CADMIUM. 
§§ 795-798-] 
added, the liquid made up to 25 c.c.,and hydrogen sulphide passedthrough 
until the colour is fully developed. Comparison is made with a standard 
solution of pot. ant. tartrate. 
§ 795. Stibine (antimony hydride, antimoniuretted hydrogen), 
SbH 3 .—Molecular weight, 125. The gas contains 97-6 per cent. Sb, 
2-4 per cent. H. The gas, by cooling with liquid air, has recently been 
obtained in a pure state. The solidified gas melts at —88° to a colour¬ 
less liquid; the boiling-point at normal pressure is —17°. 1 The liquid 
has a sp. gr. of 2-26 at —25°, and 2*34 at —50°. 
At ordinary temperatures 1 volume of water dissolves 15 volumes 
of the gas ; 1 volume of alcohol dissolves also the same volume ; at 0° 
1 volume of carbon disulphide dissolves no less than 250 volumes of 
the gas. 
The dry gas is fairly stable, but the moist gas is unstable. In 
presence of air or oxygen at ordinary temperatures it decomposes into 
antimony, water, and a little hydrogen. 2 The gas passed into a solu¬ 
tion of mercury and potassium iodides, HgI 2 + KI (Hgl nKI, with n> 2) 
gives a brown-black precipitate of SbHg 3 I 3 ; arsine acts similarly, and 
phosphine gives, under the same circumstances, a yellow crystalline 
solid. 3 When the gas is passed over sulphur, stibine is decomposed 
according to the equation 2SbH 3 -f 6S = Sb 2 S 3 +3SH 2 , and the sulphur 
assumes a deep orange tint. The reaction takes place very slowly in 
ordinary daylight, rapidly in sunshine. Given bright sunshine, this 
reaction may be utilised as a test. The antimony sulphide may be 
freed from sulphur by digestion in CS 2 . The distinctions between the 
stains deposited by heating arsine or stibine have been already described. 
Stibine, like arsine, is intensely poisonous ; mice die in a few seconds if 
exposed to air containing 1 per cent, of stibine. 
§ 796. Quantitative Estimation. —The quantitative estimation of 
antimony is best made by some volumetric process— e.g. the sulphide can 
be dissolved in HC1, some tartrate of soda added, and then carbonate of 
soda to weak alkaline reaction. The strength of the solution of tartarised 
antimony thus obtained can now be estimated by a decinormal solution 
of iodine, the end reaction being indicated by the previous addition of a 
little starch solution, or by a solution of permanganate of potash, either 
of which should be standardised by the aid of a solution of tartar emetic 
of known strength. 
3. CADMIUM. 
§ 797. Cadmium, Cd = 112 ; specific gravity, 8-6 to 8-69; fusing-point, 227-8° 
(442° F.); boiling-point, 860° (1580° F.).—Cadmium in analysis is seldom separated 
as a metal, but is estimated either as oxide or sulphide. 
§ 798. Cadmium Oxide, CdO = 128—cadmium, 87-5 per cent. ; oxygen, 12-5 per 
1 Stock and Doht, Ber., 1902. 
3 Paul Lemoult, Compt. Rend., 1904. 
2 Stock and Guttman, Ber., 1904. 
