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discovery of M. Alibert. Of coal there are no very fine specimens, such as graced the Exhibition of 1851, the only representative of them being an ugly pile of square blocks of poor mineral from Nova Scotia, badly put together, and utterly unillustrative, rather resembling a large walking-stick than a coal seam, but—by the geologists on the jury—rewarded with a medal as

one of the thickest known seams in the world.” As there are known seams of forty, sixty, and even a hundred and fifty feet in thickness, this medal at least seems undeserved.

The coals, like the ores, are distributed over the whole building, and, for the most part, soon became in such a state that no judgment could be formed as to their merits. Of the whole number, the Austrian are perhaps the most complete, but they are badly placed, at the bottoms of wooden boxes, and almost out of sight. The Zollverein specimens are well arranged, well selected, and instructive; the Belgian are large, and also well selected; but from other countries the varieties are rarely sufficiently marked to justify an opinion. One thing, however, is very clear and very satisfactory. Almost every country in Europe, and many countries elsewhere, possess coal, and are aware of the fact. There is more progress in this matter than might, at first, be supposed, and the progress is steady. It might have been made very clear. There are some fair examples of coke.

While coal has long been steadily advancing in use, and is constantly better known and more worked, another form of carbon-graphite, or plumbago-has very long remained stationary. For many years there has been actually no yield whatever of the best kinds of this mineral in the old locality, and no new deposit has been heard of. Suddenly the Exhibition brings us acquainted with M. Alibert, a Frenchman, who has found, far away in the wildest parts of Siberia, a mass of graphite so large and important that its discoverer makes royal presents of it in the most liberal manner, and seems ready to supply the European market into the bargain. Russia, on this occasion, has again astonished the world. In 1851, the enormous and costly display of veneered malachite made it impossible for other exhibitors of that beautiful stone to be attended to. In 1862, the plumbago trophy carries off the palm, and is equally unapproachable.

To those who have not seen this curious exhibition it is almost impossible to give an idea of the effect. Cut and broken into every shape; rough and polished, and of many sizessurely so much black lead was never prepared for view before, and, probably, never will be again. It is said to be equal in quality to the best from Borrodale, and is already largely manufactured into pencils by the celebrated German manufacturer, M. Faber. The value of the black lead exhibited must very much exceed a thousand pounds sterling.

With some of M. Alibert's plumbago, and also serving as the footing for a group of stuffed animals, are exhibited the largest specimens ever seen of that singularly hard and rare mineral, nephrite, or jade. The principal stone weighs upwards of half a ton. As well might we expect to see a diamond weighing a pound as a precious stone of this magnitude ; but there it is before us in the nave of the building, not staring one in the face, but modestly retiring, and probably not noticed by one out of ten thousand persons who think they have seen all the remarkable things, and who actually have looked at the stuffed animals that partly conceal this treasure. As it lies in the case uncut, the value is estimated at about £1,600 sterling. Other wonderful specimens of polished pietra dura are adjacent, cut into vases and columns, little remarkable for their form, but of the most extreme hardness. These articles are among the most characteristic of the Russian and Swedish manufactures in stone.

3. Manufactured Minerals. Of other stones, valuable for their great beauty, and worked into decorative shapes, there are many specimens. The rich dark green and red serpentines of the Lizard, in Cornwall, are the most striking and numerous articles of this kind exhibited. Some are very good, but in many of them an absence of good taste must be remarked, for an attempt has been made to use them for purposes for which they are not adapted. Very beautiful in places, these stones abound in flaws and weak white parts. Thus a large flat surface is generally a failure, while smaller and worked surfaces conceal or avoid the flaw.* Except the black marble of Derbyshire, there is no more beautiful or costly marble in the British islands, and few finer in Europe, than this serpentine ; and, although there are many objects constructed of it in bad taste, there is a decided improvement in taste and style of manufacture when comparison is made with 1851.

With much that is beautiful in marble manufacture, there is much that is weak, and much that is positively bad, nor is the bad taste confined to our own countrymen. In all these matters progress is desirable, and nothing can promote it more than the means of comparison afforded by a grand exhibition open to the whole world.

With the good taste in style generally observable in Italian works of art, there is an adaptation of material to its object which cannot be too carefully

* This variety of serpentine requires to be treated almost like agates for cameos. The places and colours of the flaws should be studied and converted into beautics.

studied. Thus the forms adapted for marble fail in granite. The granite manufactures, chiefly from Aberdeen and Cornwall, are beautiful in quality, but small in number and variety.

Of constructive materials, slates are the most remarkable. The exhibition of them in 1862 is far superior to that in 1851. Probably no such collection as that now made was ever brought together, and certainly none could be obtained out of England. These objects are not perhaps attractive; but they astonish by their size, and by the perfection of the cleavage, admitting the preparation of long, hard, firm slates, a sixteenth of an inch only in thickness, and of slabs, without a single flaw, two hundred square feet in area.

The continental slates are very poor compared with these.

One word here with regard to the imitative marbles, enamelled on slate, by Mr. Magnus. It is impossible to praise too highly the progress made by this manufacturer since 1851. He has attained so near to perfection, that it is difficult to imagine what will be his next improvement. These imitations seem especially adapted for house decoration, owing to their extreme hardness and moderate cost.

