IS1 



ISL 



of fining. Experience has taught the con- 

 sumers to reject them. 



Isinglass is best made in the summer, 

 as frost gives it a. disagreeable colour, de- 

 prives it of weight, and impairs its gela- 

 tinous principles; its fashionable forms 

 are unnecessary, and frequently injurious 

 to its native qualities. It is common to 

 find oily putrid matter, and exuviae of in- 

 sects, between the implicatedmembranes, 

 which, through the inattention of the cel- 

 larman, 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 can- 

 iiot be doubted to answer every purpose 

 more effectually in its native state, with- 

 out any subsequent manufacture what- 

 ever, especially to the principal consum- 

 ers, who hence will be enabled to procure 

 sufficient supply from the British colonies. 

 Until this laudable end can be fully ac- 

 complished, and as a species of isinglass, 

 more easily produceable from the marine 

 fisheries, may probably be more imme- 

 diately encouraged, it may be manufac- 

 tured as follows. The sounds of cod and 

 ling bear great analogy with those of the 

 accipenser genus of Linnaeus and Artedi ; 

 and are in general so well known as to 

 require no particular 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 previously to incipient 

 putrefaction, the sounds are cut out, 

 washed from their slimes, and salted for 

 use. In cutting out the sounds, the inter- 

 costal 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 en- 

 tire. 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 sur- 

 face 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 oft'. 

 The knife is nibbed upon the brush oc- 

 casionally, to clear its teeth ; the pockets 

 ai'e cut open with scissars, and perfectly 

 cleansed of the mucous matter with a 

 course cloth ; the sounds are afterwards 

 washed a few minutes in lime-water, in 

 !<<>! to absorb their oiiy principle, and 



lastly in clear water. They are then laid 

 upon nets to dry, but if intended to re- 

 semble the foreign isinglass, the sound of 

 the cod will only admit of that called 

 book, but those of ling both shapes. The 

 thicker the sounds are the better the 

 isinglass. 



ISIS, coral, in natural history, a genus 

 of the Vermes Zoophyta class and order. 

 Animal growing in the form of a plant ; 

 stem stony, jointed, the joints longitudi- 

 nally striate, united by spongy or horny 

 junctures, and covered by a soft porous 

 cellular flesh or bark ; mouth beset with 

 oviparous polypes. There are six species. 

 I. hippuris ; with white striate joints and 

 black junctures ; it is found chiefly in the 

 Indian seas, growing to rocks, and is from 

 two inches to two feet long. I. entrocha ; 

 stem testaceous, round, with orbicular 

 perforated joints and verticillate dichoto- 

 mous branches. Inhabits the ocean. The 

 stem is about the thickness of a finger, 

 with crowded flat orbicular joints perfo- 

 rated in the centre, the perforation is pen- 

 tangular, with the disk substriate from the 

 centre ; outer bark or flesh unequal, and 

 surrounded with a row of tubercles ; 

 branches thin, dichotomous, continued, 

 not jointed. 



ISLAND, or ICELAND, crystal, a body 

 famous among the writers of optics, for 

 its property of a double refraction ; but 

 improperly called by that name, as it has 

 none of the distinguishing characters of 

 crystal, and is plainly a body of another 

 class. Dr. Hill has reduced it to its pro- 

 per class, and determined it to be of a 

 genus of spars, which he has called, from 

 their figure, parallelopipedia, and of 

 which he has described several species, 

 all of which, as well as some other bodies 

 of a different genus, have the same pro- 

 perties-. Bartholine, Huygens, and Sir 

 Isaac Newton, have described the body at 

 large, but have accounted it either a crys- 

 tal or a talc ; errors which could not have 

 happened, had the criterions of fossils 

 been at that time fixed ; since Sir Isaac 

 Newton has recorded its property of mak- 

 ing an ebullition with aquafortis, which 

 alone must prove, that it is neither talc 

 nor crystal, both those bodies being- 

 wholly unaffected by that menstruum. 

 See CRYSTAL, ORYCTOLOGY, and TALC. 



It is always found in form of an oblique 

 parallelepiped, with six sides, and is found 

 of various sizes, from a quarter of an inch 

 to three inches or more in diameter. It 

 is pellucid, and not much less bright than 

 the purest crystal, and its planes are ajl 

 tolerably smooth, though, when nicely 

 viewed, they are found to be waved with 



