Chap, i.] Jelly, Glue, &V.. 79 



menftrua. If a part of an animal is boiled in water, it 

 is gradually diffolved, and a matter is extracted, which 

 forms a fjiid but tremulous mafs when cold, and 

 which is called jelly. This is found moft plentifully 

 in the white parts of animals, but may be obtained in 

 a fmaller or greater proportion from all. It is nearly 

 inodorous and infipid, and is foluble both in cold and 

 hot water, but more eafily in the latter. When its 

 watery parts are more fully evaporated, it forms glue. 

 The jelly of animals is very analogous to the gum of 

 vegetables, except that the latter does not contain 

 azote, and of courfe is lefs prone to the putrefaclive 

 fermentation, and is incapable of affording volatile al- 

 kali. The glue obtained by boiling animal matters, 

 differs in fome meafure according to the firmnefs or 

 laxity of the fubftance from which it is obtained ; thus 

 the fkins, tendons, cartilages, and ligaments afford the 

 firmed glue. The fkins of eels are the bafis of gold 

 iize ; and from old white leather gloves and parch- 

 ment is made a kind of glue ufed by painters. Glues 

 differ from each other in their confidence, tafte, fmell, 

 and folubility : there are fome which readily become 

 foft in cold water; others are not difiblved but in boil- 

 ing water -, but the preparation of the latter is not ge- 

 nerally known. The beft glue is tranfparent, of a yel- 

 low brownifh colour, without fmell and tafte, and en- 

 tirely foluble in water, with which it forms a vifcid uni- 

 form fluid. Animal jelly differs from glue, only in 

 poffeffing a lefs degree of confidence and vifcidity. 

 The firft is more efpecially obtained from the foft and 

 white parts of animals, and is far more abundant in 

 thofe which are young. Glue is obtained in greateft 

 perfection from the toughed parts of older animals. 

 Jelly and glue are infoluble in fpirit of wine. 



Lymph 



