ALL THE ELEMENTS OF THE BLOOD. 127 



pirical expression of its composition ; and has furnished 

 the key to its metamorphosis, under the influence of 

 acids and alkalies, which had previously been sought for 

 in vain. 



23. When fresh drawn blood is made to trickle over 

 a plate of silver, heated to 140, it dries to a red, 

 varnish-like matter, easily reduced to powder. Muscu- 

 lar flesh, free from fat, if dried first in a gentle heat, 

 and then at 212, yields a brown, pulverizable mass. 



The analyses of PLAYFAIR and BOECKMANN (se) 

 give for flesh (fibrine, albumen, cellular tissue, and 

 nerves) and for blood, as the most exact expression of 

 their numerical results, one and the same formula, 

 namely, C 48 N 6 H 39 O 16 . This may be called the empir- 

 ical formula of blood. 



24. The chief constituent of bile, according to the 

 researches of DEMARCAY, is a compound, analogous 

 to soaps, of soda with a peculiar substance, which has 

 been named choleic acid. This acid is obtained in 

 combination with oxide of lead, when bile, purified by 

 means of alcohol from all matters insoluble in that men- 

 struum, is mixed with acetate of lead. 



Choleic acid is resolved, by the action of muriatic 

 acid, into ammonia, taurine, and a new acid, choloidic 

 acid, which contains no nitrogen. 



When boiled with caustic potash, choleic acid is re- 

 solved into carbonic acid, ammonia, and another new 

 acid, cholic acid (distinct from the cholic acid of 

 Gmelin). 



Now it is clear, that the true formula of choleic acid 



