522 OF SECRETION. 



whole of this consists of a substance peculiar to Bile, in which the oleaginous 

 character certainly predominates. This substance contains a large proportion 

 of Carbon and Hydrogen, with very little Azote. We are probably to distin- 

 guish it in two very different compounds. The first of these is termed Choles- 

 terine; it is a white crystallizable fatty matter, somewhat resembling Sper- 

 maceti, free from taste and odour, not soluble in water, but dissolving freely in 

 alcohol, from which it is deposited on cooling in pearly scales. It is almost 

 entirely composed of Carbon and Hydrogen ; its constitution being 36 Carbon, 

 32 Hydrogen, 1 Oxygen. This may be pretty certainly considered as a real 

 proximate element of the Bile ; since it frequently separates itself, when present 

 in superabundant quantity, forming Biliary Concretions, which are some- 

 times composed of this alone, but more commonly contain a small portion of 

 resinous and colouring matter. Moreover, it may be obtained by a chemical 

 process of no great complexity, from the Serum of the Blood ; and it is not 

 unfrequently deposited as a result of diseased action in other parts of the body, 

 especially in the fluids of local Dropsies, as hydrocele, ovarian dropsy, &c. 

 The other substance, now termed Bilin (formerly Picromel), is that to which 

 the peculiar taste of the Bile, which is at the same time bitter and sweet, is 

 due. According to the account most recently given of this compound, by 

 Berzelius, it is a translucent, colourless, inodorous mass, without crystalliza- 

 tion ; it is very soluble in water and alcohol, but insoluble in ether ; it contains 

 nitrogen ; and is decomposed by heat, with the formation of ammoniacal pro- 

 ducts. Bilin is a readily alterable substance ; it is decomposed by acids into 

 five different substances, namely, Ammonia, Taurin, Fellinic and Cholinic 

 acids, and Dyslysin ; and it appears that this decomposition may take place in 

 the bile of the living body. The last of these products appears to be that 

 which has been spoken of by some chemists as the Resin of the Bile.* The 

 colouring matter of the bile is now termed Biliverdin. It contains no azote ; 

 and that of the Ox appears to be identical with the Chlorophyll of plants. 

 When exposed to the air, it becomes of a deep green, absorbing oxygen ; and 

 the same change is produced by nitric acid, the liquor soon passing, how- 

 ever, to a red hue. This frequently takes place within the body, in cases of 

 Jaundice ; but more especially in the urine. Though the colouring matter is 

 usually present but in small quantity during health, it sometimes accumulates 

 in disease, so as to produce solid masses, which include little else.t 



663. The amount of the secretion of Bile appears to bear some proportion 

 to that of the Food digested. That its formation is continually going on to a 

 certain degree, appears unquestionable ; but that its quantity is greatly in- 

 creased during the solution of food in the stomach, appears also to be well 

 established. Whether the stimulus to the increased secretion at that period 

 is occasioned by an increased flow of Blood, or is propagated through the 

 Nervous System, there is no evidence ; the analogy of the Salivary, Lachry- 



* By Demar5ay it is considered that the organic matter of Bile is to be regarded as a 

 Soap, formed by the union of an acid with soda. Of this acid, which he has named the 

 Choleic, the following is the composition according to Liebig; C. 76, H. 66, N. 2, 0. 22. 

 Dr. Kemp, whose analyses are the most recent, agrees with Demargay in regarding the 

 organic matter of Bile as an electro-negative body in combination with soda; but he holds 

 that this is neither the choleic acid of Demarcay (since it is not precipitated from the soda, 

 as that acid is, by acetic acid), nor the bilin of Berzelius (not being precipitated from the 

 soda by carbonic acid). He has therefore termed it Bilic acid. It has a peculiar bitter, 

 sweet taste ; and in mass resembles a fine resin. Dr. Kemp has further pointed out, that 

 there is a much greater difference than is usually imagined between the bile in the 

 hepatic ducts, and that of the gall-bladder; the former, in the Ox, being destitute of the 

 bitter taste of the latter, and having a different smell. 



f A full account of the latest researches of Berzelius on this subject will be found in 

 Graham's Chemistry, [Am. ed., p. 704.] 



