The Use of the Microscope in the Rubber Industry. 247 
latex, and have been ground up and incorporated in the dry 
rubber. Fig. 9 shows the angular appearance of the particles. 
Another defect in rubber, from the point of view of its appear- 
ance, is spots due to the presence of moulds. This is of common 
occurrence on pale crepe. Fig. 10 is a photograph of a piece of 
clean crepe. Fig. 11 shows a similar piece of crepe which has 
been affected with moulds. Fig. 12 is a microphotograph of a 
small piece of rubber, after staining with cotton-blue and treat- 
ment with xylol, showing fungus mycelium. 
In some cases surface defects may appear on both kinds of 
finished rubber which may have originated quite differently from 
the above-mentioned faults, such as films caused by vegetable 
debris in the water used in washing the rubber. This film may 
appear at first sight to be a simple case of rust due to serum, but 
microscopic examination shows at once the difference between the 
two films. In the case of other deposits micro-chemical analysis 
may have to be resorted to, especially when the deposit is only 
present in small quantities, as is usually the case. 
Diseases. 
The part played by the microscope in the investigation of the 
diseases of Hevea brasiliensis is a very important one, but it differs 
very little materially from its use in the investigation of the 
diseases of other trees and plants cultivated for their economic 
products, so that it is unnecessary here to point out its essential 
use under this heading. 
Summary. 
In the foregoing the use of the microscope has been shown to 
be of very great value in determining the causes and origin of the 
defects which appear in finished smoked sheet and crepe as put on 
the market. By the examination of these defects planters can be 
advised as to the best methods of eliminating the causes, and can 
offer to the buyers products which are of standard quality. 
I am indebted to the Council of . the Rubber Growers’ Associa- 
tion for permission to publish this short paper in connexion with 
the use of the microscope in an important industry. 
EXPLANATION OF PLATE XIII. 
Fig. 7. — Dirt in pale crepe rubber, x 46. 
Fig. 8. — Dirt in pale crepe rubber, x 200. 
Fig. 9. — Particles of bark in rubber, x 200. 
Fig. 10. — Clean crepe. 
Fig. 11. — Spotted (mouldy) crepe. 
Fig. 12. — Section of spotted crepe, x 200. 
