MEDICINAL PROPERTIES OF PLANTS. J7 



sophers have distinguished by the name of adhesion has some 

 properties in common with chemical attraction, such as the 

 point of saturation, and elective affinity, and that hence it 

 Appeared to me, to be very properly termed attraction of 

 surfaces. 



I shall not hesitate however, to renounce the principle I 

 have adopted, that of an attraction of surfaces, and retract 

 the explanations of some interesting phenomena, which I have 

 deduced from this principle, and given in the papers already 

 mentioned, if convincing facts and just reasonings show me 

 their incompetency. 



Abstract of an Essay on the Medicinal Properties of Plants 

 compared with their external Form and natural Classifica- 

 tions: by Mr, Decandolle*. 



O branch of study deserves the name of science, till it Indication of 

 is sufficiently advanced, to be able to determine facts a priori. * he virtues o{ 

 The materia medica, which rests entirely on the basis of ex- 

 perience, has but three means of forming a judgment of the 

 properties of substances; which are, their sensible qualities, 

 their chemical composition, and their natural analogy. The 

 object of Mr. Decandolle's work, which forms a quarto vo- 

 lume, is to ascertain how far the analogy of the forms of 

 vegetables affords indications of their properties. 



Camerarius first decidedly took up the affirmative side of Have plantssi- 

 this question in \699- He was followed by Isenflamm, ^nce'simii 

 Wilka, Gmelin, and more especially by Linneus and de Jus- lar virtues-? 

 sieu. On the other hand Vogel, Plaz, and Gleditsch wrote 

 against it. Notwithstanding what has been written by these 

 learned men, Mr. Decandolle has contrived to treat the ques- 

 tion with some novelty, not only in consequence of the pro- 

 gress, that the study of natural affinities has made within these 

 twenty or thirty years; but because, confining himself ex- 

 clusively to no system, he has formed his deductions not from 



* Annates de Chimie, Vol. LXI, p. *U, January, 1807. 

 Vol. XIX.— Jan. 1808. C a fe\r 



