HALOID COMPOUNDS OF SILVER, MERCURY, LEAD, AND COPPER. 1137 
Volume at 0 °C. ..... 
99 
124 . 
. . . = -998765 
99 
133 . 
... - -998608 
99 
142 . 
. . . = -998450 
99 
148 . 
. . . = -997469 
99 
1513. 
. . . = -983609 
99 
153 . 
. . . = -981560 
59 
156-5. 
... - -980510 
99 
163 . 
... - -980510 
>9 
200 . 
... - -982377 
95 
300 . 
... - -989298 
59 
400 . 
. . . = -996219 
>9 
500 . 
. . . -1-003140 
99 
527 (solid) .... 
. . . =1-005008 
59 
527 (liquid). . . . 
. . . -1-040908 
Phase of contraction on 
heating. Expansion 
on cooling. 
Phase of expansion on 
heating. Contraction 
on cooling. 
Obviously the iodide possesses two points of similar density at different tempera¬ 
tures. Thus the density at 124° C. is the same as that at about 430° C. 
If 5‘6 75 be the specific gravity at 0° C., the specific gravity at the maximum 
density will be 5*771; at the minimum density 5*673, and in the molten condition at 
527° C., the specific gravity will be 5*522. 
4. Bromide of Silver. 
Precipitated bromide of silver was fused, and cast in warm glass tubes. The mass 
when warm was found to be somewhat tenacious; the surface of the fused rod was 
smooth and brilliant, the fracture crystalline. Repeated fusion seemed to render the 
substance more crystalline. Although crystalline, the bromide was very compact, 
and altogether unlike the crystalline condition of the iodide; the rod contracted a 
good deal in cooling, and easily came out of the tube in which it was fused. Rods 
6 inches long by *3 inch diameter had their ends levelled by means of a fine steel saw, 
and were placed in the expansion-apparatus, and tested as described in the case of the 
iodide of silver bars. The coefficient of cubical expansion for 1° C. was found to be 
*00010500. 
Fizeau by his optical method found the coefficient to be *000104061. The co¬ 
efficient increases with the temperature, at least to the extent of *000004 for each 
100° C. increase of range. The expansion is very considerable in passing from the 
solid to the liquid condition. 
The volumes corresponding to different temperatures and certain physical properties 
are tabulated with those of the chloride of silver (see p. 1138). 
The bromide fuses to a reddish-brown liquid, not unlike bromine, and it solidifies to 
a bright yellow transparent solid when seen in thin layers. In thick layers it appears 
to be brownish-yellow. It is brittle even before it is quite cold. During the process 
7 f 2 
