Page:Popular Science Monthly Volume 35.djvu/112

100 good in pastry, and mixed with fowls' eggs they improve omelets.

The question whether fowls or ducks are the better investment for the production of eggs has to some extent been settled experimentally in Germany and France in favor of ducks. They laid more eggs than the fowls, and, though they were rather smaller, they proved to be decidedly superior in nutritive material. It may be doubted whether as much attention is paid in England to the production of eggs as the utility of the food demands, and particularly by the poor, to whom their value is a consideration. Efforts should be made to induce all persons conveniently circumstanced to keep hens and ducks, and there is reason to believe that ducks are more profitable than hens, having regard to the number and size of the eggs laid by them. The solid matter and the oil in a duck's egg exceeds that of a hen's egg by as much as one fourth.

Eggs, their dietetic use apart, are of great utility in many branches of industry. In some, as in confectionery, both the whites and yolks are used, but usually the two find separate applications. The whites are employed in calico-printing, in photography, in gilding, in clarifying wines and liquors, and by the bookbinder on the leather previous to lettering or tooling.

An egg-oil is obtained in Russia in large quantities and of various qualities; the best so fine as to far excel olive-oil for cooking purposes. The less pure and very yellow qualities are chiefly used in the manufacture of the celebrated Kazan soap. Both of these products were shown at the London International Exhibition in 1862, and at subsequent exhibitions. Neither the oil for cooking purposes nor the soap are sufficiently cheap for general use; they are consumed only by the wealthy classes as luxuries; the soap, being regarded chiefly in the light of a cosmetic, is a much-valued addition to a Russian lady's toilet necessaries. The yolk is also used for medicinal purposes. It was used in the middle ages for the painter's art, before the discovery of oil-colors, as in the chapter-house at Westminster.

Eggs, whether to be used in culinary or pharmaceutical preparations, should be fresh. To determine this they should be examined by the light of a lamp. Fresh eggs are easily known by their transparency when held up to the light. By keeping they become cloudy, and when decidedly stale a distinct, dark, cloudlike appearance is discernible opposite some portion of the shell. Another simple mode is by placing the egg against the closed eyelid, and if the end of the egg is void it will feel warm, whereas if the egg is new laid it continues cold. A way to tell bad eggs is to put them in a pail of water, and, if good, they will lie on their sides; if bad, they will stand on their small ends, the large