Making Laboratory Reagents for General Use
Dilute Acids

3 molar:
Acetic acid, 3 N. Use 172ml of 17.4 M acid (99-100%). Dilute to one liter.
Hydrochloric acid, 3 N. Use 258ml of 11.6 M acid (36% HCI). Dilute to one liter.
Nitric acid, 3 N. Use l95ml of 15.4 M acid (69% HNO3). Dilute to one liter.
Phosphoric acid, 9 N. Use 205ml of 14.6 M acid (85% H3PO4). Dilute to one liter.
Sulfuric acid, 6 N. Use 168ml of 17.8 M acid (95% H2SO4). Dilute to one liter.


Dilute Bases

Ammonium hydroxide, 3 M, 3 N. Dilute 200ml of concentrated solution (14.8 M, 28% NH3) to 1 liter.
Barium hydroxide, 0.2 M, 0.4 N. Saturated solution, 63g per liter of Ba(OH)2.8H2O. Use some excess, filter off BaCO3 and protect from CO2 of the air with soda lime or ascarite in a guard tube.
Calcium hydroxide, 0.02 M, 0.04 N. Saturated solution, 1.5g per liter of Ca(OH)2. Use some excess, filter off CaCO3 and protect from CO2 of the air.
Potassium hydroxide, 3 M, 3 N. Dissolve 176g of the sticks (95%) in water and dilute to 1 liter.
Sodium hydroxide, 1 M, 1 N. Dissolve 39.989g of the pure powder (99.9%) in water and dilute to 1 liter.
Sodium hydroxide, 3 M, 3 N. Dissolve 126g of the sticks (95%) in water and dilute to 1 liter.


General Reagents

Aluminum chloride, 0.167 M, dissolve 22g of AlC13 in 1 liter of water.
Aluminum nitrate, 0.167 M, 0.5 N. Dissolve 58g of Al(NO3)3.7.5H20 in 1 liter of water.
Aluminum sulfate, 0.083 M, 0.5 N. Dissolve 56g of Al2(SO4)3.18H2O in 1 liter of water.
Ammonium acetate, 3 M, 3 N. Dissolve 230g of NH4C2H2O2 in water and dilute to 1 liter.
Ammonium carbonate, 1.5 M. Dissolve 144g of the commercial salt (mixture of (NH4)2CO3.H,O and NH4CO2NH2) in 500ml of 3 N NH4OH and dilute to 1 liter.
Ammonium chloride, 3 M, 3 N. Dissolve 160g of NH4Cl in water. Dilute to 1 liter.
Ammonium molybdate:
1. 0,5 M, 1 N. Mix well 72g of pure MoO5 (or 81g of H2MoO4) with 200ml of water, and add 60ml of conc. ammonium hydroxide. When solution is complete, filter and pour filtrate, very slowly and with rapid stirring, into a mixture of 270ml of conc. HNO3 and 400ml of water. Allow to stand over night, filter and dilute to 1 liter.
2. The reagent is prepared as two solutions which are mixed as needed, thus always providing fresh reagent of proper strength and composition. Since ammonium molybdate is an expensive reagent, and since an acid solution of this reagent as usually prepared keeps for only a few days, the method proposed will avoid loss of reagent and provide more certain results for quantitative work.
Solution 1: Dissolve 100g of ammonium molybdate (C.P. grade) in 400ml of water and 80ml of 15 M NH4OH. Filter if necessary, though this seldom has to be done
Solution 2: Mix 400ml of 16 M nitric acid with 600ml of water.
For use, mix the calculated amount of solution 1 with twice its volume of solution 2, adding solution 1 to solution 2 slowly with vigorous stirring. Thus, for amounts of phosphorus up to 20 mg, 10ml of solution 1 to 20ml of solution 2 is adequate. Increase amount as needed.
Ammonium nitrate, 1 M, 1 N. Dissolve 80g of NH4NO3 in 1 liter of water.
Ammonium oxalate, 0.25 M, 0.5 N. Dissolve 35.5g of (NH4)2C2O4.H2O in water. Dilute to 1 liter.
