Nitric and Nitrous Acids to Bromine and Iodine. 285 



constitute a serious objection to the method *. There are few 

 chemical processes which are not attended with some sacrifice of 

 materials ; and it seems a matter of very little consequence on 

 what material that loss falls, provided the total expense, in com- 

 parison with other methods, is not increased. Indeed, plans 

 might easily be devised, by which all the iodine which escapes 

 oxidation might be condensed, and saved for another operation. 

 And if it be objected that the process of ebullition is tedious, I 

 shall leave to others to determine whether more time and trouble 

 are expended, than in the numerous steps of other methods. 



It will give me .much pleasure, if the suggestion of M. Serul- 

 lag, whose recent loss science deplores, shall be found to facili- 

 tate the process ; but in the only experiment which I have made 

 on the subject, I could not observe that the employment of an 

 acid, which had been highly charged with nitrous acid, by pass- 

 ing through it a current of deutoxide of azote, offered greater 

 advantages. 



Major-General Sir Howard Douglas^ Bart. ^c. on Military 

 Bridges y and the Passage of Rivers in Military Operations'^. 



The passage from one point of a country to another, with fa- 

 cility, will always, among a commercial and warlike people, 

 form a topic of general interest for discussion. In ancient times, 

 one of the greatest obstacles to the free intercourse of one na- 

 tion with another, and of different parts of the same kingdom 

 with each other, was generally understood to arise from the bad- 



■ I speak here of the result of my own experiments, which were not con- 

 ducted with any particular view to economy ; but I observe that M. Duflos, 

 in following out these experiments, has succeeded in converting half an ounce 

 of iodine into iodic acid, by means of 2^ ounces of nitric acid, without any loss 

 of iodine at all. — Bullet, des Sciences, Oct. 1831. 



•f This article is to be considered as illustrative of the highly interesting 

 and very important work, entitled, " An Essay on the Principles and Con- 

 struction of Military Bridges, and the Passage of Rivers in Military Opeia. 

 tions." By Major-General Sir Howard Douglas, Bart. &c. Second edition, 

 pp. 417. 



