Chemical Experiments on Guaiacum. 107 



makes its appearance, the properties of which will be after- 

 wards mentioned. 



The changes of colour produced by nitric and oxymuriatic 

 acids in the alcoholic solution arc very remarkable, and, I 

 believe, peculiar to guaiacum : there is, moreover, much 

 reason to suppose thai the above alterations in colour ara 

 occasioned by oxygen *. It likewise appears from that 

 which has been stated, that the blue and green oxides (if 

 they may be so called by wav of distinction) are soluble in 

 the mixture of nitric acid and alcohol, while the brown pre- 

 cipitate is insoluble. 



F. Alkalis do not form any precipitate when added to the 

 solution of guaiacum in alcohol. 



3. Guaiacum is less soluble in sulphuric ether than in al- 

 cohol : the properties of this solution nearly coincide with 

 those just mentioned. 



4. Muriatic acid dissolves a small portion of guaiacum, 

 the solution assuming a deep brown colour; but if heat be 

 applied, the resin melts into a blackish mass, preventing any 

 further action from taking place. 



5. Sulphuric acid forms with guaiacum a deep red liquid, 

 which, when fresh prepared, deposits a lilac-coloured preci- 

 pitate on the addition of water : a precipitate is also formed 

 by the alkalis. If heat be employed in forming this solu- 



" The following experiments appear to verify this supposition : 

 Fifty grains of freshly putvciised guaiacum were introduced into a glass 

 jar containing 60 cubic inches of oxymuriatic acid gas. The resin speedily 

 assumed a brown colour, having passed through several shades of green and 

 blue. Liquid ammonia was poured on this brown substance while yet 

 immersed in the acid ; the whole became green ; it therefore seemed thus to 

 be deprived of part of the oxygen which it apparently had acquired by the 

 preceding experiment. An equal portion of the same guaiacum was exposed. 

 Under similar cii -cumstaiices, to the action of oxymuriatic acid, excepting 

 that the glass in which the experiment was made was covered with a black 

 varnish, and placed in a dark apartment. On examining the result of this 

 mi It, the ri sin was found to have undergone precisely the same changes 

 as when exposed to light. Ammonia had also the same eifect. 



Guaiacum was also exposed over mercury to oxygen ga" '> the resin as- 

 sumed, after some days, the green colour which a longer exposure to the at- 

 mosphere produces : this change was likewise found, by a second experiment, 

 to be ef&cted without the pres-.-'.ice of light. 



lion, 



