Of Magnefian Earth . 463 
Mefirs. Black and Margraaf, and particularly 
the former, have thrown great light on the Che¬ 
mical Hiftory of Magnefian Earth. The EfiTay 
of the former, in particular relates a number of 
experiments made in the mod accurate manner, 
and of dedu&ions the molt clear and fatisfa&ory, 
of any treatile extant. An effay the more valu¬ 
able, as befides the difcrimination of that earth 
from the Calcareous, it has laid the foundation 
of the many valuable difcoveries relative to the 
nature of fixed air and the various Gafes, which 
have been the fources of the mod valuable im¬ 
provements in Chemiftry. Happy I mud efteem 
myfelf if, following fuch great matters, I have 
been able to add any new or ufeful information.* 
The 
de la fner diflout de meme la matiere inflammable, non 
feulement des corps dont nous parlons, mais de tous les 
corps organifes qui croiflent et pendent dans Ton fein: 
elle elabore a fon gre la matiere inflammable, et la reduit 
dans la etat convenable pour former differentes matieres 
falines. De cette union il refulte differentes fels, fuivant 
Petat des fubftances, et les proportions dans lefquelles ces 
fubftances fe font combinees. Je penfe que les fels 
contenant de l’acide vitriolique et ceux contenant de 
l’acide marin, font les fels que la nature forme le plus 
abondamment dans la mcr; ils font. Pun et l’autre, des 
fels primtifs. Chymie Experimentale et Raifonnee 
vol. I. p. 205. 
* The principal improvements, which I ventured to 
i° Black’s procefs for preparing Magnefia 
Alba; thofe, I mean of employing a larger quantity of 
• water. 
