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tains to the two volcanic glafles, excluilvely 

 of artificial glafles. 



It remained to attempt the folution of an 

 Important queftion. Is the muriatic acid 

 combined with thefe two volcanic fub- 

 ftances, or only mechanically united ? I 

 conceived that forae elucidation of this 

 doubt might be obtained by expofing one 

 of thefe two glafles to a fire not fufficicntly 

 fl:rong to caufe fufion. I put fix ounces of 

 the fpotted glafs, reduced to powder, in a 

 glafs retort with a lured belly ; joining to it 

 the glafs receiver, communicating as before 

 wuth the mercurial apparatus. This 1 heated 

 in a fand-bath for twelve hours fucceflively. 

 At the end of an hour and a half there ap- 

 peared, in the neck of the retort, a large 

 drop of limpid liquor, which foon after fell 

 into the receiver. Afterwards a fecond 

 formed in the fame place, which remained 

 adhefive, no other humidity arifing to in- 

 creafe it. No vapour of any kind was vi- 

 fible in the retort or the glafs receiver, and 

 it was not till after the firfl: two hours that 



the 



