Scientific Intelligence. — Mineralogy. 365 



acid, which flows upon the walls, carrying with it lime and 

 other oxides which occur in its way. Several other examples 

 are known of the daily formation of sulphuric acid, and conse- 

 quently of the decomposition of hydro-sulphuric gas. 



12. Discovery of Iodine in an Ore of Zinc. — It is well known 

 that M. Vauquehn was the first who discovered iodine in the 

 mineral kingdom. He found this simple substance in argenti- 

 ferous ores of the neighbourhood of Mexico ; and, according to 

 M. Del Rio, these ores come from the province of Zacatecas. 

 M. Bustamente afterwards found indications of it in a lead ore 

 of a greyish-white colour, from the mines of Catorce. In the 

 last place, M. Mentzel has just determined its presence in an 

 ore of caduciferous zinc from Upper Silesia. 



13. Inquiries into the structure of Bodies zvhich crystallize 

 regularly ; by M. Savart. — In this investigation, the author has 

 had in view to determine, by means of the sonorous vibrations, 

 the elastic state of rock-crystal and carbonate of lime. As it 

 would occupy too much time to expose the mode of experiment 

 which M. Savart has employed to attain this object, we shall 

 only say, that he has discovered in these two substances three 

 systems of axes of elasticity, which refer to the primitive form 

 of each of them. Thus, in rock-crystal, the small diagonals 

 of the three rhomboidal faces which form the obtuse solid angle 

 of the primitive rhomboid possess the same degree of elasticity ; 

 and each of these lines is the axis of greatest elasticity of each 

 system, while the other diagonals of the same faces of the crys- 

 tal are the intermediate axes, and the edges <^hemselves of the 

 rhomboid (parallel four to four, consequently reducible to three, 

 as they are twelve in number), are the directions of less elasti- 

 city. M. Savart laboured particularly to bring out the diffe- 

 rences and approximations which exist between the results to 

 which his method leads, with respect to the intimate structure 

 of bodies, and those to which the inquiries respecting light had 

 led the observers who have preceded him. Thus, he shewed 

 that the disposition of the nodal lines of a circular lamina of 

 rock-crystal, inclined in a given manner with respect to the op- 

 tical axis, is always intimately connected with the direction it- 

 self of that axis, or of its projection upon the plane of the la- 



JULY OCTOBEE 1829- B b 



