1867.] 



Extractive Matters of SJrine. — Part I. 



91 



bodies of a definite character, or wliether they are merely accideBtal mix- 

 tures of Tarious excrementitioiis substances thrown out by the system, and 

 differing in their nature according to circumstances. In the former case a 

 farther exploration of this field would be justified by the probability of 

 arriving at definite results. In the latter case, however, the investigation 

 would certainly have to be abandoned at once, from the want of a secure 

 basis on which to found further research. 



In order to arrive at a positive conclusion on this point, the readiest 

 means was, as it seemed to me, to ascertain the exact composition of the 

 extractive matters obtained at different times from various sources ; for, 

 being neutral uncrystallizable bodies, it was evident that a mere examination 

 of their chemical and physical properties would lead to no certain result. 

 This portion of the investigation has occupied me for some time, commen- 

 cing in the year 1856, and will form the subject of the present communica- 

 tion. The successive series of experiments which were made will be 

 distinguished by letters with the respective dates attached. 



A (1856). 



In this, as well as in the subsequent series of experiments, I made use of 

 neutral and basic acetate of lead for the purpose of separating the extractive 

 matters from the other constituents of urine, the same means having pre- 

 viously been employed with this view by Scherer. Having taken a quantity 

 of ordinary urine, I added to it a solution of acetate of lead, which produced 

 a copious precipitate, consisting of sulphate, phosphate, chloride, and urate 

 of lead, together with lead compounds of extractive matter. This precipi- 

 tate was filtered off and thrown away. In the filtered liquid, which was 

 lighter in colour than the original urine, basic acetate of lead produced a 

 second precipitate as abundant as the first, and consisting principally of 

 lead compounds of the extractive matters mixed with basic chloride of lead. 

 This precipitate, after being well washed with water, was treated with an 

 excess of cold dilute sulphuric acid, with which it was allowed to remain in 

 contact for some time. The extractive matter set at liberty by the acid 

 communicated to the liquid a brown colour, a peculiar urinous odour being 

 at the same time evolved. The excess of acid was removed by adding car- 

 bonate of lead, and stirring the mixture well in a, mortar. After all 

 effervescence had ceased, the liquid, which was now of a fine yellov/ colour 

 like urine itself, was filtered and evaporated ; but in order to avoid any 

 decomposition which might have been caused by the application of artificial 

 heat, the evaporation was conducted at the ordinary temperature by means 

 of a current of air in the apparatus formerly emiployed in the preparation 

 of indican zifter evaporation there was left a thick brown syrup, which 

 was poured into a flask and treated with cold alcohol, with which, after 

 being well shaken, it was left to stand for some time. The alcohol left a 

 portion of this syrup undissolved as a brovvu glutinous mass {a). The 

 liquid, which had a deep yellow colour, was poured off, and there was added 

 to it an alcoholic solution of acetate of lead, which produced a cream- 

 ^ See Memoirs of the Majicliester Literary and Philosophical Society, vol. xiv. p. 183. 



H 2 



