454 On phlogiston. 



tube. Two drachms of the fulphate of mercury, of a white 

 colour and (trong acrid tafte, had fublimed on the fides ot 

 the glafs. A part of the fulphate of mercury, was colour- 

 ed by an immenfe number of minute particles of revived 

 mercury, which gave it the appearance of raercurius cine- 

 reus. 



Secondly. One ounce of turbith mineral, was boiled 

 fifteen times, fix hours each time, in half a pint of diftill- 

 cd water, which was renewed eveiy time ; and it could not 

 be freed from the fulphuric acid, for the water always pre- 

 cipitated a folution of muriated barytes. 



Thirdly. One ounce of turbith mineral was boiled three 

 hours, in a folution of cauftic potafh, when it loft its yel- 

 low colour, and was converted into a calx of the colour of 

 brickduft. Upon being dried it was found to have lofi: one 

 hundred and fixty grains in weight. 



The liquor in which it was boiled, by fpontaneous eva- 

 poration in the open air, gave chryftals of vitriolated tar- 

 tar. 



Thefe experiments were repeated with turbith mineral, 

 made by precipitating a folution of the fulphate of mercury 

 by potalh, with the fame refult. 



They clearly prove, contrary to what has been advanc- 

 ed by Lavoiller, Monnet, Bucquet, Fourcroy, Chaptal and 

 other French chemifts, that turbith mineral, is not a pure 

 oxyd of mercury, but contains fulphuric acid, and may be 

 confidered as a fulphate of mercury. 



The reafon that thofe gentlemen were deceived in regard 

 to the compofition of this fubftance muft have been, either 

 that they did not break the veiTels in which their experi- 

 ments were made, to difcover any refiduum, or from the 

 circuaiftance, of obtaining oxygenous gas from the turbith, 

 equally as good as from any acknowledged calx of mercury. 



The reafon that turbith mineral yields oxygenous gas, 

 when it is expofed to a red heat is, that the fulphuric acid 



quits 



