Dr. KEMP, ON THE NATURE OF THE BILIARY SECRETION. 45 



moreover, found other substances denominated cholic acid and taurin, which have since been 

 proved to be products of manipulation. In the year 1826, Demar<|:ay employed himself in the 

 laboratory of Liebig in preparing, and submitting to analysis, a substance obtained from the 

 bile when treated with diluted sulphuric acid, and to which he subsequently gave the name 

 choleic acid. This body was in all probability the picromel of Thenard, and the matter 

 which remained after removing the choleic acid, denominated choloidic acid by Demarij'ay, bears 

 a striking resemblance to the biliary resin of Thenard ; as, however, no elementary analysis 

 was made by that chemist, the matter must remain in doubt. The choleic acid of Demar(,ay 

 is an important body, as Professor Liebig has acceded to the opinion that it is the essential 

 organic ingredient of the bile; a conclusion, however, which subsequent researches tend to 

 overthrow ; indeed, the opinion of Demarcjay was grounded on the following circumstance. 

 After he had prepared his choleic acid, and combined it with soda, the compound possessed a 

 considerable number of the physical characters of the Bile, and in estimating the quantity of 

 soda which combined with a given quantity of his choleic acid, he found the quantity of the 

 base almost precisely the same as that contained in the same quantity of the dried bile. One 

 unfortunate oversight, however, occasioned this erroneous inference of the identity of the two 

 bodies. The choleate was converted into the sulphate of soda, in order to estimate the 

 quantity of the base. On applying the same method to the bile, the chloride of sodium 

 contained in that fluid became converted into sulphate of soda, and thus the quantity of soda 

 combined with the organic body was supposed to be considerably greater than it really was; 

 for on looking over the analysis of Thenard it will be seen that the quantity of chloride of 

 sodium stands in the proportion of 4 : 5 to the soda ; a quantity much too large to be over- 

 looked, as it would occasion an error in the second whole number of the atomic weight. Indeed, 

 the circumstance of the similarity found in the dried bile and in the choleate of soda in this 

 one experiment, was evidently purely accidental, as the chloride of sodium is always present in 

 bile, and that in constantly varying proportions. In fact, the choleic acid of Demar^ay seems 

 to be a product of decomposition of the bile effected by means of sulphuric acid ; and the 

 errors in the late work of Professor Liebig on the subject have arisen from not taking into 

 account the other product of manipulation, the body which Demar^ay has denominated 

 choloidic acid. The labours of Demarc^ay were however exceedingly valuable, as they directed 

 the attention from proximate to ultimate analysis, and were the means of inducing the illustrious 

 Berzelius to make one more effort towards effecting the solution of this difficult problem*. 

 A paper, which has recently appeared I believe in an English form, was in the year 1841 

 laid before the Royal Academy of Stockholm, purporting to be an analysis of the bile of the 

 ox, and the characteristic properties of its component parts. This elaborate research was 

 conducted in the same manner as his former analysis, the object being to eliminate what he 

 considered the proximate principles of the bile ; and the results confirmed all his former in- 

 vestigations on this subject. He concludes by stating the theory, that the bile in its healthy 

 and perfectly fresh state is essentially composed of bilin, a body agreeing in every physical 

 character with the biliary matter of his former analysis, and that this body is continually 

 undergoing a change into two acids, fellic acid and cholic acid ; that at the same time these 

 two acids form Unary compounds with bilin, to which compounds he has given the names 

 Bilifellic Acid and Bilicholic Acid. To this theory we shall have occasion again to advert. 



These last researches of Berxelius seemed to discourage any farther attempt to elicit facts 

 by means of proximate analysis; and at the request of Professor Liebig, I commenced a series 

 of ultimate analyses, with the limitations alluded to above. It appeared desirable also to extend 



• Uebcr die Analyse dcr OctiKcngallc, und die characterisi- I den Kongl. Vel. Acad. Ilandl. IIJ4I. S. 1 — (i4, iibersetzt von 

 renden Eigenfthaftcn ihrcr Bestandtheilc ; von J, Derzcliuii. (Aus I Dr. VViggcrs. 



