Formation of Minerals in the Humid Way, 327 



and the principles I have just explained have been the starting-point 

 of the researches which I am about to submit to the Academy. 



The concretionary repositories seem to be formed by solution ; 

 the mineral species which we there find would then be the products 

 of the humid method, derived from liquid deposits, and to a certain 

 extent may be compared to geysers and thermal springs. Moreover, 

 the principles most generally prevalent, even at the present day, in 

 these springs, are the carbonic and hydrosulphuric acids, the alkaline 

 salts, and amongst others the carbonates and sulphurs ; these, then, 

 are the reagents which I have proposed first to employ. But amongst 

 the different influences which may modify, in the subterranean 

 canals, the usual chemical reactions, we must undoubtedly reckon 

 first pressure and a temperature increasing indefinitely with the 

 depth ; and I have endeavoured to realise this double experimental 

 condition. 



It is very evident that this creates numerous difficulties; and we 

 must not be surprised if the crystalline state of the products thus 

 formed is sometimes imperfect, and always microscopic. Besides, it 

 is not the size of the crystals which results from such problems, it 

 is the mere fact of their creation ; and in order to obtain more, 

 all that is required, according to the expression of Daubenton, " is 

 time, space, and rest," — powerful means, which belong to nature 

 alone. 



The method which I have pursued essentially consists in producing 

 all the chemical reactions in a liquid condition, and in glass tubes, 

 hermetically sealed, heated from 100 to 350 degrees. I have 

 almost solely employed solutions of carbonic and hydrosulphuric 

 gases, of bicarbonates and alkaline sulphurs, alone or mixed in va- 

 riable proportions ; I have, then, I repeat, as for a starting-point 

 the composition of many mineral waters, and their most energetic 

 principles. 



By these means of procedure I have artificially formed a great 

 number of natural compounds. Each family of minerals generally 

 group themselves around a common generating agent; so that we 

 might then classify them thus in relation to the presumed composi- 

 tion of the thermal depositions which have served to produce them. 

 I did not wish to make this approximation too absolutely ; as it 

 appears to me to go beyond the immediate interpretation of the 

 facts ; and I shall limit myself here to the mention of the com- 

 pounds which I have obtained, and the different classes of minerals 

 to which tht^y belong. 



Native Metals. — Copper and silver, mixed but not combined, as 

 observed in certain mineral repositories in North America. 



Native Arsenic. i')i(ioj*:| jii.'\ *' 



Ojoides. — Red iron ore Fe^ O^.- ftuHrtz SiO^ in regular six- 

 sided prisms, acuminated with six planes, with strise, and sometimes 

 with unequally-developed acuminating planes, so frequent in natural 



