512 



NATURE 



[January 6, 19 16 



THE CERAMIC INDUSTRIES.^ 



THE intimate relation between the various in- 

 dustries and clay is seldom appreciated. 

 The g-as industries, coking plants, iron, steel, and 

 non-ferrous metallurgy; glass manufacture; and 

 the. ceramic industries are all to a large extent de- 

 pendent on good refractory materials. It is 

 therefore obvious that a manufacturing country 

 must devote much attention to its clays, for pro- 

 gress in these industries is largely dependent on 

 improved refractories. In the pre-war days, con- 

 sumers were pushing the firebrick manufacturers 

 for improved methods of manufacture to meet the 

 more severe fire-tests imposed by modern con- 

 ditions. It was the custom to vaunt the German 

 methods of manufacture, and to condemn the be- 

 nighted British. There is much truth in the old 

 firebrick manufacturer's contention that God has 

 given each manufacturer particular clay-beds, 

 and that no improvements in methods of manu- 

 facture will make a bad clay into a good one. 

 As a matter of fact, there appears as much differ- 

 ence in the character of clays from different beds 

 as there is between different individuals ; and to 

 get each clay to do its work most efficiently it 

 must be humoured in manufacture and in use. If 

 the firebrick be not in a suitable environment, it 

 will break down. Experience is constantly bring- 

 ing to light cases where good firebricks do satis- 

 factory work in one furnace, and fail in another, 

 where, at first sight, the conditions appear simi- 

 lar, thus showing that firebricks are sometimes 

 very sensitive to local conditions. 



Satisfactory progress can be made only by the 

 co-operation of maker and user. The experience 

 of both must be pooled for the common good. 

 We can then find what clays are best adapted for 

 particular purposes, and the manufacturer will 

 have a more clear and definite idea in what direc- 

 tions he can best modify his methods to make his 

 clays do their best work. This gigantic task has 

 been undertaken from the point of view of the 

 gas engineers under the energetic lead of Mr. 

 S. J. Bywater, and slow progress has been made 

 in certain directions. To hasten the final victory, 

 the Geological Survey can help very materially. 

 We want to know the specific character of the 

 different clay beds in the country, and a host of 

 other questions which can best be answered on 

 the geological side. There have been a score 

 of elaborate reports on the clay deposits of 

 different parts of the United States, and half-a- 

 dozen likewise for Canada. Several of these have 

 the character of pot-boilers, and cannot be of 

 much practical use ; a few photographs of clay- 

 banks, a few diagrams from the machinery cata- 

 logues, and a few clay analyses do not fulfil the 

 required purpose. In England we have lagged 

 far behind even this. We therefore welcome with 



1 (i) " A Handbook to the Collection of Kaolin, China Clay, and China 

 Stone in the Museum of Practical Geology." By J. Allen Howe, Curator. 

 With an appendix by Allan B. Dick. (London, 1914.) 



(2) " A Study of the Atterberg Plasticity Method." Bv C. S. Kinnison. 

 No. 46. Technological Papers of the Bureau of Standards. (Washington, 1915.) 



(3) " Preliminarv Report on the Clay and Shale Deposits of the Province 

 of Quebec." By J. Keele. Memoir 64 of the Canada Geological Survey. 

 (Ottawa, 1915.) 



NO. 2410, VOL. 96] 



pleasure the appearance of the work on "China 

 Clay and Cornish Stone " by Mr. J, Allen Howe, 

 curator of the Jermyn Street Museum (i). Is it too 

 much to hope that this work is the forerunner of a 

 series dealing with the whole of the different types 

 of clay in our country? This particular memoir 

 is of most use to the pottery industry, since the 

 materials here discussed have some special quali- 

 ties which are not required from fire clays per se, 

 and which give the china clays a special commer- 

 cial value. The mere fact that the pamphlet has 

 appeared is a hopeful sign. It has long been the 

 plaint of the clay industries that a great deal of 

 public money has been spent year by year to 

 publish a pile of Memoirs of the Geological Sur- 

 vey of the United Kingdom. Of course, pure 

 geology is exceedingly important and necessary, 

 but why the applications should have been virtually 

 neglected is not always clear. 



In the introduction to his brochure, Mr. Howe 

 makes a contribution towards rectifying the 

 general muddle as to the precise meaning of the 

 terms "china clay" and "kaolin"; he then gives 

 a general description of the methods of extracting 

 china clay practised in the south-west of Eng- 

 land ; then follows a general sketch of the dis- 

 tribution of china clay in various parts of the 

 world. There are also discussions on Cornish or 

 China stone ; on the uses of these materials ; and 

 on the origin of china clay. There is a review 

 of some recent work on the nature of kaolinite and 

 related minerals. This is followed by a collection 

 of analyses, physical tests, statistics, and a biblio- 

 graphy. Mr. Allan B. Dick contributes an excep- 

 tionally valuable appendix on the identification of 

 transparent mineral grains under the microscope. 



There are some very useful and trustworthy 

 data in the chapter on analyses and physical tests. 

 These are mixed with a lot of old and inaccurate 

 work which possibly might have been omitted 

 without the loss being felt. Perhaps, however, 

 there is something in the argument that bad data 

 are better than no data at all. The table of ex- 

 portation of china clay to foreign countries recalls 

 a scandalous anomaly. We know that before the 

 war several factories on the Continent were pur- 

 chasing English china clay delivered on the works 

 at a lower price than that paid by the Stafford- 

 shire potters. It appears that in 1913 Germany 

 purchased more than 70,000 tons at about 

 ;^8o,ooo ; this is interestins- in view of the investi- 

 gations recently made at Charlottenburg with the 

 patriotic object of displacing English china clays 

 by German clays in Deutschland. 



In "A Study of Atterberg 's Method of Measur- 

 ing Plasticity " (2) Mr. C. S. Kinnison compares 

 the results made bv Atterberg's method with those 

 based on wet to dry contraction of clays, and on 

 the water of plasticity method. The results are not 

 very promising. This is not surprising. In my 

 opinion, plasticity is a mechanical property, the 

 magnitude of which is primarily estimated by the 

 potter's thumb, and unless the proposed methods 

 measure approximately the same mechanical pro- 

 perty they do not measure plasticity at all, but 

 rather some other quality of clay. 



