M. C. Lea on the Platinum Metals. 89 
A dilute solution of the salt is always olive-green, whether 
seen by reflected or transmitted light. If it appears red by trans- 
mitted, when very dilute, this can only arise from the presence 
of bichlorid of ruthenium, or sesquichlorid of rhodium. 
8 its concentration increases, it gradually acquires a red 
color, visible by both reflected and transmitted light, but more 
conspicuous by the latter. A very strong solution is almost 
Opaque to transmitted rays; by dilution, passes to a deep wine 
red. This wine-red solution is by reflected light olive-green, but 
with a distinct tinge of red. Nor has it before been remarked, 
I believe, that the crystallized salt exhibits the same dichroism. 
The crystals are deep green by reflected light, almost black. 
When placed so that light can strike through a dihedral angle, 
its color is rub . 
_ Strong and weak solutions of this salt differ so much in color 
(in tint, not merely in intensity,) that at first one has a difficulty 
in believing that they contain one and the same substance. 
New Ruthenium Reaction.—A series of experiments on the re- 
actions of the platinum metals are as yet unfinished, but I take 
the present opportunity to mention a new and very beautiful re- 
action of the sesquichlorid of ruthenium. : 
Vhen a solution of hyposulphite of soda is mixed with am- 
monia, and a few drops of solution of Ru,Cl, are added, and 
the whole boiled, a magnificent red-purple liquid is produced, 
which, unless the solutions are very dilute, is black by transmit- 
ted light. The coloration is permanent, and the liquid may be 
€xposed to the air without alteration. : 
This reaction is obtained with great ease and certainty, and 
“pada believe, be found far superior to any known test for ru- 
hilum. 
agent, : 
ent strengths, A portion of perfectly pure Ru, Cl, was weighed 
ay a delicate balance, and the following indications were 
ined: 
With 5,55 Ru,Cl,, bright rose purple. 
With 55155 an Pe A ces samen eaty ag ae 
With subse paler, but still perfectly distinct. : 5 
With ;;,';;5, the color, though very pale, was still unmis- 
bly present, 
El Sick pom xD SERiES, VoL. XXXVIII, No. 112.—Juxy, 1864. _ 
12 
