THE RUBBER INDUSTRY — GIBBONS 197 



thumb basis. The work was conducted by men who had grown up 

 with the business and was carried out with the utmost secrecy. 



As would be expected under such conditions, a number of fallacies 

 developed, which flourished to a remarkable degree. For example, 

 as late as 1892 there were definite statements in rubber handbooks 

 that vulcanization occurs only between the melting point of sulfur 

 and a temperature of 160° C. These statements were repeated in 

 later editions published after the turn of the century. While these 

 temperatures, at that time at least, may have defined the limits 

 actually used by manufacturers, the statement itself is entirely 

 erroneous and resulted from a failure to comprehend one of the four 

 essentials mentioned by Geer— that is, the importance of time. 

 Although the quantitative relation between reaction rates and tem- 

 perature was known as early as 1889, these findings were not applied 

 generally in the rubber industry until many years later. 



One of the most important tasks of the rubber manufacturer during 

 this period and even later was the choice of the proper types of crude 

 rubber. Handbooks on rubber devoted much space to a discussion 

 of various botanical species which produce rubber and to the types 

 of rubber obtained from them. Crude rubber produced in those 

 days was prepared by the natives of South and Central America, 

 Africa, and the East Indies. Primitive methods were used. The 

 best rubber, known as fine Para, was obtained from Brazil. This 

 was produced by dipping a stick in latex and coagulating the latex 

 by holding the stick over a fire of urucuri nuts. The smoke of this 

 fire contained certain acidic materials, such as acetic acid and phenols, 

 which coagulated the latex. The operation of dipping and drying 

 was repeated until a substantial mass, called a "biscuit," was obtained. 

 For many years this product was a standard of quality. It owed 

 its excellence both to the particular tree, Hevea, hrasiliensis, from 

 which the latex was obtained, and also to the method of preparation ; 

 although crude from the standpoint of operating eflBciency, this 

 method was more satisfactory than those used elsewhere. In other 

 localities, for example, latex was allowed to dry on the surface of 

 the tree, and the film of rubber, together with much adhering 

 foreign matter, was peeled off. In still other cases natives smeared 

 the rubber on their bodies and allowed it to dry. 



The rubbers prepared by these diverse methods differed greatly in 

 properties from one type to another. Also, there was great varia- 

 tion in shipments of supposedly the same grade of raw material. 

 The prices of these different grades varied both on absolute and 

 relative bases, and a vast amount of experience and skill was required 

 in order to make the best use, from the standpoint of both cost and 

 quality, of available raw materials. 



