THE INDIA RUBBER WORLD 



H- Length ^ 

 Fig. I.— Illustration of Strip Test. 



Fig. Z.^IUustration of Grab Test 



(rf) The total warp and filling specimens shall be grouped each 

 by themselves, forming two batches. The aggregate dry weight 

 of the warp and filling specimens shall thus be obtained and the 

 moisture regain at the time of the test determined. 



{e) The following formula shall then be applied, based upon 

 the assumption that the standard moisture regain of manufactured 

 cotton is 6.5 per cent of the dry weight, that the actual percentage 

 regain is between the limits of 3 and 6.5 per cent of the dry 

 weight, and that for 1 per cent of moisture regain there is an 

 increase of 6 per cent in the tensile strength of the fabric. 



Tensile strength corrected (Tensile strength from machine reading) X 139 



to standard moisture regain 100 



X Actual Percentage Regain 



Example. — A specimen of fabric broki 

 tensile strength of 294 pounds as read from the machi 

 before and after drying the specimen was found to con 

 regain equal to 3 per cent of the bone-dry weight. The 

 corrected to a common basis of 6.5 per cent moisture regain 



294 : 



139 



By weighing 



ile strength 

 Id therefore 



346 pounds. 



STANDARD SIZES FOR CHECKS AND INVOICES. 



The Standardization Committee of the Purchasing .\gents' 

 -Association has evolved several aids for both seller and pur- 

 chasing agent or accounting officer. 



The committee considered as the standard check size, iVz by 

 S'/i inches, which has already been adopted by over 100,000 

 business houses, with Federal Reserve Board Approval. The 

 fact that most of these business concerns use a voucher check 

 just double the size of the standardized check, and file the 

 original invoice with a copy of the voucher, led to the selection 

 of 854 by 7 inches as the master size for the standardized invoice. 



On account of filing devices, any other sizes selected should 

 be such that they readily fold to 8^ by 7 inches, so SYz by 7, 

 SYz by 11, and ^Y: by 14 inches were the sizes preferred. It was 

 decided to allow the printing to run either way of the sheet, to 

 suit the sales organization. 



G. H. Money of the Federal Rubber Co., Cudahy, Wisconsin, 

 is one of the members of the Standardization Committee. 



DETERMINATION OF SULPHUR IN VULCANIZED RUBBER.^ 



P. Dekkcr has subjected to accurate investigation some 

 methods for determining free sulphur (in the acetone extract) 

 and of the combined (and total) sulphur, described in recent 



> "Communications of the N'etherland Government Institute for Advising 

 the Rubber Trade and the Rubber Industry," Delft, Holland. 



'Should insoluble sulphates remain behind on the filter, (hey are fused 

 with potassium-sodium-carbonate. 



literature. As a result of this study the following method has 

 been adopted by the Nctherland Government Institute at Delft 

 fur the determination of combined and total sulphur: 



One gram of the sample is gently heated in an Erlemeyer 

 fla.sk of 200 to 300 cc. with 40 cc. nitric acid (specific gravity 

 1.4) and 6 grams of magnesium nitrate free of water till the 

 liquid begins to foam, when the flame is removed. In case the 

 foaming is so strong that there is danger of overflowing, the 

 flask is cooled for a moment, ."^s soon as the foaming has ceased 

 it is gently boiled for one hour, then one to two drops of bro- 

 mine are added and boiling continued for one-half hour. The 

 liquid is then placed in a porcelain dish and evaporated nearly 

 to dryness, 10 cc. strong hydrochloric acid is added and further 

 evaporated till the residue becomes solid on removing the still 

 liquid mass from the water bath. The residue is then dissolved 

 in warm water, filtered, and sulphuric acid determined in the 

 usual manner.^ 



nple and direct 

 libber compound 



cthod of determining the cubic foot cost 

 s here reproduced. The chart was de- 



LAY A STRAIGHT-EDGE ON THE CHART TO 

 INTERSECT THE "SPECIFIC GRAVITy'aND 

 "price PER pound" SCALES AT TH£ PROPER 

 POINTS; READ THE CUBIC rOOT COST AT 

 THE INTERSECTION OF THAT SCALE 



CopyniOHT -AA SOMERVILLE ^m 



signed and copyrighted by Dr. .\. A. Somerville of the R. T. 

 Vanderbilt Co. for free distribution to rubber chemists and 

 compound men. It is of the well known "alignment"' type, con- 

 sisting of three mathcinatical scales covering a complete range 

 of practical compounding possibilities, namely, a specific gravity 

 scale from 1.00 to 2.00; a cost per pound scale from 5 to 50 

 cents, and a cubic foot scale covering all resultant combinations: 

 of the other two scales. 



Buy \V.\r S.aving Stamps — Build for American prosperitv 

 and your own success. 