Ammonium sulfate, 0.25 M, 0,5 N. Dissolve 33g of (NH4)2SO4 in 1 liter of water.
Ammonium sulfide, colorless:
1. 3 M. Treat 200ml of conc. NH4OH with H2S until saturated, keeping the solution cold. Add 200ml of conc. NH4OH and dilute of 1 liter.
2. 6 N. Saturate 6 N ammonium hydroxide (40ml conc. ammonia solution +60ml H2O) with washed H2S gas. The ammonium hydroxide bottle must be completely full and must be kept surrounded by ice while being saturated (about 48 hours for two liters). The reagent is best preserved in brown, completely filled, glas-stoppered bottles.
Ammonium sulfide, yellow:
Treat 150ml of conc. NH4OH with H2S until saturated, keeping the solution cool. Add 250ml of conc. NH4OH and 10g of powdered sulfur. Shake the mixture until the sulfur is dissolved and dilute to 1 liter with water. In the solution the concentration of (NH4)2S2, (NH4) 2S and NH4OH are 0.625, 0.4 and 1.5 normal respectively. On standing, the concentration of (NH4)2S2 increases and that of (NH4)2S and NH4OH decreases.
Antimony pentachloride, 0.1 M, 0.5 N. Dissolve 30g of SbCl5 in 1 liter of water
Antimony trichloride, 0.167 M, 0.5 N. Dissolve 38g of SbC13 in 1 liter of water.
Aqua regia. Mix 1 part concentrated HNO3 with 4 parts of concentrated HCl. This formula should include one volume of water if the aqua regia is to be stored for any length of time. Without water, objectionable quantities of chlorine and other gases are evolved.
Barium chloride, 0.25 M, 0.5 N. Dissolve 61g of BaCl2.2H2O in water. Dilute to 1 liter.
Barium hydroxide, 0,1 M, about 0.2 N. Dissolve 32g of Ba(OH)2.8H2O in 1 liter of water.
Barium nitrate, 0.25 M, 0.5 N. Dissolve 65g of Ba(NO3)2 in 1 liter of water.
Bismuth chloride, 0.167 M, 0.5 N. Dissolve 53g of BiCl2 in 1 liter of dilute HCl, Use 1 part HCI to 5 parts water.
Bismuth nitrate, 0.083 M, 0.25 N. Dissolve 40g of Bi(NO3)3.5H2O in 1 liter of dilute HNO3, Use 1 part of HNO3 to 5 parts of water.
Cadmium chloride, 0,25 M, 0.5 N. Dissolve 46g of CdC12 in 1 liter of water.
Cadmium nitrate, 0.25 M, 0.5 N. Dissolve 77g of Cd(NO3) 2.4H2O in 1 liter of water.
Cadmium sulfate, 0.25 M, 0.5 N. Dissolve 70g of CdSO4. 4H2O in 1 liter of water.
Calcium chloride, 0.25 M, 0.5 N. Dissolve 55g of CaCl2.6H20 in water. Dilute to 1 liter.
Calcium nitrate, 0.25 M, 0.5 N. Dissolve 41g of Ca(NO3)2 in 1 liter of water.
Chloroplatinic acid:
1. 0.0512 M, 0.102 N. Dissolve 26.53g of H2PtCl4.6H2O in water. Dilute to 100 ml. Contains 0.100g Pt per ml
2. Make a 10% solution by dissolving 1g of H2PtCl6.6H2O in 9ml of water. Shake thoroughly to insure complete mixing. Keep in a dropping bottle.
Chromic chloride, 0.167 M, 0.5 N. Dissolve 26g of CrCl3 in 1 liter of water.
Chromic nitrate, 0.167 M, 0.5 N. Dissolve 40g of Cr(NO3) 3 in 1 liter of water.
Chromic sulfate, 0.083 M, 0.5 N. Dissolve 60g of Cr2(SO4)3.18H2O in 1 liter of water.
