ON PEPPER. (J3* 



to different refalts. Vegetable fabftances not on!)' pafs through 

 a fuit of changes while they conftitute a part of the living 

 plant, but many of them are dill fufceptible of continuing the 

 fuit even after they are feparated from the parent that produced 

 them. Thu^ gluten when kept moift runs into cheefe; oil when 

 long expofed to the fun and air hardens into tvax, or refcu, and 

 the milky juices of plants into giim-refms . Our analyiis fre- 

 quently accelerates or occafions thefe changes, and even pro- 

 duces others altogether new. Hence the principles which we 

 exlra6l from vegetable bodies are not always the conftituent<J of 

 thefe bodies; but a new fet of principles formed during the 

 analyfis, and of courfe varying according to the nature and 

 circumftances of the experimental inveftigation. Hence we 

 are feldom able to form again the old vegetable compound by 

 uniting together all the ingredients which we have extracted 

 from it. 



Thefe difficulties increafe with the complicated nature of the Complication of 

 vegetable body; for the greater the number of conftituents isjP"'^^*^^ ' 

 the more liable are they to undergo alteration during an analy- 

 fis. Indeed fome vegetable principles feem incapable of ex- 

 ifting except in combination, and are decorapofed or new mo^ 

 dified the inftant we attempt to feparate them. 



The variety of fiates in which the vegetable principles fuc- Loofe nomen- 

 cellively exift, together with the difficulty of examining ^^^*^''' tables! ° ^^^' 

 properties without altering their nature, has rendered it necef- 

 fary for chemifls to apply the names of them with greater lati- 

 tude than is ufual in other departments of the fcience. A ger 

 neral refemblance, indeed, in the moft ftriking properties, 

 feeras to have been thought fufficient to entitle vegetable prin* 

 ciplesto the fame name. If we examine all the bodies termed 

 gum, we Qiall find them running on the one hand into ^^mch, 

 and on the other intoyi/^or; and forming a pretty long feries, 

 having fugar and flarch at the two extremities: no two of the 

 fubftances conftituting the feries are exadly the fame; but the 

 fame name is ufiially applied to all thofe that have a general 

 refemblance. This will be eafily feen by the following table, 

 jn which I have fubdivided the feries into five genera. 



ri. Common sugar Inftancesin 



Genus I. Sugar . - 4 2. Sugar of grapes ftTch.^^' 



Ls. Sugar of beet, 



II. Sarcocoll 



