144 



placed in this category. While it is certainly true that every part of 

 the tree, even including the fruit until complete maturity is reached, 

 abounds in a viscid milk easily obtainable by tapping, it is, however, 

 extremely doubtful whether rubber of requisite quality and in quanti- 

 ties needed for commercial exploitation can be extracted. Like vur 

 milkweed and osage-orange, this tree no doubt contains a rubber-like 

 principle which will appear after a reasonable amount of coaxing and 

 a considerable expenditure of time, but after all scaicely worth the 

 search. Mr. R H. Biffin, who has examined the phenomena of coagu- 

 lation in the latices of a number of plants, obtained the following re- 

 sults with that of the breadfruit. 



"When diluted and centrifugalized it separates readily, giving a 

 creamy white layer which dries to a resinous mass somewhat resem- 

 bling gutta-percha. At the ordinary temperature this is quite hard 

 and brittle, but if the temperature is raised slightly it becomes plastic, 

 and at the temperature of boiling water it is soft and excessively 

 sticky. The substance is soluble in carbon hi- sulphide, and insoluble 

 in water and alcohol."* 



From this it becomes apparent that unless superior methods of ex- 

 traction and treatment for its gum are found, the breadfruit will 

 scarcely enter into competition with any of the commercial rubbers. 

 Experiments recorded by Watt with the milk of the jak {A. intdgri- 

 folia) were, however, more promising in that the rubber prepared 

 from its gum was leathery, waterproof, and capable of removing pencil 

 marks, thus fulfilling at least the requirement which gave rubber its 

 name. 



The breadfruit trees throughout Porto Rico are scarred with ma- 

 chete marks made by the natives for the purpose of obtaining milk, 

 which they boil with coconut oil to obtain tlie thick, gummy substance 

 used in caulkiag canoes and rendering bottles water-tight ; this is also 

 used as a birdlime before it hardens. The milk is used as a medium 

 for paint in the F'acific Islands, serving its purpose well, although for 

 interiors it does not give as smooth a finish as paint prepared with 

 oil. 



*Kew Bull. 140. pp. 177-181. August, 1898. 



(To be continued.) 



[I.ssued 16th June, 1904.] 

 Printed at the Govt. Printing Office, Kingston, Jam. 



