Elements of human physiology / by Henry Power.

  • Henry Power
Date:
1888
Catalogue details

Licence: Public Domain Mark

Credit: Elements of human physiology / by Henry Power. Source: Wellcome Collection.

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    dioxide, tlioiigh. there are certain by-products which prove that the action is complex. Pasteur's experi- ments have shown that 100 parts of cane sugar, in fermenting, first become converted into 105-4 parts of glucose, which then break up, yielding (approxi- mately) of alcohol 51*1 parts, of carbon dioxide 49*4, succinic acid 0*7, glycerine 3*2 parts, matter passing to the yeast 1 part, and traces of the higher alcohols, such as fusel oil and the compound ethers. Omitting the by-products, the decomposition may be thus broadly formulated : Glucose. A]cohol. Carbon dioxide, C,Hi,Oe = C,H,0 + 2C0j. The range of temperature most favourable to the process of fermentation is from 20° to 24° C. (68° to 75° F.). Heat is liberated during the process, about 83 heat-units being evolved for each unit weight of sugar destroyed. Fermentation can be arrested by the addition of small quantities of certain reagents named antiseptics, examples of which are found in corrosive sublimate, sulphurous acid, boracic acid, thymol, and carbolic acid. Ferments have been separated into two groups, the ^'formed and the unformed or soluble ferments. In the case of the alcoholic fermentation, the exciting agent of the process appears to be a uni- cellular alga named saccharomyces, the various forms of which act with different degrees of activity in different fluids. The cells, which are sometimes separate, sometimes arranged in chains, multiply by gemmation or budding, and are about mm. in diameter. The ferment of wine and beer is therefore a formed ferment, and the breaking up of the molecule of sugar is regarded by many as a physio- logical function of the cell; but it is only right to add that sweet fruit, kept in an inert atmosphere, devoid
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