color disappears and the fluid becomes colorless. The addition of do of sulphate of ammonia, removes the remaining hyponitric acid; much of the hydrochloric acid has been removed by the nitrate, and sulphurous and arsenous acids carried to their highest stage of oxydation. The oxyds present, aid the further purification; by continuing the concentration to 1.78, a trifling addition of oxyd of lead is made, but it is essential to the success of the process that this point of density be reached. The fluid must now be cooled in deep vessels of lead, the temperature of it being gradually reduced to 32° F., and allowed to become perfectly clear. The clear part must then be run into shallow lead vessels so placed that they may be refrigerated to 0 Fahr. As the whole acid has nearly the hydrate composition of SO3+2HO, it would form by repose a solid crystalline mass. In ordinary cases, the regular crystals form solid masses, which are allowed to increase, till one-half the bulk of the fluid has assumed the solid state, when the remaining liquor is rapidly removed, the crystals broken up and washed with some acid resulting from the crystals of a former operation.

When crystallized in this way, nearly all the contamination which can be detected, arises from the fine granular sediment of anhydrous sulphates and arseniates of iron and lead, mixing with the crystals from careless washing. These substances are deposited in the cooling, but more abundantly in the course of the crystallization of this acid. The crystals melted in lead kettles which have been recently washed with ordinary sulphuric acid, afford an acid nearly pure, and if required in the concentrated state, may be transferred directly to the platinum alembic, melted and boiled. For the most delicate researches, the crystals must be melted in glass, or stone-ware, recrystallized out of contact with metals or dust, leaving one-half or one-third of the acid in a fluid state. If the subsequent use of the acid does not require the removal of the water, which is very rarely the case, the crystals being a perfectly definite hydrate when fluid, enable us to weigh and apportion the quantity of real acid with great precision.

In the laboratory, when used for cases of difficult decomposition, it may be added to the crystallized bisulphate of potash, mixed with the substance to be acted on, and the whole brought to any state of dryness in the platinum utensils employed in such operations.

All the acid from which the pure acid has been abstracted, may be used for generating nitric, or hyponitric acid in the manufacture of sulphuric acid. The manufacture may best be carried on during the winter months, and the crystals obtained, stored, or melted.

This hydrate is remarkable for the regularity and great size of its crystals. They are oblique four sided prisms, and often present faces of twelve by sixteen inches. Their capacity for heat is also surprising; small parcels exposed at the mean temperature of 46° F., melt with extreme slowness.

Lowell, Mass., April 28th, 1848.

II. MINERALOGY AND GEOLOGY.

6

1. On the Wave of Translation in connexion with the Northern Drift; by W. WHEWELL, D.D., F.G.S., (Lon. Quart. Jour. Geo. Soc., Aug. 1847.)-The great geological problem of the "Northern Drift" has been attacked in various ways; and the diffusion of Scandinavian rocks and northern detritus over a vast area in the northern part of Europe has been ascribed to various kinds of natural machinery. Of late, a large part of this operation has been attributed to "Waves of Translation," produced by the sudden upheaval of the bottom or shore of the sea. This view is advocated in the Geology of Russia' by Sir Roderick Murchison.* There are some very simple numerical calculations which belong to this subject, and which may throw some light on the probability of such a theory. These calculations must necessarily be hypothetical as to their quantities, but as to their quantities only; and even these will be capable of correction by a more careful survey of the facts. For the mathematical doctrine on which they proceed is rigorously true, and does not depend upon any hypothetical view of the structure of the masses which we have to deal with. Mr. Scott Russell tells us that the wave of translation may be regarded as a mechanical agent for the transmission of power, as complete and perfect as the lever or the inclined plane. Assuming this property of the wave of translation as a basis, I shall point out some of the results of its operation in the case now to be considered.

It has been stated to the Geological Society, that, by supposing the sudden elevation of a submarine district, there is no difficulty in accounting for a current of twenty-five or thirty miles an hour at the bottom of the sea, as a consequence of the "wave of translation." In making this assertion, I think it has not been sufficiently considered that what is thus called a " current," is really a transient motion for each point of the bottom of the water. The great wave is solitary; the fluid before, and behind it is at rest; and the particles move only while the wave is passing over them. Therefore the effect of such a wave upon loose materials immersed in the fluid would be only one of two :-either it would carry a single mass along with it, giving to it its own velocity,or it would give a transient motion to a series of masses in succession, as it passed over each, moving each but a small distance. A single wave of translation cannot explain the situation of a long line of masses each of which is moved through a great distance.

