58 Dr. Davy’s observations on the changes which have 
it were polished, preserving admirably the original impression 
of the die ; whilst others are rough and deformed ? I am 
disposed to reply in the negative, not having yet discovered 
such a connexion ; excepting thus far, that the protoxide of 
copper, and its submuriate, frequently appear in minute 
crystalline elevations rising above the surface of the coin. 
Generally, I suspect the difference of texture in question 
depends on other circumstances, and very likely in different 
degrees of rapidity of operation of the mineralizing cause. 
It is a curious question for consideration, the manner in 
which the crystalline structure is acquired exhibited by these 
incrustations; and still more so, how crystals are formed, 
especially such as were discovered on the helmet, and on the 
adhering calcareous deposit. There being no reason to sup- 
pose deposition from solution, are we not under the necessity 
of inferring, that the mineralizing process witnessed in its 
effects, depends on a slow motion and separation of the 
particles of the original compound ? and, must we not con- 
clude, that this motion is connected with the operation of 
electrochemical powers?* Supposing the oxides first formed 
upon the bronze in a state of negative electricity, with respect 
to the metal, their agency, in a long course of ages would 
be to separate the least oxidable metal, the copper, in its 
pure form ; and all the changes are such as may be accounted 
for from agencies of the same kind, but of different intensity. 
And may not similar explanations be given of other like 
* The separation of the copper from the tin in the bronzes found in the ancient 
cities destroyed by volcanic eruptions, must be referred to another source ; namely, 
the crystallizations dependent upon degrees of heat a little below the point of fusion 
of the alloy. 
