Diamonds in California. — Turiicr. 189 
in a laboratory buried at vastly greater depths than we have 
reached or are likely to reach, where the temperature is con- 
formable with that of the electric furnace, where the pressure 
is fiercer than in our puny laboratories and the melting point 
higher, where no oxygen is present-, and where masses of car- 
bon-saturated iron have taken centuries, perhaps thousands 
of years, to cool to the solidifying point. 
The method of the formation of the volcanic orifices, which 
were subsequently filled with the peridotyte-breccia, is con- 
sidered by Crookes as possibly explained by the erosive action 
of escaping gases. Through a cylinder of granite a hole was 
drilled 2-10 of an inch in diameter. This cylinder was made 
the stopper of an explosive chamber in which a quantity of 
cordite was fired, the gases escaping through the vtnt in the 
granite cylinder. The pressure was about 1,500 atmospheres, 
and the whole time of escape was less than half a second. 
Nevertheless, the erosion produced by the escaping gases and 
by the heat of friction, scoured out a channel half an inch in 
diameter and melted the granite along the orifice. If granite 
is "thus vulnerable at comparatively moderate gaseous pres- 
sure, is it not easy to imagine the destructive up-burst of 
hydrogen and water gas, grooving for itself a channel in the 
diabase and quartzyte. tearing fragments from resisting rocks, 
covering the country with debris, and finally, at the subsi- 
dence of the great rush, filling the self-made pipe with a water- 
l:)urned magma in which rocks, minerals, iron oxide, shale, 
petroleum, and diamonds are churned together in a veritable 
witches' caldron?" 
Crookes regards the peridotyte-breccia more as a nuid 
lava than as a true igneous intrusion. While de Launay sup- 
poses water vapor to have accompanied the eruption of the 
peridotyte, he nevertheless regards it as an igneous intru- 
sion, and Lewis likewise appears in the rtiain to take the same 
ground, although he regards some of the material as a tuff. 
The specimens of kimberlyte that were shown in the collec- 
tion of George F. Kunz at the Chicago Exposition certainly 
presented all the appearance, both megascopicallv and in tliin 
section, of a serpentine derived from a peridotyte-poriihyry. 
and the description of the rocks by Lewis and de Launay 
clearly shows that a large portion of it is serpentine derived 
