the Nature of fome Mineral Subjlances . 619 
as in the firfl. experiment. The quantity of neutral fait 
here obtained was only half a dram, and it was compofed 
of flat, cubical cryftals of regenerated fea-fait, intermixed 
with about an equal quantity of brown cryftals of tartar of 
vitriol. The quickfilver was all diflipated in the operation, 
as in the fifth experiment. Four grains of the cubic cry- 
ftals, mixed with oil of vitriol, boiled up, and lent out 
copious fumes of acid of fait. The remainder of the neu- 
tral fait was diflolved in diftilled water, and mixed with 
a fufficient quantity of a folution of chalk in acid of 
nitre; the precipitate, here obtained, being edulcorated 
and dried, weighed eight grains and a half. Hence we may 
conclude, that this mineral is conypofed of quickfilver 
united to a greater proportion of acid of vitriol, than of 
acid of fait. 
The horn-mercury ufed for this experiment was 
intermixed with minute globules of quickfilver, which 
could not well be feparated, to which the fmall produce 
of half a dram of neutral lalt was owing ; and, indeed, 
to obtain the three drams of liorn-mercury employed 
for this experiment, it was neceftary to deftroy feveral 
beautiful fpecimens. 
The ingenious M. le sage, of the French Academy 
of Sciences, has publifhed many experiments to fliew, 
that the acid of fait contributes to mineralize a great 
variety of mineral fubftances ; but I have tried a great 
number of them without obtaining an atom, either of 
acid of fait, or acid of vitriol. Among thefe are the 
Vol. LXV1. 4 M following, 
