520 



THE INDIA RUBBER WORLD 



[June 1, 1917. 



YOUNG'S GRAVITOMETER FOE LIOUIDS. 



Voung"s Gravitometer for liquids is a new instrument de- 

 signed for accurate and rapid determination of the specific 

 gravities of liquids. The regular range of tlic instrument is 0.60() 

 to 2.000. From 0.600 to 0.700 no weight is required, but a dif- 

 ferent weight is furnished for each 0.100 of gravity. For the 

 range 0.600 to 2.000 there arc required 14 weights. The second 

 and third decimal places are shown on the scale. 



In making a determination the plummet is immersed in the 



liquid to be tested. If the pumtcr swings between and 100 

 on the scale, the specific gravity is 0.600 plus the reading of the 

 pointer on the scale. If the pointer swings beyond the 100 mark, 

 it is necessary to place on the hanger of the plummet the one 

 weight which will bring the pointer between and 100. This 

 weight gives the first decimal place, and the remaining two places 

 are read at once from the position of the pointer on the scale. 

 Higher ranges and special weights are provided for specific quan- 

 tities above 2. [Eimer & Amend, 211 Third avenue, New York 

 Cit>-.] 



RUBBER HOSE FOR USE ON AIRPLANES. 



A PAPER on the construction and tests of gasoline and other 

 ^^ hose for use on airplanes may be found in "The Journal 

 of Industrial and Engineering Chemistry' (April, 1917), by 

 Percy A. Houseman, formerly chief examiner. Aeronautical 

 Inspection Department Laboratories, London, England. Previous 

 to initiating a system of inspection in England the quality of 

 rubber used for gasoline on airplanes was quite unsatisfactory. 

 The following specifications and tests for gasoline hose were 

 found suitable for controlling the quality. 



Flexibility. The hose is bent to a circle having a diameter D 

 which varies according to the inside diameter of the hose d as 

 follows: Up to one-half inch, 8d.- nine-sixteenths to one inch, 

 10 d; one and one-sixteenth to one and one-half inch, 12 d; over 

 one and one-half inch, 14 d. The diameter of the tube so bent 

 should not change at any point by more than ten per cent from 

 its original diameter. 



Immersion in Gasoline. A three-inch sample of the hose is 

 boiled in gasoline for one hour under a reflu.x condenser, fol- 

 lowed by 24 hours' standing in gasoline at room temperature. 

 The approximate increase in weight and volume of the sample 

 is recorded. The decrease in bore at narrowest part should not 

 exceed 25 per cent. 



The adhesion of rubber to canvas must remain good, and the 

 "nerve" of the rubber must not be seriously impaired when 

 examined immediately after the gasoline treatment 



Permeability to Gasoline. A sample of the hose 14 inches- 

 long is held vertically and plugged with a glass stopper at the 

 bottom. A glass tube is fitted in the top, and is filled with gaso- 

 line to a head of 12 inches above the top of the hose sample. 

 The length of the hose exposed to the action of the gasoline ii 

 12 inches. The level of the gasoline in the glass tube should not 

 be allowed to fall more than three inches, additions of gasoline 

 from a known volume being made as necessary. The amount of 

 gasoline which permeates through the walls of the hose is noted 

 during the first and second days, as a guide to the behavior of 

 the sample. During the third 24 hours, by which time the rate 

 of permeation has become approximately, constant, the gasoline 

 passing through the walls should not exceed 100 cc. per square 

 foot of original internal surface. 



Dry Heat. A piece of the tube is heated for two hours at 

 132 degrees C. The rubber should remain clastic and show no 

 signs of stickiness or brittleness, nor should any surface cracks 

 show on stretching the sample. 



Acetone Extr.-\ct. Free sulphur, mineral sulphides and sulphur 

 of vulcanization are determined. The free sulphur should not 

 exceed one per cent. 



Ash. The amount and composition of the ash are determined. 



Quality of Canvas. This is left to the judgment of the 

 manufacturer. 



Rubber hose for use with gasoline on French airplanes is 

 required to contain 45 per cent mineral matter with a margin 

 of 5 per cent ; 50 per cent rubber with the same margin, and 

 to have a density of 1.6 (0.1). 



The preferred construction of gasoline hose consists in pre- 

 paring the fabric with a layer of rubber on one side double the 

 thickness of the fabric, so that in cross section of the finished 

 hose the fabric is embedded as a spiral in the rubber. Such a 

 hose shows improved flexibility, better behavior under the im- 

 mersion test and "less tendency to separation between rubber 

 and fabric, and a smaller constriction of the bore. Two plies of 

 fabric are used in five-eighths-inch hose ; three plies between 

 five-eighths and one and one-quarter-inch hose, and four plies 

 for larger sizes. The larger sizes are used for oil and water. 



TURPENTINE AND ROSIN IN RUBBER MANU- 

 FACTURE. 



A LTHOLTGH classed as "naval stores," turpentine and rosin 

 ^* are used to-day for a wide variety of purposes having noth- 

 ing whatever to do with shipping. A list recently prepared by 

 the Bureau of Chemistry, U. S. Department of Agriculture, gives 

 44 industrial uses of turpentine, 67 uses of rosin, 20 uses of 

 rosin oil and rosin oil products, and 13 uses of pitch. Those ap- 

 plicable to rubber manufacture follow : 



TfRPENTIXE. 



Solvent for gums in varnishes. 



Ingredient of waterproof cements for leather, rubber, glass, 

 metals, etc. 



Solvent for waterproofing compositions. 



Raw material for producing isoprene used in making sjm- 

 thetic rubber. 



In rubber substitutes. 



Solvent for rubber, caoutchouc and similar substances. 

 RO.SIN. 



Rubber substitutes. 



Adulteration of ceresin and paraffin waxes. 



Adulteration of shellac and certain resins. 



In waterproofing compositions for paper, cardboard and fabrics. 



In the manufacture of condensation products. 



ROSIN* OTL .^ND ROSIN OU. PRODUCTS. 



Rubber substitutes. 



PITCH. 

 Rubber compounding. 



To which might be added the use of rosin oil, pitch and rosin 

 in frictions, tapes, etc. 



Of value for daily reference in every rubber office — "The 

 Polyglot Rubber Trade Directory, 1916." 



