103 Chemical Experiments on Gualacum. 



tion, the resin is speedily decomposed ; and, if the whole of 

 the acid be evaporated, there remains a black coaly substance, 

 together with some sulphate of lime. 



6. Nitric acid appears to exert a more powerful action oil 

 guaiacum than on any of the resinous bodies. 



One hundred grains of pure guaiacum, previously reduced 

 to powder, were cautiously added to two ounces of nitric 

 acid, of the specific gravity of 1*30. The resin at first as- 

 sumed a dark green colour, a violent effervescence was pro- 

 duced, attended with the emission of much nitrous gas, and 

 the whole was dissolved without the assistance of heat; which 

 is not the case with the resins in general ; for, when these 

 bodies are thus treated with nitric acid, they are commonly 

 converted into an orange-coloured porous mass. 



The solution thus formed yielded, while recent, a brown 

 precipitate with the alkalis, which was redissolved on the 

 application of heat, forming a deep brown liquid. 



Muriatic acid also separated the gualacum from this solu- 

 tion ; not, however, without having undergone some change. 



Sulphuric acid caused no precipitate. 



After this solution of guaiacum in nitric acid had remained 

 undisturbed for some hours, a considerable proportion of cry- 

 stallized oxalic acid was deposited. 



When guaiacum was treated with dilute nitric acid, the 

 results were somewhat different. A slight effervescence took 

 place, and part of the resin was dissolved, the remainder 

 being converted into a brown substance resembling the pre-> 

 cipitate obtained from the alcoholic solution as above men- 

 tioned (2. E.)> 



This brown substance appears to be guaiacum, the pro-* 

 perties of which are materially altered by its combination 

 with oxygen ; and I am led to think that the changes of 

 colour produced by nitric and oxymuriatic acids are the 

 consequence of the different proportions of oxygen with 

 which the guaiacum has been united ; for we know that the 

 colours of metallic and many other bodies are greatly in- 

 fluenced by the same cause. 



The brown substance was separated by filtration ; the fiU 



trated 



