l8 RESEARCHES ON THE MANUFACTURE 
proper degree of withering simply by a glance at, and a touch 
of, the leaves. In cloudy or rainy weather we can, of course, not 
make use of the sun for withering the leaves, but are compelled 
to do so by artificial heat. For this purpose a shelf of bamboo 
sticks is built over the furnace and the leaves thinly spread 
upon rough cloth are put upon it. There they are allowed to 
wither slowly by the gentle heat ascending from the furnace. 
Withering in hot pans is also resorted to. The next operation 
to which the withered leaves are subjected is 
Rolling. This operation is resorted to for the same purpose 
as in the case of green tea. Rolling on a coarse straw mat is 
sometimes done. This must, however, be strictly avoided, 
since not only many of the leaves are broken, but also a por¬ 
tion of the sap flows out and is absorbed by the mat. The 
most essential point in the process of rolling is to give the 
leaves a good twist without losing much sap. It is on the 
sap that the strength of tea is dependent, so that the more 
sap is lost, the weaker is the product. Formerly rolling was 
exclusively performed by hand, but recently a simple rolling 
apparatus has been invented, which is generally employed in 
the manufacture of black tea. It consists of a strong wooden 
rectangular box with a sliding lid provided with handles. The 
bottom of the box, as well as the inner face of the lid, is made 
rough by steps cut in the wood, and upon the ribbed face of 
the lid a coarse cloth is nailed. About 250 vie of withered 
leaves are placed between these two rough faces and there they 
are rolled together by backward and forward motion of the 
lid. After sufficient rolling, the leaves are subjected to fermenta¬ 
tion. It is advisable, though rather tedious, to pick out open 
or untwisted leaves, since the tea mixed with such leaves 
fetches but a low price in the market. 
Fermenting. This is the most important operation in the 
manufacture of black tea, since the quality of the tea is in¬ 
fluenced much more by this than by any other operation. 
Indeed, it is chiefly during this operation that the leaves lose 
their disagreeable raw smell, and acquire their characteristic 
