Mr. G. S. Johnson. 



Comparison between Sarcous and Urinary Tabular Kreatinins. 



Besides the differences apparent in the above table, it will be 

 remembered that sarcous kreatinin appears in the efflorescent form 

 only after its solution has been kept at 60 C. for some time ; whereas 

 the natural kreatinin of urine, when prepared most carefully without 

 heat, is always efflorescent (C4H7N 3 0.2H 2 0). 



Also the tabular crystals formed by sarcous kreatinin are not so 

 large as those formed by the tabular kreatinin of urine. 



Having thus isolated and examined a sarcous kreatinia by the 

 mercuric chloride method, my attention was turned in the next place 

 to the examination of the filtered solutions from which the spherical 

 mercury salts of the sarcous kreatinin had been separated. These 

 filtrates were three in number, viz., from portions A, B, and C. In 

 each case, the filtrate was allowed to stand for at least a week, in 

 order to ensure that it remained perfectly clear. This having been 

 ascertained, my next endeavour was to separate the mercuric chloride 

 from the solutions, if possible, without adding any reagent to them 

 which would be likely to alter the orgauic constituents during subse- 

 quent evaporation. 



Finally, I effected this separation by means of pure lead hydrate, 

 Pb(HO) 2 . When lead hydrate is added in excess to solution of 

 mercuric chloride, a yellow substance remains undissolved, and, on 

 filtering after a short time, the filtrate is found to be pure water, all 

 traces of lead, mercury, and chlorine remaining in the undissolved 

 matter. Here, then, was a method which removed the HgCl 2 with- 



