But there is more difficulty in the purification than he anticipated. Yet there was pluck in the old man pointing out the killing contamination and suggesting a possible remedy. He had the fond idea that thereby a certain charm, “or innocent magick,” would make a transformation scene like Arabia, which is therefore “styl’d the Happy, attracting all with its gums and precious spices.” In purer air fogs would be less dense, breathing would be easier, business would be livelier, life would be happier.
Few, I suppose, have laid their hands on this curious Latin thesis, or its quaint translation, directing the King’s attention to the fogs that were ruining London. Since that time the city has increased, from little more than a village, to be the dwelling-place of six millions of human beings, yet too little improvement has been made in the removal of this fog nuisance. King Edward’s drive through London would be even more dangerous on a muggy, frosty day than was Charles II.’s, when science was little known.
CHAPTER XXV
ELECTRICAL DEPOSITION OF SMOKE
A good deal of scientific work is being done in the way of clearing away fog and smoke; and this, through time, may have some practical results in removing a great source of annoyance, illness, and danger in large towns. Sir Oliver Lodge and Dr. Aitken have been throwing light upon the deposition of smoke in the air by means of electricity.
If an electric discharge be passed through a jar containing the smoke from burnt magnesium wire, tobacco, brown paper, and other substances, the dust will be deposited so as to make the air clear. Brush discharge, or anything that electrifies the air itself, is the most expeditious.
If water be forced upwards through a vertical tube (with a nozzle one-twentieth of an inch in diameter), it will fall to the ground in a fine rain; but, if a piece of rubbed (electrified) sealing-wax be held a yard distant from the place where the jet breaks into drops, they at once fall in large spots as in a thunder-shower. If paper be put on the ground during the experiment, the sound of pattering will be observed to be quite different. If a kite be flown into a cloud, and made to give off electricity for some time, that cloud will begin to condense into rain.
Experiments with Lord Kelvin’s recorder show that variations in the electrical state of the atmosphere precede a change of weather. Then, with a very large voltaic battery, a tremendous quantity of electricity could be poured into the atmosphere, and its electrical condition could be certainly disturbed. If this could be made practically available, how useful it would be to farmers when the crops were suffering from excessive drought! It might be more powerfully available than the imagined condensation of a cloud into rain by the reverberation caused by the firing of a range of cannon.
But what is the practical benefit of this information? If electricity deposits smoke, it might be made available in many ways. The fumes from chemical works might be condensed; and the air in large cities, otherwise polluted, might be purified and rendered innocuous. The smoke of chimneys in manufacturing works might be prevented from entering the atmosphere at all. In flour-mills and coal-mines the fine dust is dangerously explosive. In lead, copper, and arsenic works, it is both poisonous and valuable.