp. gr. 1.84) in sufficient water to make 1 liter of solution.
(d) Dissolve 5 g of KMnO₄ in sufficient water to make 1 liter of solution.

Blal΄s reagent (for pentose). Dissolve 1 g of orcinol (CH₃.C₆H₃(OH)₂) in 500 ml of 30% HCl to which 30 drops of a 10% solution of FeCl₃ has been added.

Boutron-Boudet soap solution:
(a) Dissolve 100 g of pure castile soap in about 2500 ml of 56% ethyl alcohol.
(b) Dissolve 0.59 g of Ba(NO₃)₂ in 1 liter of water.
Adjust the castile soap solution so that 2.4 ml of it will give a permanent lather with 40 ml of solution (b). When adjusted 2.4 ml of soap solution is equivalent to 220 parts per million of hardness (as CaCO₃) for a 40 ml sample.
See also Soap solution.

Brucke΄s reagent (protein precipitation). See Potassium iodide-mercuric iodide.

Clarke΄s soap solution (or A.P.H.A. standard method). Estimation of hardness in water:
(a) Dissolve 100 g of pure powdered castile soap in 1 liter of 80% ethyl alcohol and allow to stand overnight.
(b) Prepare a standard solution of CaCl₂ by dissolving 0.5 of CaCO₃ in HCl (sp. gr. 1.19), neutralize with NH₄OH and make slightly alkaline to litmus, and dilute to 500 ml. One ml is equivalent to 1 mg of CaCO₃.
Titrate (a) against (b)and dilute (a) with 50% ethyl alcohol until 1 ml of the resulting solution is equivalent to 1 ml of (b) after making allowance for the lather factor (the amount of standard soap solution required to produce a permanent lather in 50 ml of destilled water). One ml of the adjusted solution after subtracting the lather factor is equivalent to 1 mg of CaCO₃.
See also Soap solution. 

Cobalticyanide paper (Rinnmann ΄s test for Zn). Dissolve 4 g of K₂Co(CN)₅ and 1 g of KClO₃ in 100 ml of water. Soak filter paper in solution and dry at 100° C. Apply drop of zinc solution and burn in an evaporating dish. A green disk is obtained if zinc is present.

Cochineal. Extract 1 g of cochineal for four days with 20 ml of alcohol and 60 ml of distilled water. Filter.

Congo red. Dissolve 0.5 g of congo red in 90 ml of destilled water and 10 ml of alcohol.

Cupferron (Baudisch ΄s reagent for iron analysis). Dissolve 6 g of the ammonium salt of nitroso-phenyl-hydroxyl-amine (cupferron) in 100 ml of H₂O. Reagent good for one week only and must be kept in the dark.

Cupric acetate (Barfoed΄s reagent for reducing monosaccharides). Dissolve 66 g of cupric acetate and 10 ml of glacial acetic acid in water and dilute to 1 liter.

Cupric oxideammoniacal; Schweitzer΄s reagent (dissolves cotton, linen and silk, but not wool):
1. Dissolve 5 g of cupric sulfate in 100 ml of boiling water, and add sodium hydroxide until precipitation is complete. Wash the precipitate well, and dissolve it in a minimum quantity of ammonium hydroxide.
2. Bubble a slow stream of air through 300 ml of strong ammonium hydroxide containing 50 g of fine copper turnings. Continue for one hour.

Cupric sulfate in glycerin-potassium hydroxide (reagent for silk). Dissolve 10 g of cupric sulfate, CuSO₄.5H₂O, in 100 ml of water and add 5 g of glycerin. Add KOH solution slowly until a deep blue solution is obtained.

Cupron (benzoin oxime). Dissolve 5 g in 100 ml of 95 % alcohol.

Cuprous chloride, acidic (reagent for CO in gas analysis):
1. Cover the bottom of a two-liter flask with a layer of cupric oxide about one-half inch deep, suspend a bunch of copper wire so as to reach from the bottom to the top of the solution, and fill the flask with hydrochloric acid (sp. gr. 1.10). Shake occasionally. When the solution becomes nearly colorless, transfer to reagent bottles, which should also contain copper wire. The stock bottle may be refilled with dilute hydrochloric acid until either the cupric oxide or the copper wire is used up.
Copper sulfate may be substituted for copper oxide in the above procedure.
2. Dissolve 340 g of CuC1₂.2H₂O in 600 ml of conc. HCl and reduce the cupric chloride by adding 190 ml of a saturated solution of stannous chloride or until the solution is colorless. The stannous chloride is prepared by treating 300 g of metallic tin in a 500 ml flask with conc. HCl until no more tin goes into solution.
3. (Winkler method). Add a mixture of 86 g of CuO and 17 g of finely divided metallic Cu, made by the reduction of CuO with hydrogen, to a solution of HCl, made by diluting 650 ml of conc. HCl with 325 ml of water. After the mixture has been added slowly and with frequent stirring, a spiral of copper wire is suspended in the bottle, reaching all the way to the bottom. Shake occasionally, and when the solution becomes colorless, it is ready for use.

