320 ESSAYS axp OBSERVATIONS 
there appeared many regularly fhaped chry- 
ftals, long, flender, and prifmatical, of the 
nitrous kind; which being removed, and — 
more of the moifture exhaled, the chryftals 4 
which formed were not fo large nor fo regu- 
larly fhaped as the peceeding, but the whole 
appeared like a mafs of white falt ‘coarfely 
powdered: however I could difcover, among 
thefe chryftals, fome that had a quad rangu- 
lar bafe, but long fides, like two cubes joined, 
others varioufly compounded or broken: e- 
ven this part of the falt had the cooling 
nitrous tafte; and, part of it put upon a 
live-coal, fparkled and excited a bright flame 
like falt-petre. 
Acaln, I took two ounces of that neutral 
falt, called ¢artarus foludilis, the preparation 
of which is very well known; in this com- 
pofition, the native acid of white tartar, or the 
chryftals of tartar, is impregnated with an 
alcaline ley, or o/. zart. p. d. from the union 
of thefe in due proportion, arifes a mild 
neutral falt, which diffolves more eafily in 
water, than tartar or its chyftals; whence 
it hath the epithet of foluble. I put two 
ounces of this preparation into a {mall glafs 
retort, and poured upon it one ounce of oil of — 
vitriol 
