386 



NATURE 



[September 15, 1923 



Mr. VVyld's account of the history of the jirocess and 

 of its successive developments leaves nothing to be 

 desired in point of accuracy and completeness. It 

 forms indeed a most interesting section of the chapter 

 devoted to the exploitation of the natural deposits 

 of sulphur which occur in various parts of the 

 world. 



The book, of course, deals with a great variety of 

 processes for obi;iiinii: sulphur: from raw ores; 

 from spent oxide in the manufacture of coal-gas ; 

 from pyrites ; from sulphur dioxide, as from smelter\' 

 fumes ; from sulphuretted hydrogen and sulphites and 

 sulphides and from sulphates of the alkaline earths. 

 These last-named processes became of the utmost im- 

 portance to Germany during the War, owing to her 

 inability to import sulphur or any considerable supply 

 of pyrites. History affords many instances where a 

 nation or manufacturing community under the stress 

 of necessity, often occasioned by war, has been com- 

 pelled to adopt new methods or to modify existing 

 ones, and such modifications have frequently taken a 

 permanent place in industry. What, however, is to 

 be the ultimate fate of the processes which Germany 

 was compelled to adopt remains to be determined. 

 Certain of them have been found to be economically 

 unsound when compared with pre-War methods, and 

 have already been given up, but their stor^' is inter- 

 esting as a chapter in industrial progress and as 

 showing what knowledge, skill, resourcefulness, energy, 

 and application will achieve in overcoming obstacles 

 which at first sight seemed well-nigh insuperable. 



In an industry such as that described in this book 

 analytical control is frequently of the utmost im- 

 portance, but it is too often neglected, or only in- 

 adequately carried out, owing, in many cases, to the 

 want of suitable methods or to the time required to 

 make the results available to the management. 



A commendable feature in the book is the space 

 allotted to descriptions of the most suitable analytical 

 methods at the disposal of the works chemist. The 

 treatise in this respect becomes a veritable vaie mecum, 

 and should be indispensable to everj' well-ordered 

 factory. The improvement of analytical processes 

 applicable to the conditions of chemical works was a 

 constant problem with the late director of the chemical 

 department of the Zurich Polytechnic, and certain of 

 the methods described in this book are the outcome 

 of investigations made by him in conjunction with 

 his senior pupils. 



The various forms of pyrites, brimstone, and spent 

 oxide are the usual sources of sulphur dioxide, mainly 

 as an " intermediate " in the manufacture of sulphuric 

 acid. For small-scale operations sulphur dioxide is 

 made by heating charcoal or sulphur with sulphuric 

 NO. 281 I, VOL. I 12] 



acid, usually of 74 per cent. SO, or 165" Tw. As th. 

 gas is easily liquefied, the temperature of a mixtur< 

 of snow or powdered ice and salt being sufficient ti 

 effect its condensation, it may lie preserved as a liquid 

 in ordinary soda-water syphons, whence the liquid or 

 the gas may be liberated as desired. This section tjf 

 the book contains a full account of the physical and 

 chemical properties of this compound, the modes of 

 its detection and estimation, and of its employment in 

 the manufacture of wood pulp and as a disinf< 

 and antiseptic agent and also as a bleaching a, 

 especially for wool, silk, straw, etc., and to a limited 

 extent in wine-making in the form of meta bisulp' ''■■ 

 Other sulphur compounds of which full and act > 

 accounts are given are sulphur trioxide and the various 

 nitrogen-sulphur compounds. Indeed, the chemical 

 history of the various sulphur compounds, so far as 

 these have any relation to sulphuric acid and its 

 manufacture, may be said to be accurate and 

 complete. 



As regards the actual manufacture of sulphuric acid, 

 a comparison with the accounts given in the earlier 

 editions shows what the influence of the War has 

 been on the production of this important chemical 

 Pre-War plant was found to be utterly inadequate tu 

 meet the demand for this acid, as incidentally required 

 in the manufacture of munitions, and, as is well known, 

 it was necessary' to make special arrangements to this 

 end. Some account is given of the means installed a 

 Queen's Ferr)^ and other places. The section on burners 

 for sulphur and on the plant needed in connexion 

 with the use of pyrites has been carefully rcNnsed and 

 brought up-to-date, and constitutes one of the most 

 valuable sections of the work. 



The volume on the manufacture of hydrochloric acid 

 and salt-cake exhibits, perhaps in a more strikin_ 

 manner, the changes, almost revolutionarj^ in character, 

 which have overtaken this special branch of the alkali 

 manufacture. The Hargreaves' process is no longer in 

 operation in this country-. Pan and furnace methods 

 are still worked, but with the gradual disappearance 

 of the Leblanc process it may be anticipated they will 

 give way to one or other of the more modem processes 

 described in this volume. 



As the editor points out, the manufacture of hydro- 

 chloric acid is no longer necessarily connected with 

 the manufacture of salt-cake, and fuller treatment has 

 therefore been given to its manufacture from chlorine 

 and to other modem developments. 



The revised work is a most valuable addition to the 

 literature of one of our staple industries, and the 

 editor is to be congratulated on the care and thorough- 

 ness with which he has completed his task. 



T. E. Thorpe. 



