FACTS AND OBSERVATIONS. 301 
the water used for slaking the lime, and' thus he says, if 
properly worked, he invariably gets a good quality iron. 
A patent, we perceive, has also recently been taken out for 
obtaining from the slag of blast furnaces an aluminate of 
soda and potash, so that that which has long been thought of 
no value can by science be rendered useful. 
Cause of Phosphorescence in Minerals. —Accord¬ 
ing to Dr. Phipson, the cause of phosphorence is a vibratory 
movement of matter. The light of the sun, acting upon a 
mineral substance, occasions a certain vibration, electric, 
chemical, or magnetic; but this vibration not being able to 
continue when the action of light ceases, that is, w T hen the 
substance is placed in obscurity, the body gives back light 
whilst losing the electric, chemical, or magnetic vibration 
occasioned in it by the rays of the sun. The magnetic vi¬ 
bration, he considers, is probably commonest. 
Benefits derived from Vaporization. —It is the 
opinion of M. Morin that a greater benefit results from the 
diffusion of watery vapour in the air than is generally enter¬ 
tained, namely, that dependent on the development of a 
certain quantity of electricity and the production of active 
oxygen, which possess in a high degree the property of 
destroying, by burning, miasms and emanations from putre¬ 
fying substances. In this way it is that storms and tempests 
become such purifiers of the atmosphere as they are known 
to be. Differences in the thermal state of the air sensiM}" 
modifies its electrical state. 
From experiments instituted by M. Morin, he also finds 
an acid is generated, this being most probably, he says, a 
nitrogen product. 
Vanadic Acid. —The oxide of the metal vanadium, which 
as yet has not been applied to any useful purpose, neverthe¬ 
less appears to be pretty generally diffused in metallic and 
other combinations. Dr. Phipson has made the following 
somewhat curious calculation :—“ A ton of London clay 
contains,” he says, <f 1 lb. 2 oz. of vanadic acid ; say 1 lb. 
to the ton in round numbers. If we suppose that there 
exists only about a million tons of this clay at the west end 
of London—for instance, in the Hyde Park and Bayswater 
districts alone—we have evidently upwards of 445 tons of 
vanadic acid. And if we calculate the quantity of this acid 
which exists in the London clay of the metropolis, supposing 
London to cover fifty square miles, and taking the stratum 
