408 



THE INDIA RUBBER WORLD 



[September i, 1908. 



The Analysis of India-Rubber. 



DIE ANALYSE DLS KAUTSCHUIvS, DER GUTTAPERCHA, BALATA 

 UND IHRER ZUSAETZE. Mit einschluss der chemie der genannten 

 stoffe. Von Dr. Rudolf Ditmar. Wien und Leipzig; A. Hartleben. 1909. 

 [Paper. 8vo. Pp. viii + 288 + plates. Price, 10 marks.] 



THOUGH much research work has been done in the analysis 

 of india-rubber and compounding ingredients, and the 

 chemistry of these substances, during the six years that 

 have elapsed since the appearance of Dr. Weber's book, the 

 records have been scattered through very many technical pub- 

 lications, accessible in their totality to only a few persons. 

 That Dr. Ditmar should have undertaken a new collective work 

 in this field, brought up to date, will be welcomed by all who 

 are interested in the technology of rubber. In so far as the 

 book is intended as an introduction to the subject, and to enable 

 the chemist of general scientific education to handle analytical 

 propositions in the rubber factory. Dr. Ditmar has achieved his 

 purpose. 



The author says in his preface that his book has had its origin 

 in practice, but in parts of it sufficient account has not been taken 

 of practical needs for the laboratory of a rubber factory. Many 

 details as to general layout, apparatus, and tests that may be in 

 every way sufficient for a school laboratory must be changed for 

 a laboratory which is in constant touch with the needs and 

 difficulties of manufacture. The main difficulty for the chemist 

 in applying his science to the rubber business has always been 

 the want of practical knowledge of factory operation, and with 

 too much reason this lack often has prejudiced the rubber worker 

 against scientific advice and supervision of the business. The 

 fundamental causes of most difficulties in the factory cannot be 

 detected by an occasional superficial insight into methods ; the 

 ability to apply the result of scientific research successfully to 

 practical problems of manufacture can be obtained only by per- 

 manent close relation to and observation of all phases of factory 

 practice. It is important to impress upon the young chemist that 

 a familiarity with the factory, gained by research work based 

 upon its difficulties, will be of greater value to him than any 

 amount of learned theory which he does not know how to apply. 

 A book on the practical analysis of rubber ought to bear more 

 upon this point, and suggest a closer connection between theory 

 and the solving of practical difficulties. 



The first three chapters relate to the theory of india-rubber, 

 gutta-percha and balata, based upon the most recent research. 

 The compilation is well done, though perhaps the space devoted 

 to each feature is not always proportional to its importance. 

 Then follow 50 pages devoted to testing and the treatment of 

 compounding ingredients. Comparatively little original informa- 

 tion is given, and there is a failure at times to point out the 

 specific qualities of compounds in reference to their practical 

 application. 



Chapter V, entitled ".Analyse des Kautschuks," opens with 

 plans for a rubber factory laboratory. It may be suggested that 

 the author does not recognize sufficiently that such a laboratory 

 should serve four distinctly different purposes: (i) A testing 

 place for raw material, as a function of the purchasing depart- 

 ment; (2) a testing place for manufactured articles, as a func- 

 tion of the sales department; (3) a controlling place for 

 manufacturing processes, as a function of the manufacturing 

 department; and (4) an experimental place for improvements 

 and inventions under its own supreme management. 



The most interesting and valuable part of the book, for the 

 analytical chemist, is the compilation of the modern endeavors 

 to find a direct method for the estimation of the rubber sub- 

 stance itself in vulcanized articles and a direct method for the 

 rubber combined sulphur which could be depended upon in 

 every case. None of these newer methods has proved so satis- 



factory as to justify the rubber industry in changing materially 

 its testing methods, which are still based for the most part upon 

 Henriques and Weber. Among the sulphur tests the Eschka 

 estimation by means of the magnesia mi.xture, which is much 

 applied in America, and the useful Koneck rapid method receive 

 scant treatment. Several conclusions as to the usefulness of test- 

 ing methods for practical purposes must be accepted with re- 

 serve, partly because based upon only a few experiments, partly 

 because the practice has no interest in results derived from these 

 methods. The analysis of gutta-percha and of balata also re- 

 ceives attention. 



The final chapter, on the technical testing of rubber articles 

 for practical serviceability, is filled largely by the rather old in- 

 vestigation of Heinzerling and Pahl. The oxidation method of 

 the author does not take sufficient account of the surface action 

 and therefore is hardly as reliable as it appears in the record. 



The too common fault of comparing vulcanized rubber sam- 

 ples on a wrong basis for technical serviceability is not pointed 

 out strongly enough. It is essential to find the best conditions 

 for each brand of rubber at first by a series of tests with one 

 brand only, before comparing several brands. Even different 

 consignments of the same brand will sometimes show different 

 conditions. Certainly samples with different qualities should 

 not be subject to the same heat, time, and compound tests with 

 a view to getting an idea of their value. 



The serial test of a single class of rubber for finding the best 

 condition should be so arranged that it can be expressed con- 

 veniently by comparison curves, not taking a single figure of 

 strength or elasticity as indicative, but an average valuation 

 figure. This formula has proved satisfactory for this purpose : 



breaking strength X stretch of hrcak 

 percentage of permanent set 



Any convenient unit of size and time to be taken, but this 

 unit of course constant for one whole investigation. 



For arriving at such a curve it is of course essential to start 

 with such conditions of heat, time, and amount of sulphur or 

 other effective compound as are in the greatest possible con- 

 formity with practical conditions, changing only one function 

 for the series simultaneously, keeping the other functions con- 

 stant. Only by finding out in this way the best condition for 

 each class of samples is to be obtained a comparison based on 

 the results of every class, for the technical valuation of rubber. 



While generally the book possesses the defects of lack of 

 system and of too positive conclusions, especially when derived 

 from results which do not take sufficient account of practical 

 conditions, yet as a collective description of the latest research 

 on rubber it is a meritorious work and will prove useful. Dr. 

 Ditmar's fear of serious differences between the old and the 

 modern rubber man is hardly justified, at least by conditions in 

 America. A modern rubber chemist, who has gained the neces- 

 sary practical knowledge, will meet only with support, coopera- 

 tion and appreciation whenever he meets the intelligent superin- 

 tendent or manager of a rubber factory, and these desirable 

 relations will be improved, rather than otherwise, by the study 

 of books like Ditmar's. erwin meyer, ph.d. 



The American Rubber Co. (Boston), who state that they own 

 property in Cambridge assessed at $233,400, and do an annual 

 business of $5,000,000, have filed a bill in equity in the Middlesex 

 superior court to restrain various other factories named in their 

 complaint from constructing and maintaining a railway in Binney 

 street, Cambridge, alleging that the same would inconvenience 

 the public and deprive the plaintiffs from a proper use of the 

 street. 



