467 
—— — ———— 
placed on a wire screen over a zinc-lined trough four feet long, two feet wide and 
eighteen inches deep. The meshes of the wire netting are just of sufficient width 
to allow the eggs to fall through. These are then placed in clean kegs, and the 
best German (Liineburg) salt is rubbed in by hand. This extracts in a short time 
(ten to fifteen minutes) fluid from the eggs, which are then placed in quantities 
of 8 to 10 lbs. in sieves and drained. The ecaviare is therefore ready for the mar- 
ket in a few hours. That from the Lake Sturgeon is said to be of superior quality 
to that of the marine species and there is therefore a constantly increasing 
demand for it. 
Certain economic uses of fish, other than as food, require now to be noticed. 
One of these is the manufacture of isinglass which has been carried on to a cer- 
tain extent in the States, and the important source of which is the sounds or 
air-bladders of Sturgeon. The method employed is to remove from the vertebral 
column by means of a knife the absolutely fresh sounds, to place them in clean 
water, and in strong brine on the following day after the thin lining has been 
scraped off. They are then dried on frames covered with network and finally 
exposed to the sun for four or five weeks to bleach the isinglass. Such isinglass 
manufactured at Sandusky, Ohio, to the amount of 3,000 lbs. per annum is worth 
$1 a Ib. 
Sturgeon oil obtained by pressure from the livers brings 40 cents a gallon, 
and at Sandusky about 25 barrels of oil per annum are secured in this manner. 
The Sturgeon therefore which was formerly regarded as of no economic import- 
ance is destined to be one of the most valuable fish, especially of Lake Erie. 
The recent abundance of the Alewife in Lake Ontario has been taken 
advantage of for the manufacture of fish-oil and guano. After the fish have 
been cooked twenty minutes they are subjected to hydraulic pressure ; a million 
fish yield 500 gallons of oil and 63 tons of fertiliser. 
