May 1. 19-'0.1 



THE INDIA RUBBER WORLD 



507 



INTERESTING LETTERS FROM OUR READERS. 



RUBBER AND METALLIC SUBSTANCES APPLIED TO CLOTH. 



To THE ElllTilR : 



p\E.-\R SIR: I am writing to ask if you know anything of 

 '^ the process used in decorating cloth like the enclosed sample. 



I know it was an ancient art in India. The question is how to 

 reproduce it with modem methods. 



If you can refer nie to any writing on the process of applying 

 rubber to cloth which may be used with metallic substances, I 

 shall be very grateful. 



This is a technical subject about which I know very little and 

 I was unable to get satisfaction from books. 



I shall be very grateful to you for an early reply. 



Grace G. De.vny, 

 In charge of textile laboratory. 

 Univcr.^ity of Washington, Seattle, Washington. 



REPLY BY THE EDITOR. 



The sample of cloth ornamented with gold flowers which you 

 sent me is of exceeding interest. It may be a rubber product. 



PKt 



\BRic Orx.\mexted with "Goi.d and Rubher'' 



at least in part. The milk of a rubber tree, the Ficus elastica, 

 was used in India more than a thousand years ago. It is prob- 

 able that the rubber from it was also used. A native could easily 

 make a thick rubber paste and apply it to fabric in crude lines 

 of ornamentation ; then, while still adhesive, dust it thickly with 

 metallic powder. That used on the sample looks like pyrites. If 

 it is, exposure of the decorated surface to the sun would result 

 in the type of vulcanization known as solarization, or sun-cure, 

 the three concomitants, rubber, sulphur (or a sulphide) and 

 heat, being present. I do not, of course, assert that this is the 

 fact, but it is not impossible. 



I recall something of this sort of native work in Kuala Lum- 

 pur, F.M.S., where a coolie decorated his Chinese shoes with 

 stripes in blue and crimson. The body of the stripe was freshly 

 coagulated rubber exposed to heat to render the surface sticky. 

 This was then dusted, one stripe with a blue powder, the other 

 with a crimson. The whole was then thoroughly dried out in 

 strong sunlight. 



With regard to work of this type, in our own day Charles 

 Goodyear did some very fine ornamental work on fabric and 

 leather, using a thick rubber cement which was dusted over 

 with "flock" of various colors. None of this work is in existence 

 to-day, as far as I know. 



Twenty-five to thirty years ago, when the rubber surfaced 



"gossamer" was popular, the unvulcanized surface was orna- 

 mented by applying starches, and in a few instances, metallic 

 powders, after which the garment was cured. 



To imitate the sample to-day, a thick paste of rubber applied 

 from a collapsible tube in the form of decoration, this to be 

 dusted while sticky with bronze powder, brass filings, or any 

 mineral powder desired. If the rubber paste is to be sun-cured, 

 it should contain sulphur. Or it could be cured in dry heat, or, 

 containing no sulphur, be exposed to the fumes of chloride of 

 sulphur. There is no doubt that very beautiful and permanent 

 decorative effects could be obtained by the process outlined. 



The Editor. 



special library census. 



To THE Editor : 



r^E.\R SIR : At a time when the Government is counting 



'-^ up its inhabitants, the Special Libraries Association is 



enumerating the special library collections of the country, be- 

 cause there does not exist at present an adequate directory of 

 special libraries. 



In the spirit of cooperation, and in order to list the special 

 information sources of the country, the Special Libraries Asso- 

 ciation — the national body of special librarians — submits the fol- 

 lowing questions and respectfully asks you to take the trouble 

 to answer them. When compiled, the directory will not be 

 used as a mailing list for advertisers, but merely for the pur- 

 pose stated, namely, to have in a central place, a record of 

 the special information sources of the country. 

 A special library has been defined as : 



A good working collection of information either upon 

 a specific subject or field of activity; it may consist of 

 general or even limited material serving the interests of 

 a special clientele ; and preferably in charge of a specialist 

 trained in the use and application of the particular 

 material. 

 If your library comes within the above qualifications, the 

 Special Libraries Association will appreciate ihc following in- 

 formation from you : 



(1) Name of institution or company. 



(2) Name by which library is known. 



(3) Name of librarian or custodian. 



(4) Can it be classified as any of the following: Financial; 



business; legal; engineering or technical; institutional; 

 municipal ; reference ; agricultural. 



(5) If not, how can it be classified? 



(6) Does it serve a special clientele? 



(7) Would your librarian be willing to assist other special 



libraries to a reasonable extent? 

 The above data should be sent to William F. Jacob, Chair- 

 man Library Census Committee, care of General Electric Com- 

 pany, Schenectady, New York, who will be glad to answer any 

 questions relating thereto. 



To THE Editor : 



DE.\R SIR: I have read with great interest the paper on the 

 "Expansion of Rubber Compounds during Vulcanization," 

 communicated by C. W. Sanderson to the Rubber Division 

 of the American Chemical Society and reprinted in your 

 journal, February 1, 1920. Mr. Sanderson states that one of 

 the first questions which arose in connection with the expansion 

 of rubber was whether or not there was a break in the curve, 

 or, in other words, a volume change at the point of vitlcanha- 

 lion. The author does not, however, explain what he means by 

 the point of vulcanization, and, as matter of fact, vulcanization 

 has now been shown to take place perfectly gradually although 

 it increases more rapidly than the rise in temperature. He 

 also states that "we know that a physical change takes place, 

 and that the specific gravity increases." The specific gravity is. 



