lines of melting, which flash out in the clear ice at the first touch of the sunbeams, and grow steadily larger. The lines which join these tiny pools are the ends of the cleavage planes, and are covered with melting frost fronds of marvellous beauty. The lighter portions between are the bases of the ice crystals, now standing as sharply apart as the basaltic columns of the Giant's Causeway.

The melting still goes on, the channels and sluiceways grow steadily larger, and the water trickles out of them, leaving them here and there filled with air, and shining like tubes of quicksilver.

If at this time one pours over the outside ends of these sun-carven wandering channels through the ice some bright

man's guiding finger through coal and steam and pliant gas, the sunbeams of other ages have built up.

Nothing could well seem more incongruous than the expression "ice flora." And yet modern science has shown us that beyond the realm of the visible is a race of tiny plants so minute that they may cling unheeded among the ice crystals, exclusive as these are to nearly all foreign particles, both large and small. So hardy, too, are some of these invisible plants that neither the squeezing nor the freezing which they suffer in their crystal prison-house can extinguish their life spark. But when the ice melts and they find their chosen food and warmth, they may go swarming on in their various

ways, as active for man's weal or woe as before they became ice-bound.

A good many of the bacteria which are found in all natural surface waters are expelled or killed when the water freezes, but as many as ten per cent., and often more, may remain alive. A large number of studies on this subject have shown that the bubbly and snow ice is apt to contain many more bacteria than the clear ice does. These bacteria in ice have, as a rule, no influence whatsoever upon the health of the ice-consumer, if the ice has been formed on bodies of water which are clear and pure. But ice which is formed on sewage-polluted or otherwise filthy water may contain disease producing bacteria, and hence be very dangerous for domestic use.

It has thus come to be firmly established as a primary principle in sanitary science that sewagepolluted water should not be used for domestic purposes, either in its natural state or in its condition as ice. No water which is unfit to drink as water is fit to use for a similar purpose as ice. Its coldness may benumb the sense of taste, so that no warning of its nature comes to the consumer. Its intrinsic clearness and beauty may put him off his guard, but all ice cut from sewagepolluted waters is dangerous, and should by law be kept from the domestic market.

Ice manufactured from distilled water should, it would seem, be germ free. In fact, however, it is extremely difficult to prepare absolutely germ-free water on the large scale, and almost impossible to keep it so if once prepared, because every exposure to the air, or contact with utensils in common use, brings to it varying and often large numbers of germs which can live and grow in the water. But these small numbers of common bacteria are

not of the slightest importance to the salubrity of the water.

Every one should understand that of all the myriads of bacteria about us in earth and air and water, the great majority are harmless. With very few exceptions, the bacteria which can do us harm are those, and those alone, which come from the bodies of men and animals afflicted with disease. So far as water is concerned and the same applies to ice

it is only sewage pollution or stagnant filth which we have to fear and shun. Good, pure, uncontaminated water, and ice made from such water either by nature or by man, are entirely wholesome, and they are not made more wholesome by distillation or other purifying procedure-they are not more wholesome when germ free.

cerned, we may rest assured that as regards bacteria, one is just as wholesome as the other, provided the water used is pure. If the water is impure from sewage or other unwholesome thing, then the natural ice is never fit for domestic use. If water is impure, the processes of artificial ice-making, if carefully performed, are capable of furnishing even from it a product which is harmless and wholesome, whether it be absolutely germ free or not; for absolute freedom from germsif these are not disease-producing formsis neither necessary nor especially desirable. It is not bacteria, but disease-producing bacteria, which make of practical significance the invisible flora of either water or ice.

So in the manufacture of ice, if the water which is used be contaminated and impure, the preliminary distillation is of primary importance for the salubrity of the ice; but if the water be pure, the distillation is only valuable for the technical purpose of removing the dissolved air.

In point of fact, most of the artificial ice which the writer has examined-and there have been many and abundant samples from various sources collected, and for a period of many months-do contain bacteria in varying numbers. The preliminary distillation, if carefully done, destroys any disease - producing germ forms which might be present in the water used. But a certain number of the more hardy harmless forms may be carried bodily over with the steam into the condensers.

In most of the ice-manufactories the distilled water is filtered through charcoal before it is run into the freezingcans, for the purpose of removing certain organic compounds which have come in the process of distillation. But these charcoal beds afford breeding-places for such germs as may have escaped the ordeal of the heat. The writer has repeatedly found that while the distilled water before passing on to the filter beds was very nearly germ free, the number was increased a thousandfold on leaving them.

