REAGENTS AND SOLUTIONS 643 



Silver Nitrate Solution. 1 Dissolve 29.042 grams of silver nitrate in 

 i liter of distilled water. Each cubic centimeter of this solution is 

 equivalent to o.oi gram of sodium chloride or to 0.006 gram of 

 chlorine. 



Sodium Acetate Solution. 2 Dissolve 100 grams of sodium acetate 

 in 800 c.c. of distilled water, add 100 c.c. of 30 per cent acetic acid 

 to the solution, and make the volume of the mixture up to i liter with 

 distilled water. 



Sodium Alcoholate (N/io) Solution. 3 The sodium alcoholate is 

 made by dissolving 2.3 grams of cleaned metallic sodium in i liter of 

 absolute alcohol. It is advisable that it be slightly weaker than stronger 

 than tenth-normal. It may be standardized against pure benzoic acid 

 in washed chloroform. It may also be standardized against N/io HC1 

 provided the alcoholate solution contains not more than traces of 

 carbonate. 



Sodium Alizarin Sulphonate. 4 Dissolve- 1 gram of sodium alizarin 

 sulphonate in 100 c.c. of water. 



Sodium Hydroxide Saturated Solution. 5 Shake up about 120 gm. 

 of best quality NaOH with 100 c.c. of distilled water in a 300 c.c. 

 Erlenmeyer flask (Pyrex). Stopper and allow to stand for a couple of 

 days or until the sodium carbonate settles to the bottom leaving a 

 clear solution of NaOH practically free from carbonate, and containing 

 about 55 gm. NaOH per 100 c.c. 



Sodium Sulphide Solution. 6 Saturate a i per cent solution of 

 sodium hydroxide with hydrogen sulphide gas and add an equal volume 

 of i per cent sodium hydroxide. 



Sodium Thiosulphate Standard (N/io) Solution. 7 Weigh out 25 

 grams of ordinary c.p. sodium thiosulphate or 24.83 grams of the pure 

 dry recrystallized salt. Dissolve in water and dilute to a liter. Boiled 

 distilled water must be used. Keep in a bottle with a siphon arrange- 

 ment and carrying a soda lime tube to exclude C02. 



It is best standardized against acid potassium iodate KH(IOs)2. 

 Weigh out accurately 0.3249 gram of acid potassium iodate. Dissolve 

 in 50 c.c. of water, heating gently if necessary. Transfer the solution to 

 a 100 c.c. flask, rinsing the beaker carefully and make to mark with 

 water. This solution is exactly decinormal. Pipette out 25 c.c. into an 



1 Volhard-Arnold method, p. 572. 



1 Uranium acetate method, p. 568 



1 Determination of hippuric acid, p. 537. 



4 Topfer's method, p. 177. 



'Preparation of standard alkali and Nessler's solution pp. 497, 508. 



' Kriiger and Schmidt's method, p. 533. 



7 Determination of acetone, p. 557. 



