488 



THE INDIA RUBBER WORLD 



IJULY 1, 1912, 



EXPERIMENTAL MILL FOR LABORATORY PUR- 

 POSES. 



SPECIFIC GRAVITY FROM A MANUFACTURER'S 

 STANDPOINT. 



jV/IORRIS A. PEARSON, formerly with the Parrel Foundry 

 ^"■^ and Machine Co., but now associated with the Turner, 

 Vaughn and Taylor Co., Cuyahoga Falls, Ohio, in the capacity 

 of rubber machinery designer, has recently designed an experi- 

 mental mill for laboratory purposes, in which will be found 

 several new and novel features. 



The rolls are of the usual size, 6 inches by 12 inches, made of 

 chilled iron, but fitted with a new type of steam connection. The 

 whole machine is placed on a cast-iron base cored out under- 

 neath to receive the motor and reducing gears. The arrange- 

 ment is such that both are easily accessible from the outside 

 while the design is compact and neat. The controller of the 

 motor is within easy reach of the operator, on the right-hand 

 side of the base. A new type of automatic guide is used in 

 order to get the greatest possible working space on the rolls. 

 All gears, both connecting and driving, have cut teeth and are 



-An Experimental Mill. 



fully protected by means of substantial gear guards. The mill 

 is complete in every way, with motor, gears, etc., ready for opera- 

 tion. It is of sufficient height to be set directly on the floor or 

 flush with it and requires only 2 feet 6 inches by 3 feet floor 

 space. 



This mill is also built to accommodate varying speeds, in order 

 to get different frictions. This will be true of experimental 

 calenders as well, which are designed along the same line as the 

 mill and to be used with it. Following an increased demand, a 

 laboratory washer has recently been designed which will make 

 the laboratory outfit complete. 



In addition to the above, Mr. Pearson has developed a full 

 line of mills, crackers, presses, etc., which are now ready for the 

 market. The company above noted has been well known to the 

 trade for the past IS years, through the popularity of their Tub 

 Washers and Reclaimed Water Separators. 



aUAYULE AND RAW KUBBER. 



Under No. 9018 the Bureau of Manufactures, Department of 

 Commerce and Labor, publishes an inqttiiry ' from an .'American 

 consul in a European country, who reports that a resident of his 

 district would like to communicate with persons in the LInited 

 States controlling guayule and raw-rubber interests in Mexico 

 or Central America. He desires connections for his trade with 

 European rubber industries, and estimates that he could dispose 

 of about $1,000,000 worth of this product to the local trade. 



The factory of the Hardman Tire and Rubber Co., at Belleville, 

 N. J., was seriously damaged by fire on June 1, the damage 

 being estimated at $150,000. The building was a modern brick 

 structure and replaced one also destroyed by fire about five years 

 ago. The factory had 200 employes. 



■"PHE following letter has been received from W. T. Bonner, 

 •'• Chemical Engineer. Trenton, New Jersey, in regard to the 

 article which appeared on page 424 of our June issue, by Dr. 

 Lothar E. Weber, on "The Significance of Gravity in Rubber 

 Manufacture." 

 To the Editor of The Indi.\ Rubber World : 



Dear Sir: — The writer has read with interest Dr. Weber's 

 article in the June edition of your paper on specific gravities of 

 rubber compositions, the main idea being to show the difference 

 between the actual and apparent gravities of rubber compounds. 



Dr. Weber's position is a correct one, and should receive the 

 unqualified approval of rubber manufacturers and chemists. 

 That the true gravity of a composition must be equal to the 

 gravities of its component parts is a fact, and under careful 

 conditions will be found to agree. 



However, Dr. Weber loses sight of a fact that is of great im- 

 portance to the rubber manufacturer. It is not the relative dif- 

 ference between the apparent and the real from a technical 

 standpoint, but rather the indicated gravity of the manufactured 

 article as it appears and is used in commerce, and vot of the 

 compound from which the article is made. The question of air 

 or vacuo occupying space in an article of rubber composition is 

 not of as much importance to the manufacturer as the specific 

 gravity of the article offered for sale. This is and should be to 

 him as definite a standard as atoms and molecules are to the 

 chemist. The manufacturer and his customer want to know the 

 weight per volume of the goods as offered for sale in their com- 

 mercial form. This should be as obvious to the chemist as it 

 is to the manufacturer, but at the same time it is equally im- 

 portant that both fully understand both sides of the question. 



For illustration take sheet packing — a square yard of a stated 

 thickness weighs so many pounds. In its commercial shape it 

 has a specific gravity to correspond to its commercial weight 

 and volume. To disintegrate a sample and exhaust the air 

 would give a true specific gravity of the compound, but a false 

 standard of the goods or article. Volume and weight by which 

 it is known and used would not agree. The fact that its true 

 weight per volume is heavier has no bearing upon the market 

 value, but it is a guide to the manufacturer, who by the differ- 

 ence can tell if his goods are "sponging" more than is good for 

 quality and service. 



Again — to carry the illustration still further — a manufacturer 

 receives an order for "sponge" stock, one of the requirements 

 may be that it not only float, but be capable of sustaining added 

 weight before equaling that of water. A compound with a 

 specific gravity as much as 1.35 properly sponged might fill the 

 requirements. Then by taking the specific gravity of the fin- 

 ished goods it is simple to estimate not only how much lighter 

 the product is than water, but how much added weight it will 

 sustain. 



By the foregoing it can be readily seen why a standard of 

 specific gravity is just as necessary to the article in commercial 

 form, as the actual or technical standard of the composition. 



Atomic and molecular weights are constant. Variations are 

 produced by additions and conditions. Even the rubber mole- 

 cule undergoes a slight permanent expansion when vulcanized, 

 and consequently is of lighter specific gravity than the uncured. 

 While the work of Dr. Weber is of great value to the manufac- 

 turer, as a guide to, intelligent work and exact conditions, yet 

 the manufacturer's standard of gravity, as applied to his finished 

 product, is to him of equal importance, and should be duly 

 recognized. W. T. Bonner. 



The accepted authority on South American rubber — "The Rub- 

 ber Country of the .\mazon," by Henry C. Pearson. 



