638 EEPORT— 1887. 



10. On the Action of Light on the Hydracids of the Halogens in the i)resence 

 of Oxygen} By Arthuk Richardson, Ph.D. 



The author pointed out some of the couditions which influence the decom- 

 position of the gaseous hydracids of chlorine, bromine, and iodine, in presence of 

 oxygen when exposed to sunlight. 



Dry, or even partially dry, hydrochloric and hydrobromic acids are unacted on 

 by sunlight, when mixed with varying proportions of oxygen. 



Perfectly dry hydriodic acid, on the other hand, readily decomposes when 

 exposed in the presence of oxygen. The gases when saturated with moisture are 

 shown to suffer decomposition to a degree dependent on the amount of oxygen 

 with which they are mixed, in excess of that required for the complete oxidation 

 of the hydrogen of the acid. In the cases of hydrochloric and hydrobromic acids, the 

 amount of decomposition is very small when enough oxygen only is present to 

 unite with all the hydrogen of the acid, the amount of decomposition inci'easing as 

 more oxygen is added. 



In a note the author showed that phosphonium bromide and iodide are formed by 

 the action of light on moist amorphous phosphorus and hydrobromic or hydriodic 

 acid. 



FRIDAY, SEPTEMBER 2. 



The following Papers and Report were read : — 



1. On the Present Position of the Alhali Manufacture. 

 By Alfred E. "FLETCnER. F.G.S., F.I.U. 



Reference was made to a paper read at the last ^Manchester meeting, giving an 

 account of the position of the manufacture in 1861, and to papers read before the 

 Societv of Chemical Industry in lt'8j and 1884 by W. Weldon, and in 1886 by 

 E. K.'Muspratt. 



It was noticed that the present is the centenary year of the Leblauc process, 

 and that until 1877 all the soda of commerce was manufactured by it. 



A sketch was given of the successive improvements that have been made in the 

 details of the process, and in the mechanical appliances devised for carrying it out. 

 Mention was made of the Weldon and the Deacon chlorine processes ; of the 

 mechanical revolving black-ash furnace proposed by Ellison & Russell in 1853, 

 and subsequently perfected Ijy Stevenson & Williamson of Jarrow, and b_y Duffy 

 of St. Helen's ; of the finishing furnaces of Schofield and of M'Tear ; of tlie 

 mechanical salt-cake furnaces of Jones & Walsh, of M'Tear, of Cammack & 

 Walker, and of Black & Larkin ; of the improved hand salt-cake furnaces of 

 Gamble, of Gaskell, Deacon, & Co., and of Wigg. 



Mention was also made of the successive introduction of improvements in the 

 chemical details of the process ; of the Henderson process for recovering copper 

 from the burnt pyrites, wliereby at present 12,000 tons are annually produced ; also 

 that of Olaudet for recovering silver and gold from the same source, by which 

 means .360,000 ounces silver and .3,000 ounces gold are gained yearly. The 

 total quantity that has been recovered by this means is over 2f million ounces 

 of silver and 1.5,000 ounces of gold ; also of the method of Carey, Gaskell & 

 Hurter of treating their black-ash liquors by heat for the production of mono-car- 

 bonate to be used in the production of bi-carbonate of soda. 



The recent rapid extension of the ammonia-soda process was then described ; 

 patented by Dj'er & Hemming in 1835, successfully applied by Solway in 1866, 

 and introduced in England in 1874 by Brunner, Mond, & Co., who now manu- 

 facture 100,000 tons nearly pure carbonate of soda annually by its means. Figures 

 were given to show the rapid growth of this process, which in great measure is 

 replacing that of Leblanc, but reason was given for believing that the increase 

 cannot go on further until chlorine is produced in connection with it. 



' Published in extenso in the CJtem. Soc. Trans. Nov. 18S7. 



