GEOLOGY. 321 



the mineral species 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 the sulphates ; these then are 

 the reagents I propose 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 

 endeavored to realize 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 some- 

 times imperfect, and always microscopic. Besides, it is not the size^f 

 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, is 

 time, space, and rest powerful means which belong to nature alone. 

 The method I have pursued essentially consists in producing all the 

 chemical reactions in a liquid condition, and in glass tubes, hermeti- 

 cally sealed, heated from 100 to 350 C. I have almost solely em- 

 ployed solutions of carbonic and hydrosulphuric gases, of bicarbonates 

 and alkaline sulphurs, alone or mixed in variable proportions ; I have, 

 then, I repeat, as a starting point, the composition of 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 gen- 

 erating agent; so that we might then classify them thus in relation to 

 the presumed composition of the thermal depositions which have served 

 to produce them. I do not wish to make this approximation too abso- 

 lutely ; as it appears to me to go beyond the immediate interpretation 

 of the facts ; and I shall limit mvself here to the mention of the corn- 



/ 



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

 which they belong. 



Notice Metals. Copper and silver, mixed but not combined, as 

 observed in certain mineral repositories in North America. Native 

 arsenic. 



Oxides. Red iron ore Fe 2 O 3 . Quartz Si O 3 , in regular six sided 

 prisms, acuminated with six planes, with strias, and sometimes with 

 unequally-developed acuminating planes, so frequent in natural crys- 

 tals. Red copper ore, or red oxide of copper, in red shining translucent 

 octahedrons. 



Carbonates. Carbonates of magnesia, of iron, of manganese, of 

 cobalt, of nickel, of zinc, of copper or malachite. 



Sulphates. Sulphate of baryta, in the primitive form. 



Sulphurates. Realgar, in transparent crystals, with the colors, 

 lustre and form, as in mineral veins. Sulphuret of antimony, in 

 acicular, shining, metallic-looking crystals. Sulphuret of bismuth with 

 similar characters as the preceding. Sulphurets of iron, of manganese, 

 of cobalt, of nickel, of zinc, of copper. These last mentioned are 



