January i, 1907.] 



THE INDIA RUBBEK \A^ORLD 



109 



A RUBBER GOODS MERCHANT ON RUBBEK. 



At a meeting of an engineer's club the feature of the 

 evening was a talk on "Rul>ber," by a gentleman long 

 connciteil with that interest, not as a manufacturer, but 

 in selling rubber goods. Liberal extracts are given here, 

 to indicate the dealer's point of view in regard to various 

 questions concerning rubber that come up for discussion. 



THOSE who have been engaged of late years in tlie 

 manufacture and sale of mechanical rubber goods 

 have been obliged constantly to study the advances 

 that have taken place, particularly in the increase 

 of steam pressure and consequent temperatures, in order to 

 keep themselves in touch with the requirements necessitated 

 by these advances, to enable them to deliver to the consumer 

 an article of manufactured rubber that vi-ould perform prop- 

 erly the work required. 



It seems but a short time since compound engines carry- 

 ing but 35 pounds pressure were all we had to meet, in ma- 

 rine engines, of which a very few still remain, and in which 

 most any ordinary rubber will answer. But when we meet 

 successfully a continuous advance up to 300 pounds steam 

 pressure, the problem becomes an intricate one, and requires 

 the same kind of mechanical ability and application to the 

 conditions as is required to operate the engines themselves. 



When, in railroad work, the first steam and airbrake hose 

 was used, the ordinary standard stock article was quite suf- 

 ficient. Now every first class manufacturer knows the sever- 

 ity of the specifications the}' are required to fill bj- the mas- 

 ter car builders. 



In the United States nav^-, v^-hose bureau of purchase a 

 dozen years ago was at the mercy of the lowest bidder almost 

 without consideration of quality, to-day the most rigid speci- 

 fications are in force. A high quality of pure rubber and 

 very little objectionable matter must be found in the severe 

 chemical analyses given to all rubber purchased by the 

 chemists employed by the navy department. 



Imagine, if you please, the lining of a hose but j',; inch in 

 thickness being given a tensile strength test equal to 1000 

 pounds per square inch, and actually standing 1650 pounds 

 per square inch, and yet being rejected for containing some 

 slight amount of resinous e.xtract found in the natural rub- 

 ber itself and which could not be avoided by the manufac- 

 turer — yet such is actual experience. A double jacket fire 

 hose weighing about a pound to the foot is required to stand 

 400 pounds pressure to the square inch, in 50 foot lengths. 

 Hose of this quality in a 3 foot length, with the end plugged, 

 has been known to stand 1200 pounds bursting pressure. 

 Think of testing v-onr steel boilers or iron pipes to anything 

 like such severe conditions. 



SOME POINTS ox PACKINGS. 



■[Query : "In speaking of packings you said that at 500°, 

 a superheat, the rubber would be no good, or something to 

 that effect. How high can rubber be vulcanized — what tem- 

 perature Fahrenheit ? "] . Well, it depends on the quantity of 

 rubber in the compound, and the quality of the materials 

 forming the compound with it. The rubber that I spoke of 

 was the pure article. We vulcanize rubber at a temperature 

 as high as 300°, and until recent years rubber packing has 

 not been known to stand a verj- much higher temperature 



than that under which it was vulcanized ; but I had a piece 

 here somewhere which has stood 900° F. for 16 hours, and 

 which was taken out and put back again three times, mak- 

 ing four applications in all, and it didn't stick to the plates ; 

 but that would be about the life of it, and it is not good 

 enough for superheat. Von see, in the manufacture of these 

 goods we are limited to very few raw materials. The ma- 

 terials with which compounded rubber is used [for pack- 

 ings] are linen, cotton, and asbestos. 



There (indicating another sample) is a combination of as- 

 bestos and rubber — very little rubber in it. That would 

 stand a superheat up to 600°, and I have some of our prod- 

 ucts that have been in use up to that degree that have held 

 a year and they are still in use. We have also produced a 

 soft rubber and asbestos packing, thesort that standson the 

 valve stems of turbine engines, which only stands for three 

 or four weeks, but then we think that is doing prettv well 

 for soft mateiial, where metal melted. 



There (showing another sample) is a piece of the navy 

 s.tandard rubber, cut, sized, and shaped by their templets — 

 it is in the form in which they test it. They put that into a 

 breaking machine and mark a space 2 inches here and j/ 

 inch here (indicating), 2 inches long, and that 2 inches will 

 stretch to 11. That will require a pull of 45 to 50 pounds, 

 owing to the hardness with which it is vulcanized ; and must 

 return within five minutes to within ji inch of its original 

 measure, after which it must stand a total tensile strength 

 of 100 pounds. After it does that, it is analyzed by a chini- 

 ist bj- some process, and that brings out the quantitj- of the 

 rubber, and thej' determine the qualitj* of the rubber by the 

 amount of extracted matter that remains ; and if the rubber 

 stands all the physical tests but has a percentage of ingre- 

 dients that they don't like, it is rejected. 



That piece of rubber (indicating another sample) contain.s 

 50 per cent, of fine Amazon rubber. It contains some chalk 

 and lime, and 3 '/i per cent, of sulphur, and one or two things 

 that make it tough. That piece was vulcanized in a mold 

 under 300° temperature for a verj- short time. We have to 

 be very careful in sending stuff to the navy, b'or instance, 

 I discovered a quantity of rubber there which they had re- 

 jected on a pulling contest. It was sent back to the mill 

 and vulcanized for 5 minutes more, and it stood the lest all 

 right. The process of vulcanizing made it tough. 



There (indicating a sample) is a little piece of packing that 

 a friend of mine brought to me. That piece of rubber was 

 used between 300 and 400 times ; I could hardly credit it m\-- 

 self. This is one of the products that weighs 4 ;i pounds per 

 square yard at ^"j inch in thickness. It is an actual fact that 

 the best rubber goods will be lightest in weight, and lia- 

 ble to cost less originall)'. 



I remember once, about si.x vears ago, feeling quite 

 ashamed of a bill that went out of my place. Some valves 

 were ordered for a very large pump in one of the street rail- 

 way plants near Boston ; the valves, I think, were 16 inches 

 in diameter, and i '^ inches thick, a large quantity of them. 

 There was a thorough overhauling of the pump and they or- 

 dered a medium valve, which were sent to them. Two or 

 three diys later I dropped into the place and saw the chief 



