As the great amount of heat required for the liquifaction of ice and snow, is withdrawn from the atmosphere, its temperature falls very considerably; and hence the popular expression of "a cold thaw" is explained on philosophical principles.

Ice to become liquid water, renders latent 140 degrees of heat; but this water to become steam at 212 degrees, renders latent no less than 960, nay, some experimenters say, 1000 degrees of heat; it matters not how fierce may be the fire, or how vehement the ebullition of the water in an open vessel, its temperature, and that of the steam will never exceed 212 degrees, so long as the barometer indicates 30 inches as the atmospheric pressure,-the excess of heat from the fire is rendered latent in the steam, and insensible to the thermometer.

When steam, having a thermometric temperature of 212 degrees, impinges upon a cold surface, and condenses into the state of liquid water, it relinquishes its latent heat, which then becomes sensible to the thermometer.

Hence, in the process of distillation, the steam coming into contact with the upper part of the cold "worm-pipe" is condensed, and its latent heat being received by the surrounding cold water, elevates its temperature; and it may also be observed, that such heated water will float upon the yet colder portion below for a considerable time; if, however, the distillation be protracted the whole of the water in the " wormtub" will acquire the temperature of the steam, and

will be unable to condense it any longer, so that steam will freely issue from the lower end of the worm pipe instead of the liquid drops as at the outset of the process.

It is on account of steam thus containing such an enormous store of latent heat, that its power of scalding the body is so great; for whenever steam comes into contact with a surface colder than itself, it condenses and its latent heat becomes sensible.

If we conjoin this fact with that already stated regarding the cold produced during evaporation, we shall be enabled to explain why it is possible to "blow hot and cold with the same breath."

By gently blowing, or rather breathing upon our cold hands, they instantly condense the watery-vapour of the breath, and its latent heat becomes sensible, the hands are warmed; by forcibly blowing upon our hands, the watery vapour has no time to condense, but the blast incites evaporation from the skin, or abstracts heat from it, so that the hands are cooled.

When a fog occurs during Autumn or Winter, the well-known increase in the temperature of the atmosphere is referrible to the latent heat that existed in the watery vapour, becoming sensible during its condensation or change to the liquid state; and if wind subsequently occur, it is accompanied by decrease of temperature, because heat is absorbed or rendered latent by the water, for its evaporation or change into the state of vapour.

Thick and substantial walls in the interior of houses,

become damp, and often very wet, in certain states and changes of weather; they are so massive as to retain an acquired temperature for a long time, and during a winter's frost become cooled throughout; upon a sudden thaw attended by a very humid state of atmosphere, the vapour or moisture of the air is condensed in the liquid state upon these cold surfaces, because they abstract its heat and consequently cause it to run down in the form of water.

A most extraordinary fact is discovered by the chemist during his researches concerning the conversion of water into vapour; namely, that whatever may be the temperature of such vapour, it invariably contains the same quantity of heat.

The details of this discovery cannot be touched upon in this general inquiry, but a few examples of the fact may be presented, and when accurately and minutely considered, they display much to excite our wonder and astonishment regarding the habitudes of water with heat, and the important part enacted by this extraordinary compound, in all its physical states throughout The Four Seasons.

A certain weight of steam having a thermometric temperature of 212 degrees, if condensed at 32 degrees, gives out 180 degrees of its original sensible heat, and 950 degrees of latent heat; so that the whole amount of heat contained in the steam is equal to 1130 degrees.

The same weight of steam at 250 degrees of thermometric temperature, similarly condensed at 32 degrees,

gives out 218 degrees of sensible heat, and 912 degrees of latent heat, so that the whole amount of heat contained in the steam, is again equal to 1130 degrees.

Lastly, the same weight of steam at 100 degrees of thermometric temperature, similarly condensed at 32 degrees, gives out 68 of sensible heat, and 1062 degrees of latent heat; so that the whole amount of heat contained in the steam, as in the two former instances, is equal to the constant number of 1130 degrees.

Upon these incontrovertible facts, a law is established to the effect, that in proportion as the sensible or thermometric heat of steam is increased, so its insensible or latent heat is decreased; and in proportion as its sensible heat is decreased, so its latent heat is increased.

Carrying forth the results of these experiments into the vast laboratory of Nature, the chemist is led to the conclusion, that similar weights of the vapour of water, produced by the different temperatures of Spring, Summer, Autumn, and Winter, contain a similar and a constant amount of heat; and without this agent, so miraculously treasured by the Almighty, in the vapours and floods, the air and the earth, as already shown, the animated creation could not exist.

Let us now remark and appreciate the beneficial results which ensue throughout Nature by the operation of the unerring laws that we have been considering and endeavouring to illustrate by experiment.

The ice and snow of Winter do not suddenly change into floods, upon the first accession of heat from the

sun of Spring; did they so change, the earth and its productions would be immediately inundated by the emancipated waters; on the contrary, The Hand of Infinite wisdom ordains, that each mass of ice, each flake of snow, each pearl of frost, shall slowly absorb and render latent, a certain amount of heat and thus gradually become liquid water instead of suddenly changing into a destructive torrent.

And when the long imprisoned waters are freely unbound by the genial warmth of Spring, and are exposed to the heat of Summer and the glow of Autumn, they display the same Beneficence of The Creator in the adjustment of their temperature to animated beings, as they manifested during the cold of Winter.

Warm winds now glide over the liquid surface of the lake chosen as our example at page 325; the surface water gains heat by contact, but loses specific gravity, or in other words, floats upon the colder water beneath; the temperature of the surface may be 62 degrees, whilst that of the depth remains at 40 degrees; no sudden elevation of temperature can ensue from conducting power, the fishes become slowly inured to the change that at length is established, by the mechanical agitation of winds and breezes.

In concluding this rapid inquiry regarding the principal phenomena of The Four Seasons which admit of elucidation through the medium of the Science of Chemistry, it becomes necessary to imprint upon the mind of the young student of Nature, the magnitude of the Earth, as compared with the size of man;