162 PLANT PRODUCTS 



and about i pound in the flesh of pulp. There will be 16 

 pounds of potash in the berry, about 4 pounds in the " parch- 

 ment, " and about 12 pounds in the pulp. The return of 

 the pulp does not make up for the losses, and considering 

 the general nature of the soils on which these crops are 

 grown, it seems highly probable that potash manure should 

 receive more consideration. The soils on which the coffee 

 is grown are usually fairly well supplied with phosphates. 

 It is quite well known in common practice that nitrate of 

 potash is an excellent manure, but owing to its expense 

 the amount used is less than what is desirable. There is 

 good scope here for the use of increased quantities of sulphate 

 of ammonia. The cultivation both in Brazil and Madras 

 are similar in this respect, that a red soil is much preferred. 

 In Brazil steep slopes are not employed to the same extent 

 that they are in Madras. In some kinds of treatment 

 the " parchment " is fermented, and removed on the station, 

 but in others both " parchment " and silver skin are treated 

 alike, and the coffee berry is sold with both the silver skin 

 and the " parchment " adhering to it. 



Tannin. The subject of tanning leather is treated very 

 fully in another volume of this series (Bennett), but a brief 

 abstract can be given here from a different point of view. 

 The word " tannin " expresses a large number of materials, 

 which have all the common property that they are used 

 for manufacturing leather. The chief sources are the bark 

 of oak and many other trees, together with myrobalans. 

 Catechu tannin is a decomposed product of Catechin, 

 or Khair, the extract obtained by boiling the wood of acacia 

 catechu (mimosa catechu). As a rule more vigorous trees 

 yield more tannin, but the character of the soil appears to 

 be of very great importance. There are very large quantities 

 of oak bark grown in the British Isles which are not made 

 much use of owing to the cost of collection. This subj ect must 

 be treated as a part of the whole question of forestry of 

 the British Isles. Reafforestation and the management of 

 woods can only be successfully carried out if all possible 

 sources of revenue are considered. The practical management 



