VOL. LXIII.] PHILOSOPHICAL TRANSACTIONS. 365 



and what in English is called sound, be admitted, which seems particularly as- 

 certained in a certain genus, viz. the asellus ofWillugby, or gadus of Artedi, 

 his description is a little erroneous with respect to its termination near the vesica 

 urinaria; tor in cod and ling, the continuation of the sound, or air-bladder, may 

 be easily traced from thence to the last vertebra adjoining the tail. The sounds 

 which yield the finer isinglass, consist of parallel fibres, and are easily rent longi- 

 tudinally; but the ordinary sorts are found composed of double membranes, 

 whose fibres cross each other obliquely, resembling the coats of a bladder ; hence 

 the former are more readily pervaded and divided with subacid liquors ; but the 

 latter, though a peculiar kind of interwoven texture, are with great difficulty 

 torn asunder, and long resist the power of the same menstruum; yet, when duly 

 resolvetl, are found to act with equal energy in clarifying liquors. 



Isinglass receives its different shapes in the following manner. The parts of 

 which it is composed, particularly the sounds, are taken from the fish while 

 sweet and fresh, slit open, washed from their slimy sordes, divested of every thin 

 membrane which invelops the sound, and then exposed to stiffen a little in the 

 air. In this state, they are formed into rolls about the thickness of a finger, and 

 in length according to the intended size of the staple : a thin membrane is gene- 

 rally selected for the centre of the roll, round which the rest are folded alter- 

 nately, and about half an inch of each extremity of the roll is turned inwards. 

 The due dimensions being thus obtained, the two ends of what is called short 

 staple are pinned together with a small wooden peg ; the middle of the roll is 

 then pressed a little downwards, which gives it the resemblance of a heart shape, 

 and thus it is laid on boards, or hung up in the air to dry. The sounds which 

 compose the long staple, are larger than the former; but the operator lengthens 

 this sort at pleasure, by interfolding the ends of one or more pieces of the sound 

 with each other. The extremities are fastened with a peg, like the former ; but 

 the middle part of the roll is bent more considerably downwards ; and in order to 

 preserve the shape of the three obtuse angles thus formed, a piece of round stick, 

 about a quarter of an inch diameter, is fastened in each angle with small wooden 

 pegs, in the same manner as the ends. In this state it is permitted to dry long 

 enough to retain its form, when the pegs and sticks are taken out, and the 

 drying completed ; lastly, the pieces of isinglass are colligated in rows, ■ by run- 

 ning packthread through the peg holes, for convenience of package and ex- 

 portation. 



The membrane of the book sort, being thick and refractory, will not admit a 

 similar formation with the preceding ; the pieces therefore, after their sides are 

 folded inwardly, are bent in the centre, in such manner, that the opposite sides 

 resemble the cover of a book ; whence its name; a peg being run across the 

 middle, fastens the sides together, and thus it is dried like the former. This 



