636 PHYSIOLOGICAL CHEMISTRY 



(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 Solutions (N/io). 1 Weigh out 12.685 grams of pureresub- 

 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 thiosulphate 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 KI+ 

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

 precipitate. 



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.) 



Litmus-Milk Powder. 5 Add i part of powdered litmus to 50 

 parts of dried milk powder. To make a litmus milk solution add 

 i part of this powder to 9 parts of water. 



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

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



1 Determination of acetone, p. 557. 

 * Iodine test, p. 43. 



3 Amyloid formation, p. 48. 



4 Rosenheim's bismuth test for choline, p. 375. 

 6 Test for Lipase, p. 197. 



6 Gunning's iodoform test, p. 451. 



