Intelligence and Miscellaneous Articles. 77 
the torrents, become decomposed by the mutual friction of their 
particles. M. Becquerel has proved this decomposition twenty 
years ago, by crushing basalt, felspar, &c. in an agate mortar in 
presence of water; the damp paste which is formed soon furnishes 
an alkaline reaction. The decomposition of the bodies pulverized 
is sometimes facilitated by mixing them with other bodies of which 
the elements are capable of acting by double decomposition upon 
those of the former. 
Thus on triturating together in equal atomic proportions nitrate 
of lead and iodide of potassium, iodide of lead and nitrate of potash 
are obtained in a few moments. In operating with sulphate of soda 
and carbonate of lime, a double decomposition is also produced. 
In a recent communication to the Academy, M. Daubrée has 
brought forward some new evidence in support of the preceding 
observations. He operates as follows:—Into a cask, to which he 
gives a rapid rotatory movement, he puts water with fragments of 
felspar and quartz; at the expiration of a certain time a mud pro- 
duced by the trituration of the particles is deposited, and the water 
becomes alkaline. ‘The felspar is consequently decomposed, at least 
partially. 
In these investigations, M. Becquerel had hitherto operated only at 
the ordinary pressure and temperature of the atmosphere ; in the pre- 
sent case he has experimented at temperatures and pressures more or 
less elevated, with the view of obtaining an idea of what must have 
taken place in the sedimentary rocks when they were covered by 
ejected rocks, such as granite, porphyries, basalt, &c. Inthe present 
memoir the combined influence of heat and pressure in chemical and 
electro-chemical actions are alone referred to. The effects resulting 
from mechanical actions will be treated of in a particular memoir. 
The author operates as follows :—He takes a tube of 5-6 millims. 
in diameter and 2 decimetres in length, closed at one extremity ; 
into this he puts the solid substance, and pours over it the solution 
which is to react. On the top of this some sulphuret of carbon or 
wether is poured; the tube is sealed up and placed in a stove heated 
to 212°—302° F. Another tube is sometimes introduced into the 
principal one, containing another volatile liquid, the elementsof 
which are to react upon the solid body or the solution ; lastly, when 
electro-chemical effects are in question, the apparatus destined to 
produce these is placed in the tube. By means of these different 
modes of experimentation, M. Becquerel has obtained the following 
products :— 
1. Arragonite in right rectangular prisms with two bevels at each 
apex, and the angles of which are measurable by the goniometer. 
2, Protoxide of copper in pretty octahedral crystals. 
3. Sulphurets of copper in prisms, having the aspect of the native 
sulphurets. 
4, Sulphurets of silver and lead in lamellz, having a metallic aspect. 
5. Green carbonate of copper (malachite) and blue carbonate of 
copper in small nodules. 
6. Metallic iodides, bromides and cyanides, insoluble and crystal- 
lized, &c, 
