Page:Popular Science Monthly Volume 20.djvu/443

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is distilled. This spirit, as prepared from various grains, fruits, beet-roots, etc., is produced in many qualities, each of which acquires some special and relatively disagreeable flavor from whatever article has been subjected to distillation; and the alcohols are therefore classified in the arts according to the sources from which they are derived, and subdivided into those of "good taste," "middling taste, and "bad taste." Other alcohols are found along with the vinous alcohol in fermentation, but, as a rule, they do not materially affect its taste. The case is different with the aldehydic or acetonic bodies that are produced, whose pronounced and disagreeable taste is obstinately persistent in rectification. The methods which have hitherto been employed to take away these tastes depend on oxidation; this acts, however, upon the alcohol itself, and generates odorous ethereal substances which only give another bad taste instead of the original one. No better results have been obtained with other substances that have been recommended, including potash, soda, oil, fat, soap, and sodium. M. Naudine has adopted a course which has been suggested by the fact that hydrogen, in a nascent state, converts the acetones into secondary alcohols. His method consists in the subjection of the alcohol to be purified to the action of the Gladstone and Triber reducing pile, or a similar battery, whereby hydrogen is developed and acts immediately upon the impurities of the spirit.


Speed of Explosives.—M. Berthelot has been investigating the speed with which explosive phenomena are propagated in gases. For this purpose, he filled with the explosive mixture of oxygen and hydrogen, carbonic oxide, and oxygen under atmospheric pressure, an iron tube about sixteen inches long and a third of an inch in bore, so arranged that the passage of an explosive could be accurately registered at a point close to where the spark was applied, at the middle, and at the farther end of the tube. The experiment showed the speed of propagation to be about twenty-five hundred metres (8,125 feet) a second. The results should not be regarded as furnishing the absolute value of the speed of the explosive force, for the quantities measured are too small for that; but they at least give an indication that the speed is much greater than had been supposed. Bunsen, for example, in 1867, had estimated it at thirty-four metres a second for detonating gas, and one metre for carbonic oxide mixed with oxygen. The rapid propagation of explosive phenomena appears to be due to the transmission of the successive shocks of the gaseous molecules, which have been brought into a vibratory condition more intense than the heat disengaged in their combination. The phenomena of explosion are, then, more complex than a simple movement of transmission, or even than the propagation of a sonorous wave.


Fossilized Standing Trees.—M. Fayol has observed fossilized trees standing perpendicular to the planes of stratification of the beds that contain them, in the coal measures of Commentry. In the bed of Boseaux the trunks are so numerous as to resemble a fossil forest. The standing trees are fragments of trunks, without branches or roots, and occur generally in the grits, occasionally in the conglomerates, rarely in the shales, but not in the coal-beds. Prostrate trees are numerous in the shales, less abundant in the grits, and rare in the conglomerates, while numerous traces of them may be distinguished in certain parts of the coal-beds. The prostrate trees are a hundred times more numerous than the standing ones, and are found almost everywhere in the beds. These facts may be explained as the results of a transporting movement. A recently pulled-up plant, when thrown in the water, stands vertically, then sinks to the bottom in the same position, and afterward falls prostrate, remaining in each position for some hours or even days. If the trees were carried by the current to a lake or estuary, they would, according to the condition they were in, either float around for a while or sink at once, and would become fossilized in the position they took.


Disinfecting Powers of Sulphurous Acid.—Dr. Victor Fatio, of Geneva, has made a series of interesting experiments on the disinfecting power of sulphurous acid, particularly with reference to the destruction