84 



on the tree and cups, coagulated by being allowed to stand, etc., 20 to 

 40 per cent. From these data we may safely conclude that the smok- 

 ing method of preparation is by far the best in use at present, a view 

 which will be further strengthened when we compare the losses on 

 making up other sorts of rubber. 



Ceara Rubber is the product of Manihot Glaziovii, a tree growing 

 chiefly in the highlands of the State of Ceara, Brazil. Cross is respon- 

 sible for most of the descriptions of the locality in which it grows, but 

 as his experience of it appears to have been limited to Pacatuba, in 

 which place its habitat is far from typical, they are not very accurate. 

 He records it as growing at an elevation of 200 feet above sea level, 

 among granite boulders, in a country whose dryness was indicated by 

 the fact that " ferns, weeds, grasses and mosses " were absent. True, 

 it does grow among granite boulders, in the scantiest of soil in such 

 localities, but it is more at home in the mountains, up to a height of 

 3,500 feet, and even more, where there is an abundant rainfall. These 

 facts will serve to show the wide range of conditions the tree will put 

 up with, and were it not for the smallness of its yield (1 to 3 lbs per 

 annum) it would be invaluable for introducing into many of our 

 colonies. Coagulation is brought about either by smoking, as on the 

 Amazons, or by simply allowing the latex to dry on the tree trunks or 

 soil. 



The latter methods are objectionable, as the rubber invariably con- 

 tains pieces of bark or grit. 



It may also be prepared by churning the latex, and pressing the 

 resulting clots. The method is not to be recommended though, for even 

 if the clots are cut into thin slices and exposed to the heavy pressure of 

 a mandiocca press a considerable percentage of water remains in its 

 cavities, and decomposition sets in, but not to the same extent as in 

 " Ceara scrap." 



Although so impure, it commands a price usually second only to 

 u Para fine." The loss is from 20 to 25 per cent., which, in inferior 

 qualities, may even amount to 55 per cent. 



Mangabeira r ubber also comes from Ceara. Lt is the product of 

 Hancornia speciosa, a dwarf tree with somewhat the habit of a birch. 

 The rubber is prepared by the addition of an excess of salt to the latex, 

 or by Strauss' method of adding alum. Even after thirty days' drying 

 in the sun it is spongy and full of cavities of liquid. As might be expect- 

 ed, the loss on purification is enormous, amounting to from 40 to 60 per 

 cent. 



By this method of coagulating with chemical reagents it is impos- 

 sible to get rid of the coagulated proteid matter, to say nothing of the 

 greater part of the water. Morellet'sif remark that " le proceMe Strauss 

 est ingenieux, mais les resultats de son application sont manvais " may 

 well be applied to all these chemical methods, and the sooner the search 

 for coagulating agents is abandoned the better. 



