6 16 On the EffeSis of 'Terra Ponderofa, 



Exp. VI. I attempted to give the fame dog 

 thirty grains of the Nitrated Salt, with fome 

 meat, but he refufed to take it. I then dilTolved 

 that quantity in water and poured it dowrf his 

 throat, though not without fpilling fome of it. 

 It produced an immediate frothing at the mouth, 

 which was quickly followed by vomiting and 

 ficknefs. However, he recovered in the courfe of 

 three or four hours, and eat with great voracity. 



An indifpenfirble attention to bufinefs prevented 

 my profecuting thefe experiments any farther j 

 they muft therefore remain for thofe who have 

 more time and Icifure to beftow upon them 

 fhould they be deemed worthy of a continuation. 

 However, before I relinquifhed the fubjeft I was 

 defirous of knowing what effect would be pro- 

 duced by the fimple Ponderous Earth. I ftill 

 was of opinion, notwithftanding Dr. Withering's 

 and Dr. Prieftley's experiments, that the fixed 

 air might be expelled from the Aerated Barytes 

 by a ftrong heat alone, and fent fome of it to 

 Mr. Jofiah Wedgewood, jjjnior, requefting him 

 to expofe it to the greateft poffible heat in one of 

 his father's furnaces j he was fo obliging as to 

 comply and favoured me foon after with the 

 following Account of his experiment. 



** I have expofed to a very ftrong heat for 

 ** thirty-fix hours, two ounces of the Aerated 

 " Barytes, but have not been able to weigh it 

 «* fince, from an efFeft having taken place which 



<« I did 



