104 Production of Isinglass on the Coasts of India. 



cabinet work. Russian authors state that Isinglass is sometimes 

 adulterated by the intermixture of pieces of common bladder and of 

 the intestines of animals. 



In comparing the Russian and Indian processes, we observe 

 a general resemblance, though the differences are considerable enough 

 to modify some of the results. In the first place, the Russian 

 manufacture, being more extensive, has men especially devoted to the 

 preparation of the Isinglass, while others prepare the Caviare, or salt 

 the fish. The inner membrane also of the Sturgeon yields the best 

 Isinglass, while in the Sele it seems to be rejected,* and this would 

 account for the more fibrous nature of the Bengal Isinglass ; but it 

 does not follow, that in the Sele, the innermost is the best. A 

 decided improvement would be effected if the Isinglass were prepared 

 as soon as possible after the fish is caught. The Sounds should be ex- 

 tracted, split, and more carefully washed than the native fishermen 

 are likely to practise if left to themselves, besides being freely exposed 

 to the air. 



The lightest kind of roof at the nearest point, as at Saugor 

 Island, would probably enable the Sounds to be better dried than 

 when exposed to a powerful sun, as in the latter case the oily parts 



* The structure of the air-vessel cannot be said to be membranous, the inner extraneous 

 membrane which we have said is rejected, is quite different from the air-vessel itself, and 

 consists of a net of blood vessels merely. 



The value of the Isinglass appears to depend mainly on the removal of this extraneous 

 membrane, which, as well as a similar outer membrane, may be peeled off when the air- 

 vessel is fresh, If this be done carefully, the Isinglass requires nothing more to render 

 it as pure as it can be. But if these membranes are allowed to remain, or if in removing 

 them, or from any other cause, the little blood vessels of which they are composed be burst 

 or bruised, permanent stains of blood are thus left, which no subsequent washing can re- 

 move. The Isinglass being translucent, these stains, however superficial they may be, ap- 

 pear to penetrate the mass (though such is not the case) and are visible on both sides. As the 

 removal of these membranes in the first instance when the fish is caught must be left to 

 the fishermen, from whose carelessness it would be impossible altogether to avoid some stain- 

 ed or discoloured spots, we would therefore recommend the article to be sorted, and such 

 parts as are free from stains and membranes, selected as 



Firsts. — This will always be of uniform yellowish white colour, and translucent when held 

 to the light. 



Seconds. — This will consist of the discoloured parts removed from the firsts, it will 

 be translucent on the edges of the stains, which will be found to be superficial, affecting only 

 one side. 



Thirds. — This would consist of parts of firsts and seconds, from which the membrane 

 lias been imperfectly removed. — Ed. 



