124 COMPOSITION OF FIBRINE, &c. 



boiling of flesh, for the purpose of making soup, sul- 

 phuretted hydrogen, as Chevreul has shewn, is dis- 

 engaged. 



Moreover, the proportion of sulphur, for the same 

 amount of phosphorus, is not the same in fibrine 

 and albumen, from which no other conclusion can 

 be drawn, but that the formation of sulphuret of 

 potassium has no relation to the presence of phos- 

 phorus. Sulphuret of potassium is formed from 

 caseine, which is not supposed to contain any un- 

 combined phosphorus; and it is formed, also, from 

 albumen, which contains only half as much phos- 

 phorus as fibrine. 



Every attempt to give the true absolute amount 

 of the atoms in fibrine and albumen in a rational 

 formula, in which the sulphur and phosphorus are 

 taken, not in fractions, but in entire equivalents, 

 must be fruitless, because we are absolutely unable 

 to determine with perfect accuracy the exceedingly 

 minute quantities of sulphur and phosphorus in 

 such compounds ; and because a variation in the 

 sulphur or phosphorus, smaller in extent than 

 the usual limit of errors of observation, will affect 

 the number of atoms of carbon, hydrogen, or oxy- 

 gen to the extent of 10 atoms or more. 



We must be careful not to deceive ourselves in 

 our expectations of what chemical analysis can do. 

 We know, with certainty, that the numbers repre- 

 senting the relative proportions of the organic ele- 

 ments are the same in albumen and fibrine, and 