Cuprous chlorideammoniacal (reagent for CO in gas analysis):
1. The acid solution of cuprous chloride as prepared above is neutralized with ammonium hydroxide until an ammonia odor persists. An excess of metallic copper must be kept in the solution.
2. Pour 800 ml of acidic cuprous chloride, prepared by the Winkler method, into about 4 liters of water. Transfer the precipitate to a 250 ml graduate. After several hours, siphon off the liquid above the 50 ml mark and refill with 7.5% NH₄OH solution which may be prepared by diluting 50 ml of conc. NH₄OH with 150 ml of water. The solution is well shaken and allowed to stand for several hours. It should have a faint odor of ammonia.

Dichlorfluorescin indicator. Dissolve 1 g in 1 liter of 70% alcohol or 1 g of the sodium salt in 1 liter of water.

Dimethylglyoxime (diacetyl dioxime), 0.01 N. Dissolve 0.6 g of dimethylglyoxime, (CH₃CNOH)₂, in 500 ml of 95 % ethyl alcohol. This is an especially sensitive test for nickel, a very definite crimson color being produced.

Diphenylamine (reagent for rayon). Dissolve 0.2 g in 100 ml of concentrated sulfuric acid.

Diphenylamine sulfonate (for titration of iron with K₂Cr₂O₇). Dissolve 0.32 g of the barium salt of diphenylamine sulfonic acid in 100 ml of water, add 0.5 g of sodium sulfate and filter off the precipitate of BaSO₄.

Diphenylcarbazide. Dissolve 0.2 g of diphenylcarbazide in 10 ml of glacial acetic acid and dilute to 100 ml with 95% ethy1 alcohol.

Esbach΄s reagent (estimation of protein). To a water solution of 10 g of picric acid and 20 g of citric acid, add sufficient water to make one liter of solution.

Eschka΄s compound. Two parts of calcined («light») magnesia are thoroughly mixed with one part of anhydrous sodium carbonate.

Fehling΄s solution. (reagent for reducing sugars):
(a) Copper sulfate solution. Dissolve 34.66 g of CuSO₄.5H₂O in water and dilute to 500 ml.
(b) Alkaline tartrate solution. Dissolve 173 g of potassium sodium tartrate (Rochelle salts, KNaC₄H₄O₆.4H₂O) and 50 g of NaOH in water and dilute when cold to 500 ml.
For use, mix equal volumes of the two solutions at the time of using.

Ferric-alum indicator. Dissolve 140 g of ferric-ammonium sulfate crystals in 400 ml of hot water. When cool, filter, and make up to a volume of 500 ml with dilute (6 N) nitric acid.

Folin΄s mixture. (for uric acid). To 650 ml of water add 500 g of (NH₄)₂SO₂, 5 g of uranium acetate and 6 g of glacial acetic acid. Dilute to 1 liter.

Formaldehyde-sulfuric acid (Marquis΄ reagent for alkaloids). Add 10 ml of formaldehyde solution to 50 ml of sulfuric acid.

Froehde΄s reagent. See Sulfomolybdic actid.

Fuchsin (reagent for linen). Dissolve 1 g of fuchsin in 100 ml of alcohol.

Fuchsin-sulfurous acid (Schiff΄s reagent for aldehydes). Dissolve 0.5 g of fuchsin and 9 g of sodium bisulfite in 500 ml of water, and add 10 ml of HCI. Keep in well-stoppered bottles and protect from light.

Gunzberg΄s reagent (detection of HCl in gastric juice). Prepare as needed a solution containing 4 g of phloroglucinol and 2 g of vanillin in 100 ml of absolute ethyl alcohol.

Hager΄s reagent. See Picric acid.

