1 94 On CryslaUogiaphy. 



in Forming the faithful picture of the relations which ex- 

 isted anumg these various principles combined with each 

 other in the substance as yet untouched. We never pur- 

 eliaise at too high a price what contributes to the perfectiorr 

 orf a science, and we ought not to calculate time when It 

 PS necessary to arrive at innnutable truths. 



It will perhapsi be said aL-^o, that a rpiineral substance i^ 

 found in compact or granutous masses, which refuse to 

 submit to any mechanical division. 1 shall answer, that 

 frequently also these masses form a coivtinuily with cry- 

 stallized substances, or such as have a lamellatcd; texture, 

 in such a manner that it is vrsible that they are referred to 

 the same species ; and as to those w hich we meet with in an' 

 insulated state, if noihfnej more \9> then wanted ^o determine 

 them, except characters less certain than that which is de- 

 rived from the structure, it merely results that we ought to 

 regret that this hst character has not a greater generality;- 

 and' this very regret is a kind of avowal of its preeminence, 

 ill every case in which it can be employed'*. 



Will it be said that there are forms of integrant mole- 

 cules which are common to substances of different natures? 

 I si^aU observe, in the first plao», that this does not take 

 place except with respect to solids which have a peculiar 

 character of regularhy,. m such a manner that in all the 

 other cases the form of the integrant molecule is sufficient 

 of itself for determining the species. I shall answer after- 

 wards, that most of the substances which have one com-^- 

 mon molecule (and this may be said of aH those which, 

 like- the ductile metals, never Imve a lameHous texture) may 

 be easily distinguished by other characters. For example, 

 the cube agrees best as the integrant molecule with boraied 

 magnesia, muriated' soda, sulphurated lead, sulphurated 

 iron, &c. ; all of thera ascertainable independently of me- 

 chanical division. 



In a wor(> : alf that I wish to infer from this discussion- 

 is, that the character drawn from the structure ought to 

 occupy a very distinguished rank among those which are 

 made use of to njark the general charactsr {triage) of 



• Sometimes the rareness of crystals is alleged as a proof of the scanty 

 resources furnished" l)y tbe character drawn from crystallization. This 

 difficulty does not scan'i to be well founded, since a single crystal clearly de« 

 fined, is sulficient to determine a nuilritude of irregular masses, wKiirh, with 

 this crystal, would have relations indicative of an identity in nature: and if, 

 by object in)^ that crvstali are rare, it is meant- to say that there are several- 

 niineralo^^cal species which arc never presented under crystalline forms, 

 I shall ask if these are properly species per ye, and not on the other hand* 

 mixed species, in the production of which diffbrent species hare- coocurred ^ 



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