EXPERIMENTS O^' GUAIACUM. 39^ 



The coal, amounting to 30.5 grains, yielded on incineration 



3 grains of lime. To discover whctliei any fixed alkali was 



present, 200 grains of the pun-st iruaiacum (that in drops) 



were reduced to ashes : these were .dissolved in muriatic acid, 



and precipitated by ammonia: the whole was then filtrated, 



and the clear liquor evaporated to dryness, but not any trace 



of a neutral salt with a basis of fixed dlkali was preceptible. 



Sect. IV.— From the action of diiferent solvents on guaia- Enumeration 



, . , , of the :.:Ter- 



cum, It appears, that although this substance possesses many ^^^^,^_ between 



properties in common with resinorts bodies, it nevertheless guaiacmn and 



differs from them in the following particulars : 



1. By affording a portion of veii,et3ble extract. 



2. By the curious alterations which it undergoes when 

 subjected to the action of bodies, which readily communicate 

 oxigen, such as nitric and oxy-muriatic acids : and the rapi- 

 dity with which it dissolves in the former. 



3. By bemg converted into a mere j erfcct rebin : in which 

 respect guaiacum bears some resemblance to the green resin . 

 which constitutes the colouring matter of the leaves of trees, 

 &c.* 



A. By yielding oxalic acid. 



5. By the quantity of charcoal and lime which are obtained 

 from it when subjected to destructive distillation. 



Sect. V. — From the whole therefore of the above-men- Q^gjarum ap- 

 tioned properties, it evidently appears that guaiacum is a sub- pears to be, or 



,.„ ■ , ... , . , . to contain, a 



Stance very different from those which are denominated resins, peculiar 



and that it is also different fiom all those which are enume- substance. 

 rated amongst the balsams, gum resins, gums, and extracts: 

 most probably it is a substance distinct in its nature from any 

 of the above, in consequence of certaui peculiarities in the pro- 

 portions and chemical combination of its constituent elemen- 

 tary principles ; but as this opinion may be thought not suf- 

 ficiently supported by the facts which have been adduced, we 

 may for the present be allowed to regard guaiacum as com- 

 posed of a rei,in modified by the vegetable extractive principle, 



* This substance was found by Proust to be insoluble in water, 

 and soluble in alcoliol. When treated with oxy-muriatic acid, it 

 assumed the colour of a withered leaf, acquiring the resinous pro- 

 perties in greater perfection. Vide Thompson's Syst. of Che- 

 inibtiy, ed edit. vol. iv. p, 318. 



E 6 e 2 and 



