HALOID COMPOUNDS OF SILVER, MERCURY, LEAD, AND COPPER. 1159 
hitherto prepared contain so large a percentage of iodide of silver. Ag 4 I 4 .AgCl.AgBr 
contains 74 per cent. 
Cu 2 I 2 . 12 AgI contains:— 
Cu 2 I 2 .= 11-8696 Copper.= 3‘9535 
Agl.= 88-1304 Silver.= 40-4770 
Iodine.= 55'5695 
100-0000 100-0000 
The alloy possessed a yellowish-green colour in the mass, but thin layers of it were 
yellow and transparent. The powder was yellow : much brighter than that of iodide 
of silver, but not quite so brilliant as that of the other alloys. It turned slightly 
green on exposure to light. The fracture was crystalline ; the grain being much finer 
than that of the iodide of silver. The alloy violently broke the tube in which it was 
cast by expansion during cooling, but no rifts appeared in the rod; nor was it nearly 
so brittle as iodide of silver. 
Melting point =513° C. 
Specific gravity =5*6950. 
The alloy expanded on heating from 0 ° C. to 124° C. under a coefficient of 
*00000636. 
Between 124° C. and 153° C. it simply absorbed heat without undergoing either 
expansion or contraction. 
At 153° C. contraction commenced, and continued under a negative coefficient of 
*0000831 
till a temperature of 168° C. had been attained, when it increased to 
■00028899, 
and so continued till the temperature had risen to 225° C., when expansion commenced 
under the coefficient 
•00006666. 
The following volumes correspond to the temperatures given :— 
Volume at 
Q 
O 
O 
.-1-000000 
124 . 
..... =1-000788 
99 
153 . 
.-1-000788 
99 
168 . 
. = -998985 
99 
225 . 
.- -982512 
99 
300 . 
. = -987511 
99 
400 . 
.= -994177 
99 
500 . 
.-1-000843 
99 
502 (solid). 
.-1-000976 
99 
502 (liquid). 
.-1-042612 
7 I 
MDCCCLXXXII. 
