Production of Isinglass on the Coasts of India. 101 



the sound is to be opened, and as much of the lining membrane re- 

 moved as possible by the hand. A large earthen vessel is then filled 

 with sounds, and water poured into it, and the whole covered up for 

 twelve hours, when the sounds will have been brought back to their 

 original soft state, in which they may be perfectly cleaned, as if they 

 had been obtained fresh. 



" For the removal of discoloured parts, as well as for perfectly 

 softening the more solid portions of the Sounds without dissolving 

 the thinner parts, they are steeped a short time in alum water, that 

 is, an ounce of alum in four or five gallons of water. When satu- 

 rated, each Sound is to be taken out and spread on a linen or cotton 

 cloth, also saturated with alum water, and then rolled tight up and 

 set aside for twelve hours, and this process is to be repeated until 

 the Sound is perfectly bleached, when it may be either drawn out 

 between the fingers into shreds in the direction of the fibre, or rolled 

 into thin plates. When the quantity in hand is large, a little chalk 

 is sprinkled over the soft substance after it has been rolled. This 

 adheres as long as the Isinglass is soft, but may be dusted or rubbed 

 off when it dries. There is, however, no harm in allowing it to 

 remain on the surface, as in case of exposure to damp during the 

 voyage, it may act as a preservative, and it can always be easily 

 rubbed off before use." 



If we wish to compare this, with the method of preparing Isinglass 

 on the shores of the Caspian, we shall find that it is difficult to get 

 any account, which is sufficiently minute for a manufacturer to take 

 as a guide, in all the details of the operation. Most of the accounts 

 published are by scientific travellers, and therefore worthy of atten- 

 tion, but the preparation of Isinglass is only one of the numerous 

 subjects which they describe. 



The earliest account pretending to any accuracy is that of H. Jack- 

 son, published in 1783, in the 63rd vol. of the Philosophical Trans- 

 actions, who says he made an unsuccessful voyage to Russia to learn 

 the mode of making Isinglass. But he afterwards succeeded in get- 

 ting the necessary information. His object was to find a good sub- 

 stitute for brewers in fining their beer. For this purpose, he first as- 

 certained experimentally that Isinglass, or the natural membrane of 

 the Sounds of Fish, is much more efficacious than any solution of 



