S. B. Christy—Genesis of Cinnabar Deposits. 459 
der and the next day the tube was found to contain a beau- 
sity coherent mass of crystals of cinnabar, recognizable by the 
aked eye, simulating the crystals which occur in nature very 
a foctt, They appeared to be rhombohedrons although I 
have not been able to determine this with certa 
Subsequently a large number of experiment, were made, 
all with closed tubes, upon various solutions in contact with 
amorphous mercuric sulphide, for the purpose of determinin 
the action of these different reagents. Bn me 
from about 200° to about 250° C., and the pressures from 260 
to 500 lbs. per square inch. The pronase me of the pres- 
sures were not Borge! exact, owing to the pega 4 of mak- 
d 
allowed to cool sialincrevinnd till mornin 
The results of these experiments are as s follows: 
Solutions of sodium bicarbonate did not change the amor- 
phous variety of mercuric sulphide to cinnabar. Solutions of 
water-glass were equally powerless. But when through either 
of these solutions prianing: acid was passed, and the tubes 
were again heated in the digester, the transformation was 
complete. Polysulph re of —— um as well as sulphydrate 
apie the kchorsnoas sulphi a vey rapidly and perish 
nee of excess of carbonic acid seemed to retard the 
foruaban without being able to prevent it. The cinnabar 
formed was usually in the state of micro-crystals, like vermil- 
lion, but often they were larger and more like the native cinna- 
bar in appearance, though they were so minute as to make th 
determination " “the crystalline form extremely difficult. In 
all cases when the transformation had taken place, the liquid 
would stain the skin deep black, as is usual wish mercuric sul- 
phide is dissolved in alkaline sulphides. This would be an 
additional proof, if one were needed, that solution had taken 
ace. 
is Finally, I was led to try the effect of heating the amorphous 
weipiges with the New Almaden Vichy water, ‘to which sulphy. 
dric acid had been added. This water as analyzed by 
Piquet, Mining and Scientific Press, vol. xviii, p. 360, has the 
following composition : 
“ Biearbonate of sods: 05-6. 2. = .--8 wi 3 grains. 
Bicarbonate of limes. 2c... 2-5. -2- 
Sulphate of lame 2.02 ices is case re 2 
Sulphate ‘of = Juices tae saws 3°0 
Chloride re mae Lipeeeaetuees xe a4... = 
> ate EO ds wn ec i? Ss 
a ek the cnn traces.” 
Careee NO oa ee an ows 4 
