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 caviare 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, co 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 lb. 



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 lertiliser. 



