Intelligence and Miscellaneous Articles. 453 



Alcohol presents the same phenomena as water. The calorific 

 decomposition is much more active in alcohol than in water. When 

 a point and a ball are immersed in the liquid, no decomposition 

 appears to take place on the ball if it be positive, the oxygen pro- 

 bably combining with the alcohol ; the decomposition is very weak if 

 it be positive, and the gas obtained appeared to consist of bicarbu- 

 retted hydrogen. The product of the calorific action appeared to 

 be a mixture of hydrogen and carbonic oxide, which would be very 

 readily explained by the composition of hydrated alcohol. 



The author had observed in his eudiometric analyses that the two 

 wires of the inductive apparatus became unequally heated, — the 

 negative wire became red-hot and fused, whilst the other remained 

 cold. He then tried the decomposition of some gases placed in a 

 tube furnished with two wires, the extremities of which were very 

 close together. 



Sulphuretted hydrogen gave sulphur and hydrogen ; the negative 

 wire was incandescent and furnished the sulphur, the positive wire 

 remained dull. Sulphurous acid underwent no decomposition. The 

 negative wire fused, whilst the positive did not even redden. — 

 Comptes Rendus, June 27, 1853, p. 113. 







ON THE FORMATION OF CRYSTALLINE MINERALS. 

 BY A. DREVERMANN. 



The author has instituted a series of experiments upon the arti- 

 ficial production of those crystalline minerals which are formed in 

 the humid way, starting from the opinion that the crystals occurring 

 in geodes could be produced neither by gradual evaporation nor by 

 the cooling of saturated solutions. By the method employed, sub- 

 stances the most difficult of solution, as well as those which are 

 readily soluble, may be crystallized in a simple and easy manner ; it 

 also at the same time admits of an infinite variety of modifications 

 of the forces acting. The principle of the method consists in gradu- 

 ally changing the affinity of the solvent for the substance dissolved 

 in such a manner that the latter may be gradually separated. This 

 change is effected by the diffusion of one liquid into another, which 

 liquids must be so chosen, that, when they mingle, a solid substance 

 will separate. 



The arrangement of the apparatus is exactly the same as in Gra- 

 ham's experiments. Some powdered chromate of potash and nitrate 

 of lead was introduced into two tolerably long gas cylinders, filled 

 carefully with water, and then placed close together in a large 

 beaker, which was also so far filled with water that the two 

 cylinders were covered. In consequence of the upward diffusion, 

 the nitrate of lead reached the large beaker in the course of a few 

 months, when several very beautifully coloured amorphous com- 

 pounds were formed on the margin of the cylinder filled with chro- 

 mate of potash. Within the same cylinder beautiful orange-red bril- 

 liant acicular crystals of chromate of lead (PbO, CrO 3 ) were attached, 

 together with small, dark red, rhombic tables of melanochroite 

 (3PbO, 2Cr0 3 ) : these constantly grow larger. The needles of 

 chromate of lead formed in this manner attained a size of 3 or 4 



