74 Scientific Intelligence. 



In the former case, oxygen was present (a) in only sufficient 

 quantity to oxidize' the hydrogen, or (b) in large excess. Bulbs of 

 about 300 c. c. capacity were filled with the gaseous mixture and 

 sealed. The hydrogen chloride gas was prepared from sodium 

 chloride by the action of pure sulphuric acid. The oxygen was 

 freed from any chlorine it might contain by passing it through 

 sodium hydrate. After exposure to the light, the bulbs were 

 opened under water and the chlorine compounds thus absorbed. 

 The resulting solution, made up to known volume, was divided 

 into two equal parts. In the first the total chlorine was deter- 

 mined and in the second the free chlorine. In the first experi- 

 ment the moist gases were mixed in the ratio of 4 vols, hydrogen 

 chloride and 1 vol. oxygen, and the bulb was exposed to sunlight 

 for 24 days. The free chlorine formed amounted to - 34 per cent. 

 In the second experiment, in which the oxygen was 8 vols, to tour 

 of hydrogen chloride and in which the exposure was 21 clays, 

 73 - 81 per cent of chlorine was evolved, the mixture in the bulb 

 being distinctly greenish after five days. In the third and fourth 

 experiments, the gases were mixed in the same proportion and 

 exposed to sunlight for 57 days. Notable quantities of hypo- 

 chlorous oxide or other oxide of chlorine were produced. In the 

 fifth experiment the gases were both carefully dried over phos- 

 phoric oxide. After 27 days exposure in one case and 63 days in 

 another, not a trace of free chlorine could be detected. The hy- 

 drogen chloride was then saturated with moisture and mixed 

 with dry oxygen. But an exposure to sunlight of 60 days failed 

 to produce any free chlorine. Hence, a mixture of hydrogen 

 chloride and oxygen is perfectly stable in sunlight not only when 

 dry, but even in presence of aqueous vapor, provided liquid water 

 be absent. Similar experiments were then made with hydrogen 

 bromide. When the gases were moist and tli£ oxygen was that 

 required to oxidize the hydrogen, an exposure of 46 days pro- 

 duced # 64 per cent of free bromine. When, however, the oxy- 

 gen was in large excess, 7*73 per cent of bromine was set free in 

 the same time. In case the gases were dry, no bromine was 

 evolved. In the experiments with hydrogen iodide, 94*31 per 

 cent of free iodine was produced in 20 days when the oxygen was 

 not in excess and 96 - 08 per cent when an excess of oxygen was 

 used. Even dry mixtures of these gases were found to be decom- 

 posed by sunlight. Hence, the author concludes : 1st, The sta- 

 bility of the moist hydrides of chlorine, bromine and iodine is de- 

 pendent on the mass of oxygen present, in excess of that required 

 for their complete decomposition. 2d, Dry or partially dry hy- 

 drogen chloride and bromide are completely stable, even when 

 mixed with a large excess of oxygen. 3d, Dry hydrogen iodide 

 is decomposed in presence of oxygen. — J. Chem. Soc, li, 801- 

 806, November, 1887. G. f. b. 



2. On the Influence of Liquid water in promoting the Decom- 

 position of Hydrogen chloride by Sunlight in presence of Oxy- 

 gen. — In a paper immediately following the one above mentioned, 



