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There are, however, other bodies which condense oxygen, and one which we get chiefly from Norway brings us chromic acid. and chromate of potash, remarkable agents in antisepting. We must coin the word to antisept; we have none that can take its place.

But even chromic acid has not become familiar, and we must look to other oxidizers. We have chloric acid, a body with still more oxygen, and most powerful, and its compound, chlorate of potash, which may also be used. All these bodies give out oxygen, and are therefore oxidizers, antiseptics, purifiers, and disinfectants. But they are not enough, because practice has not taught us the best modes of applying the peculiar characteristics of each. Manganese condenses oxygen, forming permanganate of potash, a substance beautiful in colour and innocent in character, whilst it oxidizes powerfully all the foulest bodies, and removes the most putrid odours as if by magic. We have to thank Mr. Condy for teaching us its use. It is certainly an elegant disinfectant, a name which it bears in opposition to antiseptic, which it is not, as it does not preserve. This permanganate, sometimes called chameleon, may be put into the foulest water or the most repelling mixtures, and the sense of smell will cease to be offended, whilst we may be sure also that the injurious bodies which do not smell will be equally oxidized. It leaves potash and oxide of manganese. It would be well if we could get the permanganic acid without the potash, and when it had done its work it would quietly fall to the bottom of the vessel, and if we were using it to purify drinking-water, we should have only a little brown oxide, which would do no harm, or if it had an unpleasant appearance, we might let it sink and leave the liquid above perfectly pure. We have certainly one solution which has all these advantages, that is, pure oxide of water, or peroxide of hydrogen. It looks like water; if we pour it on the filthiest substance the smell of putrefaction ceases, and in many cases a sweet odour or fragrant perfume, created in an instant, arises in its place. The peroxide has given up its oxygen and pure water only remains, no remnant to which we can object. Is there anything beyond this? Scarcely, although it does not seem applicable to all waters. It is dear, unfortunately, but some day it may be cheaper. There are places where it can be had cheaply, but in small quantities. Here also work is needful, and although we know these remarkable qualities we do not know details, and cannot yet tell how far it can be generally used; every substance has a character as complicated as the relations to all other substances and conditions of substances can make it.

Some people deliver over all their wonders to electricity, and

imagine that by doing so the mystery is solved, instead of being increased, by the idea that such a power is doing everything. But in the atmosphere we have really an abundant action of electricity, as we well know, and we are able to detect some of this concentrated oxygen which it forms, whether it should be called ozone, or peroxide of hydrogen, or other oxide, is not of consequence now. Very likely all the names are correct, and even more. When rain falls it brings this oxygen with it, and so we find at last that we have our ground watered, not with water only, but with this purifying agent. We can trace this more vital part of the air in all places where it is exhilarating to breathe, but never in a crowded town, never near much smoke. The very rain of such latter places differs from pure rain, and it falls on ground without the full power of oxidizing and preparing food for the plant. The same rain is tainted with sulphur from the coals, and this helps, with tar and soot and ammoniacal salts, and coal-dust or ashes, to render the air unwholesome. But without forgetting this long list of evils in the smoke, we must remember the loss of concentrated oxygen, which can never enter our smoky towns for a moment. It is that mainly which makes pure air so wholesome when it sweeps through a house; it burns up everything that is disagreeable to the sense of smell as certainly as a fire, although with more discrimination.

Although knowing the wonderful position oxygen takes as a purifier in nature, we use it very little directly; we leave its work to nature. Permanganate is the form in which we can best use it, and it is scarcely fitted for universal use from its price. We want a few more oxidizers. There are numerous bodies ready to oxidize, manganese and iron freshly precipitated, ready to give and then to take, and so act as carriers, and these nitrates and chromates require attention. But the world seeks exact knowledge; we shall endeavour to distinguish here some of the known from the uncertain.

There are, however, modes of making the condensed oxygen, or ozone; the most usual, Schoenbein's earliest, is to allow fresh cut pieces of phosphorus to lie half immersed in water. This is a deoxidizing agent and of great value no doubt, at least if we could get rid of these vapours, which consist, perhaps, of phosphorus only, and afterwards of various compounds, chiefly oxides. The production of ozone by phosphorus has been applied by Dr. Moffatt to disinfection for cattle-disease, with some success. It deserves more attention-if we could remove the phosphoric vapour.

We have spent a good deal of time on oxygen, considering the length of this article, and we could spend much more; it is

Nature's great purifier, called once by Priestley vital air.' It is our greatest and best agent of purification, although, as yet, it has been too noble to allow itself to be used in the daily work of life in disinfection so fully as we require; as the dignity of labour increases, this gas, no doubt, will yield to the persuasions of mankind, and take more part in our artificial life.

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Sulphur-Nature had the first claim, but had we followed history we should have begun with sulphur, a substance called sacred or divine by the Greeks, and used in purifications. It must have been ready at hand to Ulysses, when, after killing the suitors, he fumigated the palace, not to remove the odour of the dead merely, but as a religious ceremony1 (Homer's Odyssey, Book xxii., line 492.) Cowper translates the passage thus:

'Bright blast-averting sulphur. Nurse, bring fire
That I may fumigate my walls; then bid
Penelope with her attendants down,
And summon all the women of her train,
But Euryclea thus, his nurse, replied:
My son, thou hast well said, yet first I will

Serve thee with vest and mantle. Stand not here
In thy own palace, clothed with tatters foul
And beggarly; she will abhor the sight.
Then answer thus, Ulysses wise returned:
Not so; bring fire for fumigation first:
He said; nor Euryclea his loved nurse
Longer delayed, but sulphur brought, and fire,
When he with purifying steams himself,
Visited every part, the banquet-room,

The vestibule, the court.'

