44 



ANIMAL CHEMISTRY. 



rately, to the most correct empirical expres- 

 sion of its composition; and has furnished 

 the key to its metamorphoses, under the in- 

 fluence of acids and alkalies, which had pre- 

 viously been sought for in vain. 



24. 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. Muscular flesh, free from 

 fat, if dried first in a gentle heat, and then 

 at 212, yields a brown, pulverizable mass. 



The analyses of Play fair and Boeck- 

 mann (28) 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, 

 CWEPO 15 . This may be called the em- 

 pirical formula of blood. 



25. The chief constituent of bile, accord- 

 ing to the researches of Dema^ay, is a 

 compound, analogous to soaps, of soia with 

 a peculiar substance, which has been named 

 choleic acid. This acid is obtained in com- 

 bination with oxide of lead, when bile, puri- 

 fied by means of alcohol from all matters 

 insoluble in that menstruum, 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 resolved 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 must include the analytical ex- 

 pression of these modes of decomposition ; 

 in other words, that it must enable us to 

 show that the composition of the products 

 derived from it is related in a clear and 

 simple manner, to the composition of the 

 acid itself. This is the only satisfactory test 

 of a formula ; and the analytical expression 

 thus obtained loses nothing of its truth or 

 value, if it should appear, as the researches 

 of Berzelius seem to show, that choleic 

 and choloidic acids are mixtures of different 

 compounds ; for the relative proportions of 

 the elements cannot in any way be altered 

 by this circumstance. 



26. In order to develope the metamor- 

 phoses wnich choleic acid suffers under the 

 influence of acids and alkalies, the following 

 formula alone can be adopted as the empiri- 

 cal expression of the results of its analysis, 

 Formula of choleic acid: CTN^HTO 22 . (29) 



I repeat, that this formula may express 

 the composition of one, or of two or more 

 compounds ; no matter of how many com- 

 pounds the so-called choleic a^id may be 

 made up, the above formula represents the 

 relative proportions of all their elements 

 taken together. 



If now we subtract from the elements of 

 choleic acid, the products formed by the 

 action of muriatic acid, namely, ammonia 

 and taurine, we obtain the empirical formula 

 of choloidic acid. Thus from the 



Formula of choleic acid 



Substract 



1 at. taurine C 4 NH 7 O 10 ? 

 1 eq. ammonia NH 3 > 



= C 4 N 2 H l 10 



There remains the for- 

 mula of choloidic 



acid C 72 



27. Again, if from the formula of chojeic 

 acid we subtract the elements of urea and 2 

 atoms of water (=2 eq. carbonic acid and 2 

 eq. ammonia,) there will remain the formula 

 and composition of cholic acid. Thus : 

 from the 



Formula of choleic acid 



Substract 



2 eq. car. acid =C 2 O 4 ? 

 2 eq. ammonia = N 2 H 6 } 



=C 2 N 2 H 6 O 4 



Remains the formula 

 of cholic acid =C 74 H 60 O 18 (31.) 



When we consider the very close coinci- 

 dence between these formulas and the actual 

 results of analysis (see Appendix, 29, 30, 

 31,) it is scarcely possible to doubt that the 

 formula above adopted for choleic acid ex- 

 presses, as accurately as is to be expected 

 in the analysis of such compounds, the rela- 

 tive proportion of its elements, no matter in 

 how many different forms they may be 

 united to produce that acid. 



28. Let us now add the half of the num- 

 bers which represent the formula of choleic 

 acid, to the elements of the urine of ser- 

 pents that is, to neutral urate of ammonia, 

 as follows : 



\ the formula of choleic acid = 



Add to this 



1 eq, uric acid =C 10 N 4 H 4 O 6 ? 

 leq. ammonia = NH 3 > 



The sum is =C 48 N 6 H 40 O 17 



29. But this last formula expresses the 

 composition of blood, with the addition of 1 

 eq. oxygen, and 1 eq. water. 



Formula of blood .... C 48 N 6 H 39 O 18 

 1 eq. water =HO > jjj Q 2 

 1 eq. oxygen = O $ ~~ ' 



The sum is ...-.= 



30. If, moreover, we add to the elements 

 of proteine those of 3 eq. water, we obtain, 

 with the exception 1 eq. hydrogen, exactlv 

 the same formula. 



Formula of proteine . . =C 48 N 6 H 36 O 14 

 Add 3 eq. of water . . . = H 3 O 



The sum is ..... 



differing only by 1 eq. of hydrogen from 

 the formula above obtained by adding to 

 gether choleic acid and urate of ammonia. 



31. If, then, we consider cholerc acid and 

 urate of ammonia the products of the trans- 

 formation of muscular fibre, since no other 

 tissue in the body contains proteine (for 

 albumen passes into tissues, without our 

 being able to say, that in the vital process 

 it is directly resolved into choleic acid, and 

 urate of ammonia,) there exist in fibrine, 

 with the addition of the elements of water, 

 all the elements essential to this metamor 



