I 452 j 



fa-rolled and fired as described already. A more even colour 

 is obtained by sorting the leaf and placing the different 

 grades in separate heaps to oxidise after the firing operation 

 whereby the older leaf can remain for a longer period with- 

 out injury to the other. Should the leaf have been over- 

 withered and the sap reduced to too great a degree of concen- 

 tration, the colour obtained in the oxidation will be dull and 

 dark instead of bright coppery ; this can be partially reme- 

 died by moistening the leaf with clean water, either during 

 the first rolling, or when the leaf is put to oxidise, by which 

 means the concentrated sag is better diffused over the leaves. 



708* In all cases the leaf and the atmosphere of the oxi- 

 dising room must be kept damp by sprinkling of cold water, 

 and it is advisable to protect the leaf from draughts by means 

 bf wet cloths placed over the heaps. If this is not done the 

 surface of the heaps will assume a blackened appearance, 

 owing to the leaf drying up, and the too rapid oxidation of 

 the tannin and colouring matter. A perfectly moist draught 

 of air would probably not be of any harm, it might hasten the 

 oxidation and change, but it would be necessary to frequently 

 moisten the surface of the heap during the process. The 

 change in the leaf is due, to oxidation and not fermentation 

 proper (caused by living organisms). Experiment has 

 shown that Oxygen gas readily changes the leaf from green 

 to copper in less than half hour and the Microscope has failed 

 to discover any organism or living ferment in connection with 

 'this change. Experiments have also shown, that a certain 

 moist condition of the atmosphere and of the leaf itself, is 

 necessary to obtain the desired colour, and also that the best 

 results as regards flavour, pungency &c., are obtained when 

 the temperature of the leaf does not rise spontaneously above 

 84 to 86F. Anon-living ferment or enzyme such as dias- 

 tase may be associated with this process. If the leaf is 

 placed on a cement floor, where the heat is partially absorbed 

 as it is developed, it can be. thicker than when placed on 



