Dr. Fickendey 71 
place, whilst the bluish-red colour remains. 
This, after an hour's heating at 70° C., changes 
to brown. The beans themselves can be 
made to turn brown if warmed to’ 75° C. 
and a small quantity of watery -extract from 
some fresh beans is mixed in the pulp. As 
a comparative experiment to this, take 
another lot of beans and mix them with 
some of the extract which has been pre- 
viously warmed from 80° to 100°C. ; it will 
then be seen that no brown colouring results. 
This watery extract, which also. contains 
the enzyme, is obtained by grinding fresh 
beans with cold water, afterwards filtering 
off the liquor. The resultant extract is 
coloured brown. Again, if the cacao pulp 
from heated beans is kept with the extract 
from fresh beans in glass vessels with only a 
small surface exposed, it will be noticed that 
the browning first sets in on the surface and 
penetrates downwards in proportion to the 
ability of the air to likewise enter the mass. 
Even if the beans be boiled in water the 
tannins enter into solution. This solution also 
turns brown, owing to oxidation, if a small 
quantity of the above-mentioned extract is 
mixed with it. Even a purified solution of 
tannin (obtained by precipitation by acetate 
of lead, filtering off the liquor, and separating 
the lead compounds by means of sulphuretted 
hydrogen), to which some of the extract has 
been added, also causes the brown colouration 
