( 27 ) 
tanks is attended with certain defects, particularly 
bubbles which affect its market price, far more than 
in the case of sheet coagulated by the older method 
in separate shallow, enamelled pans. 
Tank coagulation has also necessitated the general 
use of the anti-coagulant and anti-ferment Sodium 
Sulphite, the chief effect of which is to reduce bubble 
formation, since the bubbles are produced by fer- 
mentation. Bubble formation is greater in tank 
than in pan coagulation on account of the fact that 
the coagulation of latex in deep tanks is partially 
anaerobic, under which conditions bubbles, due to 
the formation of gas from the decomposition of 
the carbohydrates in the latex, are produced. 
Great care must therefore be taken that the tanks 
do not become “ sour,” and they should be washed 
periodically with a dilute solution of formalin, and 
the dividing partitions treated similarly or exposed 
occasionally to the sun. 
Gement tanks, lined with glass, and with glass or 
aluminium partitions, are now on the market and 
would appear to be. the most suitable type, preferable 
to the wooden tanks lined with glazed tiles, with 
wooden partitions, now commonly in use. 
The important points, in connection with the pre- 
paration of smoked sheet, to which attention should 
be directed are, elimination of “ rust ” and ventilation 
of the smoke house. The elimination of “ rust ” 
must be effected, on account of the broker’s pre- 
judices, although it does not affect the real quality 
-of the rubber. “ Rust ” is due to the exudation of 
serum products from the interior of the sheet, which 
•evaporate on the surface and usually form a thin 
61-48 III 
