Page:Thruston speech upon the progress of medicine 1869.djvu/10

This page has been proofread, but needs to be validated.

8

Numerous substances are now known (Isomers, they are called), identical as to the proportionate number of their elementary atoms, but differing completely in structure and properties. At the present time many of these bodies are arranged in different groups according to their typical constitution.

A recent discovery has been applied by Mr Chapman to this investigation, and seems likely to aid very materially in finding out the essential structure of bodies.

Mr Chapman states[1] that an organic body, when carefully treated with a chromic acid solution, "will oxydize down to the stable representatives of the radicals it contains, and no further;" in other words, "it may be brought down to substances having the same carbon condensation as the radical it contains:" thus, if it were required to point out the essential differences between substances, isomeric in composition, containing, that is, the same percentage of the simple elements, this process would at once declare their true constitution.

It is scarcely too much to hope that by this and other methods, the structure of many animal and vegetable products may at length become known, and that their production by artificial means may come within the reach of Chemistry.

Even albumen itself, the principle of flesh, may yet be produced artificially, although the extreme complexity[2] of most of the forms of this substance will probably render its production very difficult.

  1. The Laboratory, p. 38.
  2.  Dr Graham has pointed out the composite character of the molecules of colloid bodies like albumen.— "On liquid diffusion applied to analysis." Phil. Trans. 1862. Part I.

    Dr Thudichum reckons the atomic weight of human albumenoids as varying between 1612 and 20,000, eg. the formula for blood-crystals is given as C6oo H966 N154 Fe S3 O177.— Report on Researches intended to promote an improved chemical Identification of Diseases, 1867, p. 234.