63 



NATURALIST S CABINET. 



Jackson's remarks. 



thread through the peg-holes for convenience of 

 package and exportation. 



" The membranes of the book sort being thick 

 and refractory, will not admit a similar forma- 

 tion with the preceding; the pieces, therefore, 

 after their sides are folded inwardly, are bent in 

 the centre, in such a manner that the opposite 

 sides resemble the cover of a book, from whence 

 its name, a peg being run across the middle, 

 fastens the sides together, and thus it is dried 

 like the former. This sort is interleaved, and 

 the pegs run across the ends, the better to pre- 

 vent its unfolding. 



" That called cake isinglass, is formed of the 

 bits and fragments of the staple sorts, put into 

 a flat metalline pan, with a little water, and 

 heated just enough to make the parts cohere 

 like a pancake, when it is dried ; but frequently 

 it is overheated, as such pieces, as before ob- 

 served, become useless in the business of fining. 

 Experience has taught the consumer to reject 

 them. 



" It has long been a prevalent opinion, thai 

 sturgeon, on account of its cartilaginous nature, 

 would yield great quantities of isinglass ; but, on 

 examination, no part of this fish, except the 

 inner coat of the sound, promised the least suc- 

 cess. This being full of ruga, adheres so firmly 

 to the external membrane, which is useless, that 

 the labour of separating them supersedes the ad- 

 vantage. The intestines however, which in the 



