Triumphs and Wonders of the 19th Century: The True Mirror of a Phenomenal Era / A volume of original, entertaining and instructive historic and descriptive writings, showing the many and marvellous achievements which distinguish an hundred years of material, intellectual, social and moral progress

by James P. Boyd

Our knowledge of fermentation and bacterial action is practically all comprised in the achievements of the nineteenth century. Prior to this time it was known that fermentation took place, but its causes and character were wholly mysterious. The great work of Pasteur (1859) resulted in the fact that fermentations were chiefly caused by the activity of living cells, which have the capacity of reproduction. The most common form of fermentation is that whereby sugar is converted into alcohol and carbon dioxide. The name of the organism that produces this change is saccharomyces cerevisiae.

Another class of fermentation is seen in the process of digestion. This species of fermentation is typified by the action of sprouted barley on starch, whereby the starch is converted into sugar. The active principle of the saliva, ptyalin, has the same property, and when starchy bodies are masticated, a part, at least, of the starch which they contain is converted into sugar. The active principle of malt is known as diastase, and this, as well as ptyalin, belongs to a class of ferments which are incapable of reproduction.

LOUIS PASTEUR.

All the decompositions of organic matter, such as the decay of meats and vegetables, are now known to be forms of fermentation, due to the action of certain organisms known by the group name of bacteria. This discovery led naturally to the process of preserving organic compounds by sterilization. The principles on which this process depends are very simple. If an organic body, such as a fruit or vegetable, be subjected for some time to a high temperature,—that of boiling water will usually suffice,—the fermentation germs which it contains will be destroyed. If then it be sealed in such a way, either hermetically or with a plug of sterilized cotton, so that no living germ can reach it, decomposition cannot take place. Certain chemicals, such for instance as salicylic acid and formaldehyde, have the property of paralyzing or suspending germ action, and hence organic bodies treated with these substances may also be protected against decomposition.

The activity of fermentation is made use of in the technical arts. Bread is made light by fermentation, and wine, beer, and cider are made by the fermentation of fruits and grains. Alcohol is produced by the fermentation of grains and potatoes, their starch having previously been converted into sugar by malt.

Buchner has lately shown that all fermentation is of one kind, namely, that due to ferments of the diastase type. The fermentation produced by yeast, for instance, is not due, according to his observations, to the living cells, but to the products of their activity. By destroying yeast cells, by grinding and high pressure, and using their contents, he has secured a vigorous fermentation similar in every respect to that caused by the cells themselves.

XI. ELECTRO-CHEMISTRY.

The electric furnace, which affords a higher heat than chemists had been able to secure, has been the promoter of great advances in inorganic chemistry. Moissan (b. 1852), a French chemist, has been the most successful in applying the heat of the electric furnace to analytic and synthetic studies. One of the practical results which has come from these studies has been the virtual bridging over of the chasm which has been supposed to exist between organic and inorganic compounds. Under the influence of the heat of the electric furnace, carbon, which is the keystone of organic compounds, has been made to combine directly with the metals, forming a series of bodies known as metallic carbides. The carbide of calcium, under the action of water, yields a gas known as acetylene, which by a series of reactions can be converted into alcohol. Thus alcohol, which only a short time ago was supposed to be solely the product of organic life, is shown also to result from a simple inorganic reaction such as has been shown above.

The importance of electrolysis in metallurgical and analytical chemistry has already been noticed. So rapid has been the progress along these lines that the terms metallurgical chemistry and electro-chemistry are in some respects almost synonymous.