of Magneftan Earth. 47 j 
form a lime-water. This obnoxious tafte is alfo 
deftroyed by a further extenfion of the calcina¬ 
tion. On what can this property depend ? 
Magnefia has been defcribed as throwing out 
a phofphoric light, in the latter periods of the 
calcination. This is a phenomenon which nei¬ 
ther I, nor any of the perfons I have employed, 
m the calcination of Magnefia, have ever been 
able to obferve. Indeed I do not fee how it 
could happen, except the Magnefia contained 
vitriolic acid or alkaline fait. M. Fourcroy, 
who mentions the faft, cites the authority of 
MefTrs. Butini and Tingry, of Geneva;* and the 
procefs, which he has given, from the former 
of thefe Gentlemen, is very ill adapted to free 
the Magnefia, from the whole of the vitriolared 
tartar, formed in the mixture. Now, fuppofin°- 
aerial acid to be a compound of Air and Phlo- 
giflon, the laft portions being feparated with 
difficulty from the Magnefia, a decompofidon 
of the Gas may take place, and a new combina¬ 
tion enfue. The Phlogifton, quitting its aerial 
bafis, may unite with the Earth and Vitriolic 
Acid, and, by this union, a Pyrophorus be 
formed; and, probably, from this caufe, the 
appearances, defcribed by thefe Chemifts/may 
have proceeded. 
• Fourcroy’s Lpftures, vol. I p. 163, and z 9 z. 
END OF VOL. FIRST. 
