3°3 



expenses may be shared, and the more intelligent of the coolies on 

 the interested estates duly instructed in their work. This policy 

 was adopted by the Belgian Government on the higher reaches of 

 the Congo, and here these Amazon experts succeeded in extract- 

 ing from the African indigenous Hevea (sic) by careful extraction 

 and curing, a rubber called Ruki (after an adjacent village), which 

 is called actually better than Para itself, with a lower percentage 

 of rubber resins, and lower percentage of foreign matter, thus 

 offering a higher tensile strain. Naturally, this secured a better 

 price in the European markets than Para itself, and is in great 

 demand. This care, of course, is the ambition and goal of every 

 grower. The same course was adopted by the Liberian Govern- 

 ment in reference to the rubber trees near Monrovia, and at first it 

 exported some excellent samples, truly capable of improvement ; 

 but, upon the departure of the rubber experts, the native Krew boys, 

 either from want of care, or pure and simple laziness, abandoned 

 due care, and consequently, Liberian rubbers are to-day more or 

 less under a cloud in the market. The first and great care neces- 

 sary, and even imperative, is absolute cleanliness in the extraction 

 of the milk : the bark of the tree to be tapped should be carefully 

 cleansed, the knife to be used carefully cleaned, the V shaped cuts 

 and perpendicular central channel all should be perfectly clean 

 before the milk is allowed to run, the collecting cups and milk can 

 also need attention in this respect. The necessity of this seeming- 

 ly excessive care is clear, in view of the fact that often-times the 

 smallest particle of grit present may cause endless trouble to the 

 manufacturer, depreciating or destroying the quality of his work. 

 The manufacturer, to start with, must have his raw rubber perfectly 

 pure. To this end the imported gum is first of all heated, then torn 

 and rolled between friction rollers, under a stream of water to re- 

 move the foreign matter that may have been introduced through 

 the carelessness of the collector. This constant tearing and rolling 

 necessarily reduces the original strength of the gum. The greater 

 the proportion of foreign matter to be removed, the greater the 

 percentage of the loss of tenacity of the material. For instance 

 the removal from firm Para rubber of even 5 per cent, of impurity, 

 will oftentimes occasion the loss of 20 per cent, in strength and 

 vitality of the resulting product. It is oftentimes the one little 

 grain of sand which does the greatest mischief. As an illustration, 

 may we take the case of a cycle tyre inner tube. If a little grain 

 of sand is allowed to get into the milk in collecting, these little 

 particles are the most difficult to remove mechanically by washing, 

 hence the grain of sand eventually finds itself embedded in the 

 thin skin of the cycle tube. Upon inflation the grain of sand 

 pops out, leaving a point of least resistance, subsequent in- 

 flations tend to form a bubble, in a few days the bubble bursts ; 

 the sand has done its work, and the tube requires mending. Manu- 

 facturers know this to their cost, and are therefore willing to 

 pay highly for a perfectly clean reliable rubber, and look with sus- 

 picion on either "grilty rubber" or u barky rubber ". In the lat- 

 ter case the embedded fragments of bark or vegetable matter being 



