9§ KEW VEGETABLE SUBSTANCE. 



water, a complete folution is obtained, which pafles through 



filtering paper while hot, but on cooling acquires a mucila- 

 But much fub- ginous confiftence and a dull colour. In the courfe of forae 

 fides on cooling. houf8 this f olution depofits the greater part of the fubftance 



diflblved in the form of a compact white powder. 

 Differs from A folution of one part of gum arable, in four parts of 



folution of gum- water is much thicker, of a more tenacious confidence, and 



froths lightly, which the folution of the powder from the 



elecampane root does not. 

 Alcohol fepa- 3. On mixing the folution of the white powder with an 



rates it from equal quantity of alcohol, the mixture is at firft clear, but in 



a little time the powder feparates in the form of a tumid white 

 does not gum- fediment, leaving the fluid above it tranfparent. A folution 

 arabic. Q f gum-arabic on the addition of alcohol becomes immediately 



milky, and long retains this appearance, no kind of powder 



(eparating even in feveral days. 



Melts, emits a 4. When thrown on burning coals, the white powder melta 



thick fmoke, like fugar and evaporates, difTufin£a white, thick, pungent 

 and leaves little , 6 \" ' Ar . • . r- 



refiduum.- fmoke, with a lmell of burnt lugar. After this combuftion a 



Thus differs light refiduum only remains, which runs into the coal. Starch 

 1 emits a (imilar fmoke, but does not melt, and leaves a coally 



and from gum. refiduum much greater in quantity. Gum-arabic under the 

 fame circumftances gives out fcarcely any fmoke. 



On red hot iron Heated in an iron fpoon over charcoal the powder firft 



bums. melts, and' emits the fmoke above defcribed. As foon as the 



fpoon becomes red hot, it burns with a vivid light flame, and 



Starch. leaves a very trifling coally refiduum. Starch under the fame 



circumfiances does not melt, *is much longer before it burns, 



Gum. and leaves a conn" derable refiduum of coally matter. Gum- 



arabic only fparkles, does not take fire, and leaves a great 

 deal of coal, which is readily convertible into grayifli allies. 



Drydlftillation 5. By dry difiillaticn we obtain from this powder of the 



produces an acid, e | ecam p ane root a b rown empyreumatic acid, having the 



fmell of pyroxalic acid, but not an atom of empyreumatic 



oil. 

 Niirid acid pro- 6. The nitric acid transforms the powder only into malic 

 duces make, ac j c j an( j oxa jj c ac id, and when ufed in great excefs into 



oxaiic, and in . , , . . ,. . r . . «. 



excefs acetic, acetic acid : but we do not obtain an atom of. the laccholactic 

 Gum the fac- acid, which gum-arabic treated in the fame manner furnilhes 

 Starch fat. ' ' f° abundantly ; or of the fatty matter which is generated by 

 the aclion of nitric acid on fiarch. 



2 From 



