Chemical Science. 221 



der, which, put in the filter, pressed and dried, looks like an earthy 

 salt, and remains unchanged in the air. When moist it forms 

 extract by means of the air. The combination with soda is much 

 more soluble. 



M. Berzelius then describes the tannin obtained from various other 

 sources, as catechu, gum kino, cinchona, witli their processes, and 

 states that these kinds of tannin dilfer very much from each other. — 

 A/m. de Chimie^ xxxvii. 385. 



37. Vegetable Gelatine^ and Albumen. — M. Berzelius has lately 

 examined gluten, and says that the gliadine and zymoma of Taddei 

 are notliing else than the well known and ordinary principles of 

 vegetables named above. Boil gluten with successive portions of 

 alcohol until the latter ceases to become turbid upon cooling ; mix 

 these solutions with water, and distil ; as the aqueous residuum cools, 

 a glutinous coherent mass will separate, resembling gluten. It is 

 vegetable gelatine, and the same substance as that separated by 

 Einhol's process from barley, &c. The substance insoluble in 

 alcohol is vegetable albumen. 



Vegetable gelatine is grayish, yellow in colour, adhesive, glutinous 

 and elastic, having no taste, but a pecuhar odour. It dries into a 

 transparent, shining substance. It dissolves in alcohol ; if cold 

 alcoho Ibe used, a viscid foreign substance is separated, not gelatine. 

 It dissolves in vinegar, leaving also a viscid insoluble matter ; when 

 precipitated by an alkali, it resumes its viscid state. The mineral 

 acids, with the exception of the phosphoric, form glutinous com- 

 pounds insoluble until the excess of acid has been removed. This 

 principle combines with and neutralizes alkalies, forming solutions, 

 which, when evaporated, yield a transparent matter. Earths and 

 oxides form insoluble compounds. 



Vegetable albumen is almost perfect in its resemblance to white of 

 egg. It dissolves in alkalies, and when in excess, the solutions are 

 neutral. It then coagulates slightly by heat, but the principal part 

 is retained in solution ; it combines with acids, and when exactly 

 saturated the substance remains soluble, but excess of acid (except 

 the acetic and phosphoric) precipitates it. Before the action of 

 potash, the vegetable albumen dissolves feebly in vinegar or phos- 

 phoric acid, but by ebullition with these acids, it forms a transpa- 

 rent colourless jelly of considerable volume. 



The azoted principle contained in emulsive seeds has been con- 

 sidered analogous to the coagulum of milk. Souberian has shown 

 that that from almonds has all the properties of white of egg; it is, 

 in fact, the same substance as vegetable albumen. — Amu de Chimie, 

 xxxvii. 215. 



38. Preparation of Piperine, by Mr. Carpenter. — Digest one 

 pound of coarsely powdere 1 black popper in one gallo.i of alcohol 

 for ten days ; distil off one hilf of th j alcohol in a water bath ; add 



