366' PHILOSOPHICAL TKANSACTIONS. [aNNO 1773. 



sort is interleaved, and the pegs run across the ends, the better to prevent its 

 unfolding. 



That called cake isinglass is formed of the bits and fragments of the staple 

 sorts, put into a flat metalline pan, with a very little water, and heated just 

 enough to make the parts cohere like a pancake, when it is dried; but frequently 

 it is over-heated, and such pieces, as before observcil, are useless in the business 

 of fining. Experience has taught the consumers to reject them. 



Isinglass is best made in the summer, as frost gives it a disagreeable colour, 

 deprives it of weight, and impairs its gelatinous principles; its fashionable forms 

 are unnecessary, and frequently injurious to its native qualities. It is common 

 to find oily putrid matter and exuviae of insects between the implicated mem- 

 branes, which, through the inattention of the cellar-man, often contaminate 

 wines and malt liquors in the act of clarification. These peculiar shapes might, 

 probably, be introduced originally with a view to conceal and disguise the real 

 substance of isinglass, and preserve the monopoly ; but, as the mask is now taken 

 off, it cannot be doubted to answer every purpose more effectually in its native 

 state, without any subsequent manufacture whatever, especially to the principal 

 consumers, who hence will be enabled to procure sufficient supply from the 

 British colonies. Until this laudable end can be fully accomplished, and as a 

 species of isinglass, more easily producible from the marine fisheries, may pro- 

 bably be more immediately encouraged, it may be manufactured as follows. 



The sounds of cod and ling bear great analogy to those of the acipenser genus 

 of Linnaeus and Artedi, and are in general so well known, as to require no par- 

 ticular description. The Newfoundland and Iceland fishermen split open the fish 

 as soon as taken, and throw the back bones, with the sounds annexed, in a heap ; 

 but previous to incipient putrefaction, the sounds are cut out, washed from their 

 slimes, and salted for use. In cutting out the sounds, the intercostal parts are 

 left behind, which are much the best; the Iceland fishermen are so sensible of 

 this, that they beat the bone upon a block with a thick stick, till the pockets, 

 as they term them, come out easily, and thus preserve the sound entire. If the 

 sounds have been cured with salt, that must be dissolved by steeping them in 

 water, before they are prepared for isinglass; the fresh sound must then be laid 

 upon a block of wood, whose surface is a little elliptical, to the end of which a 

 small hair brush is nailed, and with a saw-knife, the membranes on each side of 

 the sound must be scraped oiF. The knife is rubbed on the brush occasionally, 

 to clear its teeth ; the pockets are cut open with scissars, and perfectly cleansed 

 of the mucous matter with a coarse cloth: the sounds are afterwards washed a 

 few minutes in lime-water, in order to absorb their oily principle, and lastly in 

 clear water. They are then laid upon nets, to dry in the air; but, if intended 

 to resemble foreign isinglass, the sounds of cod will only admit of that called 



