L. TECHNOLOGY. 521 



obtainable from many kinds of fish in immense quantities, 

 and which are usually thrown away. When entirely ripe, 

 these roes are capable of furnishing a large amount of albu- 

 men, and in this condition are to be stripped from the invest- 

 ing membrane, and made free from adhesion as much as 

 possible. They are then placed in a sieve, rubbed with a stiff 

 brush so as to break up their contents and allow the albumen 

 to pass through. This is to be washed with water, to which 

 one part of ammonia in three hundred is to be added, so that 

 the albumen adhering to the sieve shall be carried through. 

 The solution thus obtained is then to be placed in high ves- 

 sels and allowed to stand for some days, and when it becomes 

 clear the albumen can be poured off into flat dishes, and 

 evaporated in well ventilated rooms. The cleansing is said 

 to be facilitated by passing through coarse sand or powdered 

 glass. The best roe for this purpose is that of fresh-water 

 fishes, such as pikes, but the albumen can be obtained from 

 any species. If the roes have been kept too long, of course 

 there is a tendency to decomposition, accompanied by an un- 

 pleasant smell, but this is not at all appreciable if the labor 

 be prosecuted at the proper time. 13 C, May 15, 1871, 663. 



IMPEOVED MAXUFACTUEE OF GLUE. 



Among industrial problems, that relating to the prepara- 

 tion of glue, especially in the moist, warm weather of sum- 

 mer, without its becoming acid or more or less putrid, is one 

 of considerable moment, the greatest care and most contin- 

 ued precaution sometimes failing to secure a uniform and 

 satisfactory result. A late paper by Prof. Fleck contains the 

 following valuable hints on the subject : 



It is well known that certain salts, and especially sulphate 

 of ammonia, Epsom salts, Glauber's salts, hyposulphite of 

 soda, zinc, iron, copper, and manganese vitriol, together with 

 absolute alcohol, possess the property of separating glue from 

 its solution. This depends not upon any acquired property 

 of insolubility of the glue in water by such addition, but on 

 a simple extraction of its water by the new substance. 



If, now, sulphate of ammonia or hyposulphite of soda be 

 dissolved in as small a quantity of water as possible, so as 

 to form a concentrated solution, and this be added to a glue 

 jelly melted over steam or warm water, stirring the mass 



