URINE. 141 



ficient potash to combine with the sulphuric acid, the excess is 

 united with hydrochloric acid. 



If the urine-salts froth very much upon being treated with 

 an acid, and if we find that after combining the potash and 

 soda with sulphuric, hydrochloric, and phosphoric acids some 

 soda is still left, this must be reckoned as lactate of soda. The 

 earths occur as earthy phosphates. 



The fixed salts may likewise be determined from the residue 

 obtained in the investigation of the water- and spirit- extracts, 

 (see 5,) by exposing it to a strong heat ; and we are sometimes 

 driven to this course of proceeding in consequence of having 

 only a small quantity of urine to analyse. This method of de- 

 termining the salts is, however, unsafe, in consequence of a por- 

 tion of the lactate of soda being dissolved by the anhydrous 

 alcohol, and because, farther, small quantities of the phosphates 

 and sulphates are always associated with the chlorine-com- 

 pounds. In adopting this method, we must determine the 

 earthy phosphates and the alkaline sulphates and phosphates, 

 from the water-extract ; and the chlorine, with minute quanti- 

 ties of the sulphates and phosphates, from the saline residue of 

 the spirit-extract. 



In the determination of the urinary salts from the fixed 

 residue, it becomes a matter of importance to ascertain whether 

 the organic constituents do not contain a certain amount of 

 sulphur and phosphorus, which increase the quantity of the 

 sulphates and phosphates found after incineration. From an 

 experiment, I am led to conclude that this is not the case. I 

 determined the earthy phosphates, and the alkaline sulphates 

 and phosphates, in three ounces of filtered healthy urine, and 

 found earthy phosphates, 0-5 ; sulphate of potash, 2*45 ; phos- 

 phate of soda, 1-16. From the fixed salts of three ounces of 

 the same urine I obtained, earthy phosphates, 0*52 ; sulphate 

 of potash, 2*48; and phosphate of soda, 1-16. 



A shorter method of separating the most important constituents 



of the urine. 



Isolated and unconnected analyses of urine are of very little 

 value in physiological and pathological chemistry. In propor- 

 tion to the number of analyses made according to one uniform 

 method, is the value of each individual analysis increased. It 