Cobaltous nitrate, 0.25 M, 0.5 N. Dissolve 73g of Co(NO3)2.6H2O in 1 liter of water.
Cobaltous sulfate, 0.25 M, 0.5 N. Dissolve 70g of CoSO4.7H2O in 1 liter of water.
Cupric chloride, 0.25 M, 0.5 N. Dissolve 43g of CuCl2.2H2O in 1 liter of water.
Cupric nitrate, 0.25 M, 0.5 N. Dissolve 74g of Cu(NO3)2. 6H2O in 1 liter of water.
Cupric sulfate, 0.5 M, 1 N. Dissolve 124.g of CuSO4.5H2O in water to which 5ml of H2SO4 has been added. Dilute to 1 liter.
Ferric chloride, 0.5 M, 1.5 N. Dissolve 135.2g of FeCl3.6H2O in water containing 20ml of conc. HCl. Dilute to1 liter.
Ferric nitrate, 0.167 M, 0.5 N. Dissolve 67g of Fe(NO3)3 9H2O in 1 liter of water.
Ferric sulfate, 0.25 M, 0.5 N. Dissolve 140.5g of Fe3(SO4)3.9H2O in water containing 100ml of conc. H2SO4. Dilute to 1 liter.
Ferrous ammonium sulfate, 0.5 M, 1 N. Dissolve 196g of Fe(NH4SO4)2.6H2O in water containing 10ml of conc. H2SO4. Dilute to 1 liter. Prepare fresh solutions for best results
Ferrous sulfate, 0.5 M, 1 N. Dissolve 139g of FeSO4.7H2O in water containing 10ml of conc. H2SO4. Dilute to 1 liter. Solution does not keep well.
Lead acetate, 0.5 M, 1 N. Dissolve 190g of Pb(C2H3O2)2. 3H2O in water. Dilute to 1 liter.
Lead nitrate, 0.25 M, 0.5 N. Dissolve 83g of Pb(NO2)2 in water. Dilute to one liter.
Lime water. See Calcium hydroxide.
Magnesium chloride, 0.25 M, 0.5 N. Dissolve 51g of MgCI2.6H2O in 1 liter of water.
Magnesium chloride reagent. Dissolve 50g of MgC2.6H20 and 100g of NH4Cl in 500ml of water. Add 10ml of conc. NH4OH, allow to stand over night and filter if a precipitate has formed. Make acid to methyl red with if a dilute HCl. Dilute to 1 liter. Solution contains 0.25 M MgCl2 and 2 M NH4Cl. Solution may also be diluted with 133ml of conc. NH4OH and water to make 1 liter. Such a solution will contain 2 M NH4OH.
Magnesium nitrate, 0.25 M, 0.5 N. Dissolve 64g of Mg(NO2)2.6H2O in 1 liter of water.
Magnesium sulfate, 0.25 M, 0.5 N. Dissolve 62g of MgSO4.7H2O in 1 liter of water.
Manganous chloride, 0.25 M, 0.5 N. Dissolve 50g of MnCl2.4H2O in 1 liter of water.
Manganous nitrate, 0.25 M, 0.5 N. Dissolve 72g of Mn(NO3)2.6H2O in 1 liter of water.
Manganous sulfate, 0.25 M, 0.5 N. Dissolve 69g of MnSO4.7H2O in 1 liter of water.
Mercuric chloride, 0.25 M, 0.5 N. Dissolve 68g of HgCl2 in water. Dilute to 1 liter.
Mercuric nitrate, 0.25 M, 0.5 N. Dissolve 81g of Hg(NO3)2 in 1 liter of water.
Mercuric sulfate, 0.25 M, 0.5 N. Dissolve 74g of HgSO4 in 1 liter of water.
Mercurous nitrate. Use 1 part HgNO3, 20 parts water and 1 part HNO3.
Nickel chloride, 0.25 M, 0.5 N. Dissolve 59g of NiCI26H2O in 1 liter of water.
Nickel nitrate, 0.25 M, 0.5 N. Dissolve 73g of Ni(NO3)2.-6H2O in 1 liter of water.
