NATURE 



7Z 



THURSDAY, NOVEMBER 25, 1880 



SULPHURIC ACID AND ALKALI 

 On the Manu/ai/ure of Sulplmric Acid ami Alkali. By 

 George Lunge, Professor of Technology in the Zurich 

 Polytechnic School, formerly Manager of the Tyne 

 Alkali Works, South Shields. Vol. ii. (London : Van 

 Voorst, 18S0.) 



THIS volume forms a fitting sequel to the first volume 

 of Prof. Lunge's valuable work (noticed in N.ature, 

 vol. XX. p. 263) on the alkali manufacture. The praise 

 we bestowed upon the earlier volume may without stint 

 be applied to this. Clearness and conciseness in style 

 remarkable in a foreigner, accuracy and fulness in the 

 description of both old and new processes, and admirable 

 woodcuts of apparatus and manufacturing plant, constitute 

 the chief merits of this by far the best treatise extant on 

 the most important branch of chemical industry. The 

 value of works on technical science, as well, we may also 

 add, of the teaching of such subjects, depends not only on 

 a sound knowledge of the scientific principles upon which 

 the manufactures are based, but likewise upon a thorough 

 acquaintance with technical minutia: and the special 

 details of construction and operation, the due observation 

 of which is necessary for the manufacturer's success. 

 Either one of these conditions may be fulfilled by a host 

 of authors, but to find both fully developed, as is the case 

 with Prof. Lunge, is rare. Manufacturers themselves, 

 many of whom may be fully competent to the task, are, 

 for obvious reasons, not given to make known the details 

 of their successful manufacture. Nor is the professional 

 chemical engineer likely to do more than describe the 

 most common and well-known processes. Dr. Lunge 

 enjoys the great advantage of having had manufac- 

 turing experience, if not along the whole line, at least 

 over a very large portion of his subject; and to this 

 he now adds that of a position in which every motive 

 urges him to impart his knowledge unreservedly to his 

 readers. 



A criticism worth having of a book like the one under 

 review should by good rights imply a knowledge of manu- 

 facturing detail at least comparable with that of the author. 

 To this the present writer can lay no claim, whilst mere 

 indiscriminate praise is a mode of treatment to which he 

 would not subject the readers of Nature, either for 

 their sake or for his own. In order therefore to find out 

 how far this work really teaches what it professes to 

 teach, how far it is abreast of the improvements of the 

 day, and how far it expresses a sound opinion on vexed 

 trade questions such as " open " as against " closed " salt- 

 cake roasters, or as Hargreaves salt-cake process as 

 against the old Leblanc's process, the writer has called to 

 his assistance his friend and former pupil, Mr. John H. 

 Crossley of Widnes, in whose ability in both the theore- 

 tical and practical side of the subject he has the greatest 

 confidence, and to whom he is indebted for an opinion on 

 these questions. 



The opening chapters of the volume are devoted to a 



discussion of the various methods of making salt-cake or 



sodium sulphate the first great step in the production of 



alkali from common salt. It is a fact worthy of note that 



Vol. XXIII. — No. 57S 



although Leblanc's process had been in successful work 

 in France from the year 1797, seventeen years elapsed 

 before this was taken up in England at Walker-on-Tyne 

 by Losh. This may be perhaps accounted for by the war 

 then raging by which communication between the two 

 countries was almost entirely cut off, but especially 

 because of the high war duty on salt, which in 1805 

 amounted to no less than 30/. per ton, and which existed 

 up to the year 1823 ! This may be regarded as the year of 

 birth of the manufacture on a large scale, and in this year 

 James Muspratt, whom we are glad still to be able to 

 salute as the veteran founder of the alkali trade, erected 

 works at Liverpool, where common salt was decomposed 

 with sulphuric acid and the Leblanc process carried out 

 completely. The difference in cost of production in the 

 early part of the century and in recent years is seen by 

 the fact that in 1S14 soda crystals cost 60/. per ton, whilst 

 in 1 86 1 the price was \l. \os. 



Dr. Lunge goes into the question of " Close " versus 

 " Open " salt-cake roasters pretty fully, but deriving his 

 practical experience from Newcastle, where open furnaces 

 are almost exclusively employed, it is not surprising to 

 find a leaning towards the latter form betrayed in spite of 

 his attempt to place the matter before his readers in an 

 impartial manner. One of his arguments in favour ot 

 open roasters is that stronger sulphate is obtained by 

 their use ; he says (p. 93) " Owing to the higher tempera- 

 ture of an open roaster it is much easier to calcine the 

 salt-cake and to decompose the common salt completely. 

 In blind furnaces this can only be obtained by employing 

 a large area and consequently a very thin layer of material 

 and spending a good deal of time over the calcining 

 process. This of course is much easier with furnaces 

 possessing two muffles to one pan." 



Against this fact it may be mentioned that though 

 the Lancashire close roasters are certainly built larger than 

 the Newcastle open ones, a much larger charge is worked, 

 and many works regularly turn out salt-cake testing above 

 97 per cent., and this too in furnaces with one muffle only, 

 the double form he speaks of and figures on pp. 72 and 

 90, being certainly represented in practice by one or two 

 isolated specimens only. 



Dr. Lunge (p. 116) gives 14-15 cwt. as usual charges of 

 salt for close roasters, but as much as iS cwt. are fre- 

 quently worked at one operation. In this same cjuestion 

 the author hardly gives due prominence to the " Plus 

 Pressure ' ' system, which is now doing good work with 

 regard to close roasters. Probably the appendix to be 

 published with vol. iii. will dea I with this. 



The description (pp. 115-125) of the actual working of 

 a salt-cake furnace is very good indeed. 



Chapter IV., on Hargreaves' Process, is also excellent, 

 and is probably the best description extant ; the only fault 

 that could be found is that the figures show a double line 

 of cylinders separated by an arch, the idea being to allow 

 of having a drawing-door on each side of the cylinders. 

 This however is not by any means compensated for by 

 the greater loss of heat by radiation. Only the earlier 

 plants are built this way, the more modern erections 

 having the cylinders built back-to-back so as to form one 

 solid block. 



Dr. Lunge wisely refrains from much speculation as to 

 the future of this most ingenious process. " If wc are to 



