146 



NA TURE 



[June 15, 1893 



sulphuric acid in the cold, can yield oxygen I could not 

 understand but, on looking up the original paper, I find 

 that for barium chloride, barium peroxide should have 

 been printed. Here Cr03and HjOj mutually decompose 

 to CrjOj and water, whilst pure oxygen derived from both 

 sources comes off. This interesting reaction is not a new 

 one, as it was used by Brodie in 185 1, and adverted to in a 

 lecture by Faraday at the Royal Institution ; nor does it 

 appear to be capable of producing oxygen at a sufficiently 

 low cost to be of practical value. Of course, Dr. Thorne 

 gives an excellent description of Brin's well-known process 

 by which oxygen is now manufactured on a large scale, but 

 1 do not find any statement of a process which bids fair 

 to compete with Bri") viz. Fanta's improvement on Tessie 

 du Motay's reaction, by which oxygen is evolved from 

 manganate of soda by the action of steam. He does 

 indeed refer to Du Motay, and gives the cost of oxygen pre- 

 pared by his process at from £1 to ^4 per looo cubic feet, 

 whereas that by the Brin process is given as from 3^. to 

 -js. I cannot help thinking that this proportional cost is 

 incorrect, as I know that Fanta's process, the patent of 

 which appears to have superseded Bowman's, is now in 

 practical operation at the Bradford Gas Works, and this 

 would scarcely be the case if the cost were as great as 

 Dr. Thorne states. 



That pure oxygen can now be produced at so low 

 a figure as 3,9. per 1000 cubic feet is a great fact, and in- 

 duces the hope that we may ere long see it at is. per 1000. 

 In that case the use of oxygen to heighten the tempera- 

 ture of combustion would become general, especially for 

 welding and riveting of steel and iron. Even now its 

 uses are spreading, not only for the oxyhydrogen light, 

 but for purifying coal-gas. The addition of from o'5 to 

 roper cent, of oxygen to crude coal-gas renders its puri- 

 fication more complete and easy, as thus the sulphur 

 compounds are reduced to 12 grains per 1000 cubic feet, 

 and lime alone suffices as a purifying agent. Moreover, 

 the luminosity of the gas is said to be increased. This 

 application of oxygen is on its trial at certain gasworks, 

 but it has to be shown how far this plan of adding oxygen 

 acts more satisfactorily than the much cheaper one of the 

 addition of air, in spite of the small loss in illuminating 

 power which the presence of atmospheric nitrogen entails. 



Next I turn to "Paper," by Mr. E. J. Bevan, a short 

 but good article, in which I find a description, in which 

 one misses some illustrations, of the method of recovering 

 the soda used in the preparation of the esparto and other 

 fibres used in making paper. No example of the appli- 

 cations of science to the working up of waste products is 

 more striking than this. Before the introduction of the 

 Rivers Pollution Act of 1876, no paper-maker thought of 

 recovering his soda — all the liquors went to pollute the 

 streams on which the works are situated. Now most 

 paper-mills recover their soda, and save thereby from 80 

 to 85 per cent, of this costly article, whilst at the same 

 time they have diminished the nuisance which they 

 caused to their neighbours on the stream below them. 

 It is high time that every user of soda for disintegrating 

 or bleaching fibres of all kinds should be prohibited from 

 thus fouling the water, and that the application of the 

 "best practicable means" clause were rigidly enforced by 

 all local authorities interested in improving the quality 

 of the water of our rivers. 



NO. 1233, VOL. 48] 



The article on " Petroleum," by Mr. Boverton Red- 

 wood, is another instance of information given by 

 a high authority. It extends over forty pages, is 

 up to date, and abundantly illustrated. "Photography," 

 by Prof. J. M. Thomson, gives a clear and concise 

 account of the chief processes of the application of 

 photography to lithography and mechanical printing, 

 now becoming more and more perfect, and the article 

 concludes by giving a list of the more important 

 works on the subject. 



The two longest articles in the volume are, as might be 

 guessed. Sodium and its compounds, occupying 93 pages 

 and Sulphuric Acid and its relatives, taking up 84. The 

 manufacture of sodium is one of the most remarkable 

 advances of the time ; not long ago it could only be bought 

 by the ounce, and at an exorbitantly high price, now an 

 order for 100 tons will be executed by the Aluminium 

 Company, of Oldbury, and the price is only a few shillings 

 a pound. Castner's process for making sodium is fully 

 described, but the excellent illustrations are only of his- 

 toric interest, inasmuch as the process which thev in- 

 dicate has lately been superseded by a more economic 

 one. The article on Sodium Chloride is of a most com- 

 plete and trustworthy character, and has been written by 

 Mr. J. I. Watts, of Messrs. Brunner, Mond, and Co., where 

 he has had ample opportunities of making himself master 

 of every detail of the processes he describes. Sulphur 

 and Sulphuric Acid are interesting articles by Dr. Alder- 

 Wright, who adds to his scientific knowledge practical 

 experience of the manufacture. I cannot pretend to dis- 

 cuss the merits — which are great — of these articles I 

 will only remark that they contain information up to date, 

 and I am glad to see that Dr. Wright has consulted the 

 Journal of Chemical Industry, and has given the readers 

 of the Dictionary an opportunity of becoming acquainted 

 with Dr. Hurter's researches on the chemistry of the 

 leaden chamber, published in that journal. 



The important article " Water " is contributed, as it 

 should be, by Prof. Percy Frankland. With regard to 

 this able article, extending over fifty-five pages, I have to 

 remark that the author, whilst giving an excellent account 

 of the chemistry of water, seems to have forgotten that he 

 is writing an article in a dictionary of applied and not 

 in one of pure chemistry. Why, for example, should two 

 pages of valuable space be taken up by a long table of the 

 tension of aqueous vapour .•" Nor is it clear that so 

 many analyses of mineral waters need be quoted, no less 

 than fifteen pages being taken up by tabular matter. On 

 the other hand, greater prominence might well have been 

 given to more technical details of the various methods of 

 water purification. Here I think that the author might 

 have given some extracts from the volumes of the Chemical 

 Industry Society with profit, where, as he v/ell knows, 

 much new and important information is to be found. 

 There is not a single diagram or illustration in this 

 article showing the arrangements proposed for filtration 

 or other means of purifying water ; thus, whilst the 

 author refers to the " Stanhope " purifier, he gives no 

 drawing to explain its construction. Prof. Tilden's im- 

 portant experiments on the corrosive action of water on 

 brass and copper are not referred to, a classical subject 

 originally investigated by Davy in 1824, and reported 

 upon by him to the Admiralty of that day. Nor is the 



