298 Joty—On the Volume Change of Rocks and Minerals attending Fusion. 
head are required to traverse 0:001 inch placed in the position of the bead. 
Hence :— 
WG, Sli ESR OR OUT 
Ta ae 26800545 
Galy Temperature, Micrometer. In-Th V2—Ni 
4 Centigrade. N. Thi Va 
10°3 360° 38 0:00262 0:00786 
13°2 550 By) 0:00566 0:01098 
14°5 650 67 0:00463 0:01389 
15:0 680 7d 0:00518 001554 
15'7 720 83 000574 0:01722 
17°8 840 110 0:00760 002280 
Iisa 900 126 0:00870 0:02610 
20°1 950 144 0:00995 0:02985 
23°1 1090 182 0:01257 0:03771 
24:0 1135 q. p. Ie 0:01561 0:04083 
24-9 65 qagey 28K 0:01983 0-05949 
The following measurements of the volume contraction of molten diabase, by 
C. Barus (American Jour. of Science, vol. 42, p. 498), are, when overlapping, ir 
approximate agreement with the foregoing numbers. 
Temperature, (Vi -— Vo) 
Centigrade. aa oe 
1421° 00771 
1388 0:0760 
1319 0:0730 
1305 0-0721 
1190 0:0661 
1165 0:0652 
1112 0:0628 
1093 0:0285 
914 0:0223 
855 0:0202 
Barus records that this rock was sticky at 1190°, and very sticky at 1163°. Of 
course the composition of the two rocks will probably only possess approximate 
likeness. The results of Roberts-Austin and Rucker on the specific heat of basalt 
at high temperatures appears to show by the large absorption of heat in the 
neighbourhood of 800° C. that melting occurs at this temperature in the case of the 
To settle the question of the melting point of the Giant’s 
sample dealt with. 
At a temperature of 
Causeway basalt I made determinations on the meldometer. 
