217 



to the brown precipitate obtained, by nitric acid, from the solution 

 of guaiacum in alcohol, and possessed the properties of a resin in 

 greater perfection than guaiacum itself. If successive portions of 

 nitric acid be added to the above- mentioned residuum, or if a large 

 quantity of that acid is employed so as to form a complete solution, 

 a product may be obtained, by evaporation, which is equally soluble 

 in water and in alcohol ; both which solutions have an astringent 

 bitter taste. 



Guaiacum is soluble in the pure and in the carbonated alkalies. 

 The precipitates formed from these solutions, by dilute sulphuric acid 

 and by muriatic acid, were of a flesh colour, and approached to the 

 nature of extract ; being less acted upon by sulphuric ether, but 

 more soluble in boiling water than guaiacum. 



Mr. Brande now proceeds to the analysis, by distillation, of the 

 substance here treated of. By this method he obtained, from 100 

 grains, the following products : 



Acidulated water 5'5 



Thick brown oil, becoming turbid on cooling .... 24*5 



Thin empyreumatic oil 30'0 



Coal remaining in the retort 30'5 



Mixed gases, chiefly carbonic acid and carbonated "1 Q..-. 

 hydrogen J * 



99-5 

 The coal, on incineration, yielded four grains of lime, but no 



alkali could be discovered. 



From the foregoing experiments it appears, that although guaiacum 



possesses many of the properties common to resins, it differs from 



them in the following circumstances. 



1 . By affording a portion of vegetable extract. 



2. By the alterations which take place in it when submitted to 

 the action of bodies which readily communicate oxygen, such as ni- 

 tric and oxymuriatic acids, and by the rapidity with which it is dis- 

 solved in the former. 



3. By being capable of being converted into a more perfect resin, 

 in which it resembles the green resin that constitutes the colouring 

 matter of leaves. 



4. By yielding oxalic acid. 



5. By the quantity of charcoal and lime obtained from it by dis- 

 tillation. 



These circumstances, the author says, shows that guaiacum differs 

 not only from the substances denominated resins, but also that it 

 differs from those which are called balsams, gum-resins, gums, and 

 extracts ; and he thinks we may, for the present, consider guaiacum 

 as composed of a resin, modified by the vegetable extractive prin- 

 ciple, so that it may perhaps, without impropriety, be defined by the 

 term Extracto-resin. 



In a postscript Mr. Brande observes, that the action of oxygen on 

 some other resinous bodies is very remarkable. By digesting mastic 



