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the greatest amount of moisture in the air being 0.95° on the 19th, and 0.93° on the 8th ; the proportion was at its lowest, 0.66°, on the 3rd, 15th, and 27th. The mean for the month being 0·79.

RAINFALL.-Rain was collected as follows:

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The quantities marked * were melted snow and rain. The total fall in March was 1.159 inches.

WIND.—The general direction of the wind was :-
North—3rd, 4th, 11th, 12th, 20th, 21st, 26th, 27th, and 31st.

North-East-6th, 10th, 13th, 14th, 15th, 22nd, 23rd, 24th, 25th, 28th, 29th, and 30th.

East-9th.
South-East-7th.
South–19th.
South-West-18th.
North-West-1st, 2nd, 5th, and 8th.

The principal variations indicated by the anemograph, in March, were as follows:

On the 1st, at 5.50 P.M., the direction shifted from N. to S.W.; afterwards gradually to N.W., with a simultaneous increase in the velocity from 10 to 25 miles per hour.

It was almost calm from 8 P.m. of the 3rd to 1.30 A.m. of the 4th. Between 11 A.M. and 3.30 P.M., the same day, the direction veered from W. to N., a retrograde movement from N. to W. occurring at 2.25 the next morning.

The rate was from 25 to 30 miles per hour during the night of the 5th. A change from N.E. to S.E. was registered at 9 A.m. of the 7th, and the following morning the wind gradually veered from S.E. to S.W., between 3 and 8 A.M.; later in the day, between noon and 3 P.M., a still farther movement from S.W. to N.W. took place and the circuit was completed by the change from N.W. to N.E.,

at 4.40 A.M., on the 9th. The velocity did not exceed 10 miles per hour during the above period of revolution. On the 16th the direction changed, at 9.45 P.M., from N.W. to S.; at 11.20 P.M. another change, from S. to S.E., was recorded, the rate simultaneously increasing from 10 to 20 miles.

During the 18th a gradual veering from E., through S., to W. occurred. Through the 19th the direction was S., but at 10.45 P.M. it suddenly shifted through W. to N., and the velocity mounted from 5 to 40 miles ; this rate diminished to 30 miles at 2 A.M., the 20th ; afterwards 25 to 30 miles was maintained uniformly until the 22nd. On the 28th the wind veered from W., through N., to E., returning to N. at midnight.

THE EXPANSION OF PALLADIUM BY HYDROGENIUM.

BY W. CHANDLER ROBERTS, F.G.S., F.C.S.

The absorption of gases by metals generally,* and the relation between hydrogen and palladium specially, has lately been detailed in The Student,t it is therefore merely necessary to premise, that all colloid metals (that is, those metals that possess the crystalline character in the lesser degree) have the power of occluding gases, each metal exerting a selective power for one or more gas.

Of all metals, palladium possesses this power in the very highest degree, absorbing 900 times its volume of hydrogen. This occlusion is effected either by heating, and slowly cooling the metal in an atmosphere of the gas, or by evolving electrolytic hydrogen on its surface. Which ever method be employed the palladium increases in volume, the expansion appearing to be directly proportional to the volume of gas occluded.

From considerations already given, Mr. Graham considers the relation between the palladium and hydrogen to be that of an alloy of the following composition :

By volume.
Palladium

100

or 95.32 Hydrogenium

4.908 or

4.68

101.908 100 The density of hydrogen being 1.908.

Thus the original length of a palladium wire being 609.144 metres after charging with 936 times its volume of hydrogen, the

* “ Intellectual Observer," No. Lxvi., July, 1867.
+ THE STUDENT, No. xiv.

B

ar

wire showed an increase of 9.779 mms, 0.355 inch) or a cubica) expansion of 4.908 per cent.

The expulsion of hydrogen from the metal may be effected by heating the wire in vacuo, in air, or by evolving electrolytic oxygen on its surface, the loss of hydrogen being attended by an extraordinary contraction of the wire, which actually falls as much below the original length, as it had previously risen above it.

The following experiment depending on the unequal expansion of two metallic elements of a compound ribbon, well exhibits this singular action of hydrogen upon palladium.

A consists of two strips, one of palladium, the other of platinum, each 300mm. long, 3mm. wide, and 0.3mm. thick, these are soldered together and coiled into a circle, the palladium being inside.

This coil is

placed in a glass YA

vessel filled with acidulated water, near it is ranged a plate or wire of platinum,

B. By

of the

commutator, C, the ribbon and the wire may be alternately connected with either pole of a battery, two pint cells, Grove or Bunsen, answer best.

In the first instance, the coil must be connected with the zinc pole of the battery, hydrogen then being thrown on the surface of the palladium, which absorbs the gas, and by expanding opens the spring; this movement may be rendered still more visible by attaching to A a light index of straw or glass terminated by a tip of coloured paper.

