Page:Popular Science Monthly Volume 55.djvu/298

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286
THE POPULAR SCIENCE MONTHLY.

see that mothers are made of the same stuff all over the world, Papuan mammas being equal to any of our peasant women or fine ladies in the point of vanity as far as concerns their children."

 

Meat Extracts.—An interesting account of the history and preparation of meat extracts was recently given as a lecture before the Society of Arts (English) by Charles R. Valentine. The idea of concentrating the body of an ox into a thimbleful of elixir seems to have been a very old one. Until the work of Justus von Liebig, about fifty years ago, however, little progress of practical value was made toward this end. Liebig macerated finely divided beef in cold water, or in water not above 150° F. The water dissolved from sixteen to twenty-four per cent of the weight of the dry flesh. This infusion was heated, the albumen and red coloring matter of the blood coagulated, and was separated as a flocculent precipitate. The remaining solution has the aromatic taste and all the properties of soup made by boiling the flesh. The infusion was then evaporated at a gentle heat. The residue amounted to about twelve or thirteen per cent of the original (dry) flesh. This is in rough outline the process of meat-extract making. This extract is simply an evaporated beef tea, containing the extractive matters of beef, and in virtue of these possesses medicinal and dietetic properties of value. But it is in no sense a substitute for beef, as the latter's most important food constituent—albumen—it does not contain.


MINOR PARAGRAPHS.

It appears from tables of Some Statistics of Engineering Education, compiled by President M. E. Wadsworth, of the Michigan College of Mines, that such education has been, in the United States, on the whole a thing of comparatively recent date, the oldest school, the Rensselaer Polytechnic Institute, having been established in 1824; the next, the Lawrence and Sheffield Schools, in 1846 and 1847; and the Columbia School in 1863. Civil engineering has led in this country, and has had various periods of advance, as in 1887'88, and depression, as in 1896-97. Mechanical engineering progressed till 1886-'87, when the number of students fell off, and the same happened with electrical engineering, "which further suffers a natural reaction from having been greatly overdone." As a rule, most of the schools in the United States seem to run to specialties, one or two of the courses being usually more conspicuous than the others.

The importance of some arrangement by which vessels may be informed of each other's approach in fog and darkness has given rise to many devices; the only one, however, which has as yet proved practical is the fog-horn or siren, and this has many disadvantages. Several fatal collisions at sea during the past year have given rise to renewed interest in the subject, and a number of new methods have been suggested. M, Branley, a French physicist, in a note presented to the French Academy suggests that each vessel be provided with a number of extremely sensitive magnetic receivers, or coherers, and a powerful magnetic transmitter. Periodical signals being made with the transmitter, corresponding impressions would be made upon the receivers of approaching vessels. The principal difficulty with this scheme lies in the fact that the receivers of a vessel will be affected by its own transmitter. There are several methods by which this difficulty may be overcome, however. Different signals may be employed, or the interval between signals may be regularly varied. M. Branley calls attention to the influence of a metallic envelope surrounding a coherer, and shows that when the coherer is thus completely surrounded it is unaffected by the influence of a transmitter. By thus inclosing the receiver on a ship at the instant of the operation of the transmitter of the same vessel, the above difficulty might be avoided.

While we can not collect roses from our gardens in January and maple blossoms from the woods in February, yet, as Prof. W. J. Beal shows in a bulletin of the Michigan Agricultural College