1158 
MR. G. F. RODWELL ON THE EFFECTS OF HEAT ON CERTAIN 
The ahoy resembled the preceding. It was, however, slightly more brittle, and the 
fracture was more crystalline. The colour in the mass was brownish-yellow; in thin 
laminae bright yellow; and in powder a brilliant yellow. Unaffected by light. 
Melting point =493° C. 
Specific gravity = 5’ 70 64. 
The alloy expanded on heating from 0° C. to 159° C. under a coefficient of 
*00001999. 
Between 159° C. and 180° C. the coefficient fell to 
•00001056. 
From 180° C. to 199° C. it simply absorbed heat without undergoing either expansion 
or contraction. 
At 199° C. contraction commenced, and continued under a negative coefficient of 
•00007200 
till 213° C., when it increased to 
*0003798, 
and so continued till 234° C., when it fell again to 
*00007200, 
under which coefficient it contracted till a temperature of 282° C. was attained. 
Somewhat rapid expansion then set in, with a coefficient of 
•0002050. 
The following volumes correspond to the temperatures given :— 
Volume at 0° O.=1-000000 
„ 159 =1*008180 
„ 180 =1-003296 
„ 199' =1-003296 
„ 213 =1-002288 
„ 234 .= -994313 
„ 282 . ..= -990857 
„ 300 .= *994547 
„ 400 =1-015047 
„ melting point (493° C.) (solid).=1-034112 
„ „ „ (493° 0.) (liquid) .... =1-065601 
5. Copper-silver iodide alloy, Cu 3 I 2 .12AgI. 
The percentage of silver iodide was finally increased to 88 by alloying one molecule 
of iodide of copper with twelve of iodide of silver. This extreme was employed in 
order to test the extent to which a small percentage of iodide of copper may mask for 
a while the prominent characteristics of the iodide of silver. None of the alloys 
