66 



THE POPULAR SCIENCE MONTHLY. 



PHOSPHORIC ACID IN THE ASH. 



LEAVES OF THE MAPLE. 



DATE. 



May 1 

 7 



" 20 

 June 13 

 July 12 

 Aug. 4 

 Sept. 3 

 Oct. 3 



" 14 



REMARKS. 



Leaves small 



" small, expanded 



" larger 



" normal 



it u 



ii it 



u it 



" fading 



" fallen 



Ash. 



6.00 



6.90 



7.89 



9.40 



11.64 



12.28 



13.50 



14.75 



16.20 



PHOSPHORIC ACID OP THE ASH. 



It will be at once observed that the absolute amount of nitrogen- 

 ized substances differs widely as between the leaves of the two plants : 

 there is at first far more in those of the maple than in those of the 

 lilac, and this superiority is maintained during the whole period of 

 vegetation. 



Probably were we to examine from this point of view a large num- 

 ber of plants, we should find differences as great as these. Even be- 

 tween trees of the same species similar differences occur, according to 

 their age and vigor, and more particularly according to the surround- 

 ings. Thus, on July 12, 1873, M. Corenwinder collected leaves of the 

 common lilac in a garden situated in the open country near Saint- 

 Quentin, and in them found : 



Nitrogenized matters. 18.56 



Carbonaceous matters 72.90 



Ash 8.54 



100.00 



Comparing this analysis with that of the lilac-leaves which were 

 gathered at the same time, but in a city-garden, we see that those 

 which had plenty of air, growing in the country, remote from aggre- 

 gations of human beings, are the richer in nitrogenized substances. 

 They also grow thicker and larger, the activity of respiration devel- 