We have little space left to notice the remaining objects exhibited in this large and important class. China and pottery clays, fire-clays, and sands, do not change, and show no progress. Mica and steatite, and some other minerals exhibited, are equally stationary. There are a few educational collections in the building, but these also offer little worthy of notice; and the same remark may be made concerning the cements and artificial stones.

One word of comparative remark in regard to the different countries. Except Australia, no country has shown a great stride in advance of the last Exhibition in its mineral produce. England, Wales, and Scotland, have sent less, and what is sent is on the whole of smaller interest, than before. Ireland has hardly sent anything. France has done little, and not better than before. Belgium has done well, and the Zollverein admirably. Austria, on the whole, is good, but justice has hardly been done to its collections. Canada, and the other British provinces of North America, are respectable, and even good. Spain is slovenly, and Portugal little better. Russia decidedly good. Sweden, Norway, and Denmark, not remarkable. Brazil is good.

Thus, in a few words, we have endeavoured to sum up the impression made by a study of the minerals of the Great Exhibition of 1862. We doubt exceedingly whether another such exhibition, conducted in the same manner, would be in any sense desirable at the end of another decennial period; for the means of instituting a comparison are so very few, and the effort to compare so fatiguing, that probably very few persons have made the attempt. That the juries themselves did not examine too closely seems likely, from the profusion of medals, and “honourable mentions,” distributed without much judgment, and often entirely without or against reason.

While, however, we believe, that in the state presented to the public, the Exhibition in this department is not what it ought to have been, we are satisfied that an orderly grouping of similar objects from different countries, for the purposes of comparison, would be productive of great good. It is not easy to say how far this is practicable generally. It may not be desirable in manufactures, which of themselves are definite objects of interest. But in the case of raw material, there seems little reason to doubt that order might be attained, and no doubt whatever that it is in every sense desirable and absolutely essential to ensure a proper use being made of the opportunity offered.

No. III.

CHEMICAL PRODUCTS.—THE APPLICATION OF

WASTE.

BY WILLIAM CROOKES, F.C.S., EDITOR OF THE “CHEMICAL NEWS."

The as

progress of our great chemical manufactures during hibition of 1862, appears chiefly to have been directed towards the utilisation of waste substances. The casual visitor to the Exhibition, wandering through the Eastern Annexe, and noticing the grand scale and great importance of some of the manufactures there illustrated; the gorgeous colouring matters exhibited by Messrs. Perkin and Son; and Simpson, Maule, and Nicholson; the stupendous blocks of alum; the beautiful yellow and red crystalline masses of ferro- and ferri-cyanide of potassium; the enormous cakes of paraffin, a chemical curiosity in 1851, one of the largest chemical manufactures in the world in 1862; and, knowing the incalculable boons which science has bestowed upon our national wealth and the world's civilisation by the introduction of the lucifer match, and development of the phosphorus manufacture, artificial manure, paper, &c.,-the visitor would be little prepared to hear that most, if not all, these im

portant commercial products are manufactured from materials formerly thrown away, and at first sight apparently valueless and repulsive.

Dirt has been aptly defined as being valuable matter in the wrong place, and it is a striking characteristic of the chemistry of the present day that it converts substances, apparently the most worthless, into commercial utilities, and even fashionable luxuries. The manufactures alluded to above, and those of Prussian blue, disinfectants, glue, &c., are striking illustrations of this chemical utilization of waste materials, and we shall endeavour, in the following remarks, to show how they have all sprung into existence by the application of chemical facts and principles to such waste materials as gas-water, coal-tar, rags, and bones.

When coal is distilled in close vessels for the purposes of the gas manufacturer, various other products are obtained at the same time. A large quantity of offensively-smelling water comes over; the various sulphur compounds present in the coal yield up this element to the gaseous products, whilst a considerable bulk of tarry matter is also produced. Now the object of the manufacturer being to produce as much gas as possible in a practically pure state, all these accessory products were for many years looked upon as necessary evils, to be got rid of as quickly as possible. The gas-water and tar were thrown away into the nearest stream, where they killed the fish and poisoned the atmosphere for miles around, whilst the sulphur was removed, or at least supposed to be removed from the gas by means of lime, or, as more recently adopted, through a mixture of sawdust and oxide of iron, about which more will be said anon.

The first of these noxious products, the gas-water, has been utilized in the following manner. It owes its bad smell principally to the presence of ammonia and sulphur compounds, and it is only necessary to add some quicklime to this, for it to seize upon the acids with which the ammonia is in combination and liberate the alkali. This gas is conducted into chambers where it meets with carbonic acid, forming, after appropriate purification, the salt known in commerce as carbonate of ammonia, about 2,000 tons of which are made annually from this liquid. If, instead of distilling the gas-liquor with lime, a strong acid is added to it, hydrochloric for instance, itself a waste product, the compound known as sal-ammoniac is produced, which is of very great value in the arts, being the principal source of the more common salts of ammonia met with in commerce; the liquor ammoniæ of pharmacy, or hartshorn, being made by distilling this purified sal-ammoniac with lime, and conducting the evolved gas into water. The uses of this

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