438 BOWEX AXD AUROUSSEAU FUSIOX OF SEDIMENTARY ROCKS 



iron remains nnchanged in silicate substances of moderate iron content. 



When the material was heated in this way and the product examined 

 under the microscope, it was found that at 1,050 degrees centigrade only 

 a slight sintering was obtained, at 1.100 degrees centigrade a consider- 

 able amount of glass was formed, and at 1,150 degrees centigrade a 

 proportion of glass was formed in one hour about equivalent to that 

 formed in the fused part of the core. A temperature nearly, if not quite, 

 as high as the last (1,150 degrees centigrade) must have been attained 

 in the drill-hole in order to produce the results actually found. It is 

 true that the fusion of the core took place under a head of water suffi- 

 cient to give a pressure of about 150 atmospheres, but that this was not 

 adequate to bring about significant solution of water in the silicate melt 

 is plainly indicated by the analysis of the fused core, which shows only 

 0.26 per cent water, an amount of the order of magnitude to be expected 

 from laboratory experience of the effects of such moderate pressures. 

 For such a minute amount of water one can, with little fear of significant 

 error, calculate, from the ordinary law of freezing-point lowering, its 

 effect on the fusion temperature, and it "will be found that a lowering of 

 15 degrees to 20 degrees centigrade is to be expected. Such a small 

 effect has no importance in the present connection; nor can it be suc- 

 cessfully maintained that the amount of water now present in the fusion 

 is no indication of the amount formerly present. The core was very 

 rapidly cooled, immediately on cessation of drilling, to a temperature at 

 which the glass was rigid and in such a condition that no volatile matter 

 could escape from it. Indeed, this cooling took place under the same 

 head of water as that under which the fusion occurred; so that there 

 would be no tendency toward the escape of water from the melt. ■ Only 

 after cooling was the core slowly raised to the surface. 



The conditions are the reverse of those experienced by a natural water- 

 bearing lava, which, when poured out on the surface, maintains its high 

 temperature for a long period, relatively speaking, but has the pressure 

 exerted on it suddenly reduced — a combination decidedly favorable to 

 the escape of volatile matter. There is no avoiding the conclusion that 

 the small amount of water present in the fused core represents all of that 

 component that it was able to retain at the temperature and pressure 

 existent during fusion. A temperature very nearly equal to that required 

 for dry fusion must therefore have obtained. 



Chaxges effected IX THE Steel of the Core Barrel 



This conclusion as to the high temperature that was attained is com- 

 pletely confirmed by a study of the changes that have taken place in the 



