394 



SCIENCE. 



[N. S. Vol. XV. No. :n5. 



made to carry out the operation on a large 

 scale, the contact mass quickly became inert. 

 This was the case even when the gases had 

 been purified by passing through long pipes, 

 repeated washing with sulfuric acid, and 

 further passage through coke and asbes- 

 tos filters. In following up the cause of 

 the difiiculty, it was found that extraordinar- 

 ily small quantities of arsenic were capable of 

 inhibiting the action of the platinum in the 

 contact mass. The same is true of a few- 

 other substances such as mercury and perhaps 

 phosphorus. These substances seem to have 

 what may be considered a poisonous action 

 upon the platinum. Investigation showed 

 that the arsenic was contained in the fine 

 white fume which is formed in all eases where 

 sulfur is burned. This fume consists of finely 

 divided sulfuric acid, and its complete con- 

 densation has been one of the unsolvabl.'3 

 problems of technical industry, especially in 

 connection with smelting plants. Eventually 

 the problem was solved by the thorough wash- 

 ing and wet filtration of the slowly cooled 

 gases, with water or dilute sulfuric acid. 



After this purification from every trace of 

 mechanical impurity, as was shown optically, 

 it was found that the contact mass still lost 

 its activity after a time, and here again pa- 

 tient investigation revealed the fact of ar- 

 senic poisoning. This was finally shown to be 

 due to the action of the condensed sulfuric 

 acid from the burners upon the iron condens- 

 ers, whereby traces of arseniuretted hydrogen 

 (arsin) were generated. This, diificulty was 

 easily overcome, but when the process was 

 attempted on a large scale, it was still un- 

 successful. When the pyrites burners were 

 used to their full capacity, there was formed 

 a fume which resisted every attempt at con- 

 densation. This was unconsumed sulfur, 

 which, of itself harmless, contained minute 

 quantities of arsenic, thus again poisoning the 

 contact mass. The formation of this fume was 

 prevented by the injection of steam into the 

 burners, which has other advantages, in pre- 

 venting the action of the condensed acid on 

 the iron pipes, and in hindering the formation 

 of hard dust scales in the cooling pipes and 

 chambers. Other diificulties appeared in the 



cooling of the contact mass and in connec- 

 tion with the absorption of the sulfur trioxid, 

 which is attended by a great development of 

 heat, but they were slight in comparison with 

 those which had attended the purification of 

 the gases. At last the process was established 

 on a commercial basis, as is shown by the fact 

 that in the year 1900 the production of sulfur 

 trioxid reached the amount of 116,000 tons. 



The first interest of the process is of course 

 for the manufacture of the concentrated and 

 fuming acids, used largely in the color in- 

 dustry, but when it is considered that it is 

 the concentrated acids which are most eco- 

 nomically made in thismanner, it is not diifi- 

 cult to foresee that in the near future the 

 chamber process must be superseded for all 

 acids which would require concentration in 

 platinum stills. It is quite possible that the 

 chamber process will continue to be used for 

 many years to come, for the more dilute acids 

 which require no concentration, but even so, 

 the perfection of the contact process can be 

 looked upon as little short of a revolution in 

 this most important of the chemical indus- 

 tries. 



J. L. H. 



RELIEF SHIP FOR THE BRITISH ANTARC- 

 TIC EXPEDITION. 



Sir Clements Maekham, president of the 

 Royal Geographical Society, has issued the 

 following appeal to the Society's fellows : 



It is with some reluctance that I appeal 

 again to the fellows of the Society on behalf 

 of the relief ship, which must leave England 

 not later than July next to obtain news of, and 

 render what assistance may be necessary to, 

 the expedition on board the Discovery. I 

 make this further appeal in the belief that the 

 fellows as a body do not realize the situa- 

 tion, and entertain an erroneous impression as 

 to how much is expected of each individually. 

 I am assured that many, if not most, of the 

 fellows of the Society feel that, unless they 

 can each contribute a very considerable sum, 

 it would be useless to do anything. 



I am particularly anxious to disabuse the- 

 fellows of this impression; I assure them that 

 we shall be glad to receive any contribution. 



