REPORT ON MINERALOGY. 
359 
pression being destroyed in the calamitous conflagration of that 
city (Sept. 1827). Its plan was in some respects similar to the 
preceding ones ; but it made the number of ingredients, and 
not that of the atoms, its basis. Keferstein also published a 
mineral system in the fourth volume of his Geognostic/ies 
Teutscliland ; he has imitated Beudant, who formed his system 
upon Ampere’s circular arrangement of simple bodies, having 
constructed for himself another circular arrangement of eight 
members, on which his method is grounded. 
Notwithstanding the confusion which may naturally be ex¬ 
pected to arise from the conflict of so many different plans of 
arrangement, we may see, I think, a tendency in the chemical and 
mineralogical methods to approach towards each other. It has 
been now proved that neither course can by itself lead to a satis¬ 
factory classification. Those wdio wished to arrange by external 
characters alone, trusted much to the acuteness of their senses, 
and believed that they could, by a sort of instinct, make out 
which of the perceptible properties of substances w r ere most 
important. The chemists, on the other hand, deeming that 
their knowdedge of the constitution of a mineral must be suffi¬ 
cient to determine its nature and place, did not consider that 
w r e require observation to teach us in what mode such know¬ 
ledge is to be applied ;—for what but the comparison of external 
characters can teach us, for instance, that tellurium, sulphur, 
selenium, arsenic, discharge similar functions in the composition 
of minerals, and must be similarly employed in our classifica¬ 
tion ? 
It will probably be allow ed that a system of arrangement 
proceeding on strictly chemical principles, which should bring 
together in all cases the substances which most resemble each 
other in external properties, would satisfy the requisitions of 
the science, and that nothing short of this would do so. Such 
a system is not at present within our reach ; but it will perhaps 
be useful to look upon all methods of classification now" pro¬ 
posed, as attempts to approximate to such a perfect system, 
whether they be founded upon external characters or on che¬ 
mical principles. Our knowdedge of neither of these branches 
of the subject is as yet complete enough to lead us to expect 
from it a system which shall be exact according to both; but 
we may be held to have made some progress in the requisite se¬ 
ries of trials and conjectures, when v r e have constructed any 
chemical classes which consist of substances of similar cha¬ 
racter and properties. 
That some progress of this kind has already been made 
cannot be denied. The new system of Berzelius, or that of 
Beudant, or indeed any of the new chemical systems, w T ould 
