NATURE 



21 



THURSDAY, MARCH 14, 1918. 



REFRACTORY MATERIALS. 



fractory Materials: their Manufacture and 

 hes. By Alfred B. Searle. Pp. xii + 444. 



[London : Charles Gritfin and Co., Ltd., 1917.) 



*rice 155. net. 

 is a pleasure to have the opportunity of 

 acknowledging- that the prime importance of 



Fractory materials to our industries is at last 

 Teceiving recognition. An attempt was made in 

 1909 {vide Times, January 21, and Nature, 

 January 28, of that year) to direct serious attention 

 to this subject, but it was temporarily abandoned 

 because of the failure of the majority to realise 

 the urgency of industrial requirements. To-day 

 we are on the Ixjrder-line of danger at the other 

 extreme. Contrasted with the apathy which pre- 

 Aailed a short time ago, the present attitude ap- 

 pears to some to border on hysteria. Schemes are 

 Ijeing seriously entertained which, if not carefully 

 handled, will lead to the Germanising of research 

 in a bad sense, because certain suggestions which 

 have been made seem based on the idea that the 

 subject merely demands mechanical and routine 

 observations on contractions, porosities, hard- 

 ness, etc., and some suggestions, if adopted, 

 would tend to suppress individuality. Mere in- 

 terest in the problem phis a university degree are 

 not a sufficient admission certificate to the adytum 

 of clay-working. The neophyte requires initiation 

 into the fundamental mysteries, so to spyeak, before 

 )u' can wisely break the bond of silence. 



The author of the present work has been a pro- 

 lific writer on subjects more or less connected with 

 clay-working. Although he has made no impor- 

 tant original contribution to the art, his book is 

 a ,very useful compilation, since it is convenient 

 to have various fragments scattered in the techni- 

 cal journals collected into one volume. The serious 

 student, however, may be dissatisfied with the 

 inadequacy of the references to original sources, 

 which are seldom given in sufficient detail, and 



any future edition this blemish should be recti- 

 ' d. This is the more necessary because in some 

 ^ ases the originals have been so mutilated in 

 tianscribing as to convey erroneous impressions. 

 An example occurs in the reference to the formulae 

 of the chief alumino-silicic acids, on pp. 4 and 9, 

 where the essential point has been missed. In 

 lonnection with the action of alkalis on clays 

 (p. 5), it would have been better to give 

 some indication of the large amount of work 

 ahcady published on the same subject, instead of 

 A\.-iiting until the author of the book is able to 

 fulfil his promise. The remarks on the actual 

 composition of clays on pp. 4 and 5 are quite 

 in accord with the general experience that clays 

 are mixtures of various minerals, but there is 

 something wrong on p. 7 when analyses of nine 

 commercial clays are represented by complex 

 g-raphic formulae. 



The statement on p. 41 that, "generally speak- 

 ing, the compounds of silica are fusible, with the 

 one exception [the italics are the author's] of the 

 NO. 2524, VOL. lOl] 



alumino-silicic acids (true-clays)," needs modify- 

 ing, as it seems to imply that minerals like talc, 

 olivine, leucite, topaz, zircon, sillimanite, and non- 

 tronite are fusible or are alumino-silicic acids. 



Oh p. 42 we are informed that "the softening 

 effect of mica is seldom noticeable below 1200° C, 

 and that of felspar below 1300° C," whereas on 

 the previous page it is stated that "mica is a far 

 weaker flux than felspar." Misprints are unfor- 

 tunately rather numerous, though they do not 

 always involve serious inaccuracies. A mild case 

 occurs on p. 55, where titanitc is represented as 

 CaTiOg. 



The author apparently makes no distinction be- 

 tween yttria and ytterbia, for on p. 122 we find 

 "yttrium oxide or ytterbia," and the latter name 

 is again used instead of yttria twice on the next 

 page. Another statement to which strong excep- 

 tion may be taken appears on p. 179, respecting 

 "particles of iron sulphide (pyrite), which never 

 give a red colour to the [fired] clay, but invariably 

 show up as black or slagged spots." It would be 

 interesting to know the authority for this. The 

 proportion of grog to clay (i to 8), as given on 

 p. 284, for making saggers in Great Britain is 

 I far from being correct according to the practice of 

 potters generally, if, indeed, for any British 

 potters. 



The results obtained by Wernicke referred to 

 on pp. 96-97 doubtless justified the conclusions 

 deduced by him and Wildschrey so far as the 

 quartzites examined were concerned. But it would 

 not have been out of place to add that some, at 

 any rate, of the quartzites in the United States 

 do not conform with these conclusions ; for 

 j McDowell has expressly stated that the best 

 ' American quartzites used for the manufacture of 

 I silica bricks show under microscopical examina- 

 tion no cementing ground mass, but consist solely 

 j of interlocking quartz crystals. This might be 

 i borne in mind in connection with the list of desi- 

 \ derata in quartzites for silica bricks, as set out on 

 '\ p. 98. The statement (on p. 96) that "it is essen- 

 tial to use a quartzite composed largely of tridy- 

 mite " needs justification. Where can such quartz- 

 ites be obtained? 

 ! One of the best features of the book is the 

 \ description of processes with which the author is 

 I familiar ; where he is on strange ground, serious 

 j mistakes have been made. For example, the 

 attempt to cast glass pots by the method described 

 on p. 341 could scarcely give a satisfactory result. 

 As previously intimated, the work possesses 

 considerable value, notwithstanding such defects 

 I as those mentioned. The chapters deal with an 

 i exceptionallv wide range of products and the corre- 

 sponding raw materials, including the manufac- 

 i ture of firebricks from clay, silica, basic materials, 

 i bauxite, carbon, chromite, saggers, muffles, 

 crucibles, glass pots, retorts, as well as fused 

 silica ware, refractory porcelain, refractory mor- 

 tars, and cements. The concluding chapter dis- 

 j cusses the selection and application of refractorv 

 materials, and an appendix gives various stand- 

 I ard specifications. The general index facilitates 

 ' quick reference. J. A. A. 



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