A

to bear strong testimony to that awful event. The most ancient of these records are deeply carved, and destitute of colour, as if to save them from the destructive agency of water: they are literally "graven with an iron pen in the rock for ever." But more direct references are found on the monuments; we see a sacred ship or ark borne in religious processions, accompanied by several symbols of life and preservation, especially the winged globe, which gives so lively an image of providential protection, that it seems to have been derived from the maternal care of the female bird, hiding the callow young under "the shadow of her wings."

The notion usually formed of the ark is, that it resembled a large ship; but the Scripture represents it as an enormous wooden box or house, of an oblong form, divided into three stories. It was only necessary that it should float; no purpose could be served by its being made fit for performing voyages from place to place. In the engraving we see that such an oblong box or ark is placed in one of the light boats of the Nile, a clear proof that it is designed to float upon water.

bers. Among the labours imposed on the Israelites by Pharaoh, we find special mention made of the "treasure-cities, Pithom and Raamses." (Exodus i. 11.) From the monuments we find that the Pharaohs received vast quantities of the precious metals in tribute, and the conservation of their treasures must consequently have been a matter of difficulty and importance.

THE FORCE OF LIGHTNING.

A PERSON may be killed by lightning, although the explosion takes place at the distance of twenty miles, by what is called the back-stroke. Suppose that the tricity, hang down towards the earth, they will repel two extremities of a cloud, highly charged with electhe electricity from the earth's surface, if it be of the same kind with their own, and will attract the other

kind; and if a discharge should suddenly take place at one end of the cloud, the equilibrium will instantly is under the other. Though the back-stroke is often be restored by a flash at that point of the earth which The erection of the Tower of Babel, proved by its sufficiently powerful to destroy life, it is never so terexisting remains, is confirmed by the monuments of rible in its effects as the direct shot, which is freEgypt. Whatever other object may have been conquently of inconceivable intensity. Instances have templated by the builders of the pyramids, there is occurred in which large masses of iron and stone, no doubt that they were anxious to perpetuate their and even many feet of a stone wall, have been conown glory. In both cases, vanity has met its punish-veyed to a considerable distance by a stroke of lightment the builders of Babel were miraculously dispersed; the names of those who erected the pyramids are unknown. It must be added, that, in the upper valley of the Nile, brick pyramids are found, the materials of which are very similar to those employed by the builders of Babel. "And they said one to another, Go to, let us make brick, and burn them thoroughly. And they had brick for stone, and slime had they for mortar. And they said, Go to, let us build us a city and a tower, whose top may reach unto heaven; and let us make us a name, lest we be scattered abroad upon the face of the whole earth." (Gen. xi. 3, 4.) It is no improbable conjecture that these stupendous structures were partly intended for treasuries, and hence may have arisen the caution shown in concealing their entrances, blocking up their interior galleries, and hiding their secret cham

ning. Rocks and the tops of mountains often bear vitreous tubes, descending many feet into banks of the marks of fusion from its action, and occasionally sand, mark the path of the electric fluid. Some years ago, Dr. Fielder exhibited several of these fulgorites in London, of considerable length, which had been dug out of the sandy plains of Silesia and Eastern Prussia. One found at Paderborn was forty feet long. Their ramifications generally terminate in pools or springs of water below the sand, which are supposed to determine the course of the electric fluid. No doubt the soil and substrata must influence its direction, since it is found by experience, that places which have been struck by lightning are often struck again. A school-house in Lammer-Muir, in East Lothian, has been struck three different times.

[MRS. SOMERVILLE's Connexion of the Sciences.]

CARBONIC ACID.
No. II.

FERMENTATION has, in a former paper, been mentioned as a productive source of Carbonic Acid; a fact so well understood in breweries and distilleries, that the workmen never venture into a fresh-emptied vat, until it has for several days been exposed to the action of the atmosphere; and even then it is, in most cases, necessary to adopt other measures in order to ensure perfect saftey. When these precautions are forgotten, or wilfully neglected, health, and sometimes life, is sacrificed.

During the first stages of fermentation the quantity of gas disengaged is much greater than at any subsequent period. If a lighted candle be held over a large vessel containing malt liquor in an active state of fermentation, the flame will be instantly extinguished; and if we put our face near to the inner edge of the vessel, so as to inhale a little of the gas, its effect will be similar to that produced by the application of very strong ammonia, (spirit of hartshorn) to the nostrils.

Carbonic Acid is absorbed by liquids, imparting to them the agreeable flavour, which in malt liquors, cider, wine, and a variety of other beverages, is associated with briskness. By exposure to the air a great portion of the gas escapes, and by its loss the liquor becomes, what is termed, stale, or flat. The exhilarating effects of spring-water are almost entirely due to the presence of Carbonic Acid; for when that has been expelled by boiling, the water becomes vapid and tasteless, and it ceases to sparkle on being poured from one vessel to another. There is, however, a considerable difference with respect to springwater and fermented liquors. In the former instance, the greater part of the Carbonic Acid present is absorbed from the atmosphere, whither it has no tendency to return so long as the temperature of the water remains constant. When the temperature is increased, the gas escapes, and the earthy matter with which it is usually combined, (most commonly lime,) is precipitated. Hence it is, that the water from a deep well which has been standing all night in a bed-room, especially in warm weather, is less refreshing than when recently drawn from its source. Under these circumstances it may also be remarked, that the bottle containing the water will become coated with a thin film of white earthy matter, which is carbonate of lime deposited as above mentioned.

