6O2 PHYSIOLOGICAL CHEMISTRY 



be prepared in the form of two separate solutions which may be united 

 as needed. 



(a) Dissolve 125 grams of sodium bromide in water, add 125 grams 

 of bromine and make the total volume of the solution i liter. 



(b) A solution of sodium hydroxide having a specific gravity of 

 1.25. This is approximately a 22.5 per cent solution. 



Preserve both solutions in rubber-stoppered bottles and when needed 

 for use mix i volume of solution (a), i volume of solution (&), and 3 

 volumes of water. 



Iodine Solution (N/io). 1 Weigh out 12.685 grams of pure resub- 

 limed iodine into a small weighing bottle using a porcelain spatula. 

 Dissolve 1 8 grams of pure KI in about 150 c.c. of water. Transfer the 

 iodine to a liter flask washing out the last traces with some of the KI 

 solution, which is then poured into the flask. Stopper and shake 

 occasionally until dissolved. If necessary a few more crystals of KI 

 may be added to aid solution. Dilute to the mark and mix well. 

 Keep in glass-stoppered bottle in cool dark place. Standardize at once 

 against N/io sodium thoisulphate solution. Measure out accurately 

 25 c.c. of the iodine solution into an Erlenmeyer flask, run in sodium 

 thiosulphate until the color is pale yellow, then add a few cubic centi- 

 meters of a i per cent solution of starch (preferably soluble starch) 

 and titrate to disappearance of blue color. Care should be taken near 

 the end point. 



Iodine Solution. 2 Prepare a 2 per cent solution of potassium iodide 

 and add sufficient iodine to color it a deep yellow. 



Iodine-Zinc Chloride Reagent. 3 Dissolve 20 grams of zinc chloride 

 in 8.5 c.c. of water. Cool, and introduce iodine solution (3 grams Kl-f- 

 1.5 gram I in 60 c.c. of water) drop by drop until iodine begins to pre- 

 cipitate. 



Kraut's Reagent. 4 Dissolve 272 grams of potassium iodide in 

 water and add 80 grams of bismuth subnitrate dissolved in 200 grams 

 of nitric acid (sp. gr. 1.18). Permit the potassium nitrate to crystallize 

 out, then filter it off and make the filtrate up to i liter with water. 



Lead Acetate, Basic. (See Basic Lead Acetate.) 



LugoFs Solution. 5 Dissolve 4 grams of iodine and 6 grams of potas- 

 sium iodide in 100 c.c. of distilled water. 



Magnesia Mixture. 6 Dissolve 175 grams of magnesium sulphate 

 and 350 grams of ammonium chloride in 1400 c.c. of distilled water. 



1 Determination of acetone and acetoacetic acid, p. 5 33. 

 z Iodine test, p. 45. 



3 Amyloid^ formation, p. 49. 



4 Rosenheim's bismuth test for choline, p. 357. 



6 Gunning's iodoform test, page 436, and Bardach's reaction, p. 101. 

 6 Method for determination of total phosphorus, p. 554. 



