398 Intelligence and Miscellaneous Articles. 



first sight for azurite. It is separated from the remainder of the 

 material by washing with cold water, which does not alter it at 

 all. Its composition is represented by the following formula : — 

 CuO. CO^ + Nab, CO*. 



ITiis is the first example of a double carbonate of copper, anhy- 

 drous and undecomposable by water. 



Bicarbonate of potash also furnishes a crystallized blue product, 

 but this is decomposed by water with great facility. 



In these experiments the tribasic nitrate of copper may be replaced 

 by any other salt, such as the carbonate ; only the alkaline bicarbon- 

 ate must be in excess. 



Experiments to produce azurite by the action of carbonic acid at 

 high pressures (10 to 14 atmospheres) upon ordinary carbonate of 

 copper or upon malachite, mixed or not with carbonate of lime, gave 

 no result. The carbonates were neither dissolved nor altered. 



Becquerel produced azurite two years ago, but his process differs 

 essentially from the author's. — Comptes Rendus, Aug. 1, 1859, p. 218. 



NOTE ON SOME NEW EXPERIMENTS IN ELECTRO-PHYSIOLOGY. 

 BY C. MATTEUCCI. 

 In delivering my recent course of lectures, I was led to try some 

 new experiments upon two points of great interest in electro-physio- 

 logy. I long since showed that an electric current which is trans- 

 mitted across or perpendicularly to the axis of a nervous filament, 

 does not possess, like a current which traverses the nerve longitudi- 

 nally, the property of exciting it and producing contractions in the 

 muscles in which the nervous filament ramifies. The importance of 

 this result, with regard to the still unknown theory of the physiolo- 

 gical action of the current upon the nerves, is easily understood. Un- 

 fortunately the experiment, which may be easily enunciated, is ex- 

 ceedingly difficult to perform in such a way as to lead to a reliable 

 result. Whenever I have paid attention to this subject, I have always 

 tried to render the experiment more perfect. In my electro-physio- 

 logical course I operate as follows. 



Upon a small slip of wood I fix two square plates, of 50 millims. 

 in dimension, one of zinc and the other of copper, at a distance of 

 about 80 millims. A strip of filtering-paper, or of cloth of the same 

 width as the plates, slightly soaked in well- or distilled water, 

 is placed upon the two plates. When a copper wire attached to one 

 of the metallic plates is brought in contact with the other, a current 

 circulates in the moist conductor, having nearly the same intensity 

 at all points. A galvanoscopic leg, supported upon a plate of gutta 

 percha, being rapidly prepared, its nervous filament is stretched upon 

 the paper, sometimes parallel to the electric current, sometimes per- 

 pendicular to it. Then, whenever the metallic circuit is established 

 between the two plates, the frog is seen to contract if the nerve is 

 stretched parallel to the current, whilst there is no sign of contraction 

 if it be perpendicular to it. This result is constant, whatever be the 

 distance of the nervous filament liom the metallic plates; and what 

 is still more interesting, the contraction takes place M'hen the nervous 

 filament, stretched longitudinally, touches the paper for a length 