Nickel sulfate, 0.25 M, 0.5 N. Dissolve 66g of NiSO4.6H2O in 1 liter of water.
Potassium bromide, 0.5 M, 0.5 N. Dissolve 60g of KBr in 1 liter of water.
Potassium carbonate, 1.5 M, 3 N. Dissolve 207g of K2CO3 in 1 liter of water.
Potassium chloride, 0.5 M, 0.5 N. Dissolve 37g of KCI in 1 liter of water.
Potassium chromate, 0.25 M, 0.5 N. Dissolve 49g of K2CrO4 in 1 liter of water.
Potassium cyanide, 0.5 M, 0.5 N. Dissolve 33g of KCN in 1 liter of water.
Potassium dichromate, 0.125 M. Dissolve 37g of K2Cr2O7 in 1 liter of water.
Potassium ferricyanide, 0.167 M, 0.5 N. Dissolve 55g of K3Fe(CN)6 in 1 liter of water.
Potassium ferrocyanide, 0.5 M, 2 N. Dissolve 211g of K4Fe(CN)6.3H2O in water. Dilute to 1 liter.
Potassium iodide, 0.5 M, 0.5 N. Dissolve 83g of KI in 1 liter of water.
Potassium nitrate, 0.5 M, 0.5 N. Dissolve 51g of KNO3 in 1 liter of water.
Potassium sulfate, 0.25 M, 0.5 N. Dissolve 44g of K2SO4 in 1 liter of water.
Silver nitrate, 0.1 M, 0.1 N. Dissolve 16.987g of AgNO3 in distilled water. Dilute to 1 liter.
Silver nitrate, 0.5 M, 0.5 N. Dissolve 84.935g of AgNO3 in distilled water. Dilute to 1 liter.
Silver nitrate, 1 M, 1 N. Dissolve 169.87g of AgNO3 in distilled water. Dilute to 1 liter.
Sodium acetate, 3 M, 3 N. Dissolve 408g of NaC2H3O2.3H2O in water. Dilute to 1 liter.
Sodium carbonate, 1.5 M, 3 N. Dissolve 159g of Na2CO3, or 430g of Na2CO3.10H2O in water. Dilute to 1 liter.
Sodium chloride, 0.5 M, 0.5 N. Dissolve 29g of NaCl in 1 liter of water.
Sodium cobaltinitrite, 0.08 M (reagent for potassium). Dissolve 25g of NaNO2 in 75ml of water, add 2ml of glacial acetic acid and then 2.5g of Co(NO3)2.6H2O. Allow to stand for several days, filter and dilute to 100 ml. Reagent is somewhat unstable.
Sodium hydrogen phosphate, 0.167 M, 0.5 N. Dissolve 60g of Na2HPO4.12H2O in 1liter of water.
Sodium nitrate, 0.5 M, 0.5 N. Dissolve 43g of NaNO3 in 1 liter of water.
Sodium sulfate, 0.25 M, 0.5 N. Dissolve 36g of Na2SO4 in 1 liter of water.
Sodium sulfide, 0.5 M, 1 N. Dissolve 120g of Na2S.9H2O in water and dilute to 1 liter. Or, saturate 500ml of 1 M NaOH (21g of 95% NaOH sticks) with H2S, keeping the solution cool, and dilute with 500ml of 1 M NaOH.
Stannic chloride, 0.125 M, 0.5 N. Dissolve 33g of SnCl4 in 1 liter of water.
Stannous chloride, 0.5 M, 1 N. Dissolve 113g of SnCl2.2H2O in 170ml of cone. HCl, using heat if necessary. Dilute with water to 1 liter. Add a few pieces of tin foil. Prepare solution fresh at frequent intervals.
Stannous chloride (for Bettendorf test). Dissolve 113g of SnCl2.2H2O in 75ml of conc. HCl. Add a few pieces of tin foil.
Strontium chloride, 0.25 M, 0.5 N. Dissolve 67g of SrCl2.6H2O in 1 liter of water.
