1154 
MR. G. F. ROWELL OH THE EFFECTS OF HEAT OH CERTA1H 
11. Copper-Silver Iodides. 
1. Copper-silver iodide , C%I s .AgI. 
Iodide of silver and iodide of copper were fused together in the proportion of one 
molecule of each. The fusing point was obviously lower than that of either of the 
constituents; the fusion was tranquil, and the mass did not oxidise at the surface. 
The alloy contains in 100 parts :— 
Iodide of copper . . . = 6F7767 Copper.=20"5515 
Iodide of silver. . . . =38-2233 Silver.=17'5430 
Iodine.= 61-9055 
100-0000 100-0000 
Specific gravity of the cast-rod = (1)5'6290, (2)5'6526. When fused in a tube, instead 
of being cast into it, the specific gravity was a little higher— 
(1) 57302 (2) 5-7500. 
The melting point of this, and of each of the other alloys, was determined for me by 
Mr. Carnelley. Cu 2 I 3 .AgI melts at 514° C. Although containing 38 per cent, of 
iodide of silver the alloy contracted on cooling, and came easily out of the glass tube. 
It was brown in colour in the mass, but when powdered it was a brilliant yellow, 
unaffected by light. In thin layers it was yellow and perfectly transparent. Fracture 
resinous. 
Bods one-third of an inch in diameter and six inches long were cast in hot glass 
tubes. The ends were sawn plane by a fine steel saw, and were afterwards worked 
smooth on sand-paper, and furnished with copper caps. They were examined in the 
expansion apparatus in the usual way. 
The alloy expanded on heating under a definite coefficient of *00004998 until a 
temperature of 223° C. was attained, when the coefficient began to diminish rapidly, 
and between 223° C. and 256° C. it fell to 
•00001999. 
Between 256° C. and 284° C. the mass simply absorbed heat without undergoing 
either contraction or expansion. 
At 284° C. it began to contract, and between that temperature and 309° C. it under¬ 
went slight contraction under a negative coefficient of 
'00003999. 
At 309° C. the contraction ceased and the mass simply absorbed heat without either 
contracting or expanding, till a temperature of 319° C. had been attained, at which 
point rapid expansion set in under a coefficient of 
•00016665 
which is more than three times greater than the coefficient of expansion between 0° C. 
and 223° C. 
