Q12 Professor Mohs’s General Reflections on 
and certainty ; for every thing comprised within its limits lies 
plainly before our eyes, and only requires to be correctly ob- 
served and rightly understood,— objects, for the attainment of 
which, we have many excellent means at our disposal. The ob- 
ject of Chemistry is less palpable at first sight. It is the product 
of ingenious operations* sometimes of very delicate ones, in 
which we call into action the peculiar powers of various sub- 
stances ; and it is necessary to be perfectly acquainted with the 
properties and action of these bodies, if we intend to form an 
opinion of what they produce, and not make use of one in place 
of another, in the same manner, as in an equation* we are enabled 
to determine the — only upon the supposition that we know 
the a and the 5. If we reflect upon all these difficulties, so far 
from finding reason to complain of the present imperfections, in 
regard to the certainty afforded by the results of the chemical 
analysis of minerals, we ought rather to be induced to pay our 
tribute of admiration to the high degree of perfection which 
this art has already attained, comparing it at the present day 
with the state in which it existed but a few years ago. 
In regard to the human intellect, the value of the information 
derived from Natural History and from Chemistry, is absolute- 
ly equal. It is an erroneous idea, that Chemistry penetrates in- 
to the interior of bodies, and, therefore, a reprehensible practice 
to reproach Natural History with being confined to their external 
appearances. It will always remain impossible to perceive the 
internal disposition. Before an object can come within the scope 
of our observation, it must first become an external object* ca- 
pable of being perceived by our senses. Hence, the analysis of 
a body does not disclose its interior* or its component particles, 
but only the exterior of the results obtained by the operations, 
the substances themselves* and their relations to each other. 
The body which has been analysed disappears, as it were, from 
nature ; and in its stead other bodies are produced, which, as 
such, did not exist before. In the same manner, tw T o or more 
bodies, if joined by chemical action, will disappear, and give rise 
to a new one, in which they no longer exist as they were before. 
It is sufficiently evident, therefore, that neither Chemistry nor 
Natural History, are capable of disclosing the essence or the 
interior of bodies ; because this does not depend upon the sci- 
