The Isinglass of Commerce. 247 



were white. Some were sprinkled or dusted with chalk, in 

 case of exposure to damp in their homeward voyage ; it 

 can be easily rubbed off. At Gwadur the air-vessels were 

 soaked in brine before being dried ; but elsewhere they are 

 simply removed and dried in the sun. 



The lining membrane of the air-vessel of the stur- 

 geon, as already noticed, yields the best isinglass, but it 

 has been rejected in the Indian forms, which accounts for 

 its more fibrous nature, although not proving that this 

 lining portion in India is of the best. East Indian isinglass 

 has some positive defects, such as retaining a fishy smell, 

 besides being partially insoluble, perhaps due to some por- 

 tions of the albuminous membranes remaining. In fact, 

 it requires more care in its preparation, which should be 

 undertaken whilst it is quite fresh ; and greater caution is 

 necessary in the drying process. If it be not properly 

 dried, it might possibly undergo a slight change or de- 

 composition, and become partially converted into a more 

 insoluble form of gelatine. A more important objection is 

 the smell, which, however, may likewise, to some extent, be 

 traced to the preparation. Care should be taken that it is 

 not contaminated by the animal fluid of the fish, for then 

 it becomes very difficult to purify. Likewise, it is too 

 thick, which may be obviated by beating or pressure, as 

 is now done with some American and Brazilian kinds. 

 " The extra labour that this would require," observes Royle, 

 " could be profitably saved by not tearing it into fibres, ,in 

 which form it is disapproved of in the market ; but it 

 might still be cut or rasped into a state fit for domestic 

 use." The same authority likewise states that — " It is pre- 

 ferable, and will be cheaper, to prepare the article and send 

 it as sheet isinglass, that is, in -the form of the slit sounds 

 themselves, or their purest membrane, washed, cleaned, and 



