60 PHILOSOPHY OF ZOOLOGY* 



readily, especially when assisted by heat. It is insoluble in 

 alcohol. 



Dr THOMSON found that a concentrated solution of gela- 

 tine, yielded, with nitro-muriatc of gold, a copious yellow- 

 ish- white precipitate* soluble by adding water ; and, with ni- 

 trate of mercury, a very copious curdy precipitate. 



When a solution of tannin is dropt into a solution of ge- 

 latine, an union takes place, and an insoluble precipitate, 

 of a whitish colour, falls to the bottom. It is on the 

 union of the tannin of the oak bark with the gelatine of the 

 hides, that the process of tanning leather depends. 



When exposed to the destructive distillation, it yields a 

 watery liquor, impregnated with ammonia, a fetid oil, and 

 a bulky charcoal, which, by incineration, gives obvious 

 traces of phosphate of lime, and phosphate of soda. It 

 consists of carbon, hydrogen, oxygen, and azote, in propor* 

 tions which have not been satisfactorily determined. 



Gelatine exists in abundance in the different parts of ani* 

 mals, as bones, muscles, skin, ligaments, membranes, and 

 blood. It is obtained from these substances, by boiling 

 them in warm water ; removing the impurities, by skim- 

 ming, as they rise to the surface ; or by subsequent strain- 

 ing and clarifying. It is then boiled to a proper consis- 

 tency. It is the characteristic ingredient of the softest and 

 most flexible parts of animals. 



It is extensively used in the arts, under the names Glue 

 and Size, on account of its adhesive quality, and to give 

 the requisite stiffness to certain articles of manufacture. In 

 domestic economy, it is likewise employed in the form of 

 jelly, and in the formation of various kinds of soup. What 

 is termed Portable Soup is merely jelly, which has been 

 dried, having been previously seasoned, according to the 

 taste, with different spices. 



2. Albumen. This substance derives its name from the 

 Latin term for the white of an egg, that liquid being con- 



