412 
Isinglass^ 
It is remarkable, that during the conversion of isim 
glass into fining, the acidity of the menstruum seems 
greatly diminished, at least to taste ; not on account of 
any alkaline property in the isinglass probably, but by its 
inveloping the acid particles. It is likewise reduceable 
into jelly with alkaline liquors, which indeed are solvents 
of all animal matters ; even cold lime water dissolves it 
into a pulpous magma. Notwithstanding this is inad- 
missible as fining, on account of the menstruum, it pro- 
duces admirable effects in other respects ; for, on com- 
mixture with compositions of plaster, lime, &c. for orna- 
menting walls exposed to the vicissitudes of weather, it 
adds firmness and permanancy to the cement ; and if 
common brick mortar be worked up with this jelly, it 
soon becomes almost as hard as the brick itself ; but for 
this purpose it is more commodiously prepared, by dis- 
solving it in cold water, acidulated with vitriolic acid ; 
in which case, the acid quits the jelly, and forms with the 
lime a selenetic mass, while at the same time the jelly 
being deprived in some measure of its moisture, through 
the formation of an indissoluble concrete amongst its 
parts, soon dries, and hardens into a firm body, whence 
its superior strength and durability are easily comprehend- 
ed. 
It has been long a prevalent opinion, that 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 success. This being full of rugae ^ adheres so firm- 
ly to the external membrane, which is useless, that the 
labour of repeating them supercedes the advantage. The 
intestines, however, which in the larger fish extend seve- 
ral yards in length, being cleansed from their mucus and 
dried, were found surprisingly strong and elastic, resemb 
ling cords made with the intestines of other animals, com 
