Production of Isinglass on the Coasts of India. 81 



contain more or less of the three staminal principles, and therefore 

 Gelatine may be one of them. 



Isinglass, as already stated, is one of the purest forms of animal 

 jelly, and is brought to market in different forms, sometimes in that 

 of simple plates, at other times rolled up in different shapes, or cut 

 into fine threads. When of good quality, Isinglass is of a whitish 

 colour, thin and semi-transparent, but tough and flexible, destitute 

 of taste as well as of smell. The inferior kinds are thicker, yellowish 

 coloured, opaque, and sometimes having a fishy smell and taste. 

 When placed in cold water, it becomes soft, then swells, and if held 

 up to the light in this state is opalescent. In boiling water, Isinglass 

 is entirely dissolved, with the exception of a very minute proportion 

 of impurities, which Mr. Hatchett ascertained did not amount to 

 more that 1.5 parts in 500; these consisted of earthy residue, 

 which appeared to be the phosphates of soda and of lime. A solution 

 of one part of Isinglass in 100 of water when cooled down assumes 

 the form of a clear and colourless jelly ; which is a compound of pure 

 gelatine and water. Though the best Isinglass is thus completely 

 dissolved in hot water ; yet much of that found in commerce does not 

 become so, in consequence of the presence of albuminous parts. 



With respect to the action of acids and alkalies, as well as of 

 tannin and other chemical re-agents, the effects are the same as those 

 produced on a solution of gelatine. 



Isinglass, being mild and unirritating in its nature, and at the same 

 time nutritious, is much employed as an article of diet for the sick 

 and convalescent, and the fine shreds into which it is cut and kept in 

 shops, give great facilities for making a jelly in the shortest possible 

 time. This can be made as palatable and nourishing as any by the 

 addition of sugar and milk, acids or spice ; about one-third or half an 

 ounce is sufficient for a pint of water. It may also be taken in the 

 form of a soup with the addition of salt, spices, and sweet herbs, or 

 it may be employed medicinally as an emollient and demulcent, 

 either externally or internally. The best kinds of Isinglass are alone 

 employed in articles of diet and for the best confectionary, being add- 

 ed in small quantities to other, especially vegetable, jellies, to give 

 them a tremulous appearance. But gelatine is now frequently sub- 

 stituted. 



M 



