ROCK TEMPERATURES IN VICTORIA. 309 
but the bulk of the gold is found im a finely crystallised 
form upon rather than in the stibnite, exactly as though 
it has been precipitated with quartz at a much later period 
than that at which the filling of the veins with antimony 
had taken place, and probably by the direct action of the 
latter. At times much of the gold can be separated in quite 
coarse grains from the rest of the vein-fillings by simple 
crushing or rubbing. 
The evidence of precipitation upon an earlier deposit’ pf 
antimony is a feature that is well worth special notice, and 
sometimes this is particularly well marked ; one specimen in 
my possession is a small sheet of antimony about a quarter 
of an inch thick, once part of a much larger sheet, thickly 
coated over with finely crystalline gold. This was from a 
crevice that had somewhat exposed the mineral: In the 
denser parts of the deposit the gold seems to occur more in 
crevices in the antimony. 
The deposit is interesting, as showing clearly that the 
auriferous contents were acquired at the last stage of forma- 
tion, and has been precipitated on stibnite that had been 
deposited at a prior date. 
ROCK TEMPERATURES AND THE RATE OF 
INCREASE WITH INCREASED. DEPTHS IN 
VICTORIA. 
By Henry C. Jenkins, A.R.S.M., Assoc. M. Inst. C.E., 
Government Metallurgist, Victoria. 
THE importance of some knowledge-as to the rate of the 
increase of temperature as we descend in the earth appeals 
both to the geologist and to the miner; to the former as 
being the starting-point of many interesting and important 
speculations, and to the latter because it points out at once 
a superior limit of depth beyond which he cannot hope to 
carry on his work without availing himself of some means 
by which he can cool his workings. The taking of steps 
to secure this end must add to the cost of his operations, and 
finally put a stop altogether to them by making them un- 
profitable ; indeed, the rise of temperature must put a limit 
to the depth at which mining operations can be carried on, 
either upon purely physical grounds or upon purely economic 
ones. 
