328 CHYMISTRY APPLIED TO AGRICULTURE. 



As soon as all liquor above the level of the upper stop~ 

 cock has passed out, the second stop-cock is turned ; and if 

 the liquor flowing through that be found clear, it is mixed 

 with the first portion. If, on the contrary, it appears cloudy, 

 the stop-cock is again closed to give it time to settle, and 

 it is not made use of till towards the termination of the 

 evaporation. 



The deposit which is formed at the bottom of the boiler^ 

 renders the last portion of the juice turbid. But as soon 

 as this is seen to be the case,^ that which remains is drawn 

 off into the bucket containing the scum. 



The deposit which is formed at the bottom of the boiler, 

 and this scum, are expressed by means of a lever press of 

 very simple and cheap construction, and which is very easi- 

 ly worked. 



I place a cylindrical willow basket upon a block of stone 

 three feet square, the upper surface of which is slightly 

 inclined and furrowed with channels an inch deep, uniting 

 in a common centre at the lowest angle. The basket is 

 lined with a bag of coarse cloth, the end of which turns 

 back and hangs down. Into this bag I put the deposit 

 and scum ; then, drawing the edges of it together, I tie 

 the mouth closely with a pack-thread. I place on the top 

 a wooden trencher of the diameter of the inside of the 

 basket. This I load with several square pieces of wood^, 

 which project over the upper part and serve as a fulcrum 

 for the lever. When thmgs are thus far arranged, I pro- 

 ceed to adjust the lever, which is five feet long. This is 

 fixed at one end to a ring-bolt which passes through a 

 stone. The other end I load with weights to the amount 

 of from 56 to 112 pounds, increasing them at pleasure, so 

 as to produce a gradual and constantly increasing pres- 

 sure, which may be rendered as powerful as is necessary. 

 The juice which is thus forced out, flows into a bucket 

 and is thrown into the evaporating vessel. 



The most diflScult operation to be performed, is that of 

 purifying the juice ; and if this be not 4:horoughly done,, 

 the processes of evaporation and graining are long and 

 troublesome ; the juice swells and bubbles up in the boiler, 

 and the sugar crystallizes imperfectly and remains mixed 

 with molasses. The lime which is thrown in to clarify the 

 juice does not always rise to the top with the scum, by a 

 prolonged period of rest in the depuratory boiler ; neither 

 is it always precipitated. It sometimes happens, that> not- 