Zinc nitrate, 0.25 M, 0.5 N. Dissolve 74g of Zn(NO3)2.6H2O in 1 liter of water.
Zinc sulfate, 0.25 M, 0.5 N. Dissolve 72g of ZnSO4.7H2O in 1 liter of water.


Special Solutions and Reagents

a-Naphthol (Molisch's reagent for wool). Dissolve 15g of a-naphthol in 100ml of alcohol or chloroform.
a-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 1g of the salt in 1 liter of distilled water. Shake the solution well to insure thorough mixing.
Bang's reagent (for glucose estimation). Dissolve 100g of K2CO3, 66g of KCl and 160 of KHCO3 in the order given in about 700ml of water at 30°C. Add 4.4g 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 300ml are diluted to 1 liter with saturated KCl solution, shaken gently and used after 24 hours; 50ml 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 173g of sodium citrate and 100g of Na2CO3 in 800ml of water. Filter, if necessary, and dilute to 850 ml. Dissolve 17.3 gof CuSO4.5H2O in 100ml 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 8g of benzidine hydrochloride (C12H8(NH2)2.2HCl) and 20ml of water, add 20ml of HCI (sp. gr. 1.12) and dilute to 1 liter with water. Eachml of this solution is equivalent to 0.00357g of H2SO4.
Bertrand's reagent (glucose estimation). Consists of the following solutions:
(a) Dissolve 200g of Rochelle salts and 150g of NaOH in sufficient water to make 1 liter of solution.
(b) Dissolve 40g of CuSO4 in enough water to make 1 liter of solution.
(c) Dissolve 50g of Fe2(SO4)3 and 200g of H2SO4 (sp. gr. 1.84) in sufficient water to make 1 liter of solution.
(d) Dissolve 5g of KMnO4 in sufficient water to make 1 liter of solution.
Blal's reagent (for pentose). Dissolve 1g of orcinol (CH3.C6H3(OH)2) in 500ml of 30% HCl to which 30 drops of a 10% solution of FeCl3 has been added.
Boutron-Boudet soap solution:
(a) Dissolve 100g of pure castile soap in about 2500ml of 56% ethyl alcohol.
(b) Dissolve 0.59g of Ba(NO3)2 in 1 liter of water. Adjust the castile soap solution so that 2.4ml of it will give a permanent lather with 40ml of solution (b). When adjusted 2.4ml of soap solution is equivalent to 220 parts per million of hardness (as CaCO3) for a 40ml 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 100g 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. Oneml is equivalent to 1 mg of CaCO3.
Titrate (a) against (b)and dilute (a) with 50% ethyl alcohol until 1ml of the resulting solution is equivalent to 1ml of (b) after making allowance for the lather factor (the amount of standard soap solution required to produce a permanent lather in 50ml of destilled water). Oneml 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 4g of K2Co(CN)5 and 1g of KClO3 in 100ml 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 1g of cochineal for four days with 20ml of alcohol and 60ml of distilled water. Filter.
Congo red. Dissolve 0.5g of congo red in 90ml of destilled water and 10ml of alcohol.
Cupferron (Baudisch 's reagent for iron analysis). Dissolve 6g of the ammonium salt of nitroso-phenyl-hydroxyl-amine (cupferron) in 100ml of H2O. Reagent good for one week only and must be kept in the dark.
Cupric acetate (Barfoed's reagent for reducing monosaccharides). Dissolve 66g of cupric acetate and 10ml of glacial acetic acid in water and dilute to 1 liter.
Cupric oxide, ammoniacal; Schweitzer's reagent (dissolves cotton, linen and silk, but not wool):
1. Dissolve 5g of cupric sulfate in 100ml 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 300ml of strong ammonium hydroxide containing 50g of fine copper turnings. Continue for one hour.
Cupric sulfate in glycerin-potassium hydroxide (reagent for silk). Dissolve 10g of cupric sulfate, CuSO4.5H2O, in 100ml of water and add 5g of glycerin. Add KOH solution slowly until a deep blue solution is obtained.
