The Diffusion Process. 59 
freshly added water first meets nearly exhausted slices, 
and passes from vessel to vessel of the battery, meeting 
sweeter and sweeter slices at every step, till it has ac- 
quired almost the same sweetness as the cane-juice ; 
while the fresh slices are first treated by water almost as 
sweet as the juice they contain, then by less and less 
sweet water, till finally the fresh entering water extracts 
almost every particle of sugar. Upon this method, of 
making the slices and the water travel in opposite direc- 
tions, depends the possibility of the transfer of the sugar 
from the cane to the artificial juice. At no part of the 
battery is there any great difference of sweetness between 
the slices and the surrounding water ; but the slices are 
every where a little sweeter than the water, and the 
sugar is every where passing from the natural into the 
artificial juice. 
By extending the time of treatment, the density of the 
artificial juice may be made to approach that of the cane 
juice with any assigned degree of approximation ; in 
actual practice a juice i° to ij° B. less than the cane 
juice has been obtained in an hour and a half, with 
almost complete extraction of the sugar. 
We now come to the coal question. It will be well 
to trust to the cane slices for nothing either as fuel or 
paper stock. No means appear at present for rendering 
the wet slices fit for burning, and it seems there is a 
difficulty in preparing them for paper stock, as if the 
least trace of sugar is left behind it spoils the product. 
If it is any use as manure let it be put on the ground. 
How much coal is it probable will be burnt per 2,000 
ffis. of dry sugar ? Suppose that 2,000 gallons of the 
normal juice of the cane are required per hhd. : of this 
H 2 
