556 



THE INDIA RUBBER WORLD 



Mav I, 1921 



Plant at Azuza, California, ior the Manufacture of Hvdrocvanic Acid, Used in Tent Fumigation 



with fumigation. Even in covering time, it is claimed that SO 

 per cent saving can be effected with rubber tents. 

 SUPERIORITY OF GAS FUMIGATION 



One of the advantages of gas as an insecticide and fungicide, is, 

 that it is not only quick and certain, but, if properly used, it will 

 disappear when the tent is removed and harm neither the tree nor 

 the fruit. Spraying mixtures, on the other hand, cannot be 

 diffused through dense foliage and often fruit is affected by the 

 chemicals, cases of arsenical poisoning having been attributed to 

 such a cause. A fumigated tree, it has been found, produces 

 cleaner, bigger, better fruit, with better color and flavor, than 

 one which has been merely sprayed. While some growers still 

 generate their own gas, most of it is prepared by fumigating 

 companies and delivered in metal drums to the groves. The gas 

 is then forced under high pressure through a hose leading under 

 the tent and issues from an atomizer, the amount being graduated 

 by registering apparatus. 



THE GENESIS OF HYDROCYANIC ACID 



A word about hydrocyanic acid (HCN) may not be amiss. 

 It is the prussic acid of the old chemistry, and very poisonous. It 

 is a colorless, mobile, volatile liquid with a peculiar peach-blossom 

 odor. It is, when vaporized, much lighter than air and diffuses 

 rapidly. On a small scale it is made by the action of one fluid 



ounce of sulphuric acid (sp. gr. 1.83) on one ounce of cyanide 

 of soda. Pure acid is produced by passing hydrogen disulphide 

 gas over dry mercuric cyanide. Its boiling point is 26.5 degrees C. 

 It is interesting to learn that hydrocyanic acid has been found in 

 the latex of rubber trees. R. T. Stokes in Chemical Abstracts, 

 volume 9, page 2607, tells of an analysis of the latex of Hcvea 

 brasiliensis by M. Kerbosch in which the presence of HCN was 

 proved by its reaction with Prussian blue. It is conceivable that 

 to some such substance the latex may owe the power it is believed 

 to possess of safeguarding the tree from attacks by insect enemies. 



USEFULNESS OF RUBBER TENTS UNLIMITED 



Perhaps, too, the day is not far distant when two substances 

 found in the latex will play an important part in saving rubber 

 from damage by pests. Rubber, gas-tight tents may be used for 

 fumigating the younger trees, and giving their insect enemies a 

 proper dosage of hydrocyanic acid. .Apparently there is prnctically 

 no limit to the usefulness of the rubber fumigating tent. It may 

 be used to rid the date-palm trees of suckers, to save the peach 

 crop, the prune, pear, apricot, and many other fruit and berry 

 crops, and in many ways to lessen the loss, estimated for 1920 

 at a billion and a half of dollars, due to the ravages of scales, 

 flies, beetles, moths, aphids, caterpillars, etc., on the products of 

 the country's farms, gardens and orchards. 



Curing Tires in Melted Metal Molds 



The Stone Process and What It Covers— The Gleason Fusible Metal Core— The Eatin Patent 



STEEL MOLDS AND CORES for tires, footwear, druggists' sundries, 

 etc., as well as vulcanizing presses and similar machinery in 

 which manufacturers of rubber goods have invested millions 

 of dollars will all be scrapped, and vulcanizing time cut almost in 

 half, if the hopes of Dr. Frank O. E. Stone are realized. Dr. 

 Stone is a young dentist, formerly of Akron, Ohio, who, after 

 much experimenting in rubber and metals, has patented a method' 

 of curing rubber by immersion in low fusible metals. 



Dr. Stone claims that he can completely eliminate molds in 

 making rubber goods, overcome variations in the physical con- 

 dition of raw and cured rubber, obtain more definite results in 

 vulcanizing than by using steam, and avoid overcuring and bloom 

 in the goods. The inventor claims that the amount of sulphur 

 and accelerators ordinarily used in vulcanizing, can be reduced, 

 and the toughness, resilience, and flexibility of cured rubber, con- 

 siderably increased. Tire casings can be cured in 50 minutes, 

 air-bags wholly dispensed with, and a closer adhesion of rubber 



'United Slates patent No. 1,368,071 Rranted February 8, 1921. 



to fabric secured. In making solid tires oxidation is eliminated 

 and closer adhesion of rubber and metal secured as steam and 

 hot water would be dispensed with. Rubber manufacturers, there- 

 fore, would be able to make a wider range of articles that 

 are now made of other materials, and the labor cost would be 

 reduced, generally speaking, 30 per cent. 



THE STONE PROCESS 



Applied to tire-making, the method is as follows : A casing, 

 having been built up on a tire core, is suspended or supported 

 in a metal trough into which fusible metals at a liquefying tem- 

 perature are poured so as to completely envelop the casing. 

 The metals are then allowed to solidify. By means external to 

 the trough, or with an electric resistance coil within the trough, 

 the fusible metals are kept steadily at a vulcanizing temperature 

 until the cure is effected. The metals are then allowed to cool, 

 when they are liquefied, poured off, and the casing removed from 

 the trough to be finished in the usual manner. 



Pressure is obtained by contraction of the liquefied metals as 

 they cool arouml tlie article they encase, from the fusing point 



