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XIX. Chemical Experiments on Guaiacum. By Mr. 

 William Brande*. 



./among the numerous substances which are comprehended 

 under the name of resins, there is perhaps no one which 

 possesses so many curious properties as that now under 

 ponsideration ; and it is remarkable that no more attention 

 has been paid to the subject, since many of the alterations 

 which it undergoes when treated with different solvents 

 have been mentioned by various authors, 



Guaiacum has a green hue externally ; is in some degree 

 transparent; and breaks with a vitreous fracture. 



When pulverised it is of a gray colour, but gradually be- 

 comes greenish on exposure to air. 



It melts when heated, and diffuses at the same time a 

 pungent aromatic odour. 



It has when in powder a pleasant balsamic smell, but 

 scarcely any taste, although when swallowed it excites a 

 very powerful burning sensation in the throat. 



Its specific gravity is 1'2289. 



§11. 



1. When pulverised guaiacum is digested in a moderate 

 heat with distilled water, an opaque solution is formed, 

 which becomes clear on passing the whole through a Jilter. 



The filtrated liquor is of a greenish-brown colour; it has 

 a peculiar smell, and a sweetish taste. 



It leaves on evaporation a brown substance, which is so- 

 luble in alcohol, nearly soluble in boiling water, and very 

 little acted upon by sulphuric ether. 



This solution was examined by the following re-agents: 



Muriate of alumina occasioned a brown insoluble preci- 

 pitate after some hours had elapsed. 



Muriate of tin formed a brown flaky precipitate under tie 

 same circumstances. 



Nitrate of silver gave a copious brown precipitate. 



* From the Ttansactiow "f the Royal Society for 180'?. 



Suspecting 



