64 Experiments and Remarks on a Substance 



Sulphate of iron, after twelve hours, produced a slight 

 brown precipitate. 



Muriate of tin had a similar effect. 



Acetite of lead formed a brownish-red deposit. 



Nitrate of lime also occasioned a brown precipitate : 



And solution of isinglass rendered it very turbid, and pro- 

 duced a yellowish-brown precipitate, which was insoluble in 

 boiling water, and possessed all the other characters of gela- 

 tine combined with the tanning substance. 



P. Guaiacum, the properties of which are so singular in 

 many respects, afforded results (when treated with nitric acid 

 in the manner which has been described) different from the 

 resins, although its external and general characters seem to 

 indicate that it appertains to those bodies. 



Nitric acid acted upon it with great vehemence, and 

 speedily dissolved it. The residuum which was afterwards 

 obtained, was also found to be almost totally soluble in 

 water, and the solution acted on the metallic salts like those 

 which have already been noticed; but with gelatine it formed 

 only a very slight precipitate, which was immediately dis- 

 solved by boiling water ; and the remainder of the solution 

 being evaporated, yielded a very large quantity of crystal- 

 lized oxalic acid ; so that in this respect guaiacum was 

 found to resemble the gums, and to be totally unlike the 

 resins*. 



§ V. 



As many vegetable substances when roasted yield by de- 

 coction a liquid which in appearance much resembles the 

 artificial tanning matter when dissolved in water, I roasted 

 some of the common dried peas, horse-beans, barley, and 

 wheat flour, the decoctions of which however did not afford 

 any precipitate by solution of isinglass. 



* The properties of guaiacum %vhich have been described, as well as those 

 •which were previously known, appear to indicate, thnt it is 3. peculiar sub" 

 Stance of a nature distinct from the resius, balsams, and even the gum resins. 



So remarkable indeed is this substance, that an accurate series of experi- 

 ments on the whol' of its properties may justly be placed amongst the che- 

 mical desiderata. 



4 Even 



