244 



THE ASH OF LEAVES. 



The per cent, of ash in leaves and the variation during the year is wor- 

 thy of special attention. 



The following figures illustrate these points : 



Mountain Ash, 6.42 per cent. ; Cherry, 6.70 per cent. ; Beech, 5.21 per 

 cent. ; Maple, 4.68 per cent. ; Elm, 6.82 per cent. 



The ash of leaves like that of wood is found to vary during different 

 seasons of the year. 



ROBINIA. CHERRY. BIRCH. CHESTNUT. 



May 6.25 6.40 



July 7.75 7.30 



September . . 8.22 4.36 4.75 



October . . . 11.74 4.68 7.24 4.55 



April 7.80 3.84 



It can thus be seen that the variation in the per cent, of ash in diflferent 

 parts of the tree during the year is very marked ; the upper portion 

 being subject to the greatest change. The ash is at its maximum in 

 the sap wood in autumn and winter, and in the heart at its minimum. In 

 the spring the ash in the sapwood falls, at the same time it rises in the 

 bark. By summer both the sapwood and the bark have reached their 

 minimum and the ash constituents go to the leaves. " At all seasons of 

 the year however the cambium and bast portions of the tree contain three- 

 fourths of the whole amount. We have every reason to believe that 

 every part of the tree contains a certain invariable amount of mineral 

 matter which is absolutely essential to its existence and that besides this 

 there may be present an inessential and variable amount of the same in- 

 gredient. The substances usually found in the ashes of all trees when 

 burned at a low temperature are potash, soda, lime, magnesia and iron 

 (K2O, NajO, CaO, MgO, FeaOj) in combination with phosphoric acid 

 (P2O5), sulphuric acid (SO3) chlorine, (CI.) carbon dioxide (CO,) and 

 silica (SiOj); iodine (I), aluminum (Al.) and manganese (Mn.) are often 

 present. One portion of these mineral constituents exists in solution in 

 the sap and the other in the tissue of the plant in the solid form. In 

 burning, portions of sulphur, chlorine, phosphorus and alkalies may be 

 lost under certain conditions, by volatilization. 



The ash remains as the skeleton of the plant, and often actually retains 

 the microscopic structure of its tissues. 



