58 



INORGANIC CONSTITUENTS. 



COMPOSITION OF THE ASHES OF SEVERAL PLANTS ANALYZED 

 BY M. BERTHIER. 



A remark made by Berthier, and arising out of the preceding 

 analyses, is the absence of alumina in the constituent principles of 

 the ashes examined. The results previously obtained by M. de 

 Saussure fully confirm this remark ; and if in some cases traces of 

 alumina were detected, the circumstance was attributed to the clay 

 which might accidentally have adhered to the plants. According to 

 M. Berthier the absence of alumina is probably owing to its insolu- 

 bility in water, and its weak affinity for the organic acids. The solu- 

 ble salts of alumina with mineral acids are, it is well known, unfa- 

 vorable to vegetation, and in an arable soil they could not exist along 

 with calcareous or alkaline carbonates : they would be immediately 

 decomposed. 



However, alumina appears actually to have been observed in the 

 state of salt in the juices of certain plants : li/copodium arniplanatum^ 

 an infusion of which is employed as a mordant in dyeing, contains 

 tartrate of alumina ;* the same salt has been detected in verjuice ; and 

 as we shall see presently, Vauquelin found acetate of alumina in the 

 sap of the birch-tree. 1 may add, that in a considerable numb({r of 

 analyses of ashes, produced from plants and seeds of my own grow- 

 ing, I always obtained traces of alumina : but I would not venture 

 to affirm that the earth here was not accidental. 



Silica is met with in only very small quantity in the ashes of wood. 

 It is found, on the contrary, in considerable proportion in the ashes 

 of several annual and biennial plants, and more especially in those 

 of the cereals. Sir Humphrey Davy found silica in the epidermis 

 of the Indian rush. 



If we compare the ashes of the same species of wood grown in 

 soils of different kinds, we see, says M. Berthier, that they may dif- 

 fer very perceptibly ; which seems to establish the fact that the soil 

 exercises a certain degree of influence on their constitution. Thus 

 oak-wood from Roque des Arcs, grown in a decidedly calcareous 

 soil, yielded ashes almost entirely ODnsisting of carbonate of lime, 



Berzelios, TraiU de Chimin, t. r. p. 130, French translation. 



