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botryoidal masses, but the tendency to form these fringes is very strong.

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Chloride of antimony with zinc also gives these black fringes. Lead salts yield crystals resembling those of silver; but leaves of irregular hexagonal plates prevail, and often grow to a large size.

A solution of acetate of thallium, containing 20 per cent. of salt, quickly gives a beautiful forest of thorny crystals.

Sulphate of cadmium gives rise to a small leaf-like growth on zine; but a strong solution of the chloride produces an appearance of sticks covered with small spines or knobs.

The new metal indium is thrown down upon zinc in the form of thick white crystals. The deposition is promoted by touching the zinc with a piece of iron.

Tin gives beautiful results. If zinc be placed in a solution of stannous chloride it is quickly surrounded with an outgrowth of prolonged octohedra, and as these advance into the liquid it is easy to observe that the additions of new metal commence at the apex, and that the wave of chemical change proceeds down the lateral edge, occupying some seconds of time in depositing the new layer of material. Frequently, also, there is a luxuriant growth of large flat leaflets, or of symmetrical structures resembling fern-leaves, but with the fronds arranged at right angles, or combinations of these with octohedra, as shown in Fig. 6. These fern-leaves often begin of a dull grey colour; but, as they advance, suddenly change to a brilliant white.

The particular form of these crystalline growths depends, therefore, primarily, on the specific character of the metal; but this is greatly modified by the strength of the solution.

The forms assumed by native metals resemble those produced by this process of substitution. In some cases, indeed, it seems almost certain that the deposition of these minerals was effected in the same VOL. VI. No. 56.)

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way, as, for instance, the silver which occurs sometimes in tufts, sometimes in large crystals, on the native copper of the Lake Superior district. Gold is frequently found in cubes more or less rolled, but the leaf gold from Transylvania bears a striking likeness to the crystals that form in our laboratory experiments. Silver is often found native as twisted hairs or wires of metal-a form that never occurs in the decomposition of its nitrate by copper, but which can be artificially produced in another way.

There has been noticed a singular tendency in old silver ornaments and coins to become crystalline and friable. Here is an ancient fibula from the island of Cyprus, supposed to be at least 1500 years old, which, through the greater portion of its substance, presents a fracture something like that of cast iron, and its specific gravity has been reduced in round numbers from 10 to 9. It contains a little copper. This property of certain metals, or their alloys, to change in condition and in volume, is worthy the attention of those whose duty it is to make our standards. Experiments should be instituted for the purpose of learning what metals or combinations of metals are least subject to this secular change.

These metallic crystals are Nature's first attempt at building. The material is the simplest possible-in fact, what chemists look upon as elementary. But how is the building carried on? What are the tools employed? Where are the bearers of burdens that bring the prepared pieces and lay them together according to the plan of the Great Architect? We must try to imagine what is taking place in the transparent solution. The silver, of course, existed at first in combination with the nitric element, and for every particle of silver deposited on the growing tree, an equivalent particle of copper is dissolved from the surface of the plate. The nitric element never ceases to be in combination with a metal, but is transferred from the one metal to the other. On the "Polarization Theory," the positive and negative elements of the salt constantly change places and enter into fresh combinations, one consequence of which would be a gradual passage of the nitric element from the growing silver to the copper plate. This actually takes place, and there is a diminution of the salt at the ends of the silver branches, giving rise to an upward current, and a condensation of nitrate of copper against the copper plate, which gives rise to a strong downward current. These two currents are seen in every reaction of this nature. In the case of silver and copper, however, it has been proved that the crowding of the salt towards the copper plate is more rapid than would follow from the usual polarization theory. The instrument employed for determining this point was a divided cell in which two plates, one of silver and the other of copper, connected together by a wire, are immersed each in a solution of its own nitrate, contained in each division of the cell, and separated from one another merely by parchment paper. The crystals of silver deposited on the silver plate in this experiment are very brilliant.

There are other indications of the liquid being put into a special condition by the presence of the two metals which touch one another. Thus zinc alone is incapable of decomposing pure water; but if copper or platinum be deposited on the zinc in such a manner that the water can have free access to the junction of the two metals, a decomposition is effected; oxide of zinc is formed, and hydrogen gas is evolved. At the ordinary temperature the bubbles of gas rise slowly through the liquid, but if the whole be placed in a flask and heated, pure hydrogen is given off in large quantity. We have also found that iron or lead similarly brought into intimate union with a more electro-negative metal, and well washed, will decompose pure water.

As might be expected, the action of magnesium on water may be greatly enhanced by this method; and a pretty and instructive experiment may be made by placing a coil of magnesium in pure water at the ordinary temperature, when there will be scarcely any effect visible, and then adding a solution of sulphate of copper. The magnesium is instantly covered with a growth of the other metal, and at the same time the liquid seems to boil with the rapid evolution of hydrogen bubbles from the decomposed water.

