and Rock Densities at High Temperatures. 



27 



Table V. 

 Kilogram-volumes of diabase and diabase-glass. 



Diabase 



Mean 

 Diabase-glass 



Mean 

 Diabase (Barus) 



Mean 

 Diabase-glass (Barus) 



Mean 



Date 



Temp. 



Wt. 

 specimen 



Dens. 



Kilo-vol 



10 June 1912 



11 Mar. 1913 



12 " 



33-7 



19-45 



313 



90-017 



104-553 



40-516 



2-983 

 3-968 

 3-974 



3-975 



335-4 

 336-9 

 3363 



336-2 



10 June, 1912 

 (i n it 



22 June, 1912 

 24 " 



11 Sept., 1913 



22-5 



23-8 

 34-5 

 37-8 

 28-2 



2-1807 

 6-6241 



128 05 

 80-34 

 85-802 



3-778 

 3-753 

 3-767 

 3-770 



3-747 



3-763 



360-0 

 363 4 

 361-4 

 361-0 

 364-0 



363-0 



1891 



25 

 21 



21 



21 



22-895 

 45-365 

 54-721 

 69-494 



3016 

 3-018 

 3-014 

 3-024 



3-018 



331-6 

 3313 

 331-8 

 330-7 



331-3 



1891 



21 

 19 

 19 



60-933 

 33-766 

 29-978 



3-702 

 2-745 

 2-705 



370-1 

 3643 

 369 7 



3-717 368-0 



course nothing more than an nndercooled liquid which has 

 failed to crystallize during rapid cooling, but finds a second 

 opportunity to do so with the increased mobility accompanying 

 slow reheating. The heat given off during crystallization, 

 spreading through the graphite float-crucible into the surround- 

 ing molten metal, was sufficient to cause a sudden rise of 15° 

 in the temperature indicated by the thermoelement. 



The volume to which the block shrinks is not its true crys- 

 talline volume. Not only is there insufficient time for close 

 adjustment of the crystals to one another, but the same forces 

 of differential expansion that operate to shatter a complex 

 solid rock operate here to leave the crystalline aggregate in a 

 rather porous condition, with innumerable cracks of appreci- 

 able aggregate volume between the fine crystals. The con- 

 traction of the glass block on crystallization makes it certain, 

 however, that the crystalline rock has a smaller volume than 

 the glass at this temperature. If there had been no apparent 

 volume change, or if the volume had appeared to increase, the 

 question of the true relation between glass and crystal would 

 have been left in doubt. ' 



