Page:Popular Science Monthly Volume 7.djvu/133

Rh Thus the conditions of the two phenomena are different. Again, certain fermentations may be arrested by oxygen at high pressure; the mycoderma of vinegar is destroyed or killed by the action of compressed air. Wine may be preserved from acetous fermentation by submitting it to compressed air. It is necessary, then, to distinguish in fermentation various phenomena belonging to chemical actions, and those belonging to the action of ferments, properly so called. M. Bert adds that compressed air stops the putrefaction of meat even where the latter has been impregnated with putrid germs.

Viniculture in California.—This was the subject of a paper recently read before the California Academy of Sciences by Dr. James Blake. The author analyzed the juice of four different varieties of grapes, grown in the vineyard of the California Vinicultural Society at Sonoma, viz., the Zinfindel, the Reimer, the Riessling, and the Mission grape. The last-named grape was introduced into California by the Franciscan missionaries, during the Spanish domination; the others are recent importations. The method of analysis was to ascertain the specific gravity of the juice, which was then heated, to coagulate the albuminous matters, and filtered through a Bunsen filter. Then the juice was brought up to the original quantity, and neutralized with a standard solution of potash or ammonia, so as to ascertain the amount of free acid. Another portion was evaporated to about one-third, mixed with alcohol and ether to precipitate the tartrates, and the ether and alcohol distilled off from the filtered juice, which was then neutralized to ascertain the amount of malic acid. The amount of sugar, as indicated by the specific gravity, was controlled by direct analysis of a portion of the juice, cleared by acetate of lead, by means of Fehling's copper-test. The result was as follows:

The small proportion of malic acid in the Mission grape explains the absence of aroma in the wine. The author attributes the failure to make first-class wine in California to two causes, viz.: 1. Bad quality of the grapes; 2. Injudicious choice of soil for vineyards.

"The Successor of Steam."—An article under the above title, by Dr. H. Beins, of Gröningen, has appeared in the Chemical News. The successor of steam is liquid carbonic acid. The author says: "For many years I have, with the collaboration of my brother, who is director of the Netherlands Soda Manufactory at Amsterdam, considered the question, 'How to transpose heat into mechanical power more advantageously than it is done in our common steam and other engines?' It occurred to me to make an experiment to see what degree the tension of the carbonic acid given off by natrium bicarbonate would amount to when heated in a closed space. We were surprised and much gratified to find that when natrium bicarbonate in a dry, pulverized state, or in a watery solution, is heated in a closed space, a part of the carbonic acid is given off and condensed in a not-heated portion of that space, so that, at a temperature of 300° or 400° C, liquid carbonic acid can be distilled out of this salt with a tension of from 50 to 60 atmospheres."

He then points out certain highly-important aspects of this fact: I. Carbonic acid of high tension, and, in particular, liquid carbonic acid, is an excellent motive-power for small and great industries. The weight of a carbonic-acid engine for ships, with 100 horse-power, and combustible stores for 240 hours, would be one-fifth less than the weight of a steam-engine of the same power. The former engine, too, will occupy less space. "I have experimentally found," he writes, "that a carbonic-acid engine is easily constructed. Taps and joints can be made to answer perfectly. A year ago I filled a tube of hammered copper with carbonic acid of 50 atmospheres, and not the least loss is as yet observed. Wrought metals are therefore not permeable for gases of that tension. For the great industries the carbonic-acid engine can, in almost every case, substitute the steam-engine. For the small industries, especially