Hanus solution (for iodine number). Dissolve 13.2 g of resublimed iodine in one liter of glacial acetic acid which will pass the dichromate test for reducible matter. Add sufficient bromine to double the halogen content, determined by titration (3 ml is about the proper amount). The iodine may be dissolved by the aid of heat, but the solution should be cold when the bromine is added.

Iodine, tincture of. To 50 ml of water add 70 g of I2 and 50 g of KI. Dilute to 1 liter with alcohol.

Iodo-potasium iodide (Wagner΄s reagent for alkaloids). Dissolve 2 g of iodine and 6 g of KI in 100 ml of water.

Litmus (indicator). Extract litmus powder three times with boiling alcohol, each treatment consuming an hour. Reject the alcoholic extract. Treat residue with an equal weight of cold water and. filter; then exhaust with five times its weight of boiling water, cool and filter. Combine the aqueous extracts.

Magnesia mixture (reagent for phosphates and arsenates). Dissolve 55 g of magnesium chloride and 105 g of ammonium chloride in water, barely acidify with hydrochloric acid, and dilute to 1 liter. The ammonium hydroxide may be omitted until just previous to use. The reagent, if completely mixed and stored for any period of time, becomes turbid.

Magnesium reagent. See S and O reagent.

Magnesium uranyl acetate. Dissolve 100 g of UO₂(C₂H₃O₂)₂.2H₂O in 60 ml of glacial acetic acid and dilute to 500 ml. Dissolve 330 g of Mg(C₂H₃O₂)2.4H₂O in 60 ml of glacial acetic acid and dilute to 200 ml. Heat solutions to the boiling point until clear, pour the magnesium solution into time uranyl solution, cool and dilute to l liter. Let stand over night and filter if necessary.

Marme΄s reagent. See Potassium-cadmium iodide.

Marqui΄s reagent. See Formaldehyde-sulfuric acid.

Mayer΄s reagent. (white precipitate with most alkaloids in slightly acid solutions). Dissolve 1.358 g of HgCl₂ in 60 ml of water and pour into a solution of 5 g of KI in 10 ml of H₂O Add sufficient water to make 100 ml.

Methyl orange indicator. Dissolve 1 g of methyl orange in 1 liter of water. Filter, if necessary.
Methyl orange, modified. Dissolve 2 g of methyl orange and 2.8 g of xylene cyanole FF in 1 liter of 50% alcohol.

Methyl red indicator. Dissolve 1 g of methyl red in 600 ml of alcohol and dilute with 400 ml of water.

Methyl red, modified. Dissolve 0.50 g of methyl red and 1.25 g of xylene cyanole FF in 1 liter of 90% alcohol. Or, dissolve 1.25 g of methyl red and 0.825 g of methylene blue in 1 liter of 90% alcohol.

Millon΄s reagent (for albumins and phenols). Dissolve 1 part of mercury in 1 part of cold fuming nitric acid. Dilute with twice the volume of water and decant the clear solution after several hours.

Mixed indicator. Prepared by adding about 1.4 g of xyleno cyanole FF to 1 g of methyl orange. The dye Is seldom pure enough for these proportion to be satisfactory. Each new lot of dye should be tested by adding additional amounts of the dye until test portion gives the proper color change. The acid color of this indicator is like that of permanganate; the neutral color is gray; and the alkaline color is green. Described by Hickman and Linstead, J. Chem. Soc. (Lon.), 121, 2502 (1922).

Molisch΄s reagent. See α-Naphthol.

Nessler΄s reagent (for ammoniak). Dissolve 50 g of KI in the smallest possible quantity of cold water (50 ml). Add a saturated solution of mercuric chloride (about 22 g in 350 ml of water will be needed) until an excess is indicated by the formation of a precipitate. Then add 200 ml of 5 N NaOH and dilute to 1 liter. Let settle, and draw off the clear liquid.

Nickel oxide, ammoniacal (reagent for silk). Dissolve 5 g of nickel sulfate in 100 ml of water, and add sodium hydroxide solution until nickel hydroxide is completely precipitated Wash the precipitate well and dissolve in 25 ml of concentrated ammonium hydroxide and 25 ml of water.

Nitron (detection of nitrate radical). Dissolve 10 g of nitron (C₂₀H₁₆N₄, 4,5-dihydro-l,4-diphenyl-3,5-phenylimino-1,2,4-triazole) in 5 ml of glacial acetic acid and 95 ml of water. The solution may be filtered with slight suction through an alundum crucible and kept in a dark bottle.
Nylander΄s solution (carbohydrates). Dissolve 20 g of bismuth subnitrate and 40 g of Rochelle salts in 1 liter of 8% NaOH solution. Cool and filter.

