130 



THE INDIA RUBBER WORLD 



[December 1, 1916. 



same conditions of light as the articles will be subjected to in 

 actual use, it would disclose a result ; for instance, the cover 

 on a hose. On the under side of the hose, the tensile there 

 will deteriorate very slowly while the upper side, against the 

 light and against the'building, will deteriorate rapidly, and it must 

 be the condition of light whicli causes this effect. I think this 

 accelerated age test must be a good thing for the consumer. 



Dr. Weber reported that he has found a simple method of 

 accelerated aging highly satisfactory, and described it as follows : 



I have carried out in the past five or six years a large num- 

 ber of these accelerated aging tests and while my method of 

 procedure is not the highly scientific one which Dr. Geer has 

 outlined, the results obtained have been so satisfactory that I 

 have come to have great faith in the test. 



My method of procedure is to subject the sample in question 

 to a temperature of 65 degrees C. for a period of two weeks. 

 A sample of approximately the same composition and of known 

 aging qualities is subjected to the heat treatment together with 

 the unknown sample. At the end of two weeks the two samples 

 in question are compared and from their relative condition very 

 accurate conclusions regarding the aging properties of the 

 unknown sample can be drawn. It is highly important that 

 the sample of known aging properties have a composition similar 

 to the unknown sample, for it is very readily observed that the 

 higher the rubber content the more violent is the action of the 

 heat. 



There are other precautions to be observed if misleading mter- 

 pretations are to be avoided. If the unknown sample is under- 

 cured, and at the same time contains considerable free sulphur, 

 I have found that unreliable results are obtained. On the other 

 hand, if the sample in question is at all over-cured, the heat 

 treatment shows this up in a very pronounced manner. 



I would rather feel that the contradictory results which have 

 been obtained in the accelerated aging test are largely due to 

 the fact that the action of the heat is materially influenced by 

 the nature of the compound and that the latter must be taken 

 into very careful consideration in the interpretation of the results 

 and general conclusions that are drawn. On the other hand, when 

 this factor is taken into careful consideration, very accurate and 

 reliable predictions can be made. 



Later, during a discussion regarding free sulphur in vulcanized 

 products, Dr. Weber stated that personally he could see no ob- 

 jection to it in an article properly vulcanized, and he questioned 

 if it were an accepted fact tliat free sulphur is bad for rubber. 



Mr. Potts, in concluding the discussion, made the following 

 important suggestion : 



It occurs to me that if we try to get a test to indicate what 

 kind of service the sample will give, a compound which has very 

 little free sulphur will show very little service and the accelerated 

 test will confirm that service. If there be a large amount of free 

 sulphur, then free sulphur in actual service may not have a 

 great effect on the material ; but at 65 or 70 degrees, the accel- 

 erated test may indicate a shorter service than we actually get 

 in use. 



PEODUCTION OF SOAPSTONE AND TALC. 



In the production of soapstone the United States ranks first 

 among all countries, and Virginia produces about twenty times 

 as much as the four other producing States — Maryland, North 

 Carolina, Rhode Island and Vermont. 



The production of soapstone and talc in the United States is 

 steadily increasing, according to the United States Geological 

 Survey, Department of the Interior. In 190O it was 27,913 short 

 tons, in 1910 it was 150,716 tons, and in 1915 it was 186,891 short 

 tons. 



DUSTLESS LAMPBLACK. 



The disagreeable features that invariably attend the use of 

 lampblack or carbon black are plainly evident in the compound- 

 ing room and around the mi-xing mills. Pressed lampblack has 

 been used for a long time, but even that is in a more or less 

 powdery condition and only furnishes a partial relief from the 

 flying dust. Carbon black, now used extensively by tire manu- 

 facturers, is of a more powdery consistency than lampblack and 

 therefore is subjected to greater pressure, a remedy that is only 

 a partial cure. 



Dustless lamplack may be made by mixing 60 per cent of 

 lampblack with 40 per cent of petroleum or palm oil. The 

 resultant compound is a substance that has the consistency of 

 lard or soft butter and may be compounded and milled with 

 perfect cleanliness. Tlie name "Petroblack" is obviously fitting 

 for the former and "Palmoblack" for the latter. 



HEATING APPARATUS FOR EXTRACTORS. 



DREPOXV, assistant chemist in an important American rub- 

 • ber factory, is the inventor of the interesting apparatus 

 described below. 



As a preliminary, it is not necessary to dwell upon troubles 

 attending extraction apparatus heated with open steam. More- 

 over, while electric plates are clean they are not ideal, as they 

 get out of order easily, the danger of fire is always present and 

 the cost of opei-ating is (|uite high. 



It is claimed that tlie apparatus illustrated here has taken care 

 of all the objections present in the other types, is simple and 

 cheap to operate and when once installed will last a long time. 



It is heated by steam under such conditions that not a trace 

 can escape from the heating casting. This heater is a hollow 



.-; — Heater. B — Steam Inlet. C — Steam Exhaust. D — Extraction Containers. 

 £ — .\djusting Screws. F — Water Supply Pipe. G — Waste Pipe. 



one-piece brass casting supported by three standards and adapted 

 to be placed on a bench or table. The eight holes to accommo- 

 date as many extractors are cored out of the casting at the top, 

 with jackets to prevent direct steam contact. Eight hand screws, 

 supported underneath the heater, are used to raise or lower the 

 extraction containers in the jacketed holes, so that solvents of 

 different boiling points may be run in adjacent containers and the 

 quantitative amount of solvent in circulation regulated. The 

 heater is sufficiently strong so that steam under pressure may 

 be used when it is necessary to use solvents with a high boiling 

 point; however, with solvents up to and including alcohol, the 

 free circulation is sufficient. Steam is admitted at the right end 

 and exhausted through a pipe at the left end of the heater where 

 a steam gage is located to record the pressure. 



The extraction containers are common lV2-inch test tubes 

 which fit snugly into the jacketed holes. The condensers are of 

 block tin and the tubes closed by covers of the same metal. 

 Rubber tubing connects the condensers with the water supply 

 and waste pipe, and galvanized cups attached to the frame back 

 of the brass healer afford convenient receptacles in which to 

 place the containers after removal from the heater. This has 

 been found very convenient when extractions are run for a defi- 

 nite time and especially when the removal is left to the night 

 watchman. 



