176 The Fermentation of Cacao 
Also, it is difficult to keep such a surface clean 
and free from larger insects, cockroaches, &c., 
&c. In considering what acid- -resisting smooth 
surfaces could be substituted for wood, the 
writer has passed over such materials as 
glazed eéarthenware, enamelled iron and 
‘“Ruberoid” in favour of planed slate. In 
order to test the properties of this material 
he constructed a slate sweating box of 1 in.- 
planed slate with sloping floor and_ liquor 
exit. It was rather elaborately made. with 
rounded corners and acid-resisting cement for 
joints, and was consequently more expensive 
than it need have been. However, planed slate 
in slabs is not an expensive material: I refer 
to the sort of thing supplied for old-fashioned 
public urinals. 1 have carefully experimented 
with this box, contrasting temperatures with 
wooden boxes, and am quite satisfied that in 
slate we have an ideal surface to make perma- 
nent linings for the interior of concrete sweat- 
ing boxes in place of the loose wooden 
‘casings now used on most large cacao estates. 
Litharge mixed with liquid glass solution 
makes a suitable cement for joints. Possibly 
4-in. or $-in. thick slabs would serve under 
these circumstances, but I am afraid slate 
would be too heavy and breakable a material 
for the sliding up partitions between the 
boxes ; however, the lower 18 in. of this inter- 
partition should not-be removable and could 
be made of slate while the upper part could be 
