fiXPEIlIMENTS ON GUAIACUM. * S^S 



withcrut 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-co- 

 loured porous mass. 



The solution thus formed, yielded -while recent, a browa 

 precipitate with the alkalis, which was redissolved on the ap- 

 plication of heat, forming a deep brown liquid. 



Muriatic acid also separated the guaiacum 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 crys- 

 tallized oxalic acid was deposited 



When guaiacum was treated with dilute nitric acid, the re- Dilute acid, 

 suits were somewhat ditferent. A slight effervescence took 

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

 converted into a brown substance, resembling the precipitate 

 obtained from the alcoholic solution as above mentioned, 

 (2. E.) 



This brown substance appears to be guaiacum, the proper- 

 ties of which ai'e materially altered, by its combination with 

 oxigen ; and I am led to think that the changes of colour pro- 

 duced by nitric and oxy-muriatic acids, are the consequence of 

 the different proportions of oxigen wiih which the guaiacum 

 has been united ; for we know that the colours of metallic, and 

 many other bodies, are greatly influenced by the same cause. 



The brown substance was separated by filtration ; the filtra- 

 ted liquor yielded yellow tlocculent precipitates with the alkalis, 

 ajid on examination was found to hold nitrate of lime in solu- 

 tion. 



The undissolved portion was of a deep chocolate-browpL 

 colour. A similar substance may also be obtained, by evapo- 

 rating the recent nitric solution to dryness, taking care not to 

 apply too much heat towards the end of the process. 



The substance obtained by either of these means, possesses 

 the properties of a resin in greater perfection than guaiacum ; 

 it is equally soluble in alcohol and sulphuric ether, insoluble in 

 water, &c, ; but when turned it emits a peQuliar smell, more 

 resembling animal than vegetable bodies. If, however, fresh, ^^ 



portions of nitric acid be added three or fgur times succes- • 



YoL, XIV. SuPPiEMiiNT. Eee sively 5 , 



