[ 570 ] 
vendiili, to prove that the vegetable alkali has a 
greater affinity with acids than the foffil or natron. 
It is probable, that this fait got at the Pic of Te- 
nerif is the bafis of fea fait, whofe acid has firfl been 
dillodged, either by the force of fire, or by the acid 
of decompofed fulphur, which has afterwards been 
attracied by a freffi phlogiflon, and both feparated 
by the force of fire ; though it is not at all impoffible 
but that there may be magazines of this foffil fait 
lodged native in the bowels of this mountain. 
Hitherto we have no account, that I know of, of 
its being found any-where native in a cryftalline 
, form, and in large quantity j and therefore I imagined 
that the following hiflory would be a8:reeable to the 
Societv. 
In the year 1765, Mrs White, widow to the late 
Conful V/hite of Tripoli, on her return to this 
country, ffiewed me a fubfiance which, ffie laid, 
had a very particular property of bubbling up, or 
fermenting, when mixed with lemon juice. Imme- 
diately, on feeing and faffing it, I fufpeaed it to be 
a pure native natron, or foffil alkali j and was con- 
firmed in this opinion, by mixing it with different 
acids ; and I have fince had a few pounds of it fent 
home tome, and forne gentlemen in the city have 
imported fome hundred weight of it. 
On enquiring into the hiflory of this fait, I was told 
that it was brought yearly to Tripoli, in large quan- 
tities, from the mountains in the inland part of the 
country, and that it went by the name of Trona j 
that the in’nabitants fometimes took an ounce, or 
more of it, by way of phyfic, and that it commonly 
operated both as an emetic and purgative medicine ; 
that 
