6 ANIMAL CHEMISTRY LECTttRE I. 



of animal life. It may be produced, for example, by the com- 

 bination with one another of water, valerianic aldehyd,* and 

 prussic acid, as shown in the table ; and in several other ways. 



H a Water 



C 5 H IO Valer-aldehyd 



CH N Prussic acid 



C 6 H I3 N0 8 Leucine 



(5.) The case of taurine, C 2 H 7 NS0 3 , is even more striking. 

 Like leucine, it has been found in glandular tissue, more par- 

 ticularly of the lung ; but its chief source is the bile, where it 

 exists conjugated with cholic acid, to form what is known as 

 tauro-cholic acid ; though whether the constituent taurine of this 

 acid is really formed by the liver, or merely extracted by the 

 liver from the blood of the portal vein, is not, I believe, satisfac- 

 torily ascertained. But the constitution of this highly complex 

 organic body, containing, as you see, carbon, hydrogen, nitrogen, 

 sulphur, and oxygen, is so exactly understood that it can easily be 

 put together in the laboratory, and from such well-known bodies 

 as sulphuric acid, alcohol, and ammonia, each of which again is 

 capable of being produced from its constituent elements ; so that 

 we may actually form this most interesting organic product, 

 taurine, out of sulphur, charcoal, oxygen, hydrogen, and nitrogen, 

 by processes which I hope to bring under your notice more par- 

 ticularly in a subsequent lecture. I might make similar remarks 

 with regard to the greater number of the other products included 

 in the table. Instead, however, of entering at once upon the 

 consideration of these and similar compounds, I propose to occupy 

 the remainder of this lecture with an account of certain bodies 

 of a much simpler character. I mean those fundamental com- 

 binations that serve as types to which the above class of bodies 

 and the great majority of organic as well as mineral compounds 

 are more or less directly referrible. The recognition of these 

 types, with the establishment of their nature and mutual relation- 



. * Obtainable from essential oil of valerian, fermented potato-oil, &c. 



