274 



THE INDIA RUBBER WORLD 



[February 1, 1917. 



Tests of this shoe in the laboratories of the Edison Electric 

 Illuminating Co., of Boston, Massachusetts, under the direction 

 of the National Electric Light Association, showed the following 

 characteristics: Side of shoe, dry, punctured at 31,500 volts, and 

 again at 34,000 volts; sole of shoe between electrodes in oil, punc- 

 tured at 55,000 volts; 20,000 volts applied from salt vi-ater to salt 

 water for one minute and 30,000 volts applied from salt water to 

 salt water for 45 seconds did not puncture the rubber. [Linemen 

 Protector Co., Detroit. Michigan.] 



PERKINS' SPARK PLUG TESTER. 



By means of this handy device, which is made entirely of 

 liard rubber, defects in the action of spark plugs may be in- 

 stantly located. The majority of automobiles have three or four 

 different makes of spark plugs, and in many the plugs are not 

 set at the proper gap and cause uneven running of the motor. 



knocking and loss of power, uiili aiu-uJaMt evils 

 such as heavy gas, oil and repair bills and a smok- "; 

 ing car. The use of the tester produces the best L.^,.„^J' 

 results from the spark plugs, the procedure ^sa^ 

 being as follows: Sec that gaps are set the same as the 

 gap in the tester. Place the tester with one wire touching the 

 terminal cap and the other wire touching the, base of the plug. 

 If the plug is operating as it should, a good spark will result, 

 while a broken porcelain or fouled plug will not show a spark 

 in the tester. [A. D. Perkins, New York City.] 



PNEUMATIC SECURITY BOLT. 



Although similar in part to the ordinary type of security bolt 

 for pneumatic, tires, the one here shown has the customary metal 

 head with its under seat covered by canvas, this canvas being 

 sealed by a piece of rubber and the two forming 

 a pneumatic cushion which serves to hold the 

 tube well out of the way of both bolt and outer 

 cover when fitting. This special, patented 

 form of security bolt is claimed greatly to mini- 

 mize the risk in the operation of tire changing, 

 that the covers and tubes will be nipped under 

 the beads of the cover or under the security 

 bolts. [The Self-Sealing Rubber Co., Limited, 

 of Hermetic Works, Birmingham, England.] 



A PNEUMATIC WHEEL. 



A cushion wheel that disposes of the customary pneumatic 

 tire and tube, comprises a solid tire that is cushioned on eight 

 pistons operating in radial air cylinders. This air cushion wheel 

 '■'"■^' ■ is recommended for all 



motor vehicles using solid 

 tires and also for pleas- 

 ure cars using pneu- 

 matics. 



The solid tire is flexibly 

 fixed to the radial pistons 

 that automatically com- 

 press the air in the me- 

 tallic air cylinders which 

 are attached to the hub 

 like spokes of a wheel. 

 Thus it is claimed that 

 the jars and jolts inciden- 

 tal to ruad travel are absorbed and riding quality obtained equal 

 to that of a pneumatic tire. The tire is obviously immune from 



punctures and blow-outs and moreover, it is said that the only 

 attention required is an occasional drop of oil in the metallic 

 air cylinders. [Pneumatic Wheel Co.. St. Paul, Minnesota.] 



"NEW GIANT" SINGLE-TREAD SOLID TIRE. 



'1 rucks of six and eight-ton capacity demand tires of excep- 

 tional size, and the one here shown, measuring 42 by 14 inches, 

 is claimed to be the largest single-tread solid tire ever built. 



But size is not tlie only 

 requisite. Of prime im- 

 portance, and particu- 

 larly considered in the 

 construction of this tire, 

 is the building and 

 placing of the rubber in 

 sucli form as will ac- 

 commodate the internal 

 stresses and displace- 

 ment with the minimum 

 friction. The resultant 

 stresses within the dis- 

 torted portion of the tire 

 immediately affected by 

 the load must also be 

 lakcn into consideration. 

 In the narrow-section 

 solid tire these lateral 

 -tresses are relieved by 

 the sides, but in the 

 giant solid tire the sides 

 are too widely separated 

 for such relief. To 

 meet this condition, the 

 "New Giant" has a series of grooves, scientifically arranged, en- 

 circling the outer periphery, thus making it analogous to a numr 

 her of smaller tires with the additional advantage of all portions 

 working on a single base. These grooves also tend to prevent 

 skidding and assist tractive effort. 



Some idea of the colossal size of this tire may be gained from 

 the positions of the men in the picture. C. E. Speaks, manager 

 of truck tire sales, standin.g beside it, and L. C. Clough, of the 

 truck tire department, sitting within. [Firestone Tire & Rubber 

 Co.. .'Xkron, Ohio.] 



RUBBER IN THE FLOTATION PROCESS. 



The flotation process of ore separation makes use of the 

 affinity of finely ground sulphide ores for the froth produced 

 liy agitating a solution of water containing a very small pro- 

 portion of an oil. 



The sulphide ore is mixed with about 20 parts of the solution 

 and run to cells where it is agitated either by mechanical means 

 or by blowing air through a porous bottom. A number of sub- 

 stances and constructions have been used to form this porous 

 bottom, but the most satisfactory so far, has been the cotton 

 fabric diaphragm. However, the pores of this cotton fabric 

 rapidly fill up and clog from the ore. and hence do not last 

 long. 



Rubber-coated diaphragms have been developed to eliminate 

 the trouble experienced from the regular cotton fabric. It is 

 made of one ply of coated fabric and two plies of regular un- 

 treated fabric, all stitched together in rows one inch apart in 

 both directions. In the coated fabric, every thread is completely 

 coated with rubber, but the fabric has been produced, in such 

 a way as to make it porous, and the small openings are the. 

 proper size to produce the froth required. These diaphragms are 

 necessarily more expensive than the ordinary cotton fabric type, 

 hut the increased service is considerably out of proportion to 

 the increased cost. [The B. F. Goodrich Co., Akron. Ohio.] 



