510 



THE INDIA RUBBER WORLD 



[July 1, 1913. 



the beneficial results obtained therefrom, will be destroyed, or 

 at least impaired, by an increased quantity of rubber per charge 

 and an increased temperature of lieating steam, because the 

 heating surface itself remains the same; and it is this factor 

 which remains constant — that upsets the results sought to be 

 obtained by the violation of well known, but not considered, 

 natural laws. 



E.xperience has taught us to balance the necessary healing 

 surface, to transmit a certain temperature to a certain layer 

 of material to be dried ; and it is quite erroneous to argue — 

 though a common mistake — that the same beneficial results may 

 be obtained from a larger quantity of material, by simply in- 

 ci easing the thickness of the drying material and increasing 

 temperature, in the belief that the above mentioned factor 

 would increase proportionately. This, however, is not the case, 

 as I will more fully point out. 



If one takes the conductivity of rubber alone into consider- 

 ation, and the gradual but decreasing evaporation of the water 

 contained therein, it can very easily be understood that by 

 altering some of the factors the physical laws, on which our 

 calculations are based, will be violated without any such in- 

 tention, and the penalty will be an unsatisfactorily dried rubber; 

 — the cause of which is naturally placed at the wrong door. The 

 fault is not in the apparatus, but in the method of its opera- 

 tion. The same remarks refer to the auxiliaries of an apparatus 

 for drying ruiilier. These auxiliaries consist of a condenser 

 and vacuum pump which are both calculated to correspond with 

 the capacity of the vacuum apparatus they are intended to serve. 



To illustrate what I mean : A vacuum dryer of a certain 

 drying capacity and calculated for a certain purpose is intended 

 to evaporate a certain quantity of water in a given time, and 

 of course, which is essential, at as high a vacuum as is possible 

 under practical working conditions. All this is, to a great ex- 

 tent, based on practical experience with the very material our 

 apparatus is used for. If, however, the condenser, instead of 

 handling the quantity of vapor for which its cooling capacity 

 is calculated, is burdened with ever so much larger a quantity, 

 the result must be detrimental in two ways ; it not only re-acts 

 on the dryer and the product it is supposed to turn out regard- 

 less of the time, but also re-acts on the working of the pump. 



As regards the vacuum dryer, it is essential to have its inner 

 space continuously freed from the vapor arising from the drying 

 material in order that no inner pressure may be created in 

 such apparatus to lower the vacuum. This can only be done 

 by having the arising vapors taken care of in their entirety 

 during their passage through the condenser, the capacity of 

 which cannot be changed at will. 



If more vapors are created than the condenser is intended 

 for, such vapors will partly remain in the dryer, and create 

 inner pressure. The inner pressure thus created consequently 

 reduces the vacuum in the dryer and as a consequence the 

 boiling point of the water contained in the rubber is increased, 

 and the 'rubber will be heated up to a temperature never in- 

 tended, with detrimental effects to its quality. The overcharg- 

 ing, as I said before, afifects the efficiency of the pump and pre- 

 vents it from creating the desired high vacuum. The reason for 

 this is that a dry vacuum pump — the only type we have in 

 mind in this discussion — is intended, dimensioned and con- 

 structed for pumping air and not vapor, particularly as the 

 latter expands so enormously under vacuum. If the pump 

 were intended to exhaust rarified or expanded vapor in addition 

 to rarified or expanded air, its dimensions would be so enormous 

 as to make its use practically impossible. 



If, therefore, the dry vacuum pump has to exhaust vapors 

 which have passed uncondensed through the over-taxed con- 

 denser, a burden is placed on the pump for which it was never 

 intended ; its work becomes inefficient and most naturally im- 

 pairs the vacuum and efficiency of the whole installation for 

 drying purposes. 



I have but briefly outlined some of the factors which have 

 to be taken into most serious consideration in designing and con- 

 structing a proper vacuum dryer and its auxiliaries. I submit 

 that it is wrong and unfair to subject apparatus to work for 

 which it is not intended, and to charge the inefiicient or insuf- 

 ficient results of such an abused vacuum drying installation at 

 the door of the principles of drying under vacuum, — viz. : rapid 

 and tliorough drying at a low temperature. 



Owing to the remoteness of plantations and the difficulties 

 surrounding the transportation of machinery and appliances for 

 removing impurities, only primitive and unscientific methods of 

 preparation could be adopted. The use of the vacuum drying 

 process was, in consequence, first introduced and adopted by 

 the manufacturers to dry washed rubber. In recent years, 

 however, much greater thought and study have been given to 

 the preparation of the crude rubber on the plantation. 

 Especially is this noticeable in the quality of the rubber reaching 

 the market from the Malaysian Straits Settlements, and Congo 

 Plantations, where vacuum drying apparatus has been installed 

 and is found to be of great value. This is somewhat reflected 

 in the moisture content of plantation rubber that reaches the 

 market with a low percentage of moisture, as compared with 

 IS per cent, or more, in Upriver Para. There can be little 

 doubt that in the future the planter will understand that the 

 price is based upon actual rubber and he will serve his purpose 

 best by adopting the very latest method for the treatment of 

 the raw material so as to free it from impurities and to reduce 

 its moisture to a minimum percentage. Pure and dry rubber 

 does not suffer in transit through fermentation caused by vege- 

 table impurities and moisture. This improved quality of the 

 raw material will not cause the discontinuance of the drying 

 process in the factory. It will, however, tend to restrict the 

 operation for the treatment of such rubber to remove the final 

 percentage of moisture only, and thus simplify factory operation. 



The highly satisfactory results to the manufacturer and 

 planter from the scientific and research work in the laboratory 

 have contributed materially to the advancement of the industry, 

 and its further progress can and will be accomplished by a 

 closer and more intimate relationship between the manufacturer 

 or producer and the appliance manufacturer. We are, after all, 

 in our several activities dependent one upon the other, and why 

 not recognize our mutual obligations to co-operate, that a 

 maximum productiveness by newer and better methods may be 

 secured? 



NORTH BRAZILIAN SYNDICATE. 



.\dvices have been received from Para, of the establishment 

 in that city of the North Brazilian Syndicate, Ltd., for the pur- 

 pose of representing firms, companies or syndicates of capitalists, 

 both Brazilian and domiciled in other countries. Its object will 

 be the development of the resources of Brazil while it will have 

 agents in the principal countries of Europe and .\merica. 



STATISTICAL POSITION OF PARA RUBBER. 



Statistics quoted by the "Financier" of London show that the 

 visible supply of Para and Peruvian rubber was reduced from 

 6,550 tons on May 1 to 6,350 tons on June 1. At the same time 

 last year the visible supply was 6,880 tons. There is consequently 

 a falling off of 530 tons, although the South .American output 

 for the season to date has increased by 3.000 tons. From these 

 figures it is deduced that consumption has increased 3,530 tons 

 within the vear. 



.\ new Canadian company known as the Sterling Rubber Co., 

 Ltd., is now manufacturing a line of drug sundries at Guelph, 

 Canada. F. S. Friedman is the secretary and treasurer of the 

 company. 



