266 



TEMPERATURE USED AT JAVA. 



It has before been mentioned, that all tea at Java 

 is roasted and dried at a temperature below the 

 boiling point. 



202° is given by Mr. Jacob- 

 son for the first roasting of 



black tea, and 



197° for the second roasting. 



For the first roasting of green, 

 206° ; and it is observed that, 

 during the roasting the leaves 

 nearly attain the heat of boiling 

 water. 



The second roasting of green 

 tea is stated at 190°. 



For Pekoe tea, which undergoes only one roasting, 

 the temperature of 196°* is given by him, and 

 it is stated that even at that temperature the leaves 

 crackle when they are first put into the vessel. 

 The heat employed in the drying-tube is 142°. 

 About three quarters of a pound of leaves are used 

 at one time. 



Supposing the above statement to be correct, 

 then, so far as the thermometer indicates, the ques- 

 tion whether black tea is roasted and dried at a 

 higher temperature than green, is here decided and 

 proved not to be the fact at Java. Further, I have 



* I cannot but express my surprise, that the crackling of the 

 leaves should have been obtained at a temperature of 196°. 

 It has already been seen that this effect was not produced when 

 the heating medium was steam generated by rapidly boiling 

 water. It is possible, however, that after a certain amount of heat 

 had been absorbed, the radiation from the vessel was greater 

 than the absorption, so that the vessel did not attain a tempera- 

 ture equal to boiling water. I acknowledge it was a great 

 omission not to have determined this by experiment. 



