186 On Vegetation and Soils. 



calcareous vegetables; fo that it feems to fupply the place of 

 that quantity of water which they had lefs than the granitic 

 vegetables. 



Granitic vegetables being more aqueous, ought, according 

 to the obfervations of Duhanicl, to have a fofter texture, and 

 confequently to contain more afhes. The incineration of 

 granitic and calcareous vegetables gave differences too diffi- 

 cult to be appretiated ; but, however fmall they might be, 

 fhey appeared to confirm this obfervation. 



The afhes furnifhed by incineration having been carefully 

 analyfed, Sauflure found in thofe of calcareous vegetables* 

 a greater quantity of that earth, and much more filex in the 

 granitic ; fo that the afhes of the calcareous rhododendron 

 in ioo parts contained 57 parts of the earbonat of lime and 

 5 parts of filex; while thofe of the granitic rhododendron con- 

 tained 30 parts of earbonat of lime and 14 parts of filex. 

 This great difference is one of the mofl convincing proofs 

 of the influence of the foil on vegetation. As the lime-ftone 

 of mount la Salle, where Sauflure collected the vegetables 

 the allies of which he analyfcd, contains filex, this che- 

 •mift: was defirous of knowing whether vegetables collect- 

 ed on foil entirely free from that earth contained any of 

 it. He therefore analyfcd the afhes of fome plants which 

 had grown on linie-flonc totally free from filex, in the 

 mountain of Kcculcy-de-Thoirv, in Jura, and found in one 

 or two cafes only a very fmall proportion of filex, while in 

 the afhes of the vegetables of Breven he perceived much 

 more calcareous matter than that mountain could furnifh. 

 Sauflure thence deduces this geologic conclufion, that ve- 

 getables cover with calcareous matter mountains whiclir 

 have a bafe of filex, while the inverfe of this does not take- 

 pi ace. 



In the laft place, he made a comparative analvfis of the 

 mould in which the plants of Breven and thofe of Reculey- 

 de-Thoiry grew, in order to determine the relation which 

 ought to exift between that mould, the foil, and the afhes 

 of vegetables which grow in it, and had nearly the follow- 

 ing refults : The mould of Breven gave 60 of filex, 14 of 

 aluminc, ri6 of lime, Sec. That of Reculey-de-Thoiry, 



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