Obermayer΄s reagent (for indoxyl in urine). Dissolve 4 g of FeCl₃ in one liter of HCl (sp. gr. 1.19).

o-Tolidine solution (residual chlorine in water analysis). Prepare 1 liter of dilute HCl (100 ml of HCl (sp. gr. 1.19) in sufficient water to make 1 liter). Dissolve 1 g of o-tolidine in 100 ml of the dilute HCl and dilute to 1 liter with dilute HCl solution.

Oxalic Acid (0.1 N). Dissolve 6.3 g of C₂H₂O₄ in 1000 ml of water. . Dilute to 1 liter.

Oxine. Dissolve 14 g of HC₉H₆ON in 30 ml of glacial acetic acid. Warm slightly, if necessary. Dilute to 1 liter.

Oxygen absorbent. Dissolve 300 g of ammonium chloride in one liter of water and add one liter of concentrated ammonium hydroxide solution. Shake the solution thoroughly. For use as an oxygen absorbent, a bottle half full of copper turnings is filled nearly full with the NH₄Cl-NH₄OH solution and the gas passed through.

Pasteur΄s salt solution. To one liter of distilled water add 2.5 g of potassium phosphate, 0.25 g of calcium phosphates, 0.25 g of magnesium sulfate and 12.00 g of ammonium tartrate.

Pavy΄s solution (glucose reagent). To 120 ml of Fehling΄s solution, add 300ml of NH₄OH (sp. gr. 0.88) and dilute to 1 liter with water.

Phenanthroline ferrous ion indicator. Dissolve 1.485 g of phenanthroline monohydrate in 100 ml of 0.025 M ferrous sulfate solution.

Phenolphthalein. Dissolve 1 g of phenolphthalein in 50 ml of alcohol and add 50 ml of water.

Phenolsulfonic acid (determination of nitrogen as nitrate). Dissolve 25gof phenol in 150 ml of conc. H₂SO₄, add 75 ml of fuming H₂SO₄ (15% SO₃), stir well and heat for two hours at l00 °C.

Phloroglucinol solution (pentosans). Make a 3% phloroglucinol solution in alcohol. Keep in a dark bottle.

Phosphomolybdic acid (Sonnenschein ΄s reagent for alkaloids):
1. Prepare ammonium phosphomolybdate and after washing with water, boil with nitric acid and expel NH₃; evaporate to dryness and dissolve in 2 N nitric acid.
2. Dissolve ammonium molybdate in HNO₃, and treat with phosphoric acid. Filter, wash the precipitate, and boil with aqua regia until the ammonium salt is decomposed. Evaporate to dryness. The residue dissolved in 10% HNO₃ constitutes Sonnenschein΄s reagent.

Phosphoric acid - sulfuric acid mixture. Dilute 150 ml of conc. H₂SO₄ and 100 ml of conc. H₃PO₄ (85%) with water to a volume of 1 liter.

Phosphotungstic acid (Scheibler ΄s reagent for alkaloids):
1. Dissolve 20 g of sodium tungstate and 15 g of sodium phosphate in 100 ml of water containing a little nitric acid.
2. The reagent is a 10% solution of phosphotungstic acid in water. The phosphotungstic acid is prepared by evaporating a mixture of 10 g of sodium tungstate dissolved in 5 g of phosphoric acid (sp. gr. 1.13) and enough boiling water to effect solution. Crystals of phosphotungstic acid separate.

Picric acid (Hager’s reagent for alkaloids, wool and silk). Dissolve 1 g of picric acid in 100 ml of water.

p-Nitrobenzene-azo-resorcinol (reagent for magnesium). Dissolve 1 g of the dye in 10 ml of N NaOH and dilute to 1 liter.

Potassium antimonate (reagent for sodium). Boil 22 g of potassium antimonate with 1 liter of water until nearly all of the salt has dissolved, cool quickly, and add 35 ml of 10% potassium hydroxide. Filter after standing over night.

Potassium hydroxide (for CO₂ absorption). Dissolve 360 g of KOH in water and dilute to 1 liter.

Potassium Iodate (0.1 N). Dissolve 3.57 g of KIO₃ in water and dilute to 1 liter.

Potassium iodide-mercuric iodide (Brucke΄s reagent for proteins). Dissolve 50 g of KI in 500 ml of water, and saturate with mercuric iodide (about 120 g). Dilute to I liter.

