362 THE POPULAR SCIENCE MONTHLY. 



mechanical combination of gelatin and tannin or mineral salts 

 or oil it is evident that tanned leather is not the only kind of 

 leather. Indeed, there may be said to be three kinds, depending 

 on the constituent elements. There are (1) tanned leather, in 

 which the gelatin is combined with tannin or tannic acid ; (2) 

 tawed leather, in which the gelatin is combined with mineral 

 salts ; and (3) shamoyed leather, in which the gelatin is com- 

 bined with oils and fatty substances. Sir Humphry Davy has 

 distinguished between the first of these and the second and third 

 by the statement that tanned leather is a chemical combination, 

 its characteristic being that water will not separate its constituent 

 elements or dissolve their connection, whereas in the case of the 

 others it will return them to their original components. All 

 three kinds of leather are made largely in this country. Tawed 

 and shamoyed leather are used extensively for gloves, clothing, 

 and domestic purposes. Some of the finer qualities have a wide 

 use for fancy finish and ornamentation ; but red tanned leather is 

 the oldest in this country, and overtops the others by far in ex- 

 tent and importance, and the processes described have been those 

 pertaining to its manufacture. And there is a wide variety in 

 that. The heavier grades of leather, such as are used for trunks 

 and the soles of boots and shoes, are made from the butts or the 

 back of the hides of the buffalo, ox, and cow. The lighter grades, 

 such as kip or upper leather, are made from the hides of young 

 cattle older than calves and from the hides of a small breed of 

 cattle common to India, Russia, and Africa ; while all the spongy 

 leather and morocco, or its imitation, is prepared from sheep and 

 goat skins. These distinctions, however, are only general, but 

 they indicate the lines along which the various branches of the 

 industry divide. American tanners, too, have not been slow about 

 introducing new varieties of leather. Japanned leather, used 

 largely for fancy work and for certain styles of shoes, was first 

 made in this country in 1818 by Seth Boyden, of Newark, 1ST. J. 

 In the manufacture of this the leather is first coated with a com- 

 pound of linseed oil, umber, and lampblack, applied three or four 

 times, and then is treated to a varnish made of Prussian blue and 

 linseed oil. The leather, which had previously been stretched 

 over frames, is afterward run into ovens heated up to 175 Fahr. 

 Newark, too, was the original home of the enameled leather in- 

 dustry, David Crockett having introduced that finish. This is 

 made much like the japanned leather, except that it is less smooth 

 and less highly polished, the aim being to bring the grain into 

 relief. This is used almost wholly in the coverings of carriages, 

 and it is a branch in which America has always held the lead. 

 Alligator skins were first tanned in Louisiana about 1855, and a 

 considerable business has since grown up in some of the States. 



