melt. The residue is a brown powder, which on being further heated is carbonised, no definite compound being obtained.

IV. The ferricyanide of trimethylsulphine is obtained by the action of ferricyanide of silver on the iodide of trimethylsulphine. On evaporation of the solution the salt crystallises out in pale orange-yellow transparent plates, which effloresce in the air. The salt gives all the reactions of an alkaline ferricyanide. On drying over phosphoric acid the crystals lose all their water of crystallisation. Analysis leads to the formula {(CH3),S} Fe,Cy12+15H2O. The salt when heated behaves similarly to the ferrocyanide.

3. Comparison of the Salts of Diethylmethyl-sulphine and Ethylmethylethyl-sulphine. By Professor Crum Brown and J. Adrian Blaikie, D.Sc.

(Abstract.)

It seemed to the authors to be desirable to ascertain the mode in which the salts of diethylmethyl-sulphine and ethylmethylethylsulphine respectively decompose when heated.

They prepared the iodides by the method described by Krüger,* whose observations on the iodides and chloroplatinates they substantially confirm.

The benzoates were prepared from the iodides by action of benzoate of silver. They are exceedingly soluble substances, and were only obtained as thick syrups. Heated to between 110° and 120° C. they decompose in exactly the same way, yielding benzoate of methyl without any benzoate of ethyl.

4. On the Bursting of Firearms when the Muzzle is closed by Snow, Earth, Grease, &c. By Professor George Forbes.

It is well known that if an ordinary fowling-piece, charged with shot or ball, have touched the ground or snow, so as to close the muzzle of the gun, or if the muzzle of the gun be in any way artificially closed with grease or other substances, the fowling-piece is certain to burst at the muzzle when it is discharged. This would not be the case if, instead of firing a shot, a piston were driven up the tube by hand. In this case the compressed air would drive out * Journal für practische Chemie, xiv. 193–213.

the opposing plug, which offers but a very feeble resistance to the internal pressure. These facts, thoroughly well authenticated, have not, to my knowledge, received a satisfactory explanation, though a clear idea of the conditions of the case is all that is required to explain this, at first sight, anomalous behaviour.

The explanation lies in the fact that the charge travels along the bore of the gun, if not with the same velocity as, at least with a velocity comparable to, that of the transmission of pressure through the air, i.e., the velocity of sound. Thus, as the charge advances along the barrel it is continually compressing the air immediately in front of it; but this pressure gets no relaxation by expansion into the front part of the barrel. The compression, of course, generates heat in the air, which increases the velocity of sound through it. But this does not affect the question in its general bearings. It is sufficient to notice that the snow, &c., is driven out with the full velocity of the charge (neglecting the weight of the snow-plug compared with that of the charge). But before the plug can be driven out with this great velocity the pressure behind it must be very great. Let m = the mass of the snow-plug.

0 = velocity of the bullet or wad when close to the plug

(ie., on leaving the gun).

p = the pressure of the air driving out the plug.

A the sectional area of the bore.

=

The work done in giving to the mass m a velocity v is

But w is performed by the pressure pA acting through the dis

Thus, the pressure at the muzzle of the gun is independent of the

diameter of bore and length of plug.

To take a particular example, let v = 1000 feet a second, and let p = the density of water, so that

p=ghp

when h is the height of the column of water producing an equal pressure

If w be the weight of a cubic foot of water, p= wh = w.

pressure on the square foot.

Now, w = 72 lbs. and g=32 and v2 = 1,000,000;

v2

is the

g

A pressure which the muzzle of a shot gun is not constructed to withstand, and the theory shows that this great pressure can be produced even by a plug of snow or grease of the shortest length movable inside the barrel with the greatest facility. If the velocity of the ball or wad be less than that of sound the snow-plug is not driven out quite suddenly, and if the velocity be small enough the snow-plug is driven out before the ball or wad reaches the muzzle.

5. On some New Bases of the Leucoline Series. Part III. By G. Carr Robinson and W. L. Goodwin.

Monday, 7th July 1879.