Cupron (benzoin oxime). Dissolve 5g in 100ml 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 340g of CuC12.2H2O in 600ml of conc. HCl and reduce the cupric chloride by adding 190ml of a saturated solution of stannous chloride or until the solution is colorless. The stannous chloride is prepared by treating 300g of metallic tin in a 500ml flask with conc. HCl until no more tin goes into solution.
3. (Winkler method). Add a mixture of 86g of CuO and 17g of finely divided metallic Cu, made by the reduction of CuO with hydrogen, to a solution of HCl, made by diluting 650ml of conc. HCl with 325ml 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 chloride, ammoniacal (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 800ml of acidic cuprous chloride, prepared by the Winkler method, into about 4 liters of water. Transfer the precipitate to a 250ml graduate. After several hours, siphon off the liquid above the 50ml mark and refill with 7.5% NH4OH solution which may be prepared by diluting 50ml of conc. NH4OH with 150ml 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 1g in 1 liter of 70% alcohol or 1g of the sodium salt in 1 liter of water.
Dimethylglyoxime (diacetyl dioxime), 0.01 N. Dissolve 0.6g of dimethylglyoxime, (CH3CNOH)2, in 500ml of 95 % ethyl alcohol. This is an especially sensitive test for nickel, a very definite crimson color being produced.
Diphenylamine (reagent for rayon). Dissolve 0.2g in 100ml of concentrated sulfuric acid.
Diphenylamine sulfonate (for titration of iron with K2Cr2O7). Dissolve 0.32g of the barium salt of diphenylamine sulfonic acid in 100ml of water, add 0.5g of sodium sulfate and filter off the precipitate of BaSO4.
Diphenylcarbazide. Dissolve 0.2g of diphenylcarbazide in 10ml of glacial acetic acid and dilute to 100ml with 95% ethy1 alcohol.
Esbach's reagent (estimation of protein). To a water solution of 10g of picric acid and 20g 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 34.66g of CuSO4 5H2O in water and dilute to 500 ml.
(b) Alkaline tartrate solution. Dissolve 173g of potassium sodium tartrate (Rochelle salts, KNaC4H4O6.4 H2O) and 50g 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 140g of ferric-ammonium sulfate crystals in 400ml of hot water. When cool, filter, and make up to a volume of 500ml with dilute (6 N) nitric acid.
Folin's mixture. (for uric acid). To 650ml of water add 500g of (NH4)2SO4, 5g of uranium acetate and 6g of glacial acetic acid. Dilute to 1 liter.
Formaldehyde-sulfuric acid (Marquis' reagent for alkaloids). Add 10ml of formaldehyde solution to 50ml of sulfuric acid.
Froehde's reagent. See Sulfomolybdic actid.
Fuchsin (reagent for linen). Dissolve 1g of fuchsin in 100ml of alcohol.
Fuchsin-sulfurous acid (Schiff's reagent for aldehydes). Dissolve 0.5g of fuchsin and 9g of sodium bisulfite in 500ml of water, and add 10ml 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 4g of phloroglucinol and 2g of vanillin in 100ml of absolute ethyl alcohol.
Hager's reagent. See Picric acid.
Hanus solution (for iodine number). Dissolve 13.2g 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 (3ml 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 50ml of water add 70g of I2 and 50g of KI. Dilute to 1 liter with alcohol.
Iodo-potasium iodide (Wagner's reagent for alkaloids). Dissolve 2g of iodine and 6g of KI in 100ml 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 55g of magnesium chloride and 105g 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 100g of UO2(C2H3O2)2.2H2O in 60ml of glacial acetic acid and dilute to 500 ml. Dissolve 330g of Mg(C2H3O2)2.4H2O in 60ml 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 1.358g of HgCl2 in 60ml of water and pour into a solution of 5g of KI in 10ml of H2O Add sufficient water to make 100 ml.
Methyl orange indicator. Dissolve 1g of methyl orange in 1 liter of water. Filter, if necessary.