If indeed we suppose a series of waves of translation each produced by a sudden elevation, or by some other paroxysmal action, we may obtain a greater effect. In the operation of such a battery, each shock would be transmitted through the water by means of the wave, and would do its measured work; and by accumulating such processes, any amount of result may be mathematically accounted for.

In whatever manner we frame the hypothesis in order to account for the 66 Northern Drift," the same mathematical equality, between the

* Also at an earlier date in the Memoirs of Profs. W. B. and H. D. Rogers, published in the Trans. Assoc. Amer. Geol. and Nat., 1840-42, and in this Journal.-EDS. AM. JOUR.

work done and the force exerted, will hold, as if the effect had been produced by any other mechanical power :-whether the waves be one or many, great or small. And as the amount of the work done in transporting the northern drift from its parent rocks (supposing their place known) to its present position, may be calculated upon assumed numerical bases, we may test the theory of the wave of translation, by thus calculating the amount of sudden elevation which it necessarily supposes. The numbers which I shall assume may be grossly erroneous; but the result being attained, can easily be corrected by changing it in proportion to the alteration which ought to be made in any of the numerical elements.

In the Geology of Russia' it is stated that the northern drift occupies a space 2000 miles long and 400 to 800 miles wide. If all the materials were derived from one centre, we might, as a general approximate view, suppose the area to be circular, with a radius of 800 miles ; or rather, semicircular, the northern half being for the most part cut off. But if we suppose this semicircle of 1600 miles diameter to be extended to a length of 2000, by taking the Scandinavian chain for the source of diffusion instead of a single centre, the distance travelled by each mass will be the same as in the supposed circle, which we may therefore make the basis of calculation.

Within the circle of 800 miles radius, I will take an inner circle of 200 miles radius, and I will consider the drift as occupying only the annular space between these two circles.

The mean distance from the centre of the annulus lies along a circle of which the radius is

500 miles. I will first consider places at this mean distance.

I must necessarily make some supposition about the mass of the materials which compose the drift. Let it be supposed that, at this mean distance from the centre of diffusion, every square mile, on an average, contains as much drift as would cover it entirely to the depth of one hundredth of a foot. This is equivalent to supposing that there is on each mile, a patch of drift, one-tenth of a mile square and one foot deep; or a ridge or "trainée" of drift, one-tenth of a mile long, onehundredth of a mile broad, and ten feet deep. It is easy to see that the supposition might be put in innumerable other forms; and by comparing these with many observed facts, some average result might perhaps be obtained.

Supposing this result to be, as I have said, that on every mile there is an average depth of one hundredth of a foot, I shall, for the sake of easy calculation, call this 500000 of a mile (instead of 328000). And thus, on every square mile of ground, at the mean distance from the origin, there is 500000 of a cubic mile of drift.

I will suppose the mean specific gravity of this material to be three times that of water. When the materials are immersed in water, the effective gravity will therefore be twice that of water.

The horizontal force which it requires to move a body along a surface on which it rests, depends on the form of the body, its texture and that of the surface, and other circumstances: but I think we may suppose that it would require a force and pressure of at least one-fourth the weight of the mass moved, to propel rocks and loose materials along the bottom of the sea.

This being assumed, it will require a force (pressure) equal to the weight of half a cubic foot of water to move a cubic foot of drift; and so, for any other quantities. And to move 500000 of a cubic mile of drift, will require the weight of Toooooo of a mile of water, acting as

a pressure.

Now this mass of drift, which is found on an average mile at the mean distance, has travelled 500 miles from the centre. And the laboring force which has carried it through this space, in whatever way it has acted, must be equivalent to the product of the moving pressure and the space through which it has acted; that is, it must be equivalent to the weight of 1000 of a mile of water, multiplied into 500 miles.

This is the same as of a mile of water, multiplied into one mile; or one mile of water multiplied into 6 of a mile of elevation.

