Physical Properties of Magnesium

Magnesium ribbon is brilliant and white, resembling silver. When sublimed in vacuo the cooled metallic deposit consists of beautiful silver-white crystals which are usually regular hexagonal prisms. Similar crystals crystallise from a solution of magnesium in molten sodium.

Its density is very close to Deville and Caron's original figure of 1.75: a more modern figure is 1.74. It melts at 650 ± 2° C., and boils at about 1100° C.: the actual boiling-point may be nearer 1120° C. Its specific heat has been given as 0.2456 at 0° C., 0.2519 at 50° C., and 0.223 between -185° C. and +20° C. Its electrical conductivity compared with mercury at 0° C. is 22.84 at 0° C. and 16.34 at 100° C. Its absolute conductivity for heat from 0° C.-100° C. is 37.6, its atomic refraction is 6.9, its atomic volume is about 13.3, and it is diamagnetic.

Magnesium is a relatively strong metal: its ultimate tensile stress is 23.2 kilos per sq. mm., its bending strength 17.4 kilos, and its specific resistance to compression 27.2 kilos per sq. mm. The compressibility of the metal is about 2.7×10^-6 per atmosphere.

Magnesium is malleable, but ductile only at high temperatures. At 450° C. the metal can be rolled, pressed, and readily worked.

Magnesium, condensed from vapour on cooled platinum sheets, exhibits photo-electric activity when exposed to light rays in an exhausted tube.

The stronger lines in the spectrum of magnesium, in decreasing order of wave-length (Rowland), are -

Spark: 5711.6, 5528.7, 5183.8, 5172.9, 5167.6, 4703.3, 4481.3, 4352.4, 3838.4, 3832.5, 3829.5, 3336.8, 3332.3, 3330.1, 3097.1, 3093.1, 3091.2, 2942.2, 2937.9, 2928.7, 2915.6, 2852.2, 2802.8, 2798.2, 2795.6, 2790.9, 2783.1, 2781.5, 2779.9, 2778.4, 2776.8.

Arc: 8807.0, 5711.6, 5528.7, 5183.8, 5172.9, 5167.6, 4703.3, 4352.4, 3838.4, 3832.5, 3829.5, 3336.8, 3332.3, 3330.1, 3097.1, 3093.1, 3091.2, 2942.2, 2938.7, 2937.9, 2928.7, 2915.6, 2852.2, 2848.5, 2846.9, 2802.8, 2798.2, 2795.6, 2790.9, 2783.1, 2781.5, 2779.9, 2778.4, 2776.8.