250 M. C. Lea on the Platinum Metals. 
rectly of this test, it is necessary, either to be very fa- 
miliar with the color of the precipitate which the lead 
salt produces with a ruthenium solution, or else to pre- 
pare it for comparison. 
Ru,Cl,, 1 part; chloriridiate, 50 parts. 
Hyposulphite gave a perfect reaction. - 
Sulphocyanid having failed in a solution containing a larger 
quantity of ruthenium, was not here again tried. 
Acetate of lead gave a precipitate which when carefully 
compared with that afforded by a perfectly pure iridium 
solution, exhibited a shade of difference, but scarcely suf- 
ficient to afford any criterion. At least, this must be re- 
garded as the extreme limit of the sensibility of mixtures 
of Ru and Ir to this reagent. 
Ru,Cl,, 1 part; chloriridiate, 100 parts. 
Hyposulphite, perfect ruthenium reaction. 
Ru,Cl,, 1 part; chloriridiate, 200. 
Hyposulphite, satisfactory ruthenium reaction. 
Ru,Cl,, 1 part; chloriridiate, 500 parts. va 
Even in the presence of such an enormous excess of iridium 
t, ruthenium is capable of being detected by a Poe 
tised eye by means of the hyposulphite test, although the 
clear rose color produced in the previous trials was here 
changed to an orange shade. 
jum, — 
Dr. Gibbs has proposed a test for ruthenium by the use of alka- 
line nitrite and sulphid of ammonium. It my wish to com- 
evolved by the reduction of nitric acid through a potash solu 
tion, and also with nitrite of soda prepared from the nitrate. 
18 an important point, the neglect of which may cause the pres 
ence of ruthenium to be overlooked, when it exists in sufficiently 
_ after this precaution has been taken. 
~ an interval 
ab laitend leds 
