QUANTITATIVE RELATIONS. 221 



that the various bases or basic metals might displace 

 each other in equivalent quantities, i. e. , in the ratio of 

 their molecular or atomic weights, and that, were such 

 the case, the discrepancies to be observed among analyses 

 should disappear, if the latter were interpreted on this 

 view. Liebig instanced two analyses of the ashes of fir- 

 wood and two of pine- wood made by Berthier and Saus- 

 sure, as illustrations of the correctness of this theory. 

 In the fir of Mont Breven, carbonate of magnesium was 

 present ; in that of Mont La Salle, it was absent. In 

 the former existed but half as much carbonate of potas- 

 sium as in the latter. In both, however, the same total 

 percentage of carbonates was found, and the amount of 

 oxygen in the bases was the same in both instances. 



Since the unlike but equivalent quantities of potash, 

 lime, and magnesia contain the same quantity of oxy- 

 gen, these oxides, in the case in question, really replaced 

 each other in equivalent proportions. The same was 

 true for the ash of pine-wood, from Allevard and from 

 Norway. On applying this principle to other cases it 

 has, however, signally failed. The fact that the plant 

 can contain accidental or unessential ingredients ren- 

 ders it obvious that, however truly such a law as that of 

 Liebig may in any case apply to those substances which 

 are really concerned in the vital actions, it will be impos- 

 sible to read the law in the results of analyses. 



Relation of Phosphates to Albuminoids. Liebig 

 likewise considered that a definite relation exists be- 

 tween the phosphoric acid and the albuminoids of the 

 ripe grains. That this relation is not constant is evi- 

 dent from the following statement of data bearing on 

 the question. In the table, the amount of nitrogen (N), 

 representing the albuminoids (see p. 113), found in vari- 

 ous analyses of rye and wheat grain, is compared with 

 that of phosphoric acid (P 2 5 ), the latter being taken as 

 unity. The ratios of P 2 5 to N were found to range as 

 follows : 



