and Mineralogy i 65 
of previous systems, the introduction of chemical characters usuv» 
ally passes without examination; they are placed there only to 
satisfy the understanding therefore, the mode alluded to would 
have met with acceptance. But what contradicts the principles 
of a science can never satisfy the understanding ; and it is better 
to endure censure, than, by violating the principles of natural 
history, to deserve it* 
9. Properties the" character s^^lih-Q characters ought to be 
as short and as uniform as possible. Those of the classes, genera 
and species, possess the properties just mentioned ; but in those 
of the orders, brevity is not to be attained. However, this de- 
fect is no obstacle to its employment in the mean time, and will 
probably be extenuated afterwards, if the natural historical path 
in mineralogy be more frequently trodden. 
10. Specimen of the system of characters.-— avoid becom- 
ing prolix, in discussing the various circumstances that concern 
this matter, it seems advisable to subjoin a specimen of the sys- 
tem of characters. It contains, (1) the characters of the classes ; 
(2) the characters of three contiguous orders belonging to the 
second class, the metals^ pyrites^ andi glances (3) the charac- 
ters of three genera belonging to the second of these orders, co- 
halt-pyrites, iron-pyrites, copper-pyrites ; and (4) the charac- 
ters of the species belonging to the second of these genera, the 
h&xaedral, prismatic, and rhomhoidal iron-pyrites 
|11. Use* — Immediate determination.— P £}\q mode of using this 
system of characters is the same as in zoology and botany ; it 
needs no farther explanation. Some remarks are, however, ne- 
cessary upon the condition of those individuals to be settled by 
means of it. In the characters of species, form, hardness and 
specific gravity are the principal characteristics ; and this is al- 
ways the case in every species of such a nature as to admit the 
observation of them. Hence if the settlement of an individual 
is to be completed, those three characteristics must be capable 
of being observed in it. Put the case, that, with regard to an 
individual of the genus Iron-pyrites, the form could not be dis- 
covered, though both the hardness and the specific gravity 
* Second Appendix. 
VOL. IV. NO. 7. JANUARY 18S1. E 
