THK CHEMISTRY OF THE SOIL. 



103 



The ash of the different woods contains the mineral portion of the wood from 

 which it has hem obtained. Of these ingredients tin' substances possessing 

 fertilising value are Hint', potash, and phosphoric acid. Their potash and 

 phosphoric acid are, moreover, in an exceedingly soluble condition, and are 



in such a state as to be readily assimilated by most plants. The value of the 

 ash of the different varieties of European trees has been long well known 

 and their constitution established by numerous exaet analyses. The 

 composition of the ash of our own trees has not as yet been studied 

 systematically, but from the following analyses made in the Department 

 it will be seen that they are likely to be quite as valuable : — 



Spotted-gum 

 Red-gum ... 

 Blood wood 



Box 



Blackbutt ... 

 Iron hark ... 

 Red-apple . . 

 (irape-vine 

 She-oak 

 Grass- tree ... 



The following figures indicate the content of potash (K 2 0) of samples of 

 wood-ashes from mixed timbers (varieties unknown) made at different times 

 in the Laboratory for individuals :— 346, D57, 0-06, 5-04, 4-65, 0-27, 0-83, 

 and 0-30 per cent. 



The following analyses recently made of wood-ashes from various timbers 

 specially burnt for the purpose by the Forestry Department will serve 

 further to show the variations to be expected in the potash-contents of the 

 same timbers, and even of individual specimens of the same timber : — 



None of the figures here quoted can be accepted as representative of the 

 timbers specified, as the burning has not been conducted uniformly ; the 

 variations in the unburnt carbon are considerable, the temperatures at which 

 the wood was burnt vary, also the exposure of flame. 