Potassium Permanganate (0.1 N ) : Dissolve 3.16 g of KMnO₄ in 1 liter of water.

Potassium pyrogallate (for oxygen absorption). For mixtures of gases containing less than 28% oxygen, add 100 ml of KOH solution (50 g of KOH to 100 ml of water) to 5 g of pyrogallol. For mixtures containing more than 28% oxygen the KOH solution should contain 120 g of KOH to 100 ml of water.

Potassium-cadmium iodide (Marme ’s reagent for alkaloids). Add 2 g of CdI₂ to a boiling solution of 4g of KI in I₂ ml of water, and then mix with 12 ml of saturated KI solution.

Pyrogallol, alkaline:
(a) Dissolve 75 g of pyrogallic acid in 75 ml of water.
(b) Dissolve 500 g of KOH in 250 ml of water. When cool, adjust until sp. gr. is 1.55.
For use, add 270 ml of solution (b) to 30 ml of solution (a).

Rosolic acid (indicator). Dissolve 1 g of rosolic acid in 10 ml of alcohol and add l00 ml of water.

S and O reagent (Suitsu and Okuma ΄s test for Mg). Dissolve 0.5 g of the dye (o, p-dihydroxy-monoazo-p-nitrobenzene) in 100 ml of 0.25 NaOH.

Salvanof´s Reagent. Dissolve 0.5 g of resorcinol in 1 liter of 3M HCl.

Scheibler΄s reagent. See Phosphotungstic acid.

Schiff΄s reagent. See Fuchsin-sulfurous acid.

Schiff΄s reagent. Method 2 :
1-Dissolve 5g of basic fuchsin in 900ml of boiling distilled water
2-Cool to approximately 50 ⁰C and slowly add 100ml of 1N HCl
3-Cool to approximately 25 ⁰C and dissolve 10g of K₂S₂O₅.
4-Shake for 3 minutes and incubate in the dark at room temperature for 24 hours.
5-Add 5 grams of fine activated charcoal and shake for 3 minutes.
6-Filter solution (should be clear).
7- Store at 4 ⁰C in a foil covered bottle.

Schweitzer΄s reagent. See Cupric oxide, ammoniacal.

Soap solution (reagent for hardness in water). issolve 100 g of dry castile soap in 1 liter of 80% alcohol (5 parts alcohol to 1 part water). Allow to stand several days and dilute with 70% to 80% alcohol until 6.4 ml produces a permanent lather with 20 ml of standard calcium solution. The latter solution is made by dissolving 0.2 g of CaCO₃ in a small amount of dilute HCl, evaporating to dryness and making up to 1 liter.

Sodium bismuthate (oxidation of manganese). Heat 20 parts of NaOH nearly to redness in an iron or nickel crucible and add slowly 10 parts of basic bismuth nitrate which has been previously dried. Add two parts of sodium peroxide, and pour the brownish-yellow fused mass on an iron plate to cool. When cold, break up in a mortar, extract with water, and collect on an asbestos filter.

Sodium hydroxide (for CO₂ absorption). Dissolve 330 g of NaOH in water and dilute to 1 liter.

Sodium nitroprusside (reagent for hydrogen sulfide and wool). Use a freshly prepared solution of 1 g of sodium nitroprusside in 10 ml of water.

Sodium oxalate, according to Sörensen (primary standard). Dissolve 30 g of the commercial salt in 1 liter of water, make slightly alkaline with sodium hydroxide, and let stand until perfectly clear. Filter and evaporate the filtrate to 100 ml. Cool and filter. Pulverize the residue and wash it several times with small volumes of water. The procedure is repeated until the mother liquor is free from sulfate and is neutral to phenolphthalein.

Sodium plumbite (reagent for wool). Dissolve 5 g of sodium hydroxide in 100 ml of water. Add 5 g of litharge and boil until dissolved.

Sodium polysulfide. Dissolve 480 g of Na₂S.9H₂O in 500 ml of water, add 40 g of NaOH and 18 g of sulfur. Stir thoroughly and dilute to 1 liter with water.

Sodium Thiosulfate (0.1 N) . Dissolve 25 g of sodium thiosulphate pentahydrate Na₂S₂O₃.5H₂O in 1 liter of freshly boiled distilled water, add 0.1 g of Na₂CO₃ for stability. 

Sonnenschein΄s reagent. See Phosphomolybdic acid.

