December. 1. 1919.] 



THE INDIA RUBBER WORLD 



141 



ncss testers ; namely, the existence of a noticeable variation in 

 results due to the personal element. 



Dead Weight Tvpe App.\ratus. The Plastometer is an instru- 

 ment oi this type in which the penetration by a steel ball, of 

 % or 'i-inch diameter, under a load of one kilogram, is read in 

 1/lOOths ot a millimeter. Owing to the fact that the downward 

 force of the indicating dial rod is 85 grams, the depression meas- 

 ured is not that due to an increase of load from to 1000 grains 

 but to an increase from 85 to 1085 grams. 



In the practical use of this instrument, it is recommended by 

 the makers that the readings be taken after one minute. The 

 advisability of observing this time element is seen when it is 

 noted that the initial reading is about 5 per cent lower than the 

 reading found after the lapse of 60 seconds. The reading at 20 

 seC'ind> is 2 per cent lower and that at 40 seconds 0.6 per cent 

 lower tlian the reading at 60 seconds. 



HARDNESS AND ITS RELATION TO THE MODULUS OF ELASTICITY. 



In order to get an insight into the nature of hardness, it was 

 arranged to measure the actual depression into rubber valve 

 samples using both the J4 and the J^-indi balh of the Plasto- 

 meter. This was measured in terms of the volume displaced and 

 the force of depression. Two samples were taken, one of 40 and 

 the other of 110 plastometer. 



When charted, we find that the force-depression volume plots 

 are nearly straight lines and are approximately the same regard- 

 less of the size of the ball used. The fact that the reading on 

 one instrument does not always correspond exactly with a certain 



reading on another, but holds true within certain limits only, is 

 probably explained by the fact that the plots are not straight 

 lines but are really slightly curved upward and at slightly dif- 

 ferent rates. 



Hardness may be defined as the ratio of force to volume of 

 depression and would have dimensions — 



Mass 



(Length)' (Time)' 



The modulus of elasticity, which is sometimes used to measure 

 the hardness of vulcanized rubber, is usually defined as the 

 stress required to double the length of a rubber sample. It is 

 so defined because the ratio of stress to strain is not uniform, 

 although occasionally assumed as such for computation purposes, 

 as with airplane shock absorbers. 



The dimensions of the modulus of elasticity art; — 



Mass 



(Length) (Time)'; 

 hence it varies from the dimensions of hardness by the inverse 

 of the dimension of length. 



The value of the use of an absolute or rational measure of 

 hardness would not necessarily involve a different instrument for 

 testing. The figures obtained with the present instruments could 

 be expressed in terins of any convenient units, such as pounds 

 per cubic inch, kilograms per cubic centimeter, or dynes per 

 cubic centimeter. 



The Runge Solution Process for Rubber Reclaiming. 



special Correspondence. 



THE Runce-Werke Aktiekcesell.schaft (Runge Works different value, for after the blockade instituted by the English 



Corporation) in Spandau, which up to the beginning of the war manageiuent very soon was compelled to make use of re- 



1917 was Max Frankel and Runge, the largest German claimed rubbers to an extent which every person in the business 



rubber reclaiming factory, has just made public some very inter- would previously have thought impossible, and which was also 



esting facts concerning reclaiming by the solution process. not affected by the production of synthetic rubbers. What was 



ALKALI AND SOLUTION PROCESSES. impossible in peace times was learned from the war, namely. 



First, however, a few words about the German preparation of the extraordinary adaptability of reclaimed rubber to many 



reclaimed rubbers. Among the manv processes the most im- purposes. 



portant at present are the so-called alkali process and the solution The German industries that worked in rubber learned that they 



process. In the alkali process the fiber contents of the rubber '""^' S'^'^ f"" ^^'«'g'^' 'o "^e facts that reclaimed rubbers are 



waste are removed bv being converted through the action of the already a mixture of rubber and additional materials, that they 



alkali into a substance that is soluble in water, while the mass of 'contain the rubber in a vulcanized form, and that the methods of 



rubber itself remains undissolved. In the solution process, on '''eatrng them m manufacturing must be different from those em- 



the contrary, the fibrous contents remain undissolved, while the P'">'ed with crude rubber. 



mass of rubber is dissolved by the solvent employed, leaving a rub- PRODUCTION OF THE RUNGE WORKS. 



ber solution from which, after reextracting the solvent, the mass ^he reclaimed rubber production of the Runge works, reached 



of rubber is separated. before the war the record amount of 1,850,750 pounds in 1912 



and then dropped to 1,090,432 pounds in 1914. 



GERMAN RECLAIMED RUBBER CONSUMPTION. T ,, • \, ' . j , . r ,, 



T-u ,. . , ,, • r- ■ ,ni. In the ensuing war years the output developed as folows: 



The consumption ot crude rubber in Germany in 1913 was r= j f i- 



over 20,000 tons. There are no statistics for the consumption ,.,,5 wjl"'?!; 



of reclaimed rubbers; it was relatively small and may be estimated I'lft '.'.'.'.'.'.'.'.'.'.'.'.'.'. i;692;5SJ 



at something like 6,000 tons. A slight proportion of this German I9is '.'.'.'.'.'.'.'.'.['.]'.'.'.'.'.'.'.'.'.'.'.'.'.'.'.[.'.'. zMf.lVy 



consumption of reclaimed rubber was made up of the rubber in the course of the war nearly all German users of rubber 



waste which was reclaimed in the rubber factories themselves and became favorable to the products of the establishment, so that 



then made into rubber goods. the total production of reclaimed rubber increased steadily in spite 



By tar the greater part of the reclaimed rubber worked up in of the fact that in the course of the later years of the war the 



Germany in the peace period that preceded the war was imported supplies of rubber waste became smaller and smaller and had led 



from foreign countries, especially the United States and England, to rapidly increasing limitations on the general use of reclaimed 



The chiet reason tor the slight consumption of reclaimed rub- rubber. In 1918 the reclaimed rubber production of the Runge 



ber in Germany before the war was that even in professional cir- works amounted to over two million pounds and the returns on 



eles reclaimed rubbers were not looked upon as real rubber mate- account of the rise in prices were roughly $1,666,000. The firm 



rial, but only as substitutes which must be used only with the too, was greatly hampered at times in its production by prohibi- 



greatest possible secrecy. tions against the use of certain materials, for instance, by the 



RECLAIMING INDUSTRY STIMULATED BY THE WAR. Imperial Navy Ofiice with regard to the solution reclaimed rub- 



Conditions during the war gave for reclaimed rubbers a wholly ber for ocean cables, and so on. Nevertheless in the future course 