And afterwards, at the beginning of Book xxiii., Pope writes it

'Glorious in gore !-now with sulphureous fires

The dome he purges, now the flame aspires.'

The shepherds purified their sheep with it as well as bleached their wool, and in Ovid's Fasti (Book iv., lines 739, 740), 'Let blue smoke arise from the burning sulphur, and let the sheep bleat when touched by the smoking sulphur.' The Italians may perhaps have it by tradition as a mode of purifying their vines and their wine-casks, for which, indeed, it is used over all the wine-growing shores of the Mediterranean, to such an extent, that a new Etna neighbourhood would be a commercial advantage, since the Greeks do not use as of old the volcanic island of Melos for sulphur. Brimstone was used for skin diseases and in poultices of old, and the smell of it is spoken of by Pliny as

1

Memoirs of Literary and Philosophical Society of Manchester, vol. xii.

accompanying lightning. Schoenbein first told us that the smell was in reality that of ozone.

Sulphurous acid, which is obtained by burning sulphur, arrests the action of organized bodies, whether it be that smaller movement of decaying meat, or the more noble one of living man. It first deoxidizes, but it gives off its oxygen easily, and acts as an oxidizer. It also acts as an acid, and dissolves animal matter. Its action is complex. It causes coughing, and it is in great quantities injurious to the lungs, but how much in small quantities is not well known. It purifies the air of infectious matter, destroying in a gaseous state, as it destroys putrid and living bodies subjected to it in a liquid state, and it is therefore an excellent fumigator. How much it brings of other evils is an important question.It alters the air of our towns entirely; every coal-burning town certainly is compelled to breathe it. In vitriol-works men lose their teeth, but seem after a while to become accustomed to the sulphur. How far the burning of sulphurous coal is one of the causes of the great decay of teeth, is a question which statistics of country and town teeth may answer. It is offensive in very small quantities, as is shown when gas burns with a little sulphur in it. a few grains burnt in the gas and continued during an entire evening are enough to annoy us, although the same amount rapidly burnt, and breathed only a few minutes, is less hurtful. True, all the discomfort arising from gas is not due to sulphur, as it has been proved that with incomplete combustion acytelene, a compound of hydrogen and carbon, is one of these unburnt gases given out.

Even

As a fumigating disinfectant sulphur must hold a very high place, but there is a difficulty in most cases of keeping up the supply. It burns and goes out readily. We desire to keep it constantly burning. This cannot be well done in small quantities; it would for small spaces be best to use a sulphite of soda or lime, and add a little weak muriatic acid to it; in this way the supply for fumigation might be kept up.

When the gas combines with any body, it forms a sulphite. Sulphite of soda, lime, etc., are disinfectants. They act by removing smells, not all, most decidedly, but some. The most putrid blood will become comparatively innocent when sulphites are added, but a smell remains, a concentration of that which we find in a slaughter-house. The worst part, perhaps all the dangerous part, is removed. It goes on acting, and gives up all its oxygen, until at last sulphuretted hydrogen escapes, the very substance that sulphurous acid so easily destroys. We must therefore lift the whole away before that action sets in. Schoenbein says that this acid oxidizes, and so causes an oxidating in

fluence on other bodies to set in. This is sufficiently explained by the fact of its parting with its own oxygen. Mr. Higgin of Manchester has used for many months sulphite of soda for his cattle, daily about two ounces. They have not suffered, although all around have done so. One or two others have done the same with a similar result. Mr. Crookes tried injection into the jugular veins of diseased cattle of half-an-ounce dissolved in three ounces of water. They were better for a while, but ultimately died.

The salts of sulphurous acid are active disinfectants till they lose so much oxygen as to give off sulphur, and this occurs when much liquid is present. Some persons have observed the cattle which were dosed daily with about two ounces of sulphite of soda to become much weaker. This has not always been the result. When the substances have not begun to putrefy, sulphurous acid acts as an antiseptic.

Chlorine is a great disinfectant, probably the most powerful agent for the destruction of organic structure, whether healthy or unhealthy. The latter is always most easily destroyed, as it is weak, and putrefying matter still more so, as it is already breaking up; and herein lies our protection: we may use just enough to destroy the decaying but not to injure that which is entire. In passing through bleachworks, as we have done many hundred times, we have always been pleased at the ruddy healthy faces of the men employed. This is no doubt due to the slight and constant smell of chlorine. This effect is seen at large paper-works where they bleach rags; but nature is always presenting us with new problems. If we pass to the rag department, where the vilest portions of the filthiest clothes of Europe are assorted, we meet persons, at least in some cases, more wonderful in bulk and in every symptom of healthy glow of life, than perhaps in any other place can be found. Perhaps butchers and brewers come nearest to them. The rags have long since undergone their putrefaction, and a something remains, perhaps animal matter, which has this wonderful effect. Statistics do not inform us if such people live longer. Perhaps, as with brewers, there is something dangerous in their prosperity. From De Neufville's Frankfurt tables, we do not find that either brewers or butchers had the highest term of life: theologians, sixty-five; butchers, fifty-six; brewers, merchants, fifty-six; brewers, fifty. Our own tables do not place brewers in a high scale, and give workers in chemical works a higher age, but the numbers are perhaps questionable. However this may be, the destructive power of chlorine is great. This gas was discovered by Scheele in 1774. We cannot go to the ancients for its history, but we may nevertheless believe that the ancient

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