That is, one cubic mile of water rising through 000 of a mile (or about 2 feet) would supply the power necessary to carry the drift which occupies one average mile at the mean distance from the centre of distribution.

Instead of one cubic mile of water, we may take a square of ten miles, of a mile deep; and this mass rising through of a mile, will produce the effect now spoken of.

2000

Taking any radius drawn from the centre of the annulus, the part of this radius which lies on the annulus is 600 miles. On each of these 600 miles, we suppose drift to rest. Each portion of drift has travelled a different distance from the centre. But at each different distance from the centre, there may be a different quantity of drift upon the average; the quantity probably decreasing as we recede from the centre. Let us suppose, for the sake of calculation, that the quantity diminishes exactly in proportion as the distance increases; so that at the distance of 200 and 800 miles, the quantities on a square mile are as four and one respectively.

On this supposition, the laboring force requisite to carry the drift which lies on each square mile of the same radial line, would be the same. It would take the same laboring force to carry 1000000 of a mile through 500 miles (the mean radius), as to carry 400000 through 200 miles to the inner edge of the annular space; or through 800 miles, to the outer edge of the annulus. In each case, the amount of force requisite would be, as before, the weight of 2000 of a mile of water, raised through one mile.

1600000

Here the laboring force requisite to carry the drift to the whole of the 600 miles which lie along this radius, would be or of a mile of water raised through one mile (600×2000-20

1

6 20

Now taking the whole semi-annulus, the length of the mean semicircle, of which the radius is 500 miles, is about 1500 miles.

Hence if we suppose the radical tracts a mile wide just spoken of to make up the semi-annulus, the force requisite to distribute the whole

mass of drift will be 1500 ×, or 450 cubic miles of water raised through one mile.

Now though these radial tracks do not make up the annulus, being too broad within the mean distance and too narrow beyond it, this excess and defect balance each other; and therefore we arrive at the conclusion that 450 cubic miles of water raised a mile high would produce an effect equivalent to the dispersion of the whole body of northern drift.

10

10

But we may put this result in a shape more readily conceivable. It is equivalent to 4500 cubic miles of water raised through a space of of a mile; or again, to a body of water 45,000 miles in surface and of a mile deep, raised through of a mile. If then we suppose a seabottom 450 miles long and 100 miles broad, which is of a mile below the surface of the water, to be raised to the surface by paroxysmal action, we shall have the force which we require for the distribution of the northern drift, on the numerical assumptions which have been made. And this is true, whether we suppose the elevation to have taken place at once, or by repeated operations, so long as they are paroxysmal. ` We shall have the requisite force, for instance, if we suppose this area to be elevated by ten jerks of 50 feet each, fifty jerks of 10 feet each, or by the same 500 feet any how divided into sudden movements. And as we diminish the area elevated, we must increase the total amount of elevation in the same proportion, so as to retain the same ultimate product of water paroxysmally elevated through a certain space. In all these cases, we shall have a machinery, which, operating through waves of translation, will produce the requisite effect. And if any of our data be held to be erroneous;—the area occupied ;-the amount of matter in the drift; the amount of friction or tenacity to be overcome in propelling it--the law of its diminution in quantity as we recede from the centre of distribution;-the final result will have to be proportionally diminished or augmented.

It may be asked whether, since the paroxysmal elevation may thus be reduced into successive smaller elevations, the same result would not follow if it were so reduced as to become, not paroxysmal, but gradual, and even insensible: for, it may be said, mechanical power retains its amount however much it be thus distributed through time, and divested of the character of extraordinary violence. And to this I reply, that no action except such as is of a paroxysmal character could produce the effect. This impossibility depends upon the nature of the effect to be produced. The friction of the bottom which supports the drifted materials, and the tenacity of the masses, are to be overcome: and the peculiarity of such resisting forces is this;-that except the force which acts be sufficient to overcome these resistances, it produces no effect, and is altogether lost. If we push at a mass resting on the ground, with a force insufficient to move it, the force which we exert is wasted, and disappears from all calculations which suffer force to be preserved and transferred into the change produced. A very small elevation, even if sudden, would produce a wave of translation which would pass over all the large masses, and leave them unstirred; and the wave would disappear without producing any such effects as we are here endeavoring to account for.