Page:Popular Science Monthly Volume 9.djvu/144

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126
THE POPULAR SCIENCE MONTHLY.

a simple catalogue of them would occupy several pages of this magazine. In so far as the preservation of vegetables and of certain fruits is concerned a very fair measure of success has undoubtedly been achieved; but with flesh-meat the case is different. We propose to describe here a few of the chief methods adopted for preserving meats, following for the most part a writer upon this subject in the Journal of the Society of Arts. These methods may all be reduced under the four heads of Desiccation, Refrigeration, Use of Chemical Antiseptics, and Application of Heat. Desiccation or drying has been practised from the earliest times. Charqui, or jerked beef, is an example of fairly successful preservation, but it is immensely inferior to fresh meat. Some years ago the food committee of the London Society of Arts reported favorably upon some specimens of "powdered beef" from Queensland; but the article has been unable to win its way to public favor. The reason of this no doubt is, that animal matter preserved by desiccation loses its flavor and becomes tough and indigestible, the fat becomes rancid, and in damp weather the whole turns mouldy and sour. These difficulties are to some extent obviated by mixing absorbent substances with fatty food, as in "pemmican," where sugar and spice are mixed with dry powdered meat. Meat-biscuit is made on a similar principle. Tellier, of Paris, adopts the following method: He first exhausts the air from a close vessel containing the meat, then fills it with carbonic-acid gas, again exhausts and again fills with the same gas. In this way the air is almost entirely removed. He then absorbs the carbonic acid by the use of a concentrated solution of potash, by which a very near approach to a vacuum is produced. The meat is removed from the vessel after three days, and may be kept sound without further trouble, but it will have lost 20 per cent, of its weight.

The keeping of meat by refrigeration is practised on a small scale in every household. The same thing was done on a large scale at Melbourne in 1872, when a large quantity of meat was kept for six weeks perfectly fresh in an ice-chamber. In the following year an attempt was made to ship from Australia to England meat kept fresh by the same method, but the experiment failed. Better success has attended later shipments of meat from Canada to London, and from Texas to New Orleans. The progress made in ice-making machines is such as to inspire great hopes of success in preserving meat by cold.

Among chemical antiseptics common salt of course holds a place. Many patents have been taken out for the employment of sulphur-fumes (sulphurous acid). Bisulphite of lime is very efficacious for the temporary preservation of meat, and has been practically tested with favorable results. Our readers need not be reminded of what is claimed for salicylic acid. Among other chemical agents employed for this purpose we may mention acetate of potash and chloralum.

The expulsion of atmospheric air from vessels containing meat, by means of heat, is certainly the most successful method of preservation yet adopted. Many difficult processes are in use, but the main principle—expulsion of air by heat—is the same in all. They all, too, agree in this, that they render the meat comparatively insipid.

 


NOTES.

The subject of iterated nesting by birds being under discussion in Forest and Stream, Dr. Charles C. Abbott contributes to that journal the following list of birds which he has himself observed nesting twice in summer: 1. Usually breeding twice—robin, cat-bird, bluebird, house-wren, yellow warbler, English sparrow, bay-winged bunting, chipping-sparrow, song-sparrow, orchard oriole; 2. Occasionally breeding twice—white-breasted nuthatch, scarlet tanager, yellow-bird, chewink, Baltimore oriole, purple grakle.

The American Metrological Society has, through its president, memorialized Congress for the preparation of coins, of metrical weight and uniform fineness, and for the passage of laws and conclusion of treaties whereby such coins shall become legal tender, according to their weight.

A crucial experiment was recently made at Sunderland, England, on a fire-proof house. One of the rooms was filled with tar-barrels, wood, and other combustible material, and, when the door was shut, the mass was set on fire. It simply burnt itself out, without apparently affecting the condition of the adjoining rooms or the stability of the house itself. The building material was a concrete of cement and fibre