Alclst I, 1930.1 



THE INDIA RUBBER WORLD 



725 



simple duck and duck supplemented by braiding. From the data 

 gathered, there are two conclusions concerning these relative 

 values which are obvious and irrefutable : 



1. Steam hose made with seamless tube (in practice by the 

 tube-machine method) is superior in endurance under steam 

 pressure to hose with tube made up of successive plies of a 

 sheeted stock, sometimes known as a calendered tube. The hose 

 with plied tube was found to fail by the splitting and separation 

 of trie seam necessarily formed at the surface of the tube in its 

 construction. 



2 Steam hose with its fabric constructed of successive plies of 

 frictioned duck is superior in endurance to, and the practical 

 equal in expansion and contract of hose made of a fewer num- 

 ber of plies of duck supplemented by plies of braiding. 



It is most advantageous to user and to manufacturer alike to 

 construct steam hose with a seamless tube and for its fabric ele- 

 ment a snfticieiit number of plies of duck only. 



SPECIFICATIONS FOR RUBBER JAR RINGS.' 

 GENERAL. 



'T'his specification covers the requirements for rubber jar 

 •*• rings to be used for the canning of vegetables, soups, meats, 

 fruits, etc. 



TESTS. 



TECHNICAL. 



<a) Measurements .Minimum. Ma-ximuni. 



Internal diameter 2.20 2.32 



Width of Hange 28 .34 



Thickness 078 .09 



Tensile strength 350 lbs. per square inch 



Vltimale elongation 150 per cent. 



Tensile strength and elongation determined in machine jaws 

 separating at rate of 20 inches per minute. 



PRACTICAL. 



A rubber ring may meet the tests as to thickness, width of 

 flange, and inside diameter and still be unfit for use with the 

 cold-pack method, consequently the following practical tests 

 should be applied. 



Boiling Water Test. — Select three jars, one having a very 

 even top, well fitted ; one. a top somewhat warped ; and one. a 

 very poorly fitting top. Fill the jars three-quarters full with 

 boiling water, place the rubber rings in position, partially seal 

 the jars, place them in the water bath under canning conditions, 

 and boil for four hours. At the close of the period, remove the 

 jars from the bath, tighten down the clamps, permit the jars to 

 stand over night and then open. The rubber rings when removed 

 and examined carefully should show the indentation of the top 

 on the ring clearly and distinctly. There should be no signs of 

 movement of the rubber ring, and the ring should still have much 

 of its strength and elasticity and should show no signs of cracks 

 or cuts resulting from pressure on the jar due to the vacuum 

 within. 



Ste.-\m Pressure TEST.^S'elect, fill, and seal the jars as for 

 the boiling water test. Place the jars in a steam-pressure canner 

 and sterilize for two hours under 10 pounds steam. Al the close 

 of the period permit the pressure to drop naturally and remove 

 the jars in the same manner that canned fruit or vegetables would 

 be removed. Press the clamps down, allow the jars to stand over 

 night, and then open. The conditions found should be the same 

 as specified under the boiling water test. 



Oven, or Dry He.at Test. — Many rubber rings are satisfac- 

 tory when first manufactured, but upon aging become unfit for 

 use. In order to apply this aging test, tie three new rubber rings 

 to a string and suspend them in the oven at 300 degrees F., dry 

 heat, for 1 hour. At the end of that time the rubber may show 

 small cracks on the surface when bent back upon itself, but 

 should not crack through. 



Tests Made by the Housewife.— The following tests may be 



^Submitted to Department of Agriculture by the Department of Com- 

 merce. Bureau of Standards, Washington. D. C. 



carried out by the housewife to determine the quality of jar 

 rings ■. 



(a) Tensile strength. 



Fill a light-weight pail with one gallon and seven pints of 

 water (total weight approximately 17 pounds). Place the jar 

 ring around an empty spool ; pass a wire through the center of 

 the spool and fasten to handle of the pail ; then pass the round 

 handle of a wooden spoon or broom through the ring and lift. 

 The ring should not break. 



(b) Elongation. 



Cut a six-inch piece out of a ring; take hold of the ends so 

 that there are four inches between the fingers ; stretch the piece 

 along a ruler until the fingers are ten inches apart. • The sample 

 should not break. 



(c) Twelve rings stacked should measure approximately one 

 inch. 



(d) Marking. 



Packages of rings should be plainly labeled with the year of 

 the canning season during which they are to be used. They 

 should pass these specifications throughout the year to meet the 

 approval of the Department of -Agriculture. Rings left over may 

 either be sold the following year in the original containers, or, 

 if they will still pass specifications, may be repacked or relabeled. 

 The manufacturer or dealer doing this shall assume all responsi- 

 bilitv in redating the cartons. 



WAR DEPARTMENT SPECIFICATIONS FOR RUB- 

 BER COMBS. 



NO. 336.1-1, JUNE 6, 1919. 

 /^ ENF.RAL. — The comb shall be made of highest quality black 

 ^-* bard rubber, have an oval hack, mat finish, and the entire 

 comb rubbed to a very smooth finish so that there shall be no 

 sharp edges on or between the teeth. 



Construction. — See drawings, which are a part hereof. 



Length, 7 inches; 10 teeth to the inch; 7/^-inch from the point 

 of the teeth to the tip of the back. The teeth shall be 17/32-inch 



Construction of Go\'ernment Rubber Comb. 

 long and the distance from the base of the teeth to the tip of 

 the back shall be 1 1/32-inch. Thickness of comb through heavi- 

 est part of the back shall be 13/64-inch and narrowest part, about 

 the middle of the teeth, shall be 1/16-inch through; at the heavi- 

 est part of the teeth, near the end, shall be ^i-inch. Thickness 

 of the teetli through the comb shall be 5/64-inch. 

 Weight.— Shall be not less than 9 nor more than 10 grams. 



VIROL. 



An organic accelerator described as being powerful, but not 

 expensive, is the latest material in that line oflered to rubber 

 manufacturers. It is safe and can be used in any stock. Besides 

 hastening the cure it is said both to toughen the stock and im- 

 prove its aging quality. 