PROFESSOR MACLAGAN, Vice-President, in the Chair. The following Communications were read:

1. Notice of Striated Rocks in East Lothian and in some adjoining Counties. By David Milne Home, LL.D.

I know no more interesting problem in geology than the question, What was the great agency which brought the surface of

northern Europe into the condition in which it is now occupied by man? and it seems marvellous that geologists should not yet be agreed as to what that agency was.

Our own country of Scotland is strewed with boulders, many of immense size, and which we allow have been somehow transported to their present sites from remote regions. Rocks on our hill-sides have been ground down, smoothed, and striated by ponderous bodies which have come against and rubbed upon them. Almost every where there are deep beds of clay, sand, and gravel forming knolls and elongated ridges, not only on low-lying districts, but even on our highest hills. These things have been attracting attention and provoking discussions for more than sixty years; but no explanation has yet been arrived at, which meets with general acceptance. Some geologists insist on the agency of an ice-sheet, like that in which Greenland is wrapped; Others stand up for local glaciers, such as exist in Switzerland and Norway. Some suggest icebergs and other forms of floating ice, in a sea which submerged the country. Each of these theories has its partisans ; for no crucial test has been discovered to indicate which of them, or whether any, is well founded.

The Transactions and Proceedings of our Society contain many papers regarding these phenomena. Of these papers, the earliest probably was by Sir James Hall, so long ago as the year 1812, and he was followed by M'Laren, Chambers, Fleming, and many other Fellows of our Society, who specially devoted themselves to this branch of geological research.

The last paper published on this subject in our Proceedings, was by our colleague, Mr David Stevenson, who described a portion of the hill in East Lothian known as North Berwick Law, which was found by him to have been ground down, smoothed, and striated. These effects he ascribed to the agency of a glacier, which came from the westward against the hill, first smoothing the rocks on its north side by the heavy pressure of the ice, and afterwards scratching the smoothed surface by hard stones incased in and protruding from one side of the glacier. MrStevenson suggested that the glacier might even have been, and probably was, of such dimensions as to have enveloped the whole of the Law, which reaches a height above the sea of 612 feet. At the close of his paper Mr Stevenson expressed an opinion

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that if the rocks of Stirling Castle, Craigforth, and other places were examined, interesting and instructive traces of similar glacial action might be discovered.

To this suggestion of an inquiry for cases of a similar kind, I am now here to respond, and with that view to lay before the Society an account of several striated rocks in East Lothian, Stirlingshire, and other places; I feel sure that Mr Stevenson himself will deem these cases not the less interesting, though they should warrant conclusions different from those he suggested.

I. EAST LOTHIAN STRIATED ROCKS.

The first of these which I mention, as the least complicated, are in the village of Linton.

The rock is a claystone porphyry. Several smoothed patches of rock occur here, and two of these show striations on surfaces from 3 to 4 square feet in extent.

One of these smoothed rocks is horizontal or nearly so; and on it the striæ have a direction W.N.W. and E.S.E.

The other smoothed rock dips towards the north, at an angle of about 35°, and on it, the striæ run due east and west.

The difference between the directions of the striae of these two rocks, which are only a few yards apart from one another, may be accounted for by the fact that the same agent which produced striæ in a certain direction on a horizontal surface, would, if that agent could be easily deflected, not produce striæ in the same direction on a sloping surface. It would have less power to move up an inclined plane, but would move along it more horizontally.

What the striating agent was here, and in what direction it moved, is made manifest by the following facts. Both patches of rock were, when I examined them, still partially covered by a coarse clay, full of stones or pebbles, many of which were hard and angular, but some were soft. There were among them bits of coal and limestone, which must have come from the westward, as in East Lothian there are no coal or limestone strata to the east of Linton. In one of the smoothed patches there were two small hollows or depressions, which had interrupted the continuity of some of the striæ. These depressions on their inner surface showed a vertical wall on their west side, and a sloping wall on their east