On Crysiallographyi 99 



ininerals, as well as sulphated alumine and the diamond, 

 assume the t'urin of a rtgular octahedron*. 



It wfs this sFmilitiide of forms which, at a time when 

 the study of crystallization was scarcely in its infancy, in- 

 clined Liniisus to think that the salts should be regarded as 

 the generators of crystallization ; that the union of any given 

 sail with a given kind of stone was a sort of fecundation 

 which communicated to the stone the property of crystal- 

 lizing under the form peculiar to the salt which performed 

 the iunction of the fecundating principle f. The diamond, 

 for instance, he considered as a species of alum, because it 

 crystallizes like the latter, and he gave it the name of alumen 

 adamasX' Thus Linnaeus thought he found in the nnneral 

 kingdom the basis of the sexual system, of which lie made 

 so advantageous an use in Botany. We know that Tourne- 

 fort, on observing the ramilied stalactites of the Grotto of 

 Anliparos, imagined that stones vegetated in the same way 

 as plants. Botany was the favourite study of these two ce- 

 lebrated men, and all Nature, in their opinion, spoke the 

 language of their favoflrite study. 



Linnaeus Hui)joined to his work some descriptions and 

 figures of crystals, which were su^ciently accurate, consi- 

 dering the state of science at the time; and in this respect he- 

 may be regarded as the founder of crystallography. 



Latterly, Rome de ITsle has referred the study of cry^ 

 jstallization to principles more and more conformable to ob- 

 servation. He arranged together, as far as po'?sible, crystals 

 of the same nature. Among the diiferent forms relative to 

 each species, he chose one as the most proper, from its sim- 

 plicity, to be regarded as the primitive form ; and by sup- 

 posing it truncaied in different vi'ays, he deduced the other 

 forms from it, and determined a gradation, a series of trans- 

 itions belweeii this same form and that of polyhedrons, 

 which seemed to be still further removed from it. To the 

 descriptions and figures which he gave of the crystalline 

 forms, he added the results of the mechanical measurement 



• We shall presently explain the reasons which can assisr us in conceiving 

 the nature of this resemblance in configuration between minerals of various 

 descriptions. 



f Linniei Amaml. Acad, tome i p. 4G6 & seq. 



t The learned author of this cl'.ssification was well aware that, among the 

 bodies which he associated under one and the same species, several presented 

 a form diirerent from that which was the type I'f the species. But he tried 

 to brinj^ them to this last form according to soiiie vague traces of resemblance 

 which iie caught from their external aspect ; and as but a very small number 

 of crystalline torriii had been at that tmie observed, the most of ihem ex- 

 ttemely simple, these similarities, which would have been impracticable in 

 the prcseni advanced state of science, were then of !«» dif&cuU classtiication. 

 G2 of 



