556 poisons : their effects and detection. [§ 735 . 
K. Chodomisky 1 has investigated the solubility of recrystallised 
arsenious acid in dilute acids, and his results are as follows :—100 c.c. 
of 1-32 per cent, hydrochloric acid dissolves 1-15 grm. As 2 0 3 at 18*5°. 
100 c.c. of 6 per cent, hydrochloric acid dissolves 1-27 grm. at 18*5°. 
100 c.c. of pure hydrochloric acid of the ordinary commercial strength 
dissolves 1-45 grm. As 2 0 3 . 100 c.c. of dilute Sulphuric acid at 18° 
dissolves about 0-54 grm. ; at 18-5°, from 0-65 to 0-72 grm. ; and at 
80°, from 109 to 1*19 grm. 
§ 735. Arsine—Arseniuretted Hydrogen, H 3 As.—Mol. weight, 78 ; 
vol. weight, 39 ; specific gravity, 2-695 ; weight of a -litre, 3-4944 grms. ; 
percentage composition, 95-69 As, 4-31 H; volumetric composition, 2 vol. 
H 3 As = half vol. As+ 3 vol. H. A colourless inflammable gas, of a foetid, 
alliaceous odour, coercible into a limpid, colourless liquid under ordinary 
pressure at —120° ; it solidifies at —118-9°, melts at —113-5°, and boils at 
55°. The products of the combustion of arseniuretted hydrogen are 
water and arsenious acid; thus, 2H 3 As + 30 2 = 3H 2 0 +As 2 0 3 . If sup¬ 
plied with air in insufficient quantity, if the flame itself be cooled by (for 
example) a cold porcelain plate, or if the gas pass through a tube any 
portion of which is heated to redness, the gas is decomposed and the metal 
separated. Such a separation may be compared with that of the deposit 
of carbon from ordinary flames, when made to play upon a cooled surface. 
It may also be decomposed by the electric spark ; 2 6 .( 7 ., if the gas is 
passed slowly through a narrow tube 0-7 to 0-8 mm. internal diameter, 
provided with wires 0-5 to 0-6 mm. apart, and a small induction coil 
used connected with two large Bunsen’s cells, then, under these conditions, 
arsenic as a metal is deposited in the neighbourhood of the sparks. For 
the decomposition to be complete, the gas should not be delivered at a 
greater speed than from 10 to 15 c.c. per minute. The gas burns with 
a blue-white flame, which is very characteristic, and was first observed 
by Wackenroder. It cannot, however, be properly seen by using the 
ordinary apparatus of Marsh, for the flame is always coloured from the 
glass ; but if the gas is made to stream through a platinum jet, and then 
ignited, the characters mentioned are very noteworthy. 
Oxygen (or air) and arsine make an explosive mixture. Chlorine 
decomposes the gas with great energy, combining with the hydrogen, 
and setting free arsenic as a brown cloud ; any excess of chlorine com¬ 
bines with the arsenic as a chloride. Sulphur, submitted to arseniuretted 
hydrogen, forms sulphuretted hydrogen, whilst first arsenic and then 
sulphide of arsenic separate. Phosphorus acts in a similar way. 
Arseniuretted and sulphuretted hydrogen may be evolved at ordinary 
temperatures without decomposition ; at the boiling-point of mercury 
(350 ) they are decomposed, sulphide of arsenic and hydrogen being 
1 Chem. Centrbl., 1889, p. 569. 
2 N. Klobrikow, Zeit.janal . Chem., xxix. 129-133. 
