m 



On Mr, Chenevix^ Attack 



[April, 



depend. So far I believe all are agreed. Even Mr. Chenevix 

 will ijot condemn Werner's definition in the jibstiact, though he 

 has not thought proper to take any notice of it, for what reason 

 \jQ hiniself is best able to inform us. 



But Httiiy^s definition, it seems, is infinitely preferable. Why 

 go ? Haiiy's defiijition is the same as Werner's, only he adds a 

 particular of which Werner has taken no notice. Minerals, to 

 belong tp the same species, must not only agree in their com- 

 position, but also in the form of their integrant molecules The 

 guperiority of the definition must depend upon tiiis addition. Now 

 the cleavage, for the form of the integrant molecule is neither 

 piore nor less than a mathematical hypothesis adopted by Haiiy, 

 constitutes a character of tninerals, which 1 admit to be of the 

 very first importance ; but so is the specific gravity. And I will 

 appeal to Mr. Chenevix himself, whether the specific gravity is 

 jiot as important a character as the cleavage ; for whenever 

 Hiinerals differ much in their specific gravity, flaiiy always 

 places them in distinct species, even though the form of their 

 integrant molecules be in his opinion the same. Haiiy might 

 therefore^ with as much propriety, h^ve added tp Werner'^ 

 definition of species, that minerals belonging to the same species 

 must have the scime sp(iclfic gravity^ as the same form of inte- 

 grant molecule. And several other characters stand in the same 

 situation, and have just as fair a claim to be introdi^c^d into the 

 difinition of species as the cleavage. 



Thus with respect to Haiiy's definition of mineral species, so 

 far from considering it as superior to the definition of Werner, 

 I think it inferior, in consequence of the arbitrary afldition with 

 which it is clogged. But even supposing the addition of Haiiy 

 to be perfectly correct in itself, and supposing it possible to de- 

 termine the angles of crystals with perfect accuracy, still the 

 definition would be improper as the ba§is of a system of mine- 

 ralogy, because it would exclude from the consideration of 

 Tnineralogigts all those nunierous minerals which are not crystal- 

 lized, ai)d with respect to which therefore it is impossible to 

 determine their primitive form. Now this is the case with by 

 far the greatest part of minerals. What can be more prepos- 

 terous than a defioition which excludes from the rank of species 

 the greater number of the very substances which it is its pro- 

 fessed object to classify ? Mr. Chenevix contends that this is 

 perfectly proper^ and insists upon it that all uncrystallized mine- 

 rals should be excluded. That is, that 99 hundredth parts of 

 all the minerals in nature should be discarded from the consi- 

 deration of the mint ralogist, because they happen to be incon- 

 sistent with an arbitrary definition. But Haiiy has conducted 

 himself with more moderation. He has introduced into his 

 f jstem two inineral species, neither of which contains a single 