On reversing the direction of the current, oxygen will be thrown on the surface of the metal, and by consuming the previously occluded hydrogen, causes the index to move rapidly back to zero.

A still more striking modification of the experiment consists in providing two strips of palladium foil, varnished on one side, each about 4 inches or 100mm. by 10mm., and coiling them into a loose spiral, placing them as in the former case in acidulated water, and connecting them with the battery, it is evident that when one is expanding the other is contracting, but the various convolutions performed are very singular, and of extreme interest.*

* Mr. Browning, of the Minories, has arranged the above apparatus in a compact form.

means

ARCHÆOLOGIA.

It was our duty last month to call attention to an act of vandalism which was going on in France, in the destruction of the Roman walls of the town of Dax-we have this month to point to an act of the same kind in England, though the monument threatened with demolition is not quite of equal importance. At the foot of the suspension bridge of Clifton, in Gloucestershire, there is an enclosure surrounded by ANCIENT ENTRENCHMENTS, known by the good Anglo-Saxon name of the Bar Walls, or Bower Walls. It was perhaps raised there by the Romans, as Roman antiquities are stated to have been found within its area, and, moreover, there are reasons for believing that the Britons did not make entrenchments, i.e., the bank combined with the foss, before they learnt them from the Romans, but that their defence consisted only of an embankment, or wall raised upon the ground. In this instance, the embankment is formed of limestone, and the Leigh Woods Building Company are, it is said, destroying this interesting monument simply for the sake of the materials, or, in other words, making a limestone quarry of it. Unless they are prevented, these Bower Walls will very soon have ceased to exist. This is no doubt a lamentable state of things, and we fear it is not the only case in which in our own country the existence of ancient monuments is threatened.

The PRESERVATION OF ANCIENT REMAINS is indeed a subject which, from different circumstances, is attracting considerable attention at the present time. It was first taken up within the ranks of the Ethnological Society, where, we understand, it was proposed to form a deputation, and try to obtain an interview with the Premier, in the hope of obtaining the interference of the Government in some form or other for the protection of our early monuments. This plan we suppose has not been persevered in, but we hear that the society now contemplates the formation of an archæological section, the duties of which will be to watch over the protection of our prebistoric antiquities, and to collect information from all quarters as to their present condition. Among the names which have been mentioned for this section are Sir John Lubbock, Professor Huxley, Col. Lane Fox, Mr. Franks, Dr. Thurnam, Mr. John Evans, Mr. Hyde Clarke, and Canon Greenwell. There can be no doubt that such a body, if properly conducted, would be capable of doing much good, and we understand that offers have already been made from

BOURNE.

several parts of the kingdom of complete and careful surveys of existing remains. While the Ethnological Society is displaying this activity, it is whispered that the Society of Antiquaries has some project in contemplation of making an appeal to the Government in favour of our early monuments; and we have also heard that the subject is likely to be brought before the House of Commons during the present session.

In January another ROMAN LEADEN COFFIN was found in Kent, on the property of Mr. Smeed, the great brickmaker, near SITTING

It was six feet in length, and braced round with thin iron bars. It was ornamented with crosses on the lid and sides; and everybody hoped it had been secured for the museum now being formed at Sittingbourne by Mr. George Payne, jun. But we are told that, the value of the lead, it seems, having been a consideration, this coffin has just been melted down for the metal! Mr. Alfred Jordan presented the similar coffin found at Milton to the Charles Museum at Maidstone.

A discovery of MediÆVAL COINS IN OXFORD, about a fortnight ago, illustrates both the old practice of laying by money in earthenware vessels buried in the ground—“crocks of gold," was the expression which became almost proverbial—and the loss which archæological science experiences from the little attention paid too often to antiquarian discoveries. Some workmen were occupied in digging the foundation of a house on the Cowley Road, when they came upon an earthenware vessel filled with silver coins. Instead of keeping the coins together until they had been examined by some one capable of appreciating their interest and value, the ignorant workmen allowed them to be taken away by, anybody who happened to be near the spot, and we suppose offered them a few pence, and the consequence was that they were immediately dispersed, and any historical value they might have is entirely lost. The only information of this kind which seems to have been preserved is, that some of them are stated to have belonged to the reign of Edward I.

The BRITISH ARCHÆOLOGICAL ASSOCIATION has selected for the place of its annual congress this autumn the town of St. Alban's. The name of the president has not yet transpired. It would be difficult to point to a locality of greater historical and antiquarian interest, for it is rich in remains of the Roman, Anglo-Saxon, and Anglo-Norman periods, and every one knows the part it played in the great political struggles of the fourteenth and fifteenth centuries. It cannot but be one of the most important of these meet

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