January i, 1910.] 



THE INDIA RUBBER WORLD 



123 



The India-Rub ber Trade in Great Britain. 



By Our Regular Correspondent. 



ELECTRICITY 

 IN MINES. 



THE departmental committee to inquire into the employment 

 of electricity in coal mines lias now been appointed, and 

 its findings will not be without interest to cable makers. 

 The main reason for its appointment, I may say, is a strong 

 opinion in some quarters that the West Stanley colliery explosion 

 in the Durham field last spring was due 

 to an electric spark formed by a short 

 circuit at the working face. During the 

 last two or three years the use of electricity instead of com- 

 pressed air has largely increased in working coal cutting machin- 

 ery, especially in the north of England, and many engineers have 

 predicted danger in fiery mines. To some extent, no doubt, the 

 opposition comes from the older engineers, who know little 

 about electricity and are opposed to such innovations. But at 

 the same time there are up-to-date men who recognize the risks 

 introduced by the electrical coal cutter, and who only use elec- 

 tricity instead of compressed air because it is cheaper. If com- 

 pressed air working can be cheapened — and from what I hear it 

 will be — it is possible that electrical coal cutters will be for- 

 bidden. Another alternative is to render the occurrence of short 

 circuiting practically impossible by improvements in the cables. 

 In this connection I hear that Messrs. W. T. Glover & Co., Lim- 

 ited, of Trafford Park, have had the matter under careful con- 

 sideration, and that they will shortly have some information to 

 make public concerning it. It seemed to be advisable to say 

 what I have done, because otherwise those not familiar with the 

 details of colliery working might imagine that electrical wind- 

 ing or the use of the electric light at the surface had suddenly 

 come under suspicion. At some of the South Wales collieries 

 electrical winding is in use', and found to be cheaper than steam, 

 and there is no doubt that the use of electricity for many opera- 

 tions in mining will continue to increase. Of course rubber 

 insulation has by no means a monopoly ; there is the same com- 

 petition with fibrous and bitumen cables in this as in other fields. 

 Although British cable makers are well to the fore in mining 

 business, with regard to other parts of the electrical installation 

 it is noteworthty that much of the plant has been supplied by 

 Germany. 



So far I have not seen anything in print regarding the doings 

 of the International Committee and am wondering whether work 

 on the Herculean task has been com- 

 menced in earnest. That there is scope 

 for a good deal of careful examination 

 into the reliability of methods is evident to the student of chem- 

 ical literature. Of late contributions to rubber analysis have 

 consisted chiefly of diatribes observing the unreliability of what 

 has been advanced some time previous as the solution of a 

 difficult problem. To give only one instance of several which 

 I have come across in the last year : In 1903 Weber published 

 the chloral hydrate method of discriminating between the main 

 constituents of the acetone extract from vulcanized rubber, and 

 in 1909 Frank and Marckwald published their conclusions as to 

 the unreliability of the method. The determination of the cor- 

 rect figure for the rubber resins is of course of considerable 

 importance because of the great assistance it gives in arriving 

 at an approximate valuation of the raw rubber used. As, how- 

 ever, in several widely used rubber mixings of today the acetone 

 extract contains organic matter other than the rubber resins, 

 great care is necessitated in drawing conclusions from the bulk 

 of this extract until it has been closely examined. It is this 

 inclusion of more or less new bodies in rubber mixings which is 

 so apt to invalidate what it may be sought to establish as 



RUBBER 

 ANALYSIS. 



REMADE 

 RUBBER. 



standard methods of analysis. For the determination of certain 

 constituents such as free or total sulphur or the various mineral 

 compounds, this difficulty need not arise, and methods as precise 

 as those recently published for American agricultural chemists 

 might be strongly recommended if not enforced. Rubber analysis, 

 however, is different from agricultural or mineral analysis in 

 that it is not in regular operation between buyer and seller for 

 the determination of particular ingredients. When the buyer of 

 rubber goods has them analyzed — which is by no means a fre- 

 quent occurrence — he wants to know the whole composition. 

 Moreover, he wants the result as soon as possible and he wants 

 it done cheaply. la may easily happen that some constituent 

 may be present which will largely invalidate any standard method, 

 and where time and price are important matters I imagine that 

 rubber will continue to be estimated by difference rather than 

 by the tedious though scientifically beautiful direct methods 

 which have been evolved in recent years from Teutonic 

 laboratories. 



A few months ago I referred at some length to the remaking 

 of vulcanized rubber under Gare's patent. The recent patent of 

 Hutchinson and Milne, of October, 1909, 

 for a process of reclaiming vulcanized 

 rubber is on much the same lines and 

 was. I believe, opposed by Gare. The main difference in the 

 specification, as far as I can judge, is that the ground-up waste 

 in Gare's patent is directly treated under heat, and pressure not 

 particularly specified, and in Hutchinson's patent the ground-up 

 rubber is first treated for the removal of the free sulphur and is 

 then subjected to pressure and heat exactly specified; also in 

 this process filling material may be added as well as coloring 

 matter. A good deal is made of the possibility in this process 

 of utilizing coloring matters to a much better effect on account 

 of the low temperature of the operation and the absence of free 

 sulphur. There are one or two sentences in the new specification 

 which I am not prepared to accept straight off. Thus I read 

 that even perished rubber can be rejuvenated so as to be of as 

 good or even a better quality than it was originally. I don't 

 think Gare ever claimed to do as much as this; in his works 

 he has used goods such as solid cab tires which, if decayed at 

 all, are only so to a slight extent on the surface, and if surface 

 cracking was strongly in evidence the outside of the tire was 

 cut off before being remade. I am not at all disposed to believe 

 any statement to the effect that rubber which is really perished 

 can be rejuvenated so as to possess its former properties. Of 

 course if the term perished applies only to what is surface 

 cracked, Hutchinson's statement has nothing very remarkable 

 about it. In a general way these two patents remind me of the 

 rival oil-flotation processes in ore dressing in which the final 

 decision has just been given in the House of Lords. Without 

 going into any details on a matter quite outside the province of 

 these notes I may say that the first patentee has lost his case 

 mainly because he made wide claims as to the quantities and 

 methods of treatment, while the supposed infringer, who has 

 won the day. gave precise detail of his process in his specifica- 

 tion. There is no doubt that this remade rubber business is of 

 considerable commercial importance and the patents in connec- 

 tion therewith are far more worth discussion than is the case 

 with the great bulk of rubber patents. In the Hutchinson patent 

 it is quite a relief not to read anything about "allied gums," 

 which mysterious bodies usually figure in a rubber patent, the 

 patent agent evidently having the impression that their inclusion 

 is an element of strength. 