Methyl orange, modified. Dissolve 2g of methyl orange and 2.8g of xylene cyanole FF in 1 liter of 50% alcohol.
Methyl red indicator. Dissolve 1g of methyl red in 600ml of alcohol and dilute with 400ml of water.
Methyl red, modified. Dissolve 0.50g of methyl red and 1.25g of xylene cyanole FF in 1 liter of 90% alcohol. Or, dissolve 1.25g of methyl red and 0.825g 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 1.4g of xyleno cyanole FF to 1g 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 a-Naphthol.
Nessler's reagent (for ammoniak). Dissolve 50g of KI in the smallest possible quantity of cold water (50 ml). Add a saturated solution of mercuric chloride (about 22g in 350ml of water will be needed) until an excess is indicated by the formation of a precipitate. Then add 200ml of 5N NaOH and dilute to 1 liter. Let settle, and draw off the clear liquid.
Nickel oxide, ammoniacal (reagent for silk). Dissolve 5g of nickel sulfate in 100ml of water, and add sodium hydroxide solution until nickel hydroxide is completely precipitated Wash the precipitate well and dissolve in 25ml of concentrated ammonium hydroxide and 25ml of water.
Nitron (detection of nitrate radical). Dissolve 10g of nitron (C20H16N4, 4,5-dihydro-l,4-diphenyl-3,5-phenylimino-1,2,4-triazole) in 5ml of glacial acetic acid and 95ml 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 20g of bismuth subnitrate and 40g of Rochelle salts in 1 liter of 8% NaOH solution. Cool and filter.
Obermayer's reagent (for indoxyl in urine). Dissolve 4g of FeCl3 in one liter of HCI (sp. gr. 1.19).
o-Tolidine solution (residual chlorine in water analysis). Prepare 1 liter of dilute HCl (100ml of HCl (sp. gr. 1.19) in sufficient water to make 1 liter). Dissolve 1g of o-tolidine in 100ml of the dilute HCl and dilute to 1 liter with dilute HCl solution.
Oxine. Dissolve 14g of HC9H6ON in 30ml of glacial acetic acid. Warm slightly, if necessary. Dilute to 1 liter.
Oxygen absorbent. Dissolve 300g 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 NH4CI-NH4OH solution and the gas passed through.
Pasteur's salt solution. To one liter of distilled water add 2.5g of potassium phosphate, 0.25g of calcium phosphates, 0.25g of magnesium sulfate and 12.00g of ammonium tartrate.
Pavy's solution (glucose reagent). To 120ml of Fehling's solution, add 300ml of NH4OH (sp. gr. 0.88) and dilute to 1 liter with water.
Phenanthroline ferrous ion indicator. Dissolve 1.485g of phenanthroline monohydrate in 100ml of 0.025 M ferrous sulfate solution.
Phenolphthalein. Dissolve 1g of phenolphthalein in 50ml of alcohol and add 50ml of water.
Phenolsulfonic acid (determination of nitrogen as nitrate). Dissolve 25gof phenol in 150ml of conc. H2SO4, add 75ml 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 150ml of conc. H2SO4 and 100ml of conc. H3PO4 (85%) with water to a volume of 1 liter.
Phosphotungstic acid (Scheibler 's reagent for alkaloids):
1. Dissolve 20g of sodium tungstate and 15g of sodium phosphate in 100ml 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 10g of sodium tungstate dissolved in 5g 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 1g of picric acid in 100ml of water.
Potassium antimonate (reagent for sodium). Boil 22g of potassium antimonate with 1 liter of water until nearly all of the salt has dissolved, cool quickly, and add 35ml of 10% potassium hydroxide. Filter after standing over night.
Potassium hydroxide (for CO2 absorption). Dissolve 360g of KOH in water and dilute to 1 liter.
Potassium iodide-mercuric iodide (Brucke's reagent for proteins). Dissolve 50g of KI in 500ml of water, and saturate with mercuric iodide (about 120 g). Dilute to I liter.
