130 



surface ; which will be readily ascertained by with- 

 drawing the watchstick. This is a stick thrust into 

 the tan, which, on being removed and grasped in the 

 hand, where it had been immersed, will readily give 

 the state of heat aud moisture with sufficient accu- 

 racy. If the bed should be found dry, the plants 

 should be taken out of it immediately, and the tan 

 should be soaked with water, sufficient to make it 

 quite moist. 



Bark should not be very large or small ; as the 

 first is apt to heat too violently, and the other soon 

 becomes mere vegetable mould, and ceases to ferment. 

 It should be moderately dried before it is put into the 

 pit, otherwise it will cake and heat too much ; it should 

 also be turned over, and lightly shaken up, in order 

 to bring it to a proper temperature. Previously to 

 plunging the plants, it is necessary to screen all the 

 bark in the beds annually, that the fine parts may be 

 separated from the coarser, the latter being still fit for 

 use ; for if new bark be added to old that is much 

 decayed, without screening, it will not be sufficiently 

 porous enough, and will therefore burn. When the 

 old tan is screened, that part of it which is fit for use 

 again should be spread of an equal thickness all over 

 the pit ; then bring in a sufficient quantity of new tan 

 to raise the bed to its proper height, which should 

 be full three feet thick ; and with a fork stir up the 

 bark from the bottom of the pit, mixing the new and 



