14 ANIMAL ACIDS DESTITUTE OF AZOTE. 



copper, and silver ; but could not succeed in obtaining these salts 

 constant in their composition. Water decomposes them into 

 super and subsalts. Hence it happens that, when we obtain the 

 choloidates by precipitation, the proportion of acid in them 

 varies with the concentration of the liquid, and when we attempt 

 to wash them. The consequence of this is, that the atomic weight 

 of this acid is still unknown. 



Demar9ay made three ultimate analyses of it by means of 

 oxide of copper, and obtained as a means of the three, 



Carbon, . 72-46 



Hydrogen, . 9 '5 7 



Oxygen, . 17-97 



100-00 



Now, it will be shown in a subsequent section that ox bile is a 

 compound of cJwleic acid and soda, and that choleic acid is com- 

 posed of C 42 H 36 Az O 12 . When bile is boiled with muriatic 

 acid, besides choloidic acid there is another substance formed, 

 which L. Gmelin, the discoverer, distinguished by the name of 

 taurin. This substance, which will be described in a subsequent 

 chapter of this volume, was analysed by Demarcay, and found 

 composed of C 4 H 7 Az O 10 . 



Now, if from choleic acid, . C 42 H 36 Az O 12 

 We subtract taurin, C 4 H 7 Az O 10 



And to the remainder, .^ C 38 H 29 O 2 



Add four atoms water, . H 4 O 4 



We get, . . . C 38 H 33 O 6 



Now this approaches somewhat the constitution of choloidic 

 acid: 



For 37 atoms carbon, = 27-75 or per cent. 74 



30 atoms hydrogen, = 3*75 10 



6 atoms oxygen, =6-00 16 



37-50 100 



But this formula differs too much from the analysis to be con- 

 fided in. And Dema^ay ascertained that the atomic weight of 

 choloidic acid was not 37.5. The number of atoms that would 

 suit the analysis would be 



