Inorganic Constituents of Plants, 515 



On comparing these analyses of tobacco-ash, it is at once 

 seen that plants of the same kind, grown upon the same soil, 

 yield ashes, the composition of which differs but little. This 

 is very evident with respect to those of the Debreczyner leaves 

 (1, 2 and 3). The proportion of bases combined with organic 

 acids is, so far as their oxygen is concerned, very nearly the 

 same in each case. The quantity of lime in the ashes of the 

 Banat leaves is almost the same as in those of the Debreczyner 

 leaves, whilst the quantity of potash in the former is scarcely 

 two-thirds as great as in the latter; the quantity of mngnesia, 

 however, the equivalent of which is so small, is nearly doubled. 

 The ashes of the Fiinfkirchner leaves exhibit a still wider 

 difference; in four instances the quantity of potash is scarcely 

 one-third of that in the Debreczyner leaves ; in place of this 

 potash, however, we find an increase in the quantity of lime, 

 amounting to nearly 50 per cent. Again, the quantity of 

 magnesia is the same as in the ashes of the Banat leaves, whilst 

 the lime in the latter only amounted to 27 per cent. 



It is evident that these differences depend entirely upon the 

 variable quantities of the several bases contained in the soils. 

 In these differences we recognise moreover a beautiful confir- 

 mation of the law of mutual replacement of bases laid down 

 by Professor Liebig. Supposing this law to be subject to no 

 modification, and considering the accuracy of the analyses, 

 we should have expected that in equal weights of the various 

 ashes (the abnormal matters being deducted), the quantities 

 of oxygen united to these bases would have been more nearly 

 identical. In the case of plants containing much sap, this 

 difference in the quantities of oxygen contained in the bases 

 united to organic acids, is easily accounted for ; partly by the 

 reactions which we have already stated take place during the 

 ignition of the ash, and partly by the influence which, as in 

 the case of tobacco, the presence of nitrates, according to their 

 quantity, will exert upon the amount of carbonates found in 

 the ash. 



The ashes of seeds, so far as their composition is known, 

 consist, like those of the blood of man and other animals, 

 principally of the phosphates of the alkalies and alkaline 

 earths. The curious fact, moreover, has lately been observed, 

 that the phosphoric acid is not in all seeds combined with the 

 sAme number of equivalents of fixed base. Analyses conducted 

 by ourselves and under our superintendence, show that peas, 

 beans, horse-beans, &c.,that is, theLeguminosa?, and the seeds 

 of the Coniferae (the pines), &c., contain tribasic phosphates 

 (PO5 + 3MO). The seeds of the Cerealia (rye, wheat, millet, 

 buck-wheat, and also hemp and linseed) contain, on the other 



