May 1, 1921 



THE INDIA RUBBER WORLD 



605 



INTERESTING LETTERS FROM OUR READERS 



LONDON COUNTY COUNCIL HOUSING BONDS 



To THE Editor : 



DEAR SIR : The enclosed circular of tlie London County Council 

 housing bonds describes the one method that has been suc- 

 cessful in Europe in providing funds for housing purposes. 



Why can we not adopt something that has proved satisfactory 

 elsewhere instead of wasting time endeavoring to discover some- 

 thing that is all- American? Must we have another Liberty motor 

 episode, trying to learn how to make all-American airplanes and 

 motors when we could have much more quickly adopted the kind 

 Europe was making successfully during the war, and which it 

 was proved would work? 



Americanism is one thing. Chauvinism is another. 



New York, N. Y. R. J. Caldwell. 



The securities referred to by Mr. Caldwell, which have been 

 termed one of the most meritorious issues made in years, are the 

 London County Council 6 per cent bonds to provide funds for 

 the urgent housing needs of the metropolitan boroughs. They 

 are sold for cash, or in four instalments, in denominations of 

 £5 or in multiples thereof, to be repaid at par in five, ten, and 

 fifteen years as desired by the buyer. Interest is payable semi- 

 annually, and both interest and principal are secured by the 

 property and revenues of the London County Council and the 

 rates of this council outside the city. The council allows a 

 brokerage of ^ of one per cent and pays stamp duties on all 

 transfers. The bonds are free of income ta.\ at source of issue up 

 to ilOO. — The Editor. 



PROPER AND IMPROPER NOJLCANIZATION OF INNER TUBES 



To THE Editor : 



DE.-\R Sir : — The true measure of the proper elasticity in an inner 

 tube is the stretch to break and the recovery from a stretch 60 

 to 70 per cent of breaking strain. Tensile, upon which so much 

 stress is foolishly laid, is a secondary consideration. It is always 

 possible to secure greatly increased temporary tensile strength 

 either by increasing the vulcanization beyond the limits imposed 

 for long life, or by using an excessive amount of what are loosely 

 termed accelerators. Now let us see what happens when temporary 

 tensile strength is thus artificially increased for a sales argument 

 only, because it is not a service argrument. 



Given a compound containing 90 to 95 per cent rubber by vol- 

 ume, with 3 per cent sulphur, and not more than 0.50 per cent of 

 hexamethylene tetraminc as an accelerator, if properly vulcanized. 

 a tube of this quality should stretch from 2 inches to 12 inches, 

 and be so held for ten minutes, then allowed to recover for ten 

 minutes. The stretch remaining over the original 2 inches should 

 be about 10 per cent or 2.2 inches. Tensile strength should be 

 about 2,000 pounds to 2.200 pounds per square inch. Now to 

 increase this tensile by vulcanizing to 2,600 or 3,000 pounds, what 

 happens? The stretch may not be affectc-d immediately and per- 

 haps not even for six months, but as sure as the Lord made little 

 apples, such a tube will crumble and die soon after six months, 

 and very likely earlier. When the recovery from stretch shows 

 only 2y2 to 5 per cent, there is something rotten in Denmark. 

 The tube is doomed to a young, untimely death. If excessive 

 tensile is secured by using as high as 1^ to 2 per cent of the ac- 

 celerator mentioned, the result is even worse. Such tubes probably 

 will not last three months. 



Over-vulcanizing or the use of an amount of so-called acceler- 

 ators, which are really catalysers and like poison, to be used in 

 very small doses, give very pretty attractive first effects, which are 

 really about as wholesome as the hectic flush of one in the last 

 stages of tuberculosis. Such tubes arc translucent, smooth, free 

 from all bloom or sulphur deposit, very, very attractive indeed, 

 but good only for the show window, or the salesman's grip ; abso- 

 lutely no good at all for long service. Take an extreme case, the 

 tensile strength of such a compound as given may be increased to 



4,000 pounds if the vulcanizing is continued until hard rubber is 

 secured. It can easily be seen that while this material is all right 

 for pipe stems, etc., it is scarcely the thing for an elastic tube, 

 and here endeth the tensile lesson. 

 Jersey City, New Jersey. Superintendent. 



THE EDITOR'S BOOK TABLE 

 "THE PLANTING ENGINKER." BY C. REID. COLOMBO. UV.YS 

 of Ceylon Co., Limited, Colombo, Ceylon. Cloth, 371 pages. 



THIS BOOK which is intended for the planter of rubber, tea 

 and coconuts, deals exhaustively with practical engineering as 

 applied in the manufacturing processes employed on the estates 

 in the Far East. The book comprises 27 chapters and appendix 

 grouped under the following sections : Rubber, power, electric 

 light and power, tea, transport and coconuts. 



A full description of all machinery connected with the products 

 named is given with instructions for working and general up- 

 keep. General information is afforded on electric lighting, water 

 supplies, transport by road and aerial tramway, followed by an 

 appendix of useful facts, figures and tables. A full index is pro- 

 vided and the book is liberally illustrated. The instructions are 

 simple, direct and as non-technical as possible. The book will 

 be found a valuable aid to every estate engineer. 



"PRIE.STLEV TN AMERICA," 17941804. BY EDGAR F. SMITH, 



University of Pennsylvania. Cloth, 17J pages, 7J4 by 5 inches. 



This book should be of great interest to readers, as elsewhere 

 in this issue appears a sketch of Joseph Priestley, the man who 

 named india rubber. The book deals with the adventures and 

 activities of Dr. Priestley during the years spent in America 

 after being forced to leave France and England because of his 

 radical sympathies. The book contains no illustrations, not even 

 a frontispiece of Priestley, but is attractively printed and contains 

 copies of many letters exchanged between the doctor and his 

 numerous American friends. 



NEW TRADE PUBLICATIONS 



A brochure, "The Golden Year of Goodrich, 1870-1920, 

 Fiftieth Anniversary," has just been published by The B. F. 

 Goodrich Co.. Akron, Ohio. It commemorates the fiftieth anni- 

 versary of the founding of the company, dealing not only with the 

 history of the origin and growth of the company, but the pan 

 that rubber plays in the industrial development of the world and 

 individual life. The context is written by Wilbur D. Nesbit. and 

 colored symbolic illustrations representing Earth, Air, Fire and 

 Water are reproduced from paintings by W. T. Benda. Through- 

 out are numerous croquis of places, incidents, and machinery, 

 while the last few pages are devoted to a list of the officials, 

 branches of the company in the United States, foreign branches 

 and foreign distributers. 



Technical and SaENTiFic Book Section, from the 1920 Edi- 

 tion of the Chemical Engineering Catalog. Chemical Catalog Co., 

 New York. 



This alphabetical list of authors' names includes practically all 

 the current works on chemistry and chemical technology and i3 

 preceded by a subject index. Valuable for ready reference. 



"The Rubber Industry," the first of the affiliated bulle- 

 tins for firm and affiliated members of The Rubber Association of 

 .\merica, made its appearance early last month. It is a six-page 

 leaflet which will l)e distributed at intervals of about two weeks, 

 and will cover such subjects as are likely to be of interest to 

 .Association members in connection with the rubber industry, as f<ir 

 instance, legislation, taxation, traffic and transportation frail and 

 highway >. industrial relations, foreign coinmcrce, raw materials, 

 statistics, .Association activities, meetings, etc., and miscellaneous 

 information. 



