458 S. B. Christy— Genesis of Cinnabar Deposits. 
line sulphides ; and, as free alkali is not known to exist in any 
natural mineral waters, the question has still remained, “ In 
what has this substance been dissolved, if we are to suppose it 
to have been formed in the wet way?” 
The classic researches of Daubrée on metamorphism,* and 
those of De Sénarmontt on the formation of mineral veins in 
top so as to allow the contents to slowly evaporate under pres- 
sure, after the water in the digester itself. 
through the safety valve. : 
The only disadvantage of using this form of apparatus was 
the difficulty of determining when the water was entirely evap- 
orated. This led to several explosions of the pst tubes 
within the digester and the consequent loss of many days’ 
work. The joints were all made with a lead packing, as paper, 
leather, etc., would not resist the high temperatures at which 
the experiments were conducted. The highest temperatures 
reached were in the neighborhood of 250° C. (482° P). The 
thermometer at the bottom of the bath of iron filings indicated 
360° C. and at the top 150° to 200° C. 
The first experiment made was with a tube containing amor- 
phous mercuric sulphides with a solution of potassic sulphy- 
drate (potash solution saturated with sulphydric acid.) e 
tube was open at the top and its contents were allowed to evap- 
orate to half their bulk (after the water in the digester was 
evaporated) under a pressure of 150 lbs. per square inch. The 
temperature was about 180° C. e operation was continued 
five hours. The sulphide was entirely changed to a red pow- 
ae * Ann. des Mines, 5 Seri , p. 155 and 393. 
‘She een ek ee a: 
