Intelligence arid Miscellaneous Articles. 15 



time, the chloride of magnesium, which is fixed and fusible, flows 

 along the porcelain tube, and solidifies at tiie end. It is a white 

 crystalline mass, its fracture presents large brilliant plates, it is 

 slightly flexible, looks like spermaceti, is very soluble in water, has a 

 penetrating bitter taste, and strongly attracts moisture from the air. 



To reduce this chloride, M. Bussy takes a rather strong glass tube, 

 about 4-lOths of an inch interior diameter, and about sixteen inches 

 long, bent at one end like a retort. After introducing five or six frag- 

 ments of potassium, about the size of a pea, both into the bent and 

 the straight part of the tube, fragments of chloride of magnesium are 

 also put in, placing between them some pieces of porcelain, to prevent 

 the chloride from running into one mass by fusion. This portion of 

 the tube is then heated nearly to dull redness, and the potassium 

 converted into vapour is passed over it, by heating that part of tlie 

 tube which contains it. Strong ignition ensues, which takes place 

 gradually throughout the tube. When the tube is cold, it is found 

 to contain white metallic globules disseminated throughout the un- 

 decomposed chloride. If this mass be treated with water, a dis- 

 engagement of hydrogen is produced by the action of a small portion 

 of potassium, and white flocks of magnesia are also formed at the 

 same time, derived from the decomposition of a portion of the chloride 

 of magnesium by the potash formed, and brilliant silvery white glo- 

 bules of magnesium are precipitated to the bottom of the vessel, 

 which are to be repeatedly washed. 



Magnesium is very malleable, flattening under the hammer, fusible 

 at a moderate temperature, unalterable in dry air, lose.s its metallic 

 splendour in moist air, and becomes covered with a white crust of 

 oxide ■. this effect is however but limited, and confined to the surface 

 of the metal ; when small portions of magnesium are heated in the 

 air, they burn like iron in oxygen, but larger portions are slowly and 

 difficultly converted into pure magnesia : pure water, free from air, 

 has no action on magnesium ; when boiling, it gives out some bub- 

 bles of hydrogen. Certain saline substances singularly favour the 

 decomposition of water by magnesium ; dilute acids attack it with 

 the evolution of hydrogen. Magnesium does not amalgamate di- 

 rectly with mercury without the assistance of heat ; a very small quan- 

 tity of magnesium causes mercury to lose its fluidity. — Ann. de 

 Chimie, xlvi. 434. 



ON SUBCHUOMATli; OF LEAD. BY MM. WOHLER AND LIEBIG. 

 M. Dulong's method of preparing this compound in the moist 

 way is well known. It appears that the product obtained by this 

 process is not of a fine cinnabar red colour: it has merely a deep 

 orange shade, but still fine enough to be employed in dyeing. We 

 have found that, by fusing neutral chromate of lead with nitrate of 

 potash, the subchromate may be obtained of as fine a red as 

 the best cinnabar. The nitre is to be fused at a low; red heat, and 

 pure chromate of lead thrown into it in small portions at a time. 

 On each addition of the chromate, strong effervescence occurs, oc- 



L 2 casioned 



