l'2<> On the most proper Means of [Aug. 



remained in a state of infancy, a science which every day ad- 

 vances the progress of medicine. The principles according to 

 which these philosophers directed their labours have now altered. 

 Their discoveries, in consequence, may lose some of their utility, and 

 may excite less interest ; but they will not, on that account, lose 

 their merit. These chemists cannot, and ought not, to be judged 

 but according to the knowledge of the period when they lived. 

 A man ought to be acquainted with the progress which the 

 science which he cultivates has made, both in his own and in 

 other countries; but we ought not to require of a philosopher to 

 penetrate into the progress of future ages. The name of Lavoisier 

 will be always dear to those who know the difficulties he had to 

 overcome in order to accomplish his object. Few persons are 

 possessed of a spirit of philosophy so strong as to enable them to 

 struggle against opinion generally received. It is always dan- 

 gerous to take a part against opinions to which time and expe- 

 rience have affixed the seal of truth. Those obstacles which 

 would have often been insurmountable to another did not prevent 

 Lavoisier from opening a new road in chemistry. Davy, that 

 English chemist who has drawn upon him the attention of his 

 brother philosophers in France, will he not force us by degrees 

 to believe facts which experience perhaps will one day confirm, 

 though the principles at present adopted are often at variance 

 with the views of that celebrated philosopher ? 



The analyses of minerals are very difficult to make. Hence 

 the reason why so i'ew are exact. Klaproth and Vauquelin have 

 brought the art to a state of great perfection. They have brought 

 their analyses to an uncommon degree of exactness, which it 

 would be difficult to surpass. Rose, Bucholz, Laugier, Deseo- 

 tiles, Berzelius, Ekeberg, and others, have skilfully followed 

 their footsteps. Vauquelin and Klaproth often make discoveries 

 at the same time: it seldom happens that they do not agree when 

 they operate upon specimens from the same place. Exactness 

 alone is not sufficient in an analysis. The least portion of matter 

 foreign to the body subjected to analysis, whether it be the con- 

 taining rock, or any other mineral, occasions an error in the 

 chemical result. Nature, while at work in her great laboratory, 

 lias often agents at her command that arc unknown to us. The 

 matmer in which decomposition is produced will perhaps always 

 remain a secret to us ; but it is impossible to doubt that the 

 nature of a mineral ought to change as soon as its external cha- 

 racters become quite different from what they were before. 



No system is easily constructed when the object is to construct 

 it well. Systems of mineralogy will be always more difficult 

 than those of the other branches of natural history. The nature 

 of the objects which it includes opposes itself to its perfection. 

 In mineralogy we have not the advantage, as in zoology, of 

 subjecting living beings to rules, nor, as in botany, plants which 

 in dying reproduce their genera and species. 



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