September i, 1902.] 



THE INDIA RUBBER \ArORL.D 



385 



atures then those of vulcanization. The fault lies then in the 

 production of the oil substitutes, or is caused by the presence 

 of resin in the crude rubber ; the temperature of vulcanization 

 is sufficient to dissolve the sulphur. Especially dangerous in 

 this connection are the substitutes containing a high percent- 

 age of mineral oils and mineral greases, which in themselves do 

 not compound with sulphur and always contain a large amount 

 of physically free sulphur. Red (and other) rubber goods con- 

 taining a large percentage of such substitutes bloom most 

 readily, and it is hard to explain why the articles of French 

 manufacture, which contain at least 40 per cent, of such min- 

 eral greases, are so much preferred. Besides sulphur, the solid 

 mineral greases, paraffin andceresin, segregate from them, and 

 rubber goods, especially of Paia qualities, are often seen the 

 bloom on which consists largely of paraffin. The other con- 

 current inorganic compounds are represented in the matter of 

 blooming in a small degree, and are perhaps only accidental 

 admixtures of sulphur which were taken up by it in the com- 

 pound. 



The measures, therefore, to prevent the blooming of rubber 

 goods, and red rubber goods especially, would appear to be as 

 follows : 



1. The use of suitable gold sulphurets. 



2. The greatest possible limitation of substitutes, and the 

 avoiding of those having a high degree of mineral greases. 



3. The storing of rubber in moist air. 



4. The use of crude rubber free from resins. 



To remove thoroughly the bloom where it has appeared, the 

 only remedy is to grind off the surface slightly, which perhaps 

 is possible only in few instances. 



THE NEW GUTTA-PERCHA. 



[from " THE ELECTRICAL REVIEW," LONDON, JULY l8.] 



FOR the last 20 years or more innumerable efforts have 

 been made to produce artificial Gutta-percha, but in the 

 words of one who has perhaps had more to do with Gutta- 

 percha substitutes than any other person, every attempt has 

 been foredoomed to failure, and the reason is not far to seek. 

 The chemical analysis of Gutta-percha shows it to be composed 

 of about 60 per cent, of India-rubber* and 35 percent, of resin 

 and a small proportion of impurities. At first sight it would 

 appear a comparatively simple matter to arrange to mix India- 

 rubber and resin so that finally the proportions should be as 

 above. An insurmountable difficulty, however, exists in the 

 fact that at a comparatively low temperature, the resinous 

 mass becomes fluid, so that long before a temperature is 

 reached at which India-rubber could combine with resin, the 

 latter has been reduced to a thin fluid, and the act of combina- 

 tion thereby rendered imperfect, if not impossible. In the re- 

 sult a Gutta-percha substitute is soft and readily takes the im- 

 pression of the nail, and at a temperature little above normal 

 becomes sticky. On being raised to the temperature of boil- 

 ing water it soon becomes soft, but does not usually on cooling 

 return to its original condition, and remains more or less 

 sticky and plastic. About ten years ago a German chemist set 

 to work to produce Gutta-percha synthetically, and after 

 numberless experiments and most exhaustive testing of their 

 results, he produced a material which is stated by several high 

 scientific authorities to possess properties which in no case are 

 inferior to those possessed by natural Gutta-percha, but that 

 are in some directions even superior. 

 The new Gutta-percha has been under the observation of the 



*Our contemporary here singularly permits a slip of the pen in confounding 

 gutta — a constituent of Gutta-percha — with India-rubber. — The Editor. 



German postoffice officials for several years, and the manner 

 in which this material has endured the tests to which it has 

 been subjected— both in their official testing laboratory and 

 also at the works of Messrs. Felten & Guilleaume— has justi- 

 fied them in commencing its adoption for the insulation of 

 submarine and subaqueous wires and cables to be used on 

 their telegraph and telephone systems. 



These statements are confirmed in an official certificate is- 

 sued by the imperial postoffice. 



Reports upon this material made by Prof. Weber, of the 

 Zurich Polytechnic, Mr. Ed. C. de Segundo, A. M. I. c. E., and 

 other authorities set forth the following facts : 



1. That the new Gutta-percha is fully equal to natural Gutta- 

 percha, and, in fact, possesses some characteristics which ren- 

 der it even superior to natural Gutta-percha. 



2. That it does not soften until a higher temperature is 

 reached than in the case of natural Gutta-percha. 



3. That its electrical resistance is somewhat higher than that 

 of pure Gutta-percha. 



4. That the inductive capacity is practically the same as that 

 of natural Gutta-percha, perhaps a little less. 



5. That all the ingredients used in its manufacture are 

 readily obtainable in most countries, and that there is little 

 likelihood of the prices of any of the ingredients tending to 

 rise. 



6. That no natural Gutta-percha whatsoever is used in the 

 manufacture. 



7. That the price at which it can be produced in this coun- 

 try in a quality equal to that of natural Gutta- percha for the 

 insulation of submarine cables is less than one-half the present 

 price of Gutta-percha. 



We have examined samples of this material, and while, of 

 course, we have not had an opportunity of subjecting it to the 

 elaborate tests which would be necessary to enable us to ex- 

 press our own opinion upon such properties, for instance, as 

 the inductive capacity, we can only say that as far as our ob- 

 servations go, it is very greatly in advance of any Gutta-percha 

 substitute that has hitherto been placed upon the market. 

 From the point of view of submarine telegraphy, the con- 

 stancy of the electrical resistance and of the inductive ca- 

 pacity is, of course, a condition sine gud tion to the use of this 

 material in the place of natural Gutta-percha. We are, how- 

 ever, assured that some submarine and subaqueous cables have 

 already been made on the Continent, the cores of which are 

 insulated with the new Gutta-percha, and that these cables 

 have been in use for over a year, and have yielded results as 

 regards both electrical resistance and inductive capacity that 

 are absolutely satisfactory. Apart from the question of the 

 use of this material for the insulation of submarine cores, the 

 low price at which it can be produced, coupled with the excel- 

 lence of its physical and electrical characteristics, should open 

 up a wide field for its use in many industries, and we shall look 

 forward with interest to its development in this country. The 

 German and other European patents have already been ac- 

 quired, and a company has been formed to deal with the Brit- 

 ish and Colonial patents. This company has been privately 

 subscribed and no issue will be made to the public. We hope 

 at an early date to have an opportunity of going further into 

 this interesting invention and to be able to publish the results 

 of various tests. 



A RUBBER planting company desires to be informed, through 

 The India Rubber World, where a supply of Pard rubber 

 tree seeds may be obtained, with a view to making an experi- 

 mental planting of the same in Oaxaca, Mexico. 



