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Art. XXIV . — On Metallurgic Crystallography. By Profes- 
sor Haussmann. 
r 
Introduction.—*- JL N our investigations concerning the forma- 
tion of inorganic bodies, we cannot hope to make successful 
discoveries in any other way, than by observing Nature actually 
at work in forming these bodies. And not only must we ob- 
serve Nature in her own operations ; we ought also to place na- 
tural bodies in such conditions as to excite and draw forth their 
latent powers. From effects, thus in some degree artificially 
produced, we may often be able to trace the path through 
which these bodies, as they are in their natural state, usually 
pass, and hence to develope the principles that regulate their 
formation and transformation. In these experiments, however, 
our conclusions are liable to uncertainty, from the consideration, 
that, in the case of large masses, having space and time for the 
operation to which they are subjected, the powers which these 
bodies possess, in these circumstances, are capable of producing 
very different effects from what they produce on a smaller scale, 
with space and time greatly limited. But we shall have greater 
dependence upon our conclusions, in proportion as the artificial 
conditions in which we place bodies are assimilated to those 
which lead naturally to the formations and changes we wish to 
examine. And in order to arrive at such conclusions, we shall 
find, that those observations which result from great metallurgi- 
cal processes, are likely to be much more accurate than those 
resulting from small chemical experiments, though undoubtedly 
these last are of* great importance. 
By conducting our investigations in the manner stated above, 
we cannot fail to make the observation, that the natural powers 
of bodies lead often to the same result by different processes ; 
and that some natural bodies can be made to produce the same 
formations by contrary processes. A formation often takes 
place by what is called a dry process, so exactly similar to what 
is produced by a wet process, as not to be distinguished the one 
from the other. Copper subjected to metallurgical processes, 
forms octaedral crystals, in the same manner as when subjected 
to a wet process. Crystals of arsenic acid, when produced by 
sublimation , are often similar to those which are formed from a 
