The best kinds of hides suitable for tanning into leather are those of heifers. The large ox hides are those which are used chiefly for conversion into sole leather. The skins of horses, cows, bulls, and buffaloes, are used for thick sole leather. For upper, thin, and the various fancy leathers, the skins of small animals, dogs, sheep, goats, seals, &c. The quality of the leather depends upon several circumstances; the nature of the skin, its condition in curing, upon the method of tanning, also the nature of the food upon which the animal fed, and its healthiness. Hides from cattle slaughtered in cold weather are said to produce five per cent. more leather than when taken in the warm months. Dry hides produce more leather than salted hides. For the production of 40 pounds of leather, the average is estimated 30 pounds of dry hide—60 pounds of salted, or 74 pounds of market hide. Large supplies of skins are imported from Buenos Ayres, Brazil, California, and Texas. Sheep skins are received from the Cape of Good Hope and Buenos Ayres; goat skins from Barbary; lamb and kid from Italy. Very few hides, comparatively, are obtained at home. In order to form some idea of the extent of the leather trade, as represented in the tanning establishments, a few figures will enable the reader to judge. There are, according to Morfit, 6,263 Tanneries in the United States, the largest number being in Pennsylvania. These unitedly employ 20,909 persons, and in which business is invested the sum of $18,900,557. The value of the products is $32,861,796. About 6,000,000 skins of sheep, goats and other small animals, are tanned and dressed annually, which are not included in the above estimate. The _Scientific American_, in alluding to Morfit’s excellent work on the “Arts of Tanning,” had the following notice which we here insert: “In looking over this book, and reading the different plans for improving leather, and for reducing the time occupied in tanning a skin or hide, we are more and more convinced of the important fact that the tanning art has been greatly improved by modern discoveries and application—a contrary opinion to that held by the universal mass of the people. We know it is very difficult to introduce new plans of tanning, for tanners are, like others, wedded to old things; thus the rolling of leather—an operation now generally practiced—was opposed with much bitterness by some of our most experienced tanners, one of whom said ‘he never would roll a hide while he lived,’ an assertion which he wisely lived either to forget or repudiate.