859 PaiMARY ANIMAL FLUTBS. 



Jelly. Ttlsli- The next fubftance wWch I propofe to examine is jelly, 

 and'^bSomL^'''* The pccuhar charaaeriftic of this body is its property of be- 

 concrete by cold ;C«"^'"g concrete by cold, and being liquified by the applica- 

 and }s a large (jon of a gentle heat. It enters into the compofition of the 



component part v i i , t , r , 



of animals, blood, though lels largely than the albumen. It is alfo an in- 

 gredient in the tkin, membranous texture, ligaments, carti- 

 lages and tendons. By boiling it is eafily extraded from thefe 

 fubftances, and by evaporation and cooling the whole is re- 

 duced to a mafs of greater or lefs folidity, in proportion to the 

 previous degree of concentration. By a procefs of this nature, 

 ifinglafs is prepared from the bones and cartilages of fifli; as 

 this fubftance has been confidered to confif^ of jelly nearly in a 

 ftateof purity, I employed it for the following experiments. 

 Obtamed by the F"ur grains of ifinglafs were diffolved in 200 grains of 

 folutionof ifin- w^ter, and thus a ftandard tlnid was formed, one grain of 

 glajs. One fit- , . , , . , , ^ . „ ^„ • r i • , 



tiethpaitin which contamed ^'-^ gr. or jelly. I his folution became per- 

 v«aterwjll coagu- feflly concrete by cooling. In the firft place I withed to af- 

 certain how fmall a proportion of jelly diffolved in water was 

 capable of aflTuming the concrete flate. Equal parts of the 

 ftandard fluid and of water, i.e. one part of jelly to 100 

 parts of water, produced a compound which was completely 

 fiiffened by cooling; but I found that two parts of water to 

 one of the flandard, i. e. one part of jelly (o 130 parts of 

 Water, produced a compound, which though evidently gela- 

 tinous, did not atfume the concrete form. 

 Tt is aftWely One of the mofl; aflive prccipitants of jelly is fhe tanning 



precipitated by principle. I found that a mixture of 5 grains of the fiandard 

 folution and 93 of water,, produced a copious precipitate when 

 added to an equal quantity of an infufion of galls of the fame 

 llrength with that em ployed in the experiments upon albumen. 

 In this inftance the jelly was to the water as 1 to 1000. I af- 

 terwards reduced the quantity of jelly until it compofed j^V^ 

 part only of the folution, and in this cafe a confiderable pre- 

 cipitate was flill produced by the infufion of galls. 

 — butrtotby A quantity of the ftandard folution had a few drops of the 



*j. hth. acct. aqua lithargyri acetati added to it, but no more efFefl appeared 

 to be produced than would have enfucd from mixing it with an 

 equal quantity of pure water. 



2 Nt 