When, however, the force of the two metals in contact has to traverse a layer of water, the resistance offered by the fluid prevents its decomposition. This must also be an important element in the decomposition of a metallic salt dissolved in water, and in fact we have found that the addition of some neutral salt, such as nitrate of potassium, increases the action-apparently by diminishing the resistance of the liquid. If, too, we increase the quantity of the dissolved metallic salt, we get more than a proportional increase of deposited metal. Thus, in an experiment made with the different strengths of nitrate of silver on the table, the following results were obtained in ten minutes, all the circumstances being the same except the strength of the solution :

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In fact it has been found that in solutions not exceeding 5 per cent., twice the amount of nitrate of silver dissolved in water gives three times the amount of chemical action; and this is true with other metals also in weak solution. It may be that this is not the precise expression of a physical law, but it agrees at least very closely with the results of experiment.

The power arising from this action of two metals on a binary liquid may be carried to a distance and produce similar decompositions there. This is ordinary electrolysis. Metals have often been crystallized from their solutions in this way, and Mr. Braham has made excellent preparations of crystalline silver, gold, copper, tin, platinum, &c., by using poles of the same metal as that intended to

be deposited upon them. The forms thus obtained are precisely analogous to those produced by the simple immersion of one metal into the soluble salt of another, and illustrate still further the essential unity of the force that originates the two classes of phenomena. [J. H. G.]

WEEKLY EVENING MEETING,

Friday, February 23, 1872.

SIR HENRY HOLLAND, Bart. M.D. D.C.L. F.R.S. President,
in the Chair.

HENRY LESLIE, Esq.

On the Social Influence of Music.

IN these days of railways and telegraphs, and of that general high pressure to which they have brought us, it is necessary to utilize every calming and soothing influence, and to find rational mental employment for the people as recreation after their hours of work. Such a course cannot fail to be productive of increased strength to the ties of social and family life, and consequently of powerful good to the national life.

Numerous examples taken from the various strata of society which form the national life of the kingdom are cited to show how great the social influence of music is at the present time, both as a means of education and recreation, and how refining and elevating are its results.

The Sacred Harmonic Society, which has just entered the fortieth year of its existence, has, by its noble efforts in the cause of musical art, gained a most distinguished position. It is an institution of which this country has reason to be proud, for its reputation extends throughout the whole civilized world. It has some thousands of pounds invested in Government securities; it possesses a fine library, and there is, in immediate connection with it, a Benevolent Fund, out of which help is given to cases of distress. But its claims to our admiration are not yet exhausted, for to the Sacred Harmonic Society do we owe the establishment of the Handel Festivals, which have had a great educating influence upon the whole kingdom from so many choirs and choral societies taking part in them, and having thus had their standard of performance considerably raised. The Sacred Harmonic Society distributes annually many hundreds of pounds in the engagement of artistes, thus doing good service to those who, possessed of natural talent and genius, have had sufficient perseverance to qualify themselves for the higher positions in the world of art.

After the example of a town society, the proceedings of an

The Hereford

Amateur Society in the country shall be considered, shire Philharmonic Society, established in 1863, consists of performing and non-performing members. There is an orchestra of about forty, eight or nine of whom are professional assistants, and a chorus of 120. Two concerts are annually given, and for each of these there are five rehearsals. Performing members are not allowed to take part in the performance unless they have attended at least three of these rehearsals, and when it is known that the distances to be travelled form a circle of which the diameter exceeds 100 miles, it will be understood that some zeal is displayed, and that some social good has been derived from the institution of the Society, otherwise the attendance of members would flag. The fact that a long list of names awaits election as vacancies occur is the best proof of the diligence of the members.

That the standard of the society is not a low one will be apparent from the programmes, each of which contains a symphony, a selection from an oratorio, or cantata, madrigals, part-songs, choruses, overtures, &c. All the solos and concerted pieces are sung by members, and there are four ladies who have respectively played, with orchestral accompaniments, Beethoven's Choral Fantasia, Mendelssohn's Andante and Rondo, Weber's Court-stück and Beethoven's Concerto in C minor; and at the next concert a gentleman is to play the first and second movements of Mendelssohn's Violin Concerto. The practical experience gained by the members in the preparation of classical works of this standard for public performance has enormously developed the musical capabilities of the district. Another important consideration is, that work such as the members do renders them far better qualified to enjoy and appreciate a purely professional performance when they have the opportunity of hearing one. Thus does the Herefordshire Philharmonic Society promote an extremely beneficial influence upon art, while the means of achievement are pleasantly social.

No doubt many who are present have heard of Welsh Eisteddfods, which are national gatherings in honour of the fine arts. The proceedings ordinarily consist of competitions by poets, solo singers, harpists, pianists, volunteer and other bands, and choral societies, but occasionally an oratorio or cantata is performed. Painting and sculpture are but seldom represented, but orators are highly appreciated.

Although things are done which, from their quaintness, are almost ludicrous, and the mistaken zeal of ardent supporters of the nationality causes the offering of prizes for subjects which raise a smile, still there is such unmistakable appreciation of all that is good, and such hearty enjoyment of it amongst the thousands who come from great distances to attend these Eisteddfods, that at once the thought comes uppermost, "What might not such a people do in art?" The soil exists, and all that is required is good cultivation.

If the Welsh only knew the musical strength they possess they would not fritter it away at these Eisteddfods as they do at present.

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