Page:Thruston speech upon the progress of medicine 1869.djvu/9

7 Since this time many other organic substances have been made either directly from the elements or intermediately through an ascending series of alcohols and acids. Formic acid, a secretion of ants, and bodies as high in the scale as Benzole (C$6$H$6$), have been produced by the direct union of the elements. And many other bodies have been made indirectly—such, for instance, as Alizarine, a component of madder dye; Coumarin, the odoriferous principle of the Tonka bean; Leucine, derived from Valeral-Ammonia, also a product of animal decomposition; and it has lately been reported that Neurine, the base of protagon, a substance extracted by Liebreich from the human brain, has been formed synthetically by Wurtz.

The methods by which these bodies may be made has been reduced to a system, by the labours of Berthelot and Wurtz, Frankland and Duppa. Thus, by substituting organic radicals for certain atoms of oxygen in organic ether, fatty products, with a carbon index as high as 12 (C$12$H$24$O$3$) , have been obtained, and there is scarcely any limit to this production.

Much of this success is undoubtedly due to the modern views of the constitution of organic bodies; not only the composition, or the relative proportion of the simple elements in an organic compound, is now sought for; the mode of their grouping, their structure, is examined.