May 1, 1912.J 



THE INDIA RUBBER WORLD 



385 



The German Material Testing Bureau. 



WITH a staff of 72 trained scientists and 150 assistants, the 

 Royal Material Testing Bureau, at Gross-Lichterfelde, 

 near Berlin, affords an interesting example of the appli- 

 cation of science to promoting the work of industry. Some of 

 its features were referred to by The India Rubber World in the 

 issue of January 1, 1912 (page 160), as well as on previous 

 occasions. 



The recently published report of the bureau deals with the 

 year ended March 31, 1911, during which time much good work 

 was accomplished. It is of interest to note that at the date of 

 the report, there were prospects of still further progress dur- 

 ing the year 1911-1912 (which has just closed), owing to the 

 additional funds which the Jager bequest had placed at the 

 disposal of the bureau. 



In the report the principal features of the mechanical and 

 chemical tests of rubber are dealt with in a comprehensive 

 manner. 



MECHANICAL TESTS. 

 Reference is made to a case in which a compound of regen- 

 erated rubber had been claimed to contain 69 per cent, natural 

 rubber, while the analysis showed only 40 per cent. It had been 

 wrongly assumed that the substance of the rubber was un- 

 changed by the process of regeneration, and that natural rubber 

 and regenerated material were identical. The report adds: 



"The bureau stands in e.xactly the same position as to re- 

 generated as it does with regard to natural rubber. . . . 

 Regenerated rubber should be tested for its mechanical strength. 

 Comparative tests, the results of which would be expressed by 

 figures, should be applied to compounds made with and with- 

 out regenerated rubber. . . . These would demonstrate 

 whether, and to what extent the regenerated material is in a 

 position to fully replace natural rubber in rubber compounds. 

 The bureau is quite ready to co-operate in such objective tests." 

 The testing of rubber and other insulating materials, which 

 took place in 1909-1910, was continued in 1901-1911, and 

 its scope considerably extended ; the tests applied being more 

 exacting, and the services of the bureau being called upon to 

 an increased extent. From the current income of the bureau, 

 it was found possible to increase the facilities for washing and 

 vulcanizing crude rubber, and for preparing rubber compounds. 

 By the courtesy of various manufacturing establishments, 

 officials of the bureau were allowed to practically study at those 

 plants the preparation of rubber compounds and other im- 

 portant manufacturing operations. Mechanical tests of rubber 

 were continued and further elaborated with the machine of 

 L. Schopper of Leipzig, as well as the Martens-Schopper ma- 

 chine. New machinery of this description has recently been 

 exhibited, while other improved models are being studied by the 

 above named firm. 



Various inquiries and orders for testing were received as a 

 result of the recent London Rubber Exhibition, and were largely 

 due to the exhibit of testing apparatus by the bureau, in con- 

 junction with the papers read on that occasion by Professors 

 ' Hinrichsen and Memmler, and to the co-operation of other 

 officials. As a result of negotiations with the Association of 

 German Electricians, an extensive programme was prepared for 

 exhaustive tests of insulating materials at voltages up to SCX) 

 volts. A number of factories co-operated in providing the ap- 

 paratus for carrving out these tests; the object of which, 

 amongst others, was to investigate the qualities of substitutes 

 i for hard rubber, and to define their utility as compared with that 

 1 of genuine rubber products. With this view, tests were insti- 

 tuted as to their qualities, their strength and resistance under 

 tension, pressure and flexion, as well as their hardness and 



capacity of withstanding chemical and climatic influences. Tht 

 instructive results of these tests are now being compiled by a 

 committee of the above-named association, with the object of 

 drawing up normal regulations for insulating materials. It is 

 added that there is reason to expect, that hard rubber substitutes 

 will thus "come into their rights." 



One of the principal features of the bureau's action has been 

 the carrying out of agreed tests, as well as the adoption of 

 uniform methods in selecting samples, that point not at present 

 usually receiving the attention it deserves. 



CHEMICAL TESTS. 



A prominent fact in connection with the chemical section, was 

 the increased extent to which its services were called upon by 

 the rubber industry. In this connection mention is made of 

 the work by Professors Hinrichsen and Memmler on "Rubber 

 and Its Testing," which has met with general commendation 

 from the technical press. Another interesting event was the 

 reading by Professor Hinrichsen, at the 1910 Munich Congress 

 of the German Chemists' Association, of a paper upon "Physical- 

 Chemical Rubber Studies," in which he dealt with various in- 

 vestigations made at the bureau as to the molecular dimensions 

 of rubber, the theory of processes of vulcanization and other 

 subjects. Professor Hinrichsen in collaboration with Professor 

 J. Marcusson likewise dealt with "The Determination of Fill- 

 ing Materials in Rubber Compounds." "The Optical Action of 

 the Resins Present in Rubber" also formed the subject of 

 investigation and report by these two experts, while other points 

 treated by the former included "The Tetrabromide Definition of 

 Rubber," and "Resin in Rubber." 



The relative importance of rubber in the work of the bureau 

 is illustrated by the fact that in division 5 (general chemistry) 

 the 1,071 tests made during the year 1910-1911 included 282 of 

 iron and steel, 216 of rubber in various forms, 191 of fuel, and 

 382 in IS other branches. 



The administrative policy of the establishment is prominently 

 expressed in the following statement: 



"The bureau would be much pleased, if this annual report 

 gave rise to practical suggestions as to how the usefulness of 

 the establishment to German industry could be continually in- 

 creased. Every suggestion will be conscientiously weighed." 



GERMAN OFFICIAL TESTS OF BALLOON FABRICS. 



f~\ NE of the most interesting portions of the report of the 

 ^-^ Gross-Lichterfelde Material Testing Bureau for the year 

 1910-1911 is that dealing with the tests of balloon fabrics. For 

 this purpose the rupture apparatus of Gradenwitz was installed, 

 as well as another (designed by Martens), for automatically 

 recording pressure, the latter permitting rupture tests of sam- 

 ples measuring 1/3, 1/4, 1/8, and 1/16 of a square yard. 



These appliances have been supplemented by one designed by 

 E. Heyn, for determining permeability to gas, and likewise one 

 designed by O. Bauer for ascertaining permeability to the radia- 

 tion of heat. The necessary appliances for determining the kind 

 of fiber, the strength of the fabric, and its resistance to the 

 effects of weather, sunlight and damp, had already been in- 

 stalled in the textile division, so that the bureau claims to be in 

 a position to test balloon fabrics in every manner required. 



Communications actively carried on with leading, representa- 

 tives of aviation, led to the elaboration of a plan for a com- 

 prehensive series of tests of balloon fabrics, so that the proper- 

 ties of new materials could be clearly shown. It is also con- 