In fermented liquors, whether in casks or bottles, Carbonic Acid is generated spontaneously; the fermentative process continuing in operation for many years, and constituting what is denominated ripening. The less perfectly the liquor has been fermented in the first process of its manufacture, the more abundantly will Carbonic Acid be formed afterwards; and its formation is accelerated by sudden elevations of temperature. As familiar examples we may mention ginger-beer, and ale, or porter. Ginger-beer is so imperfectly fermented, that by proper management it may be rendered fit for use in a few hours after it has been bottled. Ale and porter, on the contrary, require several weeks, and if they have been a long time in casks, many months, to bring them to maturity in bottles. It is true the process may be hastened by putting the bottles in a warm situation, but this can only be done at the risk of losing the liquor, as well as the bottles which contain it. So sensitive are malt liquors to any sudden changes of temperature, that we have known instances of many hundred bottles of ale and porter bursting in one night.

The effervescing quality of champagne and other

sparkling wines, is due to the slow fermentation which takes place in them after they are bottled. A similar process goes on whilst these wines remain in casks; but the excess of Carbonic Acid is in this case permitted to escape, otherwise its pressure would burst the casks.

Recently boiled water, in a state of repose, will absorb its own volume of Carbonic Acid gas; but this must be understood as applying only to ordinary temperature and pressure. When the water is briskly agitated in contact with the gas, the latter is absorbed more rapidly, and if at the same time the pressure is increased, the quantity of gas taken up is in exact proportion to the pressure employed. Thus, if a gallon of water will absorb an equal quantity of gas at the mean pressure of the atmosphere, under a pressure of two atmospheres it dissolves two gallons, and so on in proportion for every other increase of pressure. A knowledge of this fact enables the manufacturers of soda-water, and other artificial waters, to conduct their operations with safety, and on uniform principles; for otherwise, the use of glass bottles would be attended with great danger. We have already shown that the origin of Carbonic Acid in fermented liquors is to be traced to a natural process. With artificial waters it is otherwise. In the manufacture of soda-water, for instance, the requisite quantity of soda is added to a certain quantity of water contained in a strong vessel,-the Carbonic Acid gas, which has been separately prepared, is then pumped into the vessel, and the water briskly agitated. When a proper quantity of gas has been absorbed, the water is bottled, and it is immediately fit for use. The corks are fastened down with wire as the only means of resisting the pressure of the gas within the bottle, which is, in general, equal to about five atmospheres. Effervescing lemonade is prepared in precisely the same way as medicinal waters, excepting, of course, the flavouring ingredients.

There is a property possessed by effervescing beverages, which we believe is not much regarded, although it is one of their chief recommendations. We allude to their coldness, an effect produced by the rapid escape of gas, and its sudden transition from what may be termed a liquid, to the gaseous state. We know not how to illustrate this more forcibly than by a reference to the effect of ether, or strong spirits of wine, when dropped upon the back of the hand. A sensation of extreme coldness is immediately experienced as a consequence of the rapid evaporation of the liquid; and this is precisely what happens in the case under consideration. which had been previously held in solution by the The gas water regains its liberty; and as heat is essential to its resumption of the gaseous form, that heat is supplied by the water, whose temperature is thereby reduced very much below what it was before the cork was drawn.

Having mentioned artificial mineral-waters, it is right that we should say a few words about those which are the result of natural processes, and which the former are intended to imitate. mineral-water is applied to spring-water holding in The term solution certain ingredients which render it unfit for domestic purposes, and at the same time impart to it some specific property which operates more or less powerfully on the animal system. There are many justly celebrated mineral-springs in Great Britain, as there are also in other parts of the world. Among the latter, those of Germany are in very high repute, and it is in imitation of their products that medicinal waters are manufactured in this country. When the operations are conducted by skilful men, the waters

1837.]

thus obtained are equal in every respect to those
imported from the original springs. Mineral-waters
are for the most part strongly impregnated with
Carbonic Acid. In some instances, as much as one
hundred and sixty cubic inches of gas exist in one
hundred cubic of water. This imparts to them their
pleasant acidulous flavour, whilst it is not less import-
ant as respects its salutary effects upon the system
generally. It is well deserving of remark, that
although Carbonic Acid, as we have already men-
tioned, is destructive of life when permitted to pass
into the lungs, even in a very diluted state, its effects
when taken into the stomach are decidedly beneficial.
Let it be noticed, however, that it is improper to
take soda-water, or, indeed, any other carbonated
water, at the commencement, or during the progress
Under such circumstances it
of a hearty meal.
tends to repress the energies of the digestive func-
tions, rather than assist them.

