CHONDRIN. 



strength to that article, and likewise by linen-manufacturers, 

 gilders, polishers, painters, &c.* 



Isinglass. This substance agrees with size in being transpa- 

 rent, but it is much finer, and is therefore sometimes employed 

 as an article of food. It is prepared in Russia from the air-blad- 

 ders and sounds of different kinds of fish which occur in the 

 mouths of large rivers ; chiefly different species of Accipenser, as 

 the Sturio stellatus, Huso ruthenus, and likewise the Siluris glanis. 

 The bladder is taken from the fish, clean washed, the exterior 

 membrane separated., cut lengthwise and formed into rolls, and 

 then dried in the open air. When good, isinglass is of a white 

 colour, semitransparent, and dry. It dissolves in water with 

 more difficulty than glue, probably because it is not formed ori- 

 ginally by solution. From the analysis of isinglass by Hatchett, 

 we learri that it is almost completely convertible into gelatin by 

 solution and boiling. Five hundred grains of it left by incine- 

 ration 1 -5 grain of phosphate of soda, mixed with a little phos* 

 phate of lime. 



A coarse kind of isinglass is prepared from sea-wolves, por- 

 poises, sharks, cuttle-fish, whales, and all fish without scales. The 

 head, tail, fins, &c. of these are boiled in water, the liquid skim- 

 med and filtered, and then concentrated by evaporation till it ge- 

 latinizes on cooling. At that degree of concentration, it is cast 

 on flat slabs and cut into tablets. This species is used for clari- 

 fying, stiffening silk, making sticking-plaster, and other pur-- 

 poses.f 



SECTION II. OF CHONDRIN. 



When any of the permanent cartilages of the body,J as those 

 of the larynx, ribs, or joints, are boiled from twelve to eighteen 

 hours in water, they dissolve more or less completely, and when 

 the solution is sufficiently concentrated, it gelatinizes precisely 

 like collin, and when dried constitutes a glue, which may be used 

 for all 1 ' the purposes to which common glue is applied. It is, 

 therefore, a gelatin ; but it differs from collin by several proper- 

 ties first determined by M. J. Miiller, who gave it the name of 



* Clennell. See Johnson's History of Animal Chemistry, i. 315. 



f Fabricius de Ichthyocolla, Jackson on British Isinglass, Phil. Trans. Ixiii. 

 and Johnson's Animal Chemistry, i. 231. 



\ The cartilages of the ear and the eyelids excepted, which yield no glue in, 

 forty-eight hours boiling. 



