On chemical changes in their relation to micro-organisms / E. Frankland.

  • Frankland, Edward, 1825-1899.
Date:
1885
Catalogue details

Licence: Public Domain Mark

Credit: On chemical changes in their relation to micro-organisms / E. Frankland. Source: Wellcome Collection.

Provider: This material has been provided by The Royal College of Surgeons of England. The original may be consulted at The Royal College of Surgeons of England.

    4/28 page 160
    those which accompany the lowest forms of life; and, secondly, hecanse it is more than probable that many of those changes with which we are familiar in the bodies of the higher animals (and possibly in plants) are also brought about by micro-organisms. The chemical actions induced by living organisms are of two kinds:— 1. Synthetical; and, 2. Analytical. The first are chiefly performed by plants ; the second by animals. Of the synthetical operations the transformations of CO2, OH2, and NH3 into cellulose, starch, sugar, gum, and albumen are the most conspicuous, although Hoppe-Seyler has observed synthetical changes under the influence of certain micro-organisms, as, for instance, the transformation of glycerin into hexyl alcohol and capi'oic acid after two years’ putrefaction, 6-carbon molecules being thus produced from 3-carbon molecules. He considers that glycerin is first converted into lactic acid, and the synthesis is then performed by the combina- tion of lactic acid residues. In his opinion, animal fats are thus produced from carbohydrates. All the first named synthetical operations must be attended by the absorption of heat; or, in other words, by the transformation of actual into potential energy. What is the nature of the substance in the plant which decomposes CO2 and OH2, liberating C under the influence of solar or artificial light ? Scarcely any approach has yet been made towards the answer to this question, and yet it cannot be doubted that a satisfactory reply will sooner or later be disclosed. Has the vegetable kingdom the monopoly of the substance which effects this transformation ? This is scarcely probable, for although the secret has eluded chemical research half a centui’y beyond the time when Wohler and Kolbe found out the artificial synthesis of organic compounds, yet it cannot be doubted that it belongs to the “ knowable,” and will be discovered. As a step towards the solution of this problem, it was interesting to ascertain whether, under the influence of a powerful beam of light, the constituent atoms of CO2 and OH2 molecules become to any extent dissociated as they do under the influence of a high tempera- ture. In other words, can the luminous impulses compel these atoms to make excursions beyond the molecular boundary of their mutual attractions ? To put this to the proof, I exposed CO2, both alone and mixed with aqueous vapour, in an extreme state of attenuation to the intense light of a powei-fiil electric arc, but failed to detect the slightest decomposition. I then similarly exposed a mixture of carbonic anhydi’ide and nitric oxide, but even this searching test for wandering atoms of oxygen failed to detect any. Although light has not yet been made to produce these results, it is well known that they
    digitised image 1
    digitised image 2
    digitised image 3