150 REPORT OF COMMISSIONER OF FISH AND FISHERIES. 
which is of course very great, although diminishing in quantity, while — 
that from the true fishes appears to be increasing. 
The use of fish-oil as food or medicine is comparatively limited. Its — 
application is more generally to the manufacture of soap, and in the 
dressing of leather, for purposes of illumination, and, to some extent, in 
painting. During the late civil war in the United States, when the 
supply of turpentine was limited, the oil of the menhaden was employed 
as requiring less turpentine in its service. 
3. As manures and fertilizers.—The refuse, or so-called ‘‘serap,” left 
after the expression of oil from boiled or steamed fish, is used very 
largely as a fertilizer, for which it is especially valuable in consequence 
of the large amount of phosphorus contained in the bones, and of the - 
nitrogenous matters. This is used either directly or after being sub- 
jected to chemical treatment, and, for the most part, mixed with the 
phosphatic earths found on the coast of South Carolina and Georgia, 
with the mineralized guanos of the Sombrero Island of the West In- 
dies, or with the well-known guano of Peru or of the islands of the 
Pacific. 
4, Other purposes.—The remaining applications of fish are of much 
less moment than those to which we have already adverted, being 
usually exceptional and confined to limited areas. 
_ Although the skins of fishes have been utilized in various ways by 
different nations for a long period of time, within a few years this in- 
dustry has become prominent, and will in time represent a very impor- 
tant element in the total products of the sea. Although the skins of 
cod, salmon, and other fishes are not unfrequently used as clothing for 
both the feet and the body by the tribes of the northwest coast of 
America, it is only of late that such skins promise to come into use 
among civilized nations. A patent has been taken out in the United 
States for the manufacture of shoes from the skin of the cusk (Brosmius 
vulgaris). The skins of various species of sharks are now very care- 
fully saved in the Red Sea, the Mediterranean, and the Indian Ocean, 
and constitute a considerable article of commerce, the best material 
being furnished by the genera Scyllium, Scymnus, Spruax, Acanthias, 
Sqatina, Squalus, &c. These are used largely for polishing wood and 
metai, for covering boxes, spectacle and spy-glass cases, &c. 
The skin of the burbot or ling (Lota) is employed in Russia and Si- 
beria for trimmings of dresses and for the windows of dwellings, in- 
stead of glass. It is also made into bags for holding clothing, &e. 
The skins could be taken off from many fish which are now entirely 
wasted, and from others the meat could be employed in some form or 
other. When tanned or dressed the skins could be converted into arti- 
cles of clothing or ornament, and could be used in polishing wood or 
metal. 
AS already explained we are far from deriving all the benefit that we 
might from our sea fisheries, not only neglecting, as we do, a large part — 
