β Scribed by J.S.H.
No coin nor oath required. For personal study only.
treatment depend upon the state of division and on the access of air.
Copper has a negative susceptibility, while its salts show a positive value. Just the opposite is true of magnesium. For more than half a century it has been known that salts with positive susceptibility have a higher value when hydrated than when anhydrous, and this in spke of water's having a negative value itself.
Magnetic separation is now practiced on a large scale. In 1914, 2,2oo,ooo tons of ore were thus dealt with in Norway, in 2917 in Sweden 2,5oo,ooo tons, and in New York J,2oo,ooo tons in 1916. This is in addition to any separation of wolfram from tinstone ores and of monazite for use in gas mantles.
This subject has a further interest from its relation to nlagnetic surveys where the susceptibility of rocks has to 1)e reckoned with. When the United States Government was considering a canal through Nicaragua the direction in which the compass pointed on the lake of that name was greatly influenced by the magnetism of a dominating mountain, and in the Boer War the disastrous defeat at Spion Kop was in part due to the confusion of incorrect maps in which directions were modified by the effect of magnetized land masses upon the magnetic needle.
G. F. S.
π SIMILAR VOLUMES
Cauliflowerβshaped nodules are widespread in a single red mudstone bed in the Buntsandstein (Triassic) facies of the Iberian Range. They consist mostly of quartz, dolomite and calcite, but other minerals, such as barite, kaolinite and iron oxyhydroxides, are also present. The nodules are spherical,