222 * 8 li; 



FJHUTILlZEItS. 



Hippuric acid appears then in the form of liandsome 

 crystals. If the crystals are not colorless, or they are not 

 readily formed, dilute the residue, left by the evaporation 

 of the ether, with water, boil the mixture with lime-wa- 

 ter, filter, concentrate the colorless filtrate, and i:)recipitate 

 the hippuric acid by hydrochloric acid in excess. 



i. PhospllOric acid. — 1. This may be determmed di- 

 rectly in the urine, with the standard uranic solution. 

 Filter the urine, if necessary, add 5 c.c. of sodic acetate 

 to 50 c.c. of the filtrate, and titrate the mixture witli 

 nranic acetate as usual (§ Gl, e). 



2. To obtain a more accurate determination, add the 

 magnesia mixture to 50 c.c. of the clear urine, collect and 

 wash the precipitate in the usual manner, dissolve it, with- 

 out drying, in acetic acid in not too great excess, di- 

 lute the solution to 50 c.c. with water, add 5 c.c. of the 

 solution of sodic acetate, and titrate as before, with the 

 uranic solution (§ 01, c). 



3. To determine the phosphoric acid that is combined 

 with alkaline earths only, to 100-200 c.c. of the urine, ac- 

 cording to its strength, add ammonia until alkaline reac- 

 tion ensues, let the mixture stand 12 hours, and collect 

 and treat the precipitate in the mann-or described in 2. 

 In another precisely equal quantity of urine, the precipi- 

 tate by ammonia is ignited and weighed ; the amount of 

 magnesic pyrophosphate in this mixture may be estimated 

 by multiplying the amount of phosphoric acid in it, as de- 

 termined above, by 2.1831, subtracting the sum of the 

 phosphates from this product, and multiplying the re- 

 mainder by 2.5227. If it is desired to determine lime and 

 magnesia directly, dissolve the mixture of the phosphates, 

 obtained above by precipitation with ammonia, without 

 drying it, in as small a quantity of acetic acid ns possible, 

 precipitate the lime by ammonic oxalate, and the mag- 

 nesia as phosphate again by excess of ammonia. 



