470 Prof. Liebig on the Constitution of 



trary, that the urine of man, according to the most correct 

 analyses, contains afar larger proportion of sulphates than the 

 aliments partaken of; nay, even that] the amount of the sul- 

 phuric acid received into the system must, in many cases, be 

 equal or superior to that of the phosphoric acid contained in 

 the aliments. According to the analysis of human urine made 

 by Berzelius and Lehmann, the amount of the sulphates pre- 

 sent in urine is nearly double that of all the soluble phosphates 

 together. 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 con- 

 tained in the urine ; this acid has entered the organism with 

 the food, not in the form of a sulphate, but as sulphur. 



Gluten*, vegetable casein, flesh, albumen, fibrine, and the 

 cartilages and bones, contain sulphur in a form quite different 

 from the oxygen compounds of this substance. This sulphur 

 is separated as sulphuretted hydrogen during the putrefaction 

 of these substances; it combines with the alkalies, operating 

 upon these animal substances, and may be obtained from such 

 combinations in the form of sulphuretted hydrogen by means 

 of stronger acids. 



Now we know, from the experiments of Wohler, that the 

 soluble sulphurets become oxidized in the organism ; and that 

 thus, for instance, sulphuret of potassium becomes converted 

 into sulphate of potash; and it is therefore unquestionable that 

 the sulphur of the constituents of the blood, derived from the 

 aliments, or, what comes to the same point, the sulphur of 

 the transformed tissues, becomes finally converted into sul- 

 phuric acid by the oxygen absorbed in the process of respira- 

 tion, and thus that in the urine it must appear in the form of 

 sulphates ; and from this cause the original amount of these 

 salts contained in the aliments becomes increased. The al- 

 kaline base which we find in the urine, in combination with 

 this sulphuric acid, is supplied by the soluble alkaline phos- 

 phates ; and the latter, in consequence of the loss of part of 

 this base, are converted into acid salts. 



By these considerations and views respecting the cause of 

 the acid reaction of urine, I have been induced to prepare 



* Dietrich has examined gluten (in the hiboratory of Giessen) with re- 

 gard to its amount of sulphur ; he found wheat-gluten to contain from 

 0'033 per cent, to 0035 per cent, of sulphur, exactly the same proportion 

 as is contained in albumen or fibrine. 



