The " Art of Tanning, Currying, and Leather Dressing," by Campbell Morfitt, an able chemist, and published by Henry C. Baird, of Philadelphia, is a new book on a subject of great importance to tens of thousands in our country, for the leather interests of the United States are very extensive. There being no less than 6,293 tanneries in our country, employing 20,909 persons, and in which is invested no less than $18,900,557. With the exception of those excellent articles published in Vol. 5, Scientific American by one of the oldest, ablest, and best educated tanners in the United States, we have seen nothing published on tanning in our country which was of any consequence until now. This work is a translation from a celebrated French work, with such emencjltions and additions by Mr. Morfit as to render it a new book with all that is good belonging to the old one. It is adorned with a plate of Zadock Pratt, and a short biography of the ex-senator tanner.— There are older and perhaps more experienced tanners than he in our country, but none, we suppose, so fortunately wealthy. Some very excellent chapters are presented on the nature of tanning, the different substances employed ; the qualities of different barks and a very excellent essay on the oaks of our country, of which there is a great variety. All the processes are explained and illustrated with 200 engravings, an4 the specifications of various patents for improvements are presented. No less than ten several patent accelerating processes (foreign and home inventions) are given, among which is that of Hibbard, published in Vol. 6, Scientific American. A great many other plans are also given, but that of Prof. Eaton, which has been highly praised, is not mentioned. The patent for it was granted at such a recent date, that information of the same could not have been obtained in time for publication. In looking over this book, and reading the different plans for improving leather, and for reducing the time occupied in tunning SL 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, lor tanners are like others wedded to old things; thus the rolling of leather—an operation now generally practised —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. The whole science of tanning depends on two principles, one the removal of the hair Irom the skin, with the least injury to the gelatinous matter of which it is composed, and the other is the rendering of the skin insoluble in water, and to resist the action of the atmosphere, and yet be flexible. The hair can be removed by lime, sweating, and other means, but the employment of a substance or substances that will combine with the gelatine of the skin to form a new substance, insoluble in water and incapable of being injuriously acted upon by the atmosphere, offers a wide field for the historian of the tanning art, and presents a subject for the study of every tanner at least in our country. The art of tanning was known, we suppose, before the flood; it is practised among all nations, civilized and savage, and the gist ot it lies in soaking the skins in different solutions of various vegetable substances of an astringent character until the tanning juices of those substances have combined with the whole skin and rendered it a new substance named leather. Oak and hemlock barks, sumac, willow, blackberries, catechu, kino, c, are employed. Those who wish to get an account of the various processes and substances employed, must consult this book. We have only another remark to make, it is this, we have never known any of the metallic solutions to be employed in tanning, and from their nature, in rendering some vegetable substance* insoluble, we believe that it would be worth the , trouble for some of our tanners to make a few experiments. We would recommend the chloride of tin; it is made by feeding drop-tin into muriatic acid until effervescence ceases. The way to try it would be to make up a solution of it in a tub of cold water, until it stood about 14 in the hydrometer; the skin should have undergone through the whole tanning process before it is placed in this solution, in which it should He about two hours, and be stirred up two or three times. After this it should be well washed in cold water, and then finished in a milk-warm water bath, when it will be ready for drying. It is our opinion that a superior leather would be produced by this addition to any of the present processes.