57 



Example : 



Quantity of urine in 24 hours, 1250 cc. 



Silver solution used, - 7.5 cc. 



1 cc. silver solution equals .01 gram NaCl 



.01 X 7.5 



X 1250 = 9.375 grams. 



10 



Make two or three determinations and take the aver- 

 age for your final result. Do the same in the phosphate 

 and sulphate tests. 



If the urine of the horse is very dark colored, it may 

 be filtered through animal charcoal to make it light 

 colored. Some of the chlorides may be held by the char- 

 coal and thus diminish the amount in the urine tested; 

 or the urine may be diluted with an equal volume of dis- 

 tilled water and the result multiplied by two. 



Gravimetric MetJiod. 



A more accurate method is the following: If the urine 

 is high colored, and contains albumin, or excess of uric acid and 

 mucus, they must be removed. To do this, measure 10 cc. of the 

 urine into a platinum capsule, add 2 grams of pure potassium 

 nitrate, evaporate to dryness, and ignite at a dull red heat to 

 destroy organic matter. When cool, treat the residue with hot 

 water and filter. Acidulate the filtrate with dilute nitric acid, 

 neutralize with carbonate of lime and proceed as above. 



Estimation of Phosphoric Acid. (Estimated as PoOg). By 

 uranium acetate or nitrate. This method is based upon the fact 

 that when a solution of acetate or nitrate of uranium is added to 

 a solution containing soluble phosphates, sodic acetate and free 

 acetic acid, all the phosphoric acid will be precipitated as phos- 

 phate of uranium. This precipitate is of a light yellow color, 

 insoluble in acetic, but soluble in hydrochloric acid. The point 

 of completion of the phosphoric reaction may be ascertained by 

 placing with a glass rod a drop of the yellow mixture in contact 

 with a drop of potassium ferrocyanide solution upon a white 

 plate or filter paper. As soon as there is the slightest excess of 

 the uranium solution after the phosphates have been satisfied, a 

 brown precipitate will result in the mixture due to formation of 

 ferrocyanide of uranium. The cochineal solution, noted below, 

 serves as a better indicator for the horse urine than the ferro- 

 cyanide. The following solutions are used : 



