112 



THE INDIA RUBBER "WORLD 



[January i, 1907. 



side slip dangers find a good deal to grumble at in the prac- 

 tice. With regard to this grievance, I am afraid that unless 

 some law is passed regulating the use of flint the trouble 

 will show a rapid increase. In the south of England, espe- 

 cially in the London suburbs, chalk flints are largely used 

 as road metal, and when the round nodules get broken they 

 present sharp cutting edges. In the north of Hngland, 

 where there are no flints to be got locally, whinstone has 

 been the hardest material in common use. Of late, however, 

 in several districts waste cherl, which is an impure form of 

 flint rained and quarried for certain purposes, is being con- 

 tracted for as road metal, and as this has the same hardness 

 and cutting power when broken up, tires are likely to suffer 

 to an increasing extent where it is used. This fact apart 

 cherl must be recommended as an eflicient road metal, and 

 as going a long way to lay the dust demon in limestone dis- 

 tricts. Talking of flint roads nearI<ondon, I was asked by 

 a ladj' recently if the galosh people could not put a stronger 

 heel on their products, as they so soon wore out on flint 

 roads. I replied that the matter had possibly not occupied 

 their attention and further that it would probably not pay 

 them to put on a flint proof heel as the great bulk of the 

 galosh output went to regions where the flint is unknown. 

 I.N' an article in the November issue of this Journal Dr. 

 Esch says I have confounded carbonate of magnesia with 

 the oxide in some remarks I made on the subject 

 USE OF i^ September. This is not exactly the case, if 

 IN RUBBER, what I wrote is carefully read, but I certainly 

 assumed that Ditmar's experiments related to 

 the carbonate and in this respect am glad to be put right 

 by Dr. Esch. For the rest, in technical matters relative 

 to the rubber trade, writers in different countries can only 

 testify to their own experience. It may well be that oxide 

 of magnesia is largelj- used in the rubber trade in Ger- 

 many and America, as Dr. Esch says, but as regards this 

 countrj' there is very little used at the present time, the 

 great bulk of the magnesia employed being the hydrated 

 carbonate. This is of a particular composition for the 

 trade, and I cannot subscribe to Dr. Esch's dictum that 

 it has no more value than whiting. It is not a case of 

 M^COj versus CaCO., ; the former contains freealkali while 

 the latter does not. In saying this I am not throwing any 

 doubt upon the efficacy of the oxide as an accelerator of 

 vulcanization. It follows lime in this respect, and the use 

 of lime in small quantities where resinous rubbers are con- 

 cerned, or where the sulphur has to be limited, is a well es- 

 tablished practice. The novelty of Dr. Esch's remarks is in 

 the large quantities of magnesia oxide that are recommend- 

 ed, and it seems to me advisable to proceed with caution be- 

 fore changing from the hj-drated carbon to the oxide on the 

 large scale. Certainly there is about double the amount of 

 the magnesia oxide in the calcined product that there is in 

 the carbonate as sold but then the price is at least twice as 

 much and this is a matter which is not passed over with in- 

 difference in the trade. Dr. Esch mentions specific brands 

 of magnesia as being suitable : in this respect I don 't care to 

 emulate him ; it seems rather like trespassing upon the do- 

 main of the advertisement manager. His remarks on the 

 relative densities of the magnesia products are interesting 

 and will be welcomed by many who have been somewhat in 

 the dark on the subject. With regard to the processes of 

 manufacture he mentions, that is the interaction of solu- 



tions of magnesium and sodium salts. I may say that the 

 British firms emploj* an entirely different method into the 

 details of which with true native secretiveness they would 

 hardly thank me for entering. 



The decision of the courts permitting the reduction of 



capital of the Dunlop Pneumatic Tyre Co., Limited, on the 



lines proposed bv the directors, is being appealed 



DUNLOP. J I . o i-r 



against by the deferred shareholders, so we have 

 not yet come to a finality in these protracted and acrimoni- 

 ous proceedings. 



RUBBER AS A "FIREPROOF" MATERIAL. 



"P T'BBER is not generally included among fireproof con- 

 -^^ struction materials, which fact renders of all the more 

 interest the mention of its use in a paper on " Construction 

 of a Fireproof Excursion Steamer," read by Mr. William 

 Gatewood before an engineering society at Philadelphia. He 

 described a vessel which is being built for use on the Poto- 

 mac river. Of course the term "fireproof" does not mean 

 that the vessel is incapable of destruction by fire, but that 

 the amount of combustible material has been limited, and 

 what remains is so protected and distributed that the chances 

 of a fire starting on board are greatly reduced ; and the 

 spread of a fire would be practically impossible even should 

 one get a start. 



Rubber tiling is to be used extensively on the decks of 

 this steamer, a special cement being used, where it is neces- 

 sary to secure the adherence of the rubber to steel. The 

 covering to be used on the exposed portions of the saloon 

 and shade decks was a subject of much consideration. The 

 usual canvas was not considered a satisfactory covering on 

 account of the danger from fire, as lighted cigar ends, etc., 

 have been known to cause trouble on canvas decks. It was 

 thought that some form of asbestos tiling could be used for 

 this purpose, but samples were tested and found to be unsuit- 

 able, as the asbestos tiles were not tough enough on the sur- 

 face to stand the wear ; and the adhesion between the tiles 

 and the cement used in laying was also defective after ex- 

 posure. It was finally decided to cover the wood decking 

 with canvas to secure water-tightness, and on this to lay 

 interlocking rubber tiling. 



SPENCER'S COLORADO RUBBER. 



ANOTHER United States patent has been issued in con- 

 nection with the Colorado rubber plant. The appli- 

 cation was filed April 29. 1905, by Benjamin F. Spencer, and 

 the patent (No. 834,771) is assigned to The Western Parent 

 Crude Rubber Co., of Santa Fe, New Mexico. It relates to 

 a rubber like and waterproof gum, comprising the agglom- 

 erated gummy portions of the plant Picraiienia fioribundi 

 ulilis, and the residual portions of a volatile hydrocarbon 

 .solvent used in the preparation of the gum. 



Chicle is imported into the United States to a large ex- 

 tent by way of Canada, though produced onl\- in Mexico 

 and other countries to the southward. The explanation is 

 that the Chicle is very wet when shipped, and it is sent in 

 vessels around by Canada to dry out. The duty in the States 

 is 10 cents a pound, and the drier the gum when imported 

 the less there is to pay at the custom house. 



