Intelligence and Miscellaneous Articles. 449 



if it be touched with two fingers, the flood is seen to divide in two 

 near the point touched ; the portion emanating from the positive 

 electrode terminates in a slightly convex surface, distinctly marked 

 by a zone more brilliant than the rest. One would say that there 

 was an accumulation of electrical matter at the spot where the ex- 

 ternal influence has caused a solution of continuity. This zone is a 

 band in course of formation; it may be rendered more or less 

 distinct, and, instead of a single zone, two or more neighbouring 

 bands may be produced. 



3. By means of condensers formed by glass walls, furnished with 

 metallic armatures on the outside, and containing between them a 

 stratum of confined air connected with a manomerer, we are at pre- 

 sent endeavouring to analyse the movements caused in this gaseous 

 stratum by electrical actions ; although no spark passes, a movement 

 is perceptible in it, esjiecially at the moment when one' of the plates 

 is discharged upon the other externally. 



The preceding experiments prove that electrified gases yield to 

 electrical attractions and repulsions, that more or less conductive 

 media, composed of mobile particles, are disposed by these influences 

 in strata in which the particles are alternately dispersed and accu- 

 mulated, and that this disposition gives rise to difl"erences of tension 

 and to luminous bands. After this it is not much to assume that in 

 a gaseous column the influences of electricity give origin to dilated 

 and condensed strata, which are very thin in an ordinary gas, but 

 thicken in a rarefied gas ; that the dilated strata conducting the 

 electricity, the two opposite fluids acquire, from the two sides of the 

 condensed strata which are less conductive, a sufficient tension to 

 traverse these in the form of a discharge and to illuminate them. 

 The effects of external conductors would have their application in 

 this view. — Comptes Rendus, February 14, 1859, p. 338. 



ANALYSIS OF A NATIVE SULPHATE OF COPPER AND IRON. 

 BY M. F. PISANI. 



This mineral was found in stalactitic, mammillated masses, often 

 of considerable size, in a cave close by a mine of copper pyrites in 

 the interior of Turkey. 



It has the colour of ordinary sulphate of copper, especially the 

 fresh fracture. Inside are observed a quantity of small crystals, 

 often lining drusy cavities. It is almost entirely soluble in cold 

 water, leaving a scarcely perceptible residue. By long exjjosure to 

 air its surface assumes an ochreous tint, the eflfect of the peroxida- 

 tion of the iron, which this mineral contains in large quantity. 



On analysis it gave the following result : — 



Oxygen. Proportions. 



Oxide of copper 15-56 3-14 "1 



Protoxide of iron ... . 10'98 2-44/ 



Sulphuric acid 29-90 17-94 3 



Water 43-5G 38-72 7 



100-00 

 Phil. Maf/. S. 4. Vol. 17. No. IIG. June 1859. 2 11 



