Dr. Fickendey 71 



place, whilst the bluish-red colour remains. 

 This, after an hour's heating at 70 G, 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 iooC. ; 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 brow r n. 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 



