1889.] 



The Chemistry of the Urine of the Horse. 



335 



a capsule, dried at a low temperature, and carefully volatilised, when 

 beautiful white sparkling crystals form, which are carefully removed, 

 collected, and weighed ; or the impure mass may be dissolved in ether, 

 the solution evaporated, and then volatilised. This volatilisation 

 requires great care to avoid loss. 



I have tried many methods of obtaining these acids, but none give 

 such satisfactory results as the above. 



The examination of the twenty-four hours' urine of fifty-four horses 

 revealed the presence of hippuric acid on only eight occasions. 



The number of horses at work was seventeen, and out of these I 

 found hippuric acid twice, 2*144 grams and 18"6 grams respectively. 

 The number of horses standing idle was thirty-seven ; of this number 

 I found hippuric acid six times ; two of these observations I must 

 deduct, as the horses were not in perfect health, leaving four out of 

 thirty-five as the proportion in which hippuric acid was detected. 



In a second series of observations consisting of thirty horses, the 

 urine from which was collected and at once submitted to analysis, I 

 found that out of eighteen working horses thirteen had hippuric acid 

 in the urine and five had none. Out of twelve horses at rest three had 

 hippuric acid and nine had none. The diet in all cases was the same. 

 This would appear to reverse Liebig's theory. 



My observations show that hippuric acid is generally found in the 

 urine of working horses — seldom found in the urine of resting horses, 

 and that it is rarely found in urine twenty-four hours old. 



Diet influences the production of hippuric acid, and it is increased 

 by using meadow -hay and oat- straw, and decreased by using clover, 

 peas, wheat, oats, &c. ; as the urea rises the hippuric acid falls, and 

 vice versa. (Tereg,* Weiske and Kellner.f ) 



The mean hippuric acid found was 15"58 grams, the maximum 

 28'56, and the minimum 9"18 grams in twenty-four hours. 



Salkowski places the hippuric acid at 15*597 grams daily. 



Benzoic Acid. — Benzoic acid is generally found in stale urine, and 

 in the urine of horses which are doing no work, It may, however, 

 be found in working horses, or a urine may possess neither hippuric 

 or benzoic acids. 



The mean benzoic acid found in resting horses was 6*53 grams, 

 in those at work 3' 62 grams in twenty-four hours. 



Total Nitrogen. — In my earlier observations I believed that the 

 nitrogen of work was greater than the nitrogen of rest. 



I have explained under urea how I fell into the error, and I have 

 there fully detailed the nitrogen during rest and work in a series 

 of experiments on a pony. The nitrogen is as variable as the urea ; in 

 my earlier series it varied for horses between 46 and 70 grams per diem. 

 * ' Encyklopadie, 5 &c. 



f "Watts' 'Dictionary of Chemistry,' vol. 8, Part II. 

 VOL. XL VI, 2 A 



