142 THE SECRETIONS: 



would obviously require an immense sacrifice of time and labour 

 to institute a series of urinary analyses upon the plan that we 

 have already laid down ; our trouble will be much diminished 

 by agreeing which of the constituents are to be considered as the 

 most important, and devoting our attention to them alone. 

 We do not by any means wish to imply that elaborate analyses, 

 made on the system we have described, are not more valuable 

 than those conducted according to a simpler scheme ; we only 

 wish it to be understood that a shorter method will give results 

 that will fully answer many of our proposed ends. 



A shorter method may be properly limited to the determina- 

 tion of the solid constituents of the urine, the quantities of urea 

 and uric acid, of the fixed salts collectively, and, from them, 

 of the earthy phosphates and alkaline sulphates and phosphates 

 individually, and ultimately of the remaining constituents, as 

 lactic acid, extractive matters, and the compounds of chlorine 

 and ammonia. 



With this view we determine 



a. The specific gravity of the urine in the ordinary manner ; 



b. The quantity of solid constituents, and of the urea, ac- 

 cording to the method described in 2 and 3, from a weighed 

 and evaporated portion of urine ; 



c. The quantity of uric acid, according to the method given 

 in (4), by the addition of hydrochloric acid to a certain quantity 

 of urine ; 



d. The quantity of extractive matters and ammonia-salts, by 

 evaporating a known quantity of urine and incinerating the 

 residue. The amount of solid residue being known from 6, 

 we subtract from it the fixed salts which have been thus ob- 

 tained as a residue after incineration, the urea (b), and uric 

 acid (c) ; the difference corresponds with the extractive matters 

 and ammonia-salts; 1 



e. The fixed salts are known by the weight of the residue 

 in d ; they may be easily burnt white by the addition of a little 

 nitric acid. From these salts we can determine, 



/. The amount of earthy phosphates, and alkaline phosphates 

 and sulphates, by the method described in 7. 



1 This estimate must be always rather too high, in consequence of the alkaline 

 lactates being converted into carbonates in the process of incineration. 



