34 History of physical Science from [July, 



no action on olivile ; concentrated sulphuric acid immediately 

 chars it. Concentrated acetic acid dissolves it very readily, 

 either cold or hot. The solution is colourless ; and no precipitate 

 falls when it is mixed with water, unless the olivile has been 

 mixed with resin, in which case the resin is precipitated in the 

 state of a yellowish powder. 



The acetates of lead are the only salts that act upon solutions 

 of olivile. They precipitate its aqueous solution in very white 

 flocks, which are soluble in acetic acid. 



Alcohol is the best solvent of olivile ; when hot, it appears to 

 dissolve it in any quantity whatever. Sulphuric ether has no 

 action on it, neither have the fixed or the volatile oils ; but these 

 last bodies, while hot, dissolve a small portion of it, which they 

 allow to precipitate as they cool. — (Ann. de Chim. et de Phys. 

 iii. 105.) 



2. Extractive. — This is a term which has been applied by 

 chemists to a supposed vegetable principle, which is conceived 

 to exist in a great many extracts, though it has never yet been 

 separated nor obtained in a state of purity. The probability is, 

 that no such principle exists. Braconnot has lately turned his 

 attention to this intricate subject, and has analyzed a variety of 

 vegetables, supposed to contain extractive, without being able to 

 find any substance entitled to that name. His paper is a very 

 elaborate one, and contains much useful information ; but it i.s 

 too long to be introduced here, and is not very susceptible of ' 

 abridgment. We shall probably insert a translation of it into a 

 future number of the Annals of Philosophy. He divides vege- 

 table extracts into five genera. 



(1.) Azotized extracts, slightly bitter. — The taste is slightly 

 bitter. They are precipitated by the infusion of nut galls-. They 

 contain two annualized principles. They yield ammonia when 

 distilled. Examples ; extract of borage, bugloss, cochlearia, 

 cresses, senna, saponaria, &c. 



(2.) Azotized extracts, very bitter. — They contain two animal- 

 lized principles, one of which is veiy bitter, and soluble in 

 alcohol. They are precipitated by nutgalls. They yield 

 ammonia when distilled. Examples; extract of wild cucumber, 

 marsh trefoil, fumitory, nux vomica, &c. 



• (3.) Hydro-azotized extracts, very bitter. — When heated, they 

 burn with a lively flame, and furnish a quantity of hydrogen in 

 excess of that which is requisite to form water with the oxygen 

 present. They are precipitated by nutgalls ; and they contain a 

 hydrogenated principle often associated with other animal sub- 

 stances. Examples ; extract of opium, aloes, colocynth, 

 absinthium, gratiola, cinchona of St. Domingo, poppy, cheli- 

 donium, &c. 



(4.) Oxygenized extracts. — Their taste is often saccharine ; 

 sometimes astringent, or acid. They contain no sensible portion 

 of azote. They are not precipitated by nutgalls. When distilled, 





