[ 53 ] 



acids or alkalies; nor can it be decompofed but by the 

 addition of phlogifton ; — becaufe having the mineral al- 

 kali for its bafis, the vitriolic acid (being the other ingre- 

 dient in its compofition) cannot be detached from it by 

 any other means. From thefe circumftances, I conclude, 

 there is no doubt of its being a native Glauber's fait. 



On adminiftering it internally, to -the amount of fix 

 drams in half a pint of warm water, it operated mildly 

 three or four times, without producing naufea, ficknefs, 

 or gritting. This was repeated twice in two different per- 

 fons alternately, with an equal quantity of the common 

 Glauber's fait of the {hop?, and was allowed by both per- 

 fons to be lefs naufeous, and more eafy and pleafant in its 

 operation. Nor is this to be wondered at, as the common 

 Glauber's fait is often found not perfeftly neutralized, ha- 

 ving a portion of redundant vitriolic acid, which renders it 

 oft'enfive to the ftomach and bowels. Whereas this native 

 fait is free from that inconvenience, and operates with 

 equal mildnefs as the purging fait which I lately obtained 

 from Cheltenham water. 



In order to obtain the prefent fait in its mofl: perfe6V 

 ftate of cryftallization, the water in which it is diffolved 

 ought to be evapocated very leifurely, and not too far, be- 

 caufe a confiderable portion of water is ellential to the 

 form and tranfparency of the fait. 



From the imperfcvSl ftate of the fpecimcn whicji you fent 

 mc, the cryftals feem to have been deprived of their due 

 quantity of water; and this is ftill more evident in the 

 fample which Mr. Swaync terms " a more refined fort." 



I am, Gentlemen, 



Your very obedient fervant, 



IValcrjt-Paradc, Bath, A. FOTHERGIM,. 



Sept, 17, 1784. 



