April 1, 1919.] 



THE INDIA RUBBER WORLD 



361 



while in night extraction it is very constant. For example, 

 crimson antimony which has shown perfectly free from free 

 sulphur during night-time extraction with fresh redistilled car- 

 bon disulphide, gave during day extraction a variable result 

 as high as lour per cent. Following the night extraction the 

 carbon disulphide is evaporated to dryness and the residue of 

 free sulphur considered as the correct amount from the antimony 

 present. The extracted sample is dried for about one hour at 

 60 degrees C, weighed and preserved for further analysis. 

 DETERMINATION OF MOISTURE AND WATER OF 

 CRYSTALLIZATION. 



The moisture in antimony is usually very small in amount 

 although the water of crystallization present may run as high 

 as 15 per cent. The amount of water of crystallization is always 

 in proportion to the content of calcium sulphate. The water 

 of crystallization is not readily volatilized, requiring at least six 

 hours at 100 degrees C. to expel it completely if a vacuum is 

 not used. To avoid volatilization of free sulphur it is better to 

 use the sample which obtained from the free sulphur ex- 

 traction. For example, if from five grams one gram of free 

 sulphur has been extracted, and the antimony weighs 3.90. 

 take .78 which is equal to one gram of the original substance, 

 place it on a weighed watch glass, spreading the sample over 

 \ large area, and dry it at 100 degrees C. to constant weight. 

 If the resulting weight is .74, then the moisture and water of 

 crystallization is six per cent. 



DETERMINATION OF CALCIUM SULPHATE. ADULTERANTS. 



AND ANTIMONY OF OTHER COMBINATION THAN 



ANTIMONY PENTASULPHIDE. 



It is seldom that the antimony contains a number of different 

 substances in the same sample, therefore a qualitative test mav 

 be omitted and quantitative analysis proceeded with. Since c;il 

 cium sulphate is the material most frequently to be determine 'i 

 and the work requires much time, it is a good plan to shake a 

 small amount of the original sample with water, filter oft 

 the solution, and test with barium chloride solution. If no 

 precipitate is obtained the antimony is ready for further in- 

 vestigation ; otherwise proceed as follows : 



Take the equivalent of one gram of the sample which has 

 resulted from the free sulphur determination, place it on filter 

 paper, wet it with a small quantity of alcohol and wash it with 

 cold water. Use a glass funnel with a cock so that the wash water 

 passes through very slowly allowing enough time to act upon 

 the calcium sulphate. After about 200 cc. of water has been 

 used, occasionally test with barium chloride solution a few 

 drops of the wash water dropping from the funnel and pro- 

 ceed with the washing till the water-soluble calcium sulphate 

 has passed completely into solution. Transfer the total wash 

 water to a weighed beaker, evaporate it to dryness on steam 

 bath, and dry it at 100 degrees C. to constant weight. This 

 residue represents calcium sulphate. 



After extraction of the calcium sulphate, the antimony 

 is washed through a small hole in the bottom of the 

 filter paper into a beaker. Allow it to settle, pour off the 

 clear water and treat the antimony with approximately 100 cc 

 ten per cent caustic soda solution, stirring it for about 10 

 minutes on steam bath. If the antimony passes completely 

 into solution, further analysis in this group is not required. 

 If any residue is left, it may represent a complex mixture of 

 adulterants, but in most cases it represents only a single sub- 

 stance. 



Allow the residue to settle, pour off the clear solution, stir 

 again with about SO cc. water, transfer to filter, and wash with 

 water till the reaction is neutral. Through a small hole in the 

 bottom of the filter paper wash the residue completely down 

 with water into a weighed beaker. Allow residue to settle, 

 pour off the clear water, and evaporate the remaining water and 

 residue to dryness, and dry to constant weight. This residue 

 represents the amount of total adulterant of antimony tetra- 



oxide. Red color of residue indicates red oxide of iron or iron 

 silicates, which are the most frequently used adulterants. A 

 white residue indicates barytes, antimony tetraoxide, whiting or 

 magnesia carbonate, or silicates. To learn the true composi- 

 tion of the residue, test it qualitatively in the usual way. 



In the whole course of analysis never use a platinum crucible 

 as there is danger of mistaking the antimony tetraoxide 

 for barytes or some other mineral filler and when the antimony 

 tetraoxide is ignited with filter paper in platinum some of the 

 antimony becomes reduced and will alloy with the platinum. 



TIRE-TESTING SPEEDWAY. 

 .\ mile-high speedway, and the only one in the world for test- 

 ing half-soled tires is that of the Gates Rubber Co. on one of 

 tlieir large factory buildings in Denver, Colorado. The machine 

 consists of a long arm revolving in a huge circle, on the end 



of wliicli is attached the tire. A weight equivalent to that of 

 a heavily-loaded machine is suspended in such a way that the 

 tire itself carries the load. The tire travels on a half-mile track, 

 which is first a stretch of cement trackway on which it attains 

 a speed of 35 miles an hour. It then strikes a sandy stretch 

 which causes it to jump and skid. Then it traverses an imita- 

 tion brick roadway, following which it plunges into water and 

 mud. By way of variety an incline representing a rough moun- 

 tain road is included with a 45 per cent slope. Thus, the tire 

 continues its journey all day and every day until it has given 

 the maximum amount of mileage. By this means, if defects 

 exist they are discovered, and promptly remedied. 



MORGAN & WRIGHT GET LARGE SHIPMENT OF RUBBER. 



What is said to be one of the largest single-lot shipments of 

 rubber ever received in America was recently landed at San 

 Francisco by the S. S. Siberia Mam from Singapore and trans- 

 ferred to a train of 26 cars for shipment overland to 'Morgan & 

 Wright, Detroit, Michigan. The shipment weighed 2,240.000 

 pounds and represents a portion of the accumulated crude rubber 

 held in the Far East by the war-time embargo on importations 

 of this material. 



TIRES TO BE MADE IN SIZES NEEDED. 

 The National .Automobile Chamber of Commerce, New York 

 City, states, under date of March 21, 1919, that pneumatic tires 

 of all sizes will be available for cars and rims already made or 

 to be made, and that the manufacturers will not discontinue any 

 particular size on a fixed date, as was at first anticipated. The 

 sizes of the rims and tires in actual use or to he built will govern 

 tire production. 



