HALOID COMPOUNDS OP SILVER, MERCURY, LEAD, AND COPPER. 1139 
6. Chlorobromiodides of Silver, having the Composition :—Agl, Ag 2 Br 2 ’ 
AgAs! Agl, AgBr, AgCl; AgjLj, AgBr, AgCl; Ag 3 I 3 , AgBr, AgCl; Ag 4 I 4 , 
AgBr, AgCl. 
Compounds of silver with iodine, bromine, and chlorine are found in nature: 
embolite (ififioXiov) is a chlorobromide of silver, and minerals having respectively the 
composition Ag 3 BrCl 2 , Ag 5 Br 2 Cl 3 , Ag 4 Br 3 Cl, Ag 9 Br 4 Cl 5 , and Ag 4 BrCl 3 , have been 
analysed by Domeyko, Field, Muller, Eichter and others. They occur chiefly in 
Chili, and constitute the principal ores of the silver mines of Chanarcillo. They 
possess specific gravities which vary from 5"75 to 6'2, and according to Dana the colour 
is “ greyish-green, and asparagus-green to pistachio or yellowish-green, and yellow; 
often dark, becoming darker externally on exposure.” Yon Lasaulx has described in 
the ‘ Jahresberichte fur Mineralogie,’ for 1878, a new silver haloid mineral having the 
composition Ag 2 Br 2 , Ag 2 Cl 2 , Agl which he cites as the first instance of the three 
haloid salts occurring crystallized together in nature. Two years previously I had 
prepared, for the purposes of this enquiry, a substance having the same composition, 
and its properties were described in Proc. Roy. Soc., No. 174, 1876. It was found by 
Yon Lasaulx, associated with Beaudantite, in a mine in the district of Ems, 
Nassau, in the form of small yellow, or olive-green octohedra, never exceeding 3 millims. 
in size. 
Five compounds of the halogens with silver were prepared, the first having the 
composition Agl, Ag 2 Br 2 , Ag 2 Cl 2 , and the others increasing by one molecule of Agl to 
Ag 4 I 4 , AgBr, AgCl. The substances were fused together in a porcelain crucible, and 
cast in glass tubes. They were examined in the expansion apparatus in the usual 
manner. The coefficients and more prominent physical characteristics are given in the 
following table. Generally speaking, of all the compounds it may be said that they 
fused to a bromine-red transparent liquid, becoming successively brick-red, dull orange, 
and yellow or yellowish-brown on cooling. They furnished bright yellow powders, 
turning green on exposure to light. 
