348 REPORT OF COMMISSIONER OF FISH AND FISHERIES. 



and for this purpose is not surpassed l)y any material obtainable. Some 

 parts of the skin of certain varieties of sharks when dried and hardened 

 take a polish equal to that of stone, and bear a strong reseni})lance to 

 the fossil coral porites, and are nuich used in the manufacture of orna- 

 ments and jewelry. 



In preparing them for the use of cabinet-makers, shark skins are 

 merely cleaned and not tanned. The hard, dr}^ skins ai-e soaked in 

 lukewarm water for three or four days, shaved on the flesh side to 

 remove surplus flesh and muscular tissue, and then dried. The skins 

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

 The appearance of these skins is improved by bleaching, using chloride 

 of lime and sulphuric acid. The durability of some of them is remark- 

 able, outwearing many sheets of sandpaper of equal area. 



In tanning shark skin for leather or ornamental purposes an alum 

 process is generally employed. Each establishment usually 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 or 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-fifth pound of salt to a gallon of water. The skins 

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

 On removal thej^ are dried and are then read}^ for manufacturing. 



STURGEON SKINS. 



The skins of sturgeon are thick and unwieldy, and at first 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 horny 

 bosses, leaving space for comparatively little flexil)le membrane between 

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

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

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

 bosses may be tanned into a comparativel}' flexible and very durable 

 leather, used as laces for mill belts and as durable as the belts them- 

 selves. But it is as ornamental leather, employed so as to displa}' the 

 rows of bosses, that sturgeon skins are especially desirable. 



Some of these skins are remarkabh' attractive, particuhirly those 

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

 by rows of small but very horny bosses, between which are numerous 

 horny protuberances varying in form from a mere dot to beautiful, 

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



Considerable variation exists in the methods of tanning sturgeon 

 skins. Some varieties ma}^ be limed, while others go to pieces in a 