Potassium pyrogallate (for oxygen absorption). For mixtures of gases containing less than 28% oxygen, add 100ml of KOH solution (50g of KOH to 100ml of water) to 5g of pyrogallol. For mixtures containing more than 28% oxygen the KOH solution should contain 120g of KOH to 100ml of water.
Potassium-cadmium iodide (Marme's reagent for alkaloids). Add 2g of CdI2 to a boiling solution of 4g of KI in 12ml of water, and then mix with 12ml of saturated KI solution.
Pyrogallol, alkaline:
(a) Dissolve 75g of pyrogallic acid in 75ml of water.
(b) Dissolve 500g of KOH in 250ml of water. When cool, adjust until sp. gr. is 1.55.
For use, add 270ml of solution (b) to 30ml of solution (a).
Rosolic acid (indicator). Dissolve 1g of rosolic acid in 10ml of alcohol and add l00ml of water.
S and O reagent (Suitsu and Okuma 's test for Mg). Dissolve 0.5g of the dye (o, p-dihydroxy-monoazo-p-nitrobenzene) in 100ml of 0.25 NaOH.
Scheibler's reagent. See Phosphotungstic acid.
Schiff's reagent. See Fuchsin-sulfurous acid.
Schweitzer's reagent. See Cupric oxide, ammoniacal
Soap solution (reagent for hardness in water). issolve 100g 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 6.4ml produces a permanent lather with 20ml of standard calcium solution. The latter solution is made by dissolving 0.2g 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 330g of NaOH in water and dilute to 1 liter.
Sodium nitroprusside (reagent for hydrogen sulfide and wool). Use a freshly prepared solution of 1g of sodium nitroprusside in 10ml of water.
Sodium oxalate, Dissolve 30g 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 5g of sodium hydroxide in 100ml of water. Add 5g of litharge and boil until dissolved.
Sodium polysulfide. Dissolve 480g of Na2S.9H20 in 500ml of water, add 40g of NaOH and 18g of sulfur. Stir thoroughly and dilute to 1 liter with water.
Sonnenschein's reagent. See Phosphomolybdic acid.
Starch solution:
1. Make a paste with 2g of soluble starch and 0.01g 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 500ml of saturated NaCI solution (filtered), 80ml of glacial acetic acid, 20ml of water and 3g of starch. Bring slowly to a boil and boil for two minutes.
3. Make a paste with 1g of soluble starch and 5 mg of HgI2, using as little cold water as possible. Then pour about 200ml 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 30g of FeSO4 and 20g 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 0.5g of sulfanilic acid in a mixture of 15ml of glacial acetic acid and 135ml of recently boiled water.
Sulfomolybdic acid (Froehde 's reagent for alkaloids and glucosides). Dissolve 10g of molybdic acid or sodium molybdate in 100ml of conc. H2SO4
Tannic acid (reagent for albumen, alkaloids and gelatin). Dissolve 10g of tannic acid in 10ml of alcohol and dilute with water to 100ml.
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 25g of citric acid and 1g of salicylic acid in water and dilute to 1 liter. Use 50ml of the reagent.
Wij's iodine monochloride solution (for iodine number). Dissolve 13g of resublimed iodine in 1 liter of glacial acetic acid which will pass the dichromate test for reducible matter. Set aside 25ml 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 200ml of glacial acetic acid that will pass the dichromate test for reducible matter, add 12g of dichloroamine T (paratoluene-sulfonedichloroamide), and 16.6g 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 70g of MnSO4.4H2O in 500ml of water, add 125ml of oonc.H2SO4 and 125ml of 85% H3PO4, and dilute to 1 liter.
Zinc chloride solution, basic (reagent for silk). Dissolve 1000g of zinc chloride in 850ml of water, and add 40g of zinc oxide. Heat until solution is complete.
Zinc uranyl acetate (reagent for sodium). Dissolve 10 of UO2(C2H3O2)2.2H2O in 6g of 30 % acetic acid with heat, if necessary, and dilute to 50 ml. Dissolve 30g of Zn(C2H3O2)2.2H2O in 3g 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.



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