Page:Popular Science Monthly Volume 23.djvu/643

This page has been proofread, but needs to be validated.
625
WAYS OF PRESERVING FOOD.

count of the amount of sugar required to make it efficient. Dr. Bersch has suggested a way of cheapening it by adding salicylic acid to the sugar. His directions are to dissolve 100 grammes of sugar and three grammes of salicylic acid in hot water, and to pour the solution, after it has cooled to about 100°, over the fruit to be preserved. If the fruits are wholly covered with the solutions they can be kept in open vessels without changing; but it is best to seal the vessels with salicylic-acid paper (made by dipping common writing-paper into an alcoholic solution of the acid), so as to keep out the dust. Thus prepared, a ten per cent sugar-solution is strong enough for such fruits as cherries, apples, pears, etc., and an eighteen to twenty per cent one for the sweeter fruits. A difficulty in the application of this process arising out of the qualities of salicylic acid as to solubility may be obviated by previously dissolving the acid in glycerine. The old-fashioned way of packing meat in salt and saltpeter is bad, because it takes all the juices from the meats. It is preferable to prepare a brine by heating a kilogramme of salt, 160 grammes of white sugar, and 80 grammes of saltpeter in six litres of water over a gentle fire, and pour the mixture, after it has been cooled, over the meat.

Fruits, cucumbers, and meat, may be preserved for a long time with vinegar, by processes which are too well known to require a close description. Meat is not generally preserved by the direct action of vinegar, but by the vapors of acetic acid. For this purpose the meat is placed on a shelf in a cask, in the bottom of which concentrated vinegar has been poured. The escaping acetic vapors exercise a preservative influence which is effective for a considerable time. The processes of pickling and smoking are so well known that we speak particularly only of a rapid-smoking process, which consists in painting the meat some three or four times with a brush dipped in pyroligneous acid, after which it acquires the taste and properties of well-smoked meat.

The processes of direct drying, which have long been employed with fruits, have more recently been applied to vegetables. By late improvements they have been brought to a degree of perfection in which the freshness, taste, and tenderness of the fruits and greens, are well preserved. Potatoes are dried by Casseten, at Lubec, into a light, citron-yellow, gummy, transparent mass, which, when cooked with water and a little salt, regains the color and mealy consistency of the original tuber, and can not be distinguished by its taste from a freshly cooked potato.

Meat is dried, by the processes of Endemann and others, into a very nourishing food. By Endemann's method, the meat, cut into slices, is placed in a chamber heated to a temperature of about 140°, in which a current of air of the same temperature is kept constantly circulating. If the ventilation is sufficiently active the meat will be dry enough in three hours to be ground up in a mill. The powder,