Page:Proceedings of the Royal Society of London Vol 4.djvu/175

Rh ducts which result from this chemical action. He finds the gas which is given off to be composed of carbonic acid, mixed with a small proportion of carburetted hydrogen; and the spirit, when sub- jected to careful analysis, to resolve itself into carbonic acid, water, and a very small proportion of nitrogen : and in further proof of the existence of this last- mentioned element in spirit, the author has recourse to the ultimate analysis of the charcoal obtained from alcohol and defiant gas, a mode of experimenting which he con- ceives is less liable to error.

He states that the views thus sought to be established are con- firmed, not merely by these direct experiments, but likewise by other changes which fermented liquors undergo on being kept under cir- cumstances favourable for further chemical action ; and that having proved the existence of such a compound as one constituted of car- bon, hydrogen and nitrogen, and shown that water is decomposed during its formation, he thinks we are enabled to account for many other changes which occur during the decomposition of vegetable matter and the growth of plants : whence he proceeds to show that evidence of the presence of such a compound as the above in fer- mented liquors is afforded by the changes which take place in con- sequence of keeping them.

On subjecting to ultimate analysis the semi-fluids obtained by ex» posing fermented liquors to a temperature of 110° Fahr., the author found a decided difference between the chemical constitution of those procured from old, and those from new vinous fluids ; and on searching for the law by which these differences are regulated, he found that the spirituous part entered into such combination with the excess of oxygen before referred to, and the undecomposed ve- getable matter, so as to form with them new compounds.

After experiencing some difficulty in effecting a separation of these newly formed bodies, he found that while rectified pyroxylic spirit, of the specific gravity from 830 to 835, scarcely dissolved an appreciable quantity of the extract of malt and hops, considerable portions of the semi-fluids obtained from old ale and old porter were, by agitating, dissolved therein. By using this spirit as a solvent he effected such a separation as enabled him to discover decided differ- ences between the proximate chemical constitution of the semi- fluids obtained from old ale and old porter, and those from liquors of the same description when new.

In accounting for many of the phenomena which accompany the vinous fermentation, the author observes that the small excess of oxygen found in all these compounds, which undergo this chemical action, is an essential and indispensable circumstance ; a conclusion which is corroborated both by the formation of these new compounds which have been described, and by the generation of the acetic, tartaric, or malic acid, which is found in fermented liquors at all times, and in quantities varying according to the situations under which these fluids have been kept.