396 Analysis of Scientific Books. 
about one common point as a nucleus or primitive form; and 
he was thus almost necessarily led to form an arrangement of 
crystallized minerals only.” Assuming chemical analysis as 
the foundation of the arrangement, Haiiy nevertheless appears 
to have been chiefly governed by the form of the integrant par- 
ticles in determining the species. ‘‘ But however perfect this 
system may be, in regard to the laws by which various second- 
ary forms are derived from the same primitive form, it is not 
equally competent to establish a mineralogical method,” and 
since the integrant particles of some species, really distinct, 
have precisely the same form, the character derived from that 
form, being less general, ought to be subordinate to the true 
composition. 
Moreover, some minerals crystallize much less frequently 
than others. May not some never crystallize at all? Every 
species has integrant particles, and would not those integrant 
particles remain the same in their real nature, whether regularly 
arranged in a crystal, or collected into an amorphous mass? 
Minerals, therefore, which have never been seen crystallized, 
may constitute really distinct species ; and though their number 
be small, their claims to that rank, if well grounded, ought to 
be asserted. 
Having by this mode of reasoning shewn the insufficiency of 
primitive form, &c., to establish a mineralogical method for the 
determination of species, our author proceeds to recapitulate 
the principles on which he founds his own arrangement. These 
are, first and foremost, chemical composition, ‘‘ the only sure 
criterion for determining the species.” When this is wholly 
unknown, or known imperfectly, other characters, depending 
more or less upon it, must be employed ; these are, crystalline 
form (especially the primitive) and structure, 
The latter of which may be extended to foliated masses, not possessed 
of a regular form ; for these often easily yield to mechanical division, and 
thus enable us to discover the primitive form. 
When minerals, whose eae an are capable of combining in various 
> 
proportions, are crystallized, the form of the integrant particle may be of 
great use in limiting the species. 
The form of the integrant particle, and the primitive form, 
may be useful in distinguishing the non-essential ingredients, 
“¢ for whatever can be added to a mineral, or taken from it, 
without affecting these forms, may be considered foreign.” 
The secondary forms are also important, provided the angles 
of the crystal be accurately measured. 
The nature of amorphous minerals, whether granular or compact, may 
often be ascertained by their intimate connexion with well-defined crys- 
tals, or even with laminated masses of the same substance ; of this, epidote 
furnishes an important illustration. 
When neither analysis nor crystalline form can be resorted 
