152 THE SECRETIONS: 



the urine all the soluble salts of the food, as well as a small 

 amount of the phosphate of lime, which is soluble to a certain 

 extent in acid fluids, together with magnesia. The amount of 

 these latter substances will be in proportion to their solubility 

 in acid phosphate of soda. The other insoluble salts of the ali- 

 ments we ought to find in the faeces. In other words, assuming 

 that the materials composing the aliments become converted 

 into oxygen compounds, that is, are burnt in the organism, we 

 ought to find in the urine, all the soluble salts of their ashes, 

 and in the fseces, all the insoluble salts. Now, upon comparing 

 the constitution of the ashes of the blood or of the aliments, 

 (or, rather, the salts contained therein,) with those of the urine, 

 we find that there exists a striking difference between their re- 

 spective amount of sulphates. 



t( According to the analyses of the ashes of the grains of 

 wheat and rye (Ann. der Chemie, vol. 46, p. 79), the urine of 

 an individual feeding exclusively upon bread, ought not to con- 

 tain a trace of a sulphate, whilst the urine of an animal fed 

 upon peas or beans ought to contain sulphates together with 

 phosphates in the proportion of 9 of the former to 60 of the 

 latter. Finally, as flesh contains no soluble alkaline sulphate 

 (broth does not yield any precipitate of sulphate of baryta when 

 tested with salts of baryta), the urine of carnivorous animals 

 ought to be equally free from soluble sulphates. We find, on 

 the contrary, that the urine of man, according to the most 

 correct analyses, contains a far larger proportion of sulphates 

 than the aliments partaken of; nay, even that the amount of 

 the sulphuric acid evolved from the system must, in many cases, 

 be equal or superior to that of the phosphoric acid contained in 

 the aliments. According to the analyses of human urine made 

 by Berzelius and Lehmann, the amount of the sulphates present 

 in urine is nearly double that of all the soluble phosphates to- 

 gether. Hieronymi found the amount of sulphate of potash 

 contained in the urine of the tiger, the lion, and the leopard, 

 compared with that of the phosphates, to be as 1 to 7|. It can 

 be distinctly and positively proved that these salts have not been 

 partaken of in such proportions. But we now know the origin 

 of the greatest portion of the sulphuric acid contained in the 

 urine ; this acid has entered the organism with the food, not 

 in the form of a sulphate, but as sulphur. 