Starch solution:
1. Make a paste with 2 g of soluble starch and 0.01 g of HgI₂ with a small amount of water. Add the mixture slowly to 1 liter of boiling water and boil for a few minutes. Keep in a glass stoppered bottle. If other than soluble starch is used, the solution will not clear on boiling; it should be allowed to stand and the clear liquid decanted.
2. A solution of starch which keeps indefinitely is made as follows: Mix 500 ml of saturated NaCl solution (filtered), 80 ml of glacial acetic acid, 20 ml of water and 3 g of starch. Bring slowly to a boil and boil for two minutes.
3. Make a paste with 1 g of soluble starch and 5 mg of HgI₂, using as little cold water as possible. Then pour about 200 ml of boiling water on the paste and stir immediately. This will give a clear solution if the paste is prepared correctly and the water actually boiling. Cool and add 4g of KI. Starch solution decomposes on standing due to bacterial action, but this solution will keep a long time if stored under a layer of toluene.

Stoke΄s reagent. Dissolve 30 g of FeSO₄ and 20 g of tartaric acid in water and dilute to 1 liter. Just before using, add concentrated NH₄OH until the precipitate first formed is redissolved.

Sulfanilic acid (reagent for nitrites). Dissolve 0.5 g of sulfanilic acid in a mixture of 15 ml of glacial acetic acid and 135 ml of recently boiled water.

Sulfomolybdic acid (Froehde ΄s reagent for alkaloids and glucosides). Dissolve 10 g of molybdic acid or sodium molybdate in 100 ml of conc. H₂SO₄.

Tannic acid (reagent for albumen, alkaloids and gelatin). Dissolve 10 g of tannic acid in 10 ml of alcohol and dilute with water to 100 ml.

Titration mixture. See Zimmermann-Reinhardt reagent.

Trinitrophenol solution. See Picric acid.

Turmeric paper. Impregnate white, unsized paper with the tincture, and dry.

Turmeric tincture (reagent for borates). Digest ground turmeric root with several quantities of water which are discarded. Dry the residue and digest it several days with six times its weight of alcohol. Filter.

Uffelmann΄s reagent (turns yellow in presence of a lactic acid). To a 2% solution of pure phenol in water, add a water solution of FeCl3 until the phenol solution hecornes violet in color.

Wagner΄s reagent. See Iodo-potassium iodide.

Wagner΄s solution (used in phosphate rock analysis to prevent precipitation of iron and aluminum). Dissolve 25 g of citric acid and 1 g of salicylic acid in water and dilute to 1 liter. Use 50 ml of the reagent.

Wij΄s iodine monochloride solution (for iodine number). Dissolve 13 g of resublimed iodine in 1 liter of glacial acetic acid which will pass the dichromate test for reducible matter. Set aside 25 ml of this solution. Pass into the remainder of the solution dry chlorine gas (dried and washed by passing through H₂SO₄ (sp. Gr. 1.84)) until the characteristic color of free iodine has been discharged. Now add the iodine solution which was reserved, until all free chlorine has been destroyed. A slight excess of iodine does little or no harm, but an excess of chlorine must be avoided. Preserve in well stoppered, amber colored bottles. Avoid use of solutions which have been prepared for more than 30 days.

Wij΄s special solution (for iodine number-Analyst 58, 523-7, 1933). To 200 ml of glacial acetic acid that will pass the dichromate test for reducible matter, add 12 g of dichloroamine T (paratoluene-sulfonedichloroamide), and 16.6 g of dry KI (in small quantities with continual shaking until all the KI has dissolved). Make up to 1 liter with the same quality of acetic acid used above and preserve in a dark colored bottle.

Zimmermann-Reinhardt reagent (determination of iron). Dissolve 70 g of MnSO4.4H2O in 500 ml of water, add 125 ml of oonc.H2SO4 and 125 ml of 85% H3PO4, and dilute to 1 liter.

Zinc chloride solution, basic (reagent for silk). Dissolve 1000 g of zinc chloride in 850 ml of water, and add 40 g of zinc oxide. Heat until solution is complete.

Zinc uranyl acetate (reagent for sodium). Dissolve 10 of UO2(C2H3O2)2.2H2O in 6 g of 30 % acetic acid with heat, if necessary, and dilute to 50 ml. Dissolve 30 g of Zn(C2H3O2)2.2H2O in 3 g of 30% acetic acid and dilute to 50 ml. Mix the two solutions, add 50 mg of NaCl, allow to stand over night and filter.