348 REPORT OF COMMISSIONER OF FISH AND FISHERIES. 



uiul for this purpose is not surpassed by any material obtainal)le. Some 

 ])arts of the skin of certain varieties of sharks when dried and iiardened 

 take a polish e(iual to that of stone, and bear a strong- res(Mnbiance to 

 the fossil coral poritc^s, and are nuich used in the manufactui-e of orna- 

 ments and jewelry. 



In preparing them for the use of cabinet-makers, shai'k skins are 

 merely cleaned and not tanned. The hard, dr}^ skins are soaked in 

 lukewarm Avater for three or four days, shaved on the Hesh side to 

 remove surplus tlesh and nuiscular tissue, and then dried. The skins 

 of some species of sharks are so hard that they can not ])e shaved. 

 The ap})earance of these skins is improved by bleaching, using chloride 

 of lime and sulphuric acid. Thedura])ility of some of them is remark- 

 able, outweai'ing many sheets of sandpaper of equal area. 



In tanning shark skin for leather or ornamental purposes an alum 

 process is generall}' employed. Each establishment usuall}' has its 

 own particular method, but the general process is much the same, con- 

 sisting of a preliminary soaking, liming-, bating, and fleshing, and then 

 tanning or preserving in an alum compound. The hard skins are first 

 soaked in water four oi' five days, and then in limewater for two to six 

 days, depending on the condition of the texture, temperature of water, 

 etc. The skins are washed free of lime and bated in bran water; then 

 shaved on the flesh side to remove all excess of flesh and the like. 

 The alum solution in which they are immersed is composed of a pound 

 of alum and one-flfth pound of salt to a gallon of water. The skins 

 remain in the solution two or three days, with occasional stirring. 

 On removal they are dried and are then ready for manufacturing. 



STURGEON SKINS. 



The skins of sturgeon are thick and unwieldy, and at flrst it might 

 appear impossible to use them for any purpose other than glue or fer- 

 tilizer stock. They are covered with rows of large prominent horn}' 

 bosses, leaving space for comparatively little flexible membrane between 

 each row. In the skin of the sturgeon common on the Paciflc coast, 

 and especially in the Columbia liiver, and those common in the Great 

 Lakes and on the Atlantic coast the membrane between the rows of 

 bosses may be tanned into a comparative!}^ flexible and very dui-able 

 leather, used as laees for mill belts and as durable as the ])elts them- 

 selves. But it is as ornamental leather, employed so as to display the 

 rows of bosses, that sturgeon skins are especially desirable. 



Some of these skins are remarkably attractive, particularly those 

 from a species found on the coasts of Europe, which are distinguished 

 by rows of small })ut very horny bosses, between which are numerous 

 horny protuberances varying in foi-m from a mere dot to beautiful, 

 irregularly shaped bosses nearly half an inch in length. (See plate 35.) 



Consideral)lc variation exists in the methods of tanning sturgeon 

 skins. Some varieties may l)o limed, w liil(> otiiers go to pieces in a 



