August i, 1906.] 



THE INDIA RUBBER ^A^ORLD 



349 



THE INDIA-RUBBER TRADE IN GREAT BRITAIN. 



By Our Regular Correspondent. 



SAMl'LDS of commercial rubber lia\e been chemically 

 exaiiiiiied by I). Spence, whose results appear in the 

 last Ouiirhrly Journal o{ \.\\e Institute of Commercial 

 Research in the Tropics. Without wishing in anj' way 

 to question the accuracy of anj* of the figures, even if I might 

 (li)ul)t their utility, it must be said that some of 

 RESINS IN tilt.,,, are rather snri)risine. From the fiKiires 



RAW RUBBER i c " 



alone it would appear that Rangoon rubber, from 

 Burma, is a much better article than Para from South Amer- 

 ica, the percentage of rubber being 84.63 in the former case 

 and only 71.09 in the latter. The resin in the former is highei, 

 6.81 percent, against 2.73, but the residue, which I sujjpose 

 means fiber and dirt, is put at 8.16 for the Rangoon and 

 1 1. 71 per cent, for the Para. Leaving the other samples out 

 of consideration, the sample of hard cure Parii from South 

 America, which gave 71.09 per cent, of rubber, 14.30 per 

 cent, water, 2.73 per cent, resin, and 11. 71 per cent, residue, 

 hardly seems a fair sample. Authorities in this antl other 

 countries are fairly well agreed in putting the loss of Fine 

 rubber on washing at from 18 to 20 per cent., the bulk of 

 which is water, and 11.71 percent, residue must surelj- be 

 exceptional. The Para rubber from the Gold Coast is given 

 as being practically dry and having 2.31 per cent, resins and 

 3.30 residue, a very much superior article if one is to judge by 

 the comparative figures alone. In looking at the table of 

 resins it must be carefully borne in mind that the figures 

 must not be compared with those published by Terrj', 

 Weber, Clouth, and others, because these latter all refer to 

 washed and dried rubber. As a guide to the manufacturer 

 the percentages of resins in the dried rubber are much better 

 than any figures relating to products whose respective 

 amounts of water and dirt must be allowed for before a com- 

 parison of the amounts of resin can be made. Of course the 

 Liverpool figures may not be meant for the manufacturer's 

 eye, but it is cjuite possible that they may come before his 

 notice and at a time when pressure of business might inter- 

 fere with their careful examination. 



DiTM.\R has recently had an article in the Cummi-Zeitung 

 on a laborator3' method for estimating the durability of rub- 

 ber goods. The subject is an interesting and 



TESTING THE important one, but it is clear that it is hedged 



DURABILITY OF . . , .. ^ . ,,,.^v ^ 



RUBBER Q30DS '" wth many dithculties. Without going in- 

 to the chemical details of Ditiiiar's process, it 

 may be said that it consists in exposing the goods to oxygen 

 gas at a high temperature for a greater or less length of 

 time, the increase of weight being taken as the index of ox 

 idation, it being assumed that tliedurabilitj- varies inversely 

 as the degree of oxidation. Now no doubt laws of this sort 

 may be laid down from a scientific point of view, but one 

 has to be very cautious in accepting them as applying in 

 practice. The use of the term duraliilit}- is of doubtful value 

 because it depends entirelj' under what conditions the goods 

 are used or are intended to be used. Taking this into con- 

 sideration, it does not seem possible to devise a test that 

 shall be generally applicable to rubber goods, though I am 

 quite of opinion that comparative tests of the probable dura- 

 bilitj- of goods of a particular class in reference to an ac- 

 knowledged standard can be made to give useful results. 



This procedure has long been adopted by railway companies 

 and other large buyers of rubber goods, more especially in 

 the case of hose piping and buffers. Such mechanical tests 

 are devised for each class of goods with special reference to 

 the conditions under which they are to be used. No claim 

 has been made, as far as 1 am aware, that any of them has a 

 universal utility for testing rubber goods. And I think that 

 in the chemical tests which have been proposed in the past 

 and in those which will no doubt be devised in the future 

 they will have to be specially arranged for each class of 

 goods. With regard to the oxidatifin test proposed by Dit- 

 mar, in theory it is on the same lines as was proposed by 

 Weber to estimate the liability of cycle tires to sun crack- 

 ing, though the method of applying the oxygen is quite 

 different. Weber used a cold solution of hydrogen peroxide 

 in acetone and expressed himself as satisfied that the in- 

 crease of weight in strips of rubber owing to oxjgen ab- 

 sorbed gave a true index of the liability of the rubber to 

 sun cracking. I have not any information as to whether the 

 process has been generally adopted or found reliable by 

 others. In saying what I have I don't wish in any way to 

 discredit Ditmar's process ; I merely wish to advocate cau- 

 tion in its general adoption because otherwise in inexperi- 

 enced hands it might lead to the condemnation of goods 

 perfect!}- suited to their purpose. 



The continued growth of the rubber heel industry forms 



I think a sufficient excuse for a further reference to it in 



these columns. The pioneers of the business 



wooD-MiLNE ^ygre the Revolving Heel Co., whose head 



RUBBER HEELS. „ , , . , „. 



office and works are situated at Preston. The 

 article was first put on the market in 1896, but for several 

 j'ears it proved very uphill work, and the business was car- 

 ried on at a loss for some time. Eventually, however, the 

 utilitj^ of the pad became recognized and about 1902 the 

 business began to move with giant strides. The Revolving 

 Heel Co. now make all sorts of rubber heels, revolving, sta- 

 tionary, and tips, and have the enormous turnover of about 

 20,000,000 heels per annum. The company have always 

 made the quality of the rubber a strong point, so that now 

 the name " Wood-Milne, " which maj- be considered their 

 trade mark, is recognized as the hall mark of quality wher- 

 ever the goods are in demand. Though the business is Brit- 

 ish in its origin and development, the goods now seem to be 

 in almost world wide demand, large orders coming from the 

 various British colonies and from such out-of-the-way places 

 as Khartoum and Omdurman. Of course, public opinion as 

 to the advantages to be derived from wearing these adjuncts 

 to a leather boot is not unanimous ; such innovations are 

 sure to meet with an opposing current of conservatism. 

 The statement, however, which has often been made in my 

 presence, to the effect that onU- low class people have 

 adopted rubber heels, does not find confirmation among the 

 shoe makers who only do business with the wealthy class. 

 Without going too much into detail, it may be mentioned 

 that the boot maker to the King is now regularly putting 

 rubber heels on to his ordinary boots, which are supplied at 

 3 guineas a pair. In this case it is not a highlj- sulphured 

 pad attached mechanically, but a block of black rubber cut 



