140 THE CEARA RUBBER TREE 



the contamination of the rubber with earthy impurities. 

 The tapping is usually performed every morning, and the 

 latex from the successive tappings is allowed to accumu- 

 late in the hole where it slowly coagulates. At intervals 

 the flat cake of rubber which is formed in the hole is 

 removed, washed, pressed, and dried. 



Sometimes the coagulation of the latex is accelerated 

 by placing water or a solution of salt or alum in the hole 

 before tapping the tree. In other cases the latex is 

 collected in tin or clay cups and is afterwards coagulated 

 by one of the methods just mentioned, or by a smoking 

 process similar to that employed in the preparation of 

 Para rubber. 



(2) The trunk of the tree is tapped by first stripping 

 off tlie outer bark and then making a series of incisions 

 by means of a small axe or a knife. The latex which 

 exudes either coagulates on the stem, or, if very fluid, 

 runs down to the base of the tree and coagulates on the 

 ground or on leaves placed to receive it. The rubber 

 obtained by this method is in the form of scrap, and if 

 coagulated on the ground it is liable to be contaminated 

 with soil. 



Much of the Ceara rubber prepared in Brazil from the 

 wild trees is of inferior quality on account of the careless 

 methods of preparation employed. 



No trustworthy estimate is available as to the average 

 annual yield of rubber from wild Ceara trees. It has 

 been stated to be as much as 1 to 3 lb. per annum, whilst, 

 on the other hand, the average for several seasons, good 

 and bad, has been placed at about 4 oz. per tree. 



Cultivation of the Ceara Tree. — The introduction of 

 Manihot Glaziovii into countries outside its natural 

 habitat dates from 1876, when Cross brought to Kew 

 a number of the living plants and a quantity of the seed 

 which he had collected in Ceara. Plants were raised 

 at Kew from the seed thus obtained and were distributed 

 during the next two years to the various botanic stations 

 in the Colonics for trial. In most places the plants 

 grew exceedingly well and it was soon found that the 

 Ceara tree could be readily cultivated, as it is very liardy, 

 a quick grower, and capable of adapting itself to very 

 varied conditions of climate and soil. The trees produce 

 seed freely at an early age, and as the seeds retain their 



