February 1, 1912/ 



THE INDIA RUBBER WORLD 



211 



Coagulating by Carbonic Acid. 



[Our good friend. Wiliielm Pahl, of Donmuiid, Germany, 

 sends us the following regarding the use of his new re-agent 

 for the coagulation of the latex of the Hcvea Brasilicnsis. It 

 will be noted that he calls plantation Para rubber Hez'ca rubber, 

 and the wild product Para rubber.] 



T TEI'EA (cultivated) rubber has gained the victory over Para 

 J, X rubber. The mystery, which lias up to the present day 

 been hanging over Para rubber, has been disclosed. The 

 efficacious agent in coagulating Para rubber has been discovered. 

 Finally, it has been possible to replace the manual Para coagula- 

 tion by an ideal m'echanical coagulation. 



The science of chemistry has obtained the victory and torn 

 the veil which had been .hanging over Para rubber. The whole 

 rubber world and all the Hevca plantations have thereby gained 

 an enormous advantage. It has been discovered that carbonic 

 acid is the agent which ensures to the cultivated rubber the 

 victory over all procedures heretofore employed. 



The advantage which Hez'ea rubber now possesses, compared 

 with Para rubber, is best discerned by examining both methods 

 thoroughly and by comparing their advantages. The new rub- 

 ber combines the advantages of Hevea rubber and those of 

 Para rubber and shall consequently receive the name of "Hevca- 

 Para." 



Science — and, first of all. cliemistry — has been endeavoring for 

 decades to discover the agent which during the process of smok- 

 ing gives to the Para rubber obtained from the Hevea latex 

 its strength, elasticity and superior quality. The most distin- 

 guished men of all civilized nations participated in these re 

 searches. During 1910 Dr. Frank and Dr. Marckwald, of the 

 Chemical Laboratory, of Dr. Henriques Succ, Berlin, de- 

 voted themselves to this question. To this end they procured a 

 few nuts of the Urukuti palm tree used for smoking Para rubber, 

 submitting their smoke to a close chemical examination. They 

 discovered all sorts of substances, but did not find the most 

 vital agent. We propose to submit hereafter the whole pro- 

 cedure of smoking to an exhaustive examination. 



The rubber late.x having been collected in the wild forest by 

 the scringueiros. should now undergo the process of tlie 

 extraction of the valuable Para rubber from the latex. With 

 this end in view, the seriiigueiro gathers dry wood, kindles a fire 

 and then puts some nuts of the Urukuri palm tree upon it, thus 

 obtaining a very dense smoke. Now, it is not difficult to reply 

 to the question, why the seriiigueiro employs the Urukuri nuts. 

 These nuts are an excellent material for maintaining a good fire, 

 because (1) they have an exceptionally hard shell, woodlike, 

 thick and dry, and (2) they have rather oleaginous kernels. 



It is difficult to find in a tropical wild forest dry wood, owing 

 to the high degree of moisture in the air, and the wood having 

 grown quickly and being soft, decomposes rapidly in many cases, 

 which makes it a poor combustible. The palm tree nuts, how- 

 ever, give a perfect fire. The oil of the kernels serves to feed 

 the fire, and it is a common experience that by burning dry and 

 hard wood the best products of combustion are obtained. As 

 is known, every hydrocarbon burns to carbonic acid and water. 

 The smoke is more or less a secondary symptom and serves 

 during the smoking process chiefly as a carrier of the carbonic 

 acid which is drawn upward by the smoke; otherwise the car- 

 bonic acid would remain below, being heavier than air. The 

 smoke contains also by-substances valuable for preservation, 

 such as creosote, but this is less important than that in the pres- 

 ent case it is the carrier of the carbonic acid. 



Now it must not be lost sight of that the object of the smoke 

 is to coagulate the latex and not. as has often been done, to 

 smoke rubber, the coagulation of which has already been 



achieved. It must further be taken into consideration that the 

 seriiigueiro pours the latex during the smoking procedure only 

 while it is fluid over the stick, and to this end always makes 

 fluid again such rubber as has already coagulated previous to 

 the smoking procedure. It is obvious tliat this liquid latex must 

 coagulate instantly, as otherwise it would again flow off. All 

 trials hitherto made with the reagents found in the smoke never 

 had the result of coagulating the latex instantly. It is solely the 

 carbonic acid which causes the instantaneous coaonlation. 



WiLHEi.M P.\hl's R.\pin Co.\GULATOR KCR Ilefca Latex by 

 Carbonic Acid. 



The valuable properties which distinguish the Para rubber pro- 

 duced by the smoking procedure are : 

 L Its elasticity ("Nerve"). 



2. That It keeps as carbonates the valuable metallic salts con- 

 tamed m the latex, and which are so very important for the 

 consequent vulcanization. 



3. Ihat It or the serum contained in the rubber reacts alkaline. 



4. Ihat It has no tendency to turn moldy. 



5. 1 hat it never rots. 



6. That it never oxidizes. 



7. That it contains rubber molecules of an extraordinarily high 

 polymerization. 



8. That, consequently, it vulcanizes extremely well. 

 9 The very great viscositv of the solution and the vielding 



quality resulting therefrom. 



The Hevea rubber hitherto produced by the plantation pos- 

 sessed none of these valuable qualities. This is most astonishing, 

 in view of the fact that the tree from which the latex is collected 

 IS the same as the one from which Para rubber is obtained i. e., 

 "Hevea Brasilicnsis." 



This "Hevea" has been exported from Brazil and transplanted 

 under the same tropical condition and the same soil-qualities. 