So far as the salubrity of the natural as compared with the artificial ice is con

The examinations of artificial ice made from the distilled Croton water have shown that when it does contain a few bacteria these are not of many different species, as is the case with the undistilled Croton, but they are almost all of one single species, and this a hardy, harmless form which multiplies readily and rapidly in pure water.

Innumerable analyses have shown that water does not purge itself wholly in the act of freezing, as was formerly believed, from disease germs which may have come into it with human waste. This has been specifically and repeatedly shown to be true for that most dreaded and fatal sewage germ, the bacillus of typhoid fever.

The process of oxidation and sedimentation, which aforetime was demonstrated by most exact chemical analyses to be capable of freeing water in lakes and running streams from organic compounds abundant in sewage, is still urged by belated scientists and frantic tradesmen here and there in justification of the use of ice cut on sewage-polluted waters. But these facts regarding the

organic products of decomposition have very little bearing, in the new light, upon the actual producers of disease-the germs themselves. For these are not subject to the same purifying agencies, are not demonstrable by chemical methods, and are not removed from sewage-polluted lakes and streams within the limits which chemical experiences have led us to regard as safe.

Sedimentation does remove many harmful germs from sewage-polluted waters. Dilution does diminish the chances to incur disease for every consumer. Many individuals are, at favored times, practically invulnerable to the incursions of these tiny foes. But, after all, it is safe to say that in thickly inhabited regions sewage-polluted water is not fit for men to drink without purification, no matter how fast and far the river runs, or how wide the lake into which the sewage drains. With the size of the lake and the volume of the river, the chances of harm decrease, of course, but they stay chances still where none need to be. As our country becomes more thickly settled and our cities larger, the problems involved in pure water and ice supplies are becoming more and more urgent and difficult.

The manufacture of ice and its marketing at prices which in many regions easily compete with those of the natural product have simplified this phase of the water question in the most marked way. Other things being equal, whether the householder decides to use the natural or the artificial ice will depend much upon the climate of his home and the market price of the ice. The natural ice is just as good as the artificial when it comes from pure sources. It is claimed by some that the natural ice melts more slowly than the artificial, and is in this way, other things being equal, cheaper. But similar claims are made for the artificial ice. The writer has tested the relative rapidity of melting of the natural and the artificial ice in New York under the greatest variety of conditions; in small pieces and in large, in the dark, in the light, in diffused light and in the sunshine, in hot places and in cool, and can find no absolute constant difference in the rapidity of melting. One seems to be just about as durable as the other.

New York city is one of the most striking examples of a great town which takes

VOL. LXXXV.-No. 507.-38

extraordinary pains, or at least spends enormous sums of money, in keeping its sanitary conditions good. It has an almost ideal water supply, which, if properly and efficiently protected, would long answer its growing needs. Its means for coping with outbreaks of serious epidemic disease are carefully planned. And yet this great, wealthy, and seemingly intelligent community goes on year after year polluting its own excellent water with the frozen filth of a great sewage-polluted river.

One may even sometimes see citizens of this metropolis, keenly alive to the advantages of cleanliness, and insisting upon the use of distilled water at their tables, yet calmly plump into their glasses of pure water the frozen sewage of the upper Hudson from the vicinage of Albany and Troy.

We know that typhoid fever is nearly always present in Troy and Albany during the ice-harvesting season. We know that the waste from these victims of disease is cast into the Hudson River. We know that the typhoid germ resists freezing and long-continued cold, and yet between seven and eight hundred thousand tons of ice are cut from the Hudson in average years within twelve miles of Albany, largely for the refreshment of NewYorkers.

A good deal of the natural ice supplied to New York comes from other sources— many of them better, some unquestionably good. But, so far as I am aware, the householder cannot receive positive assurance that his supply will not be, at any rate during a part of the year, from the polluted Hudson.

In this condition of affairs it does not seem clear to the writer why any New York householder should long hesitate between the use of artificial ice made from the Croton water and the abundant chances for evil which lurk in the sewage ice of the Hudson River.

I have written thus at length of one great source of polluted ice supply, because it is typical of many in this country. And the indifference of the citizens of New York in this respect is not without analogy among the citizens of other towns, both small and large.

My readers will, I am sure, deplore with me the necessity for weaving the shadow of disease into so dainty a theme as ice and its manufacture.