6CNI Intelligence and Miscellaneous Articles. 



MfStsi'^t' is not equivalent to xJiyth of that exerted in the case of 

 oxygen. 



3. If oxygen gas is introduced in small quantities at a time into 

 the bulb filled with nitric oxide, the magnetism diminishes until the 

 proportion of the two gases becomes sufficient to form hyponitric 

 acid (NO^). The action is then apparently null. On adding still 

 more oxygen, the magnetism reappears and continues to increase. 



4. Hyponitric acid (NO4), when condensed, is a diamagnetic 

 liquid ; nothing is at present opposed to the view that the gas, in pro- 

 portion to its volume, is but very feebly magnetic. All my attempts 

 to decide this important question have failed : does nitrous acid gas 

 (NO3), which is pretty strongly magnetic, retain its specific magne- 

 tism when it becomes liquid ? 



5. The magnetism of oxygen and of nitric oxide, as also that of 

 the magnetic mixtures, is in proportion to the density of the gases. 



6. A magnetic gas, when mechanically mixed with any other in- 

 different gas, retains its magnetism, whatever the density of the 

 mixture may be ; but in the vicinity of the j^oles, separation of the 

 gases appears to take place to a certain extent, which must slightly 

 increase the attraction of the entire mass. In certain cases this 

 separation does not appear to take place instantaneously ; it is found, 

 at least in the case of a mixture of oxygen and chlorine, that the 

 magnetic attraction augments uniformly if the bulb remains for some 

 minutes exposed to the magnetic induction of the electro-magnet. 

 The primitive attraction is found to be exactly that which corresponds 

 to the quantity of oxygen contained in the mixture. 



7. A magnetic gas which has been attracted by the electro-magnet 

 for some minutes, is very distinctly repelled by it, if thepolarity of the 

 latter be changed by means of a commutator. I therefore conclude 

 that gases possess what has been called the coercive force to a 

 well-marked degree. — Comptes Rendus, Sept. 15, 1851. 



ON THE FORMATION OF DOLOMITE BY THE ACTION OF MAGNE- 

 TO smiilov «.U jSIUM VAPOURS. BY M. DUROCHER. 



Pieces of a porous limestone and anhydrous chloride of magnesium 

 were introduced into a gun-barrel, so that neither substances were 

 in contact. The closed tube was then exposed for three hours to a 

 dull red heat, in order to maintain an atmosphere of chloride of mag- 

 nesium vapour round the limestone. At the end of that time the 

 pieces of limestone were found to be covered with a crust of fused 

 chloride of calcium and chloride of magnesium, mixed with a little 

 peroxide of iron and the oxides of the two earths. The chlorides 

 were separated by washing with water, and the nuclei were thus 

 found to be partially converted into dolomite. On the addition of 

 hydrochloric acid, the limestone which had not been altered dissolved 

 first with strong eflFervescence, which subsequently became less ener- 

 getic, as is the case with dolomite. Transparent groups of crystals 

 were visible under the microscope : the mass had a white colour 

 passing into yellow and grayish -yellow, and was, like dolomite, full 



