168 Professors Rogers on the Decomposition of Rocks, Sfc. 



course to any mysterious decomposing power of the roots of 

 the growing vegetable. 



(6.) Among the points of interest incidentally determined 

 during these investigations, may be mentioned the curious 

 and instructive fact, that anthracite coal, bituminous coal, and 

 lignite, treated by the tache process, ffive unequivocal evidence 

 of alkali, while the ashes of these materials similarly treated 

 yield no trace of alkali. It thus becomes evident, that the 

 absence of alkali in the ashes of these combustibles, instead 

 of being a consequence of its absence in the coal itself, is 

 really due to the high temperature at which the ash is formed. 

 We have here the explanation of a fact which might other- 

 wise appear inconsistent with the admitted vegetable origin 

 of coal. 



(7.) Another incidental result of interest, is the extraction 

 of carbonate ofpotassafrom wood, by leaching it in fine powder, 

 with carbonated water. This effect we have found to be quite 

 distinct with maple, oak, hickory, &c. Hitherto the opinion 

 appears to have prevailed, that the alkali or its carbonate 

 could only be eliminated by the incineration of the vegetable 

 material. 



From the great rapidity with which, according to our ex- 

 periments, potassa and soda, and their carbonates, but espe- 

 cially potassa and its carbonate, rise in vapour at a strong 

 red heat, we are persuaded that a large error must be com- 

 mitted in estimating the amount of these materials contained in 

 plants, by the results of incineration ; and we believe that in 

 not a few cases, the quantity obtained is scarcely one-half of 

 what really exists in the vegetable mass. The important 

 bearing of this consideration upon the late numerous and 

 elaborate analyses of ashes, should, we think, claim the spe- 

 cial attention of chemists. Indeed, it seems a little remark- 

 able, that the source of error here referred to has not already 

 been brought to the notice of analysts, as likely to modify 

 materially their results. — [The American Journal of Science 

 and Arts ; Second Series, vol. v., No. 15, May 1848, p. 401.) 