All carbonated waters should be kept in cool situations, especially in Summer; and the more uniform their temperature, the longer will they continue good. The same caution should be observed in reference to fermented liquors. We remember very lately to have seen an account of an accident occasioned by the bursting of a cask of Seltzer water, at Paris. We are not sure whether the person who was standing near the cask, and to whom it belonged, was not killed by the concussion. If this was not the result, his life was placed in imminent peril, and it is somewhat remarkable that the same individual had been wounded twice before, by explosions of bottles of the same kind of water. The accident alluded to above, was the consequence of leaving the cask in an exposed situation during warm weather.

All inflammable substances which contain carbon, (charcoal,) yield Carbonic Acid by combustion; and hence we never kindle a fire, whether it be of wood, charcoal, peat, coke, or coal, nor do we obtain artificial light, be it from tallow, oil, wax, or gas, without producing it; the quantity bearing some relation to the elementary constitution of the substances employed. Combustion is a subject which, under one form or another, presents itself to our notice in every department of scientific research. It occupies a conspicuous place among the every-day transactions of life; nor is it less important in the more complicated processes which minister to our necessities in a thousand different forms. Were we only to glance at some of the most ordinary operations which are conducted through the agency of fire, we should occupy entire sheets of our magazine. In former volumes there have been frequent allusions to this part of the phenomena of natural objects. A vast deal yet remains to be said.

Notwithstanding the immense quantity of Carbonic Acid gas which daily ascends from the surface of the earth, there is no actual increase in its proportions. We have before stated that it is always found as forming a part of the atmosphere, slightly varying in its proportions under the influence of climate, situation, and the changes of the weather, and of the seasons. But whether we collect and examine a portion of atmospheric air in the midst of a thicklypopulated city, or at the mountain-top, the difference in its constitution is so trifling, that it is inappreciable to the senses, and can only be detected by the most careful and rigid experiments. We do well to contemplate the WISDOM and GOODNESS so significantly portrayed in all the arrangements of Providence. In no one instance are these attributes more apparent, than in the provision which has been made for withdrawing from the atmosphere those gases, whose

excessive accumulation would be inimical to the enjoyment, or unfavourable to the existence, of animated beings. This must furnish us with an interesting topic to discourse upon in our next paper.

CASE OF SOMNAMBULISM.

A WOMAN was much addicted to talking in her
sleep, and, after some observation, it was discovered
that, in doing so, she went over all the transactions
of the preceding day; everything, especially, that she
had herself said, was distinctly repeated in the order
in which she had spoken it. In general she com-
menced immediately after she had fallen asleep, and
began by repeating the first words she had spoken in
the morning, and then went through the other con-
versation of the day, adapting her tone and manner
Thus, whether she had
to the real occurrences.
called aloud to a person at a distance, or whispered
something which she did not wish to be overheard,—
whether she had laughed or sung, everything was
repeated in the order, and in the tone of voice, in
In repeating con-
which it had actually occurred.
versations with others, she regularly left intervals in
her discourse corresponding to the period when the
other party was supposed to be replying; and she
also left intervals between different conversations,
shorter in reality, but corresponding in relative length
to the intervals which had in fact taken place. Thus,
if she had been for two hours without conversing
with any other person, the interval in her nocturnal
conversation was about ten minutes. In this man-
ner she generally required about two hours to re-
hearse the occurrences of the day. She was scarcely
ever known to repeat anything she had read, but she
occasionally repeated psalms, as if she had been
teaching them to a child, and she repeated them
more correctly than she could do when awake.

She exhibited also the more common characters of
somnambulism, frequently rising in her sleep, pur-
On one occasion she awoke in
suing her ordinary occupations in the kitchen, and
even out of doors.
the act of mounting a horse at the stable-door, and
at another time was roused by spraining her ancle,
while cutting grass in a ditch at some distance from
the house. These occupations were observed to have
a relation to her engagements during the day, being
either a repetition of something she had done, or the
accomplishment of what she had intended to do, but
had been prevented from performing; and sometimes
it appeared to be something which she meant to do
at the earliest hour on the following day.

These peculiarities had been matter of interesting observation for a considerable time, when she at length fell into a state of continued unconsciousness to external things, which went on for three days, during which time she attended to all her usual occu pations. This began on a Sunday, and continued to the Wednesday. On that day her master met her returning from an outhouse, carrying a number of On his doing so she eggs, when he determined to attempt rousing her by shouting loudly in her ear. awoke as from a sleep, and spoke to him sensibly, but could give no account of the eggs, and could scarcely be persuaded that the day was not Sunday. In an hour she relapsed into the unconscious state, and was again roused in the same manner; but, after some further experiments, this expedient failed, in consequence of which she was taken to her parents, and did not recover entirely for several weeks; after this her former peculiarities became less remarkable, and gradually ceased.

[ABERCROMBIE on the Intellectual Powers.]

THE ISLAND OF AMSTERDAM, AND ITS BOILING SPRINGS.