CREAT1NE AND CREATININE IN THE URINE. 261 



urine of the cow, which, according to Boussingault, contains to 

 the extent of about 1.30 per cent. Hippuric acid is also con- 

 tained in the urine of the horse, at least when the animal is kept 

 at rest ; but if he be made to work actively, the greater part of 

 the hippuric acid disappears, and benzoic acid is found in its 

 stead. Hippuric acid, when pure, crystallises in long trans- 

 parent four-sided prisms, and has a strong acid reaction, with 

 a bitterish taste ; it is much more soluble in cold water than 

 uric acid, and it is freely soluble in hot water. When dis- 

 solved in a liquid containing putrescent albuminous com- 

 pounds, hippuric acid is converted into benzoic acid, ammonia 

 being at the same time given off. 



In the fluid of the allantois of the foetal calf (and probably 

 also of other animals), which may be regarded as a temporary 

 urinary bladder receiving the product of the corpora Wolffiana, 

 or temporary kidneys, a substance termed allantoine is found, 

 which may be artificially formed from uric acid by boiling it with 

 peroxide of lead. It is a neutral substance, in brilliant prismatic 

 crystals, free from taste, somewhat soluble in cold water. Al- 

 lantoine is decomposed by strong acids; being resolved into am- 

 monia, carbonic acid, and carbonic oxide; and when decomposed 

 by alkalies, being resolved into ammonia and oxalic acid. 



Creatine and creatinine are two new substances which have 

 been discovered in the urine of man and the mammalia ; they 

 seem to be intermediate in character between the albuminous 

 compounds and the compounds characteristic of the urine. 

 Creatine, which exists in the juice of raw flesh, is neutral, 

 colourless, crystalline, sparingly soluble in cold water, freely 

 soluble in hot water. By strong acids creatine is converted 

 into creatinine, which differs in composition by containing 

 two proportionals less of the elements of water, yet is of an 

 opposite chemical character, being possessed of a strong alka- 

 line reaction, and serving as a powerful organic base to acids. 



