September 1, 1917.] 



THE INDIA RUBBER WORLD 



717 



The sulphide is convertible into pentoxide by ignition with a 

 weighed quantity of ferric oxide and ferric nitrate. 



CHEMICAL PATENTS. 



THE tXNITED STATES. 



Rubber Composition. A flexible rubber composition is made 

 by disintegrating vulcanized fibrous rubber vi^aste, mineral oil 

 or other oily matter which prevents too fine reduction of the 

 fibers. The disintegrated mass is mixed with sulphur and then 

 subjected to heat and pressure to revulcanize the rubber. [F. T. 

 Lahey, United States patent No. 1,233,252.] 



THE UNITED KINGDOM. 



Rubber Substitutes. A substitute for rubber is made from a 

 mixture of 24 parts gelatine or glue, 28 parts glycerol, glucose 

 or molasses, 10 parts water, 8 parts each rubber, zinc oxide, and 

 diatomaceous earth or whiting, S parts of sulphur, 3.5 parts 

 calcined magnesia, 2.5 parts litharge, 2 parts formaldehyde, 

 potassium bichromate, tannin or like toughening agent, and 1 

 part coloring matter. Calamine, Pontianak, asphaltum, coal tar 

 or pitch, or like softening agent may be employed as substitutes 

 for the gelatine or glycerol. The mixture is subsequently molded 

 and vulcanized. It may be used as an inner core for tires, for 

 electric insulation, tilings, roofing, etc. |J. Flint, British Patent 

 No. 105,912.] 



LABORATORY APPARATUS. 



MOISTURE TESTER. 



accompanying illustrations show an instrument in 



the 



T-HE 

 ■*■ form of a weighing scale for the determination of moisture 

 in dried material. The instrument was designed for use in connec- 

 tion with the kiln drying of lumlier, but is equally well adapted 

 for any material the moisture content of which is desired. The 

 instrument is simple and direct, reading requires no figuring. It 



is accurately made, graduated to the metric system and can be 

 used for ordinary weighing. To determine the amount of 

 mcirture in crude rubber, for example, a specimen is selected 



sr^MpniwaipivjB ^1 



and weiglied as received ; it is then completely dried by any 

 suitable means, preferably vacuum dried for speed, and weighed 

 again immediately. Following the chart line from first weight 



to percentage scale at final weight will give the moisture content. 

 The instrument has already found a place in the rubber indus- 

 try. It is known as a lumber tester because of its initial adap- 

 tation. [Grand Rapids \'eneer Works, Grand Rapids, Michigan.] 



WATER-STILL. 



Absolutely pure water in lab- 

 oratory practice is a necessity 

 that is too well known to warrant 

 comment. The obvious practica- 

 bility of the apparatus here il- 

 lustrated will make the following 

 brief description of interest. 



The Ralston water still is a 

 simple and convenient piece of 

 apparatus suited for laboratory 

 use. The still is made of copper 

 coated with pure block tin. It 

 can be operated by an ordinary 

 gas burner; size, 14^4 inches high 

 and 9J4 inches diameter with a 

 capacity of one quart per hour. 

 [John Trageser Steam Copper 

 Works, New York City.] 



THE NEED OF STANDARDIZED TEST PIECES. 



Standardization is now the order of the day and is particular- 

 ly important in testing materials of every sort, if the results are 

 to he so correlated as to benefit the entire industry concerned. 

 In the manufacture of rubber goods the tensile strength of the 



Fig. 2 



vulcanized product is commonly determined by stretch or break- 

 ing tests, yet the conditions under which these tests are made 

 vary so greatly that exact comparison is virtually impossible 

 and their full value is consequently not obtained. European 

 testing machines as a rule call for rings, while the American 

 specify strips, and unfortunately no uniformity exists with re- 

 spect to the cross section, length and shape of the latter. Many 

 factories would gladly revise their methods by the adoption of 

 a standard practice were such available, and rubber technicians 

 can do the industry a service in threshing out this matter and 

 making recommendations. 



It is the custom of the Bureau of Standards and several manu- 

 facturers of rubber goods to cut V4-inch test pieces from vul- 

 canized sheet 3/32 inches thick, the specimen having enlarged 

 ends shaped as indicated in Fig. 1, and the elongation in the 

 tension machines being taken between the 2-inch marks shown. 

 Specimens of similar shape 6% inches long and yi inch wide 

 lietween the 2-inch marks, as shown in Fig. 2, are also in com- 

 mon use by certain manufacturers. Some firms die their test 

 pieces out of J^-inch sheet, some prepare them by molding 

 rather than cutting, and. generally speaking, there is an un- 

 fortunate lack of uniformity in shape and dimensions. The 

 length of the straight part varies and the same may be said of 

 the curves and other sections of the pieces, many factories hav- 

 ing adopted their own patterns. 



It is already conceded that strip tests do not involve certain 



