URINE. 459 



CHAPTER XII. 



OF URINE. 



No animal "substance has attracted more attention than urine, 

 both on account of its connection with various diseases, and of 

 the remarkable products that have been obtained from it. Mr 

 Boyle made several attempts to determine the nature of the salts 

 which it contained ;* though, from the imperfect state of che- 

 mistry in his time, it was not possible that he could have succeed- 

 ed. The discovery of phosphorus from urine by Brandt, in 1669, 

 naturally drew the attention of chemists to that liquid. Boyle 

 discovered the process of Brandt, and taught his operator, God- 

 frey Hankwitz, the method of extracting it from that liquid ; and 

 it is well known, that for many years Hankwitz was the person 

 who supplied all the chemists in Europe with this curious sub- 

 stance. 



The putrefaction of urine and the great quantity of ammonia 

 which it yields when distilled, must have been observed at a very 

 early period, and accordingly we find the facts connected with 

 these processes described by the earliest chemists who turned 

 their attention to urine*. Lemeri, for example, whose system of 

 chemistry was published in the latter part of the seventeenth cen- 

 tury, has a whole chapter on the subject. Margraaf improved 

 the process of extracting phosphorus from urine in the year 1743, 

 and in 1746 he extracted ammonia-phosphate of soda or micro- 

 cosmic salt from urine, and described its properties.! 



But the first person who threw any great light upon the con- 

 stituents of urine was Rouelle Junior. In his researches on 

 urine, published in the Journal de Medecine for 1773 and 1777, 

 he describes the properties of urea, which he extracted from urine 

 by means of alcohol, and obtained in the state of crystals. To 

 this substance he gave the name of soapy matter. Rouelle point- 

 ed out, likewise, some of the salts of urine, though not so suc- 

 cessfully. In 1776, Scheele discovered uric acid in urine, and 

 showed that it constituted one of the most common of the sub- 



* Shaw's Boyle, iii. 316, 376, 377. 



t Opuscules Chimiques de Margraaf, i. 30, 123. 



