94 CHEMICAL COMPONENTS OF THE HUMAN BODY. 



removed from that of the ordinary results of that metamorphosis, as would at 

 first sight appear. For, as Dr. G. Bird has pointed out, 



C. H. N. 0. S. C. H. N. 0. S. 



4eqs.Urea . . .=24220 

 2 eqs. Hydrated Uric Acid . =10 4460 

 4 eqs. Sulphuretted Hydrogen =4 4 



12 12 6 8 4 



12 12 2 8 4=2 eqs. Cystine. 

 4 =4 eqs. Nitrogen. 



12 12 6 8 4 



It is a very remarkable circumstance that the composition of Cystine should 

 present an extremely close relation to that of Taurine, the sulphurized consti- 

 tuent of the bile ( 69) ; their respective percentages of hydrogen, nitrogen, 

 and sulphur being almost precisely identical, and the difference lying only in 

 those of carbon and oxygen ; as will be seen from the following comparison : 



Cystine. Taurine. 



Carbon ^ ,..,.,,,*, ; :.,.:;,- . 30.00 19.20 



Hydrogen. ,.'" i-. ',-.., .,. *. ^ . 5.00 5.60 



Nitrogen . '.. " ." . '."'.," . 11.66 11.20 



Oxygen . ' .'';" ! . ' . " .' . 26.67 38.40 



Sulphur .< : <". = > V' ;r &* *'> - : ' : '." . 26.67 25.60 



100.00 100.00 



Here, then, we have another marked example of the vicarious nature of the 

 urinary and biliary excretions ; the former taking upon itself the removal, 

 under peculiar circumstances, of a product whose components should normally 

 find their way into the latter. 1 



67. We now pass from that group of Excretory matters of which Nitrogen is 

 the predominating constituent, to that of which Carbon and Hydrogen are the 

 principal components; and as the former are the characteristic ingredients of 

 the Urinary excretion, so are the latter of the Biliary. Regarding the organic 

 compounds we have now to consider, however, our knowledge is far less definite 

 and satisfactory than it is respecting those which have been already passed in 

 review ; and this arises from several causes, among which may be more par- 

 ticularly mentioned the great facility with which they are decomposed, both 

 spontaneously, and by the operation of reagents ; so that it is by no means easy 

 to say, in many instances, whether a given substance, extracted from the bile 

 by analytical operations, pre-existed in it, or has been subsequently formed 

 under the treatment to which that fluid has been subjected. There has, conse- 

 quently, been a vast discrepancy of opinion amongst Chemists, with regard to 

 the constitution of this excretion ; some having regarded as original components, 

 what others have considered as secondary ; and the number of proximate con- 

 stituents having been ranked high by some, whilst others have reduced it to no 

 more than four or five. According to Strecker, whose researches have been 

 more successful, and whose views seem more trustworthy, than those of any 

 other chemist, we are to regard the proper biliary matter as chiefly composed 

 of two substances, which are regarded by Lehmann as " conjugated acids" 

 ( 58, note), formed by the union of one and the same acid, the true Cholic^ 

 with Glycine and Taurine respectively, and hence termed by him the Glyco- 

 cholic and the Taurocholic. 



68. This Clwlic acid (the cTiolalic of Strecker), which was first obtained in a 

 state of purity by Demargay, is a fatty or rather a resinous acid, from which 

 nitrogen is altogether absent, whilst oxygen is present in it in only a small 

 proportion, its formula being 48C, 39H, 90. It forms tetrahedral or more 



1 See, on the whole of this subject, the excellent treatise of Dr. Golding Bird on "Uri- 

 nary Deposits," already referred to. 



