On the AjjjMcatlon of Manures. 



245 



I have likewise shown in some experiments which I made some 

 years ago/"^ that when an earth which does not naturally enter 

 into the constitution of a plant, such as strontian, is presented to 

 it, even to the exclusion of others^ little or none can be detected 

 within the vegetable tissue, so that it either is not absorbed, or is 

 again excreted, by the roots ; and this conclusion I find to be cor- 

 roborated by Liebig in the volume already referred to. 



It may appear singular, that under these circumstances a sub- 

 stance having such a resemblance to lime as strontian possesses, 

 cannot be substituted for it, especially when it has been found 

 that the proportions of the several earths and alkalies which enter 

 into the composition of a plant vary according to external condi- 

 tions. Thus I have already stated that the same plant grown on 

 a calcareous soil contains more lime, and less silex, than it does 

 in a siliceous one, and vice versa. 



But it has been shown by Liebig that the total amount of the 

 bases present never varies, the excess of one making up for the 

 deficiency of the rest. Thus, according to Saussure, one hun- 

 dred parts of the ashes of a fir, growing on the magnesian soil of 

 Mount Breven, contained : — - 



Carbonate of potass , . . 3*60 i Sum of oxygen in the potass , 0'4] 



lime . . .16-34 

 magnesia . , 6-77 



Smn of the carbonates . 56' 71 



lime. . 7-33 

 , , magnesia . 1 • 27 



Sum of the oxvQ-en in the bases . 9-01 



whilst one hundred parts of the ashes of the same tree grown on 

 the soil of Mount La Salle, which contained no magnesia, con- 

 sisted as follows, of, — 



Carbonate of potass . . .7-36 

 ,, lime . . . 51'19 

 ,, magnesia . .00*00 



Sum of the carbonates . 58* 55 



Sum of oxygen present in potass , 0*85 

 lime . S-IO 

 , J magnesia 0- 00 



Sum of the oxygen in the bases . 8-95 



Again, Berthier has analysed the ashes from two fir-trees, one 

 growing in Norway, the other in France (Depart, de 1*1 sere). 

 That from Norway contained, in one hundred parts, — • 

 Potass . . . . 14*10 of which 2*4 parts Vv ould be oxygen 

 Soda . . . . 20*70 .,5-3 

 Lime .... 12*30 , 3*45 , 



Magnesia . . . 4*35 ,, 1*69 



51*45 ~ 12-84 

 That from France, on the contrary, contained in one hundred 

 parts, — 



*Potass and soda . . . 16*8 in which 3*42 parts would be oxygen 

 Lime .... 29-5 8*20 

 Magnesia . . . . 3*2 ,, 1*20 



49*5 12-82 



* Linnsean Trans., vol. xvii. 



