a rich straw yellow. It is applied to fabrics with great readiness, requiring no mordant, and is one of the most permanent colours known. Carbazotic acid has other valuable properties; for instance, it is a valuable medicinal agent, being similar in its action to quinine, only when administered it exerts its tinctorial properties at the expense of the patient's skin, dyeing him a lively yellow. It also has an intensely bitter taste, and for these reasons it has been suggested that arsenic and other poisons should be mixed with carbazotic acid. In cases of slow poisoning, the yellow appearance of the person to whom it was administered would at once give rise to a suspicion of something wrong.

It is a curious fact, that from coal-tar may be extracted the three primary colours, red, blue, and yellow, and these being obtained, every other tint is easily produced by their admixture.

Our space forbids us even to refer to the other modes in which the former by-waste products in the manufacture of gas are utilized. We must now proceed to the next division of our subject-RAGS. We have spoken above of Baron Liebig's proposition to measure the civilisation of a country by the amount of soap which it consumes. We think a better standard of a nation's progress would be the value which it attaches to rags, for, as Dr. Lyon Playfair observes, it is quite true that as nations rise high in the world they appreciate the value of rags more, and are willing to pay a higher price for them from other countries where their value is not appreciated. First and foremost of the many applications of this humble material is the manufacture of paper; for this purpose we buy from other nations no less than 15,000 tons of rags annually, besides using up four times that amount derived from the waste of our own population, representing a money value of rags equal to £700,000. Within the last ten years, paper has been manufactured from numerous other materials, but nothing has yet been found out which can in any way compete with rags in strength of texture or beauty of quality. The manufacture of paper scarcely comes within the limits of the present article, but we may refer to a very valuable improvement which has been effected within the last few years in connection with this product. Mr. Gaine described a process by which ordinary unsized paper could be converted. into a material similar to parchment, by a momentary immersion in sulphuric acid of a certain strength, and more recently Messrs. De la Rue and Co. have taken up the manufacture of this parchment-paper commercially. The transformation effected is very striking. A sheet of common white blotting paper, which will scarcely bear its own weight when wetted, is converted in a few seconds into a substance possessing all the pro

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perties of ordinary animal parchment, and so strong that it is only torn with great difficulty. The change is more remarkable inasmuch as no chemical alteration has taken place; the acid simply produces a molecular change, and is entirely washed away from it as soon as the desired effect is produced. The applications of this novel material are very numerous; its great strength (nearly double that of parchment), and its indestructibility by water or moisture, render it a valuable material for legal documents, such as policies of insurance, scrip certificates, deeds, agreements, &c. It is also used to replace vellum in bookbinding, and takes the place of ordinary paper in schoolbooks, and other books exposed to constant wear. The manner in which it bears both oil and water colours renders it of value for artistic purposes; the chemist now employs it largely for the new process of dialytic analysis, and ladies use it extensively to replace bladder in covering preserve pots, &c.

But there is another class of rags-those from woollen materials-which cannot be thus employed for the purposes of the paper maker. Our readers are probably aware of the transformations which cast-off cloth garments undergo; their change into "mungo," "shoddy," and "devil's dust," and their re-appearance as "ladies' cloth;" their subsequent degeneration into druggets, and final utilization for ornamenting our walls in the form of flock paper. These we pass over, and will trace the history of woollen rags after they have thus been tortured and wrought into every textile form which the ingenuity of manufacturers can devise. The fibre of the wool may have become physically completely broken up, and disorganized by repeated treatment, but its chemical value remains unaltered, and the large amount of nitrogen which it contains is too valuable to be thrown away. Tons upon tons weight of this woollen refuse are sold for manure, and its excellent properties in this respect are well shown by the perfection of the early brocoli which is supplied so plentifully to the London market from Cornwall.

The class of goods called muslin-de-laine for a long time baffled the waste product utilitarian. The cotton fibre was valuable, and the woollen fibre was valuable, apart, but the difficulty lay in separating the two. Either of them could be destroyed by chemical means; thus, steeping the mixed fabric in acids converted the cotton-weft into sugar, when the wool was left available; and, on the other hand, an immersion into an alkali dissolved out the woollen-warp and left the cotton. But the manufacturer was not satisfied with this; he wanted both fibres; and Mr. F. O. Ward has lately introduced, and illustrated in the chemical department of the International Exhibition, a most ingenious process by which this

desideratum is accomplished. He takes the mixed fabric and subjects the rags to the action of steam at a pressure of four or five atmospheres. The effect of this is to char the wool, rendering it very friable, whilst the cotton is not in the least injured. The action over, the rags are beaten and sifted, when the cotton is left behind in the fibrous state, whilst the brittle matter into which the wool has been converted separates in the form of powder. The cotton, being as firm and as strong as ever, may be applied to a variety of purposes: some very excellent paper made of cotton separated in this manner is shown by Mr. Ward; the wool is sold as a manure, under the name of "crenate of ammonia."

But woollen refuse can be applied to higher purposes than forcing early cabbages; the chemical manufacturer, utilizing in another way the nitrogen which it contains so plentifully, throws it into his cauldron, and stews it down with pearlash, horns and hoofs of cattle, old iron-hoops, blood, clippings of leather, and broken horse-shoes-when it produces the beautiful yellow and red salts, known as the prussiates of potash, magnificent crystals of which may be seen in the Eastern Annexe. From these salts, the rich and valuable pigment, Prussian blue, is made; and under this form our old rags start upon a fresh career of beauty and usefulness, forming in their turn other waste products which are again seized hold of by skilful intelligence, and re-utilized.

Their

We now approach the vast and important subject of BONES. The uses to which these are applied are endless. mechanical applications for knife-handles and similar purposes do not require more than a passing reference here, but we may state that the quantity annually imported into this country represents a money value of £400,000. Chemically speaking, bone consists of a little more than half its weight of phosphate of lime, and about a third of its weight of cartilage, the remainder being made up of earthy matters unimportant for our purpose. The applications of each of these constituents of bone are numerous: the cartilage is capable of being extracted by boiling water under pressure, being converted into a gelatinous substance, and is then used in large quantities by the calicoprinter for stiffening the fabric. The substances known to housekeepers as gelatin and calf's-foot jelly usually consist of this extracted cartilage in a purified form. Isinglass is quite a different substance in its origin, although, chemically speaking, only gelatin. It is prepared from the sounds of certain species of sturgeon; and, from its somewhat high price, has long tempted manufacturers to produce an imitation in ordinary gelatin. The success which has attended this endeavour may be seen by an examination of several cases in the Eastern

Annexe. Viewed as an attempt to endow the humble gelatin with some of the elegance and refinement of its more costly competitor, these endeavours deserve all the success which has attended them; but, in the hands of some retail sellers, this legitimate imitation is often palmed off upon the public as genuine isinglass, when it assumes the character of an unjustifiable imposition.

When bones are heated without access of air, the organic matter of the cartilage is decomposed-oily products passing over and a black carbonaceous residue being left. This is known by the name of bone-black or animal-charcoal, and consists of carbon in an extremely fine state of division diffused through the inorganic constituents of the bones. Bone-black has a great affinity for several organic colouring matters, and is extensively used for decolourizing syrups, sugar, and other things. If a solution of dark brown sugar be filtered through a layer of bone-black it passes through perfectly bright and colourless; port-wine may in a similar manner be obtained as colourless as water, without its flavour being much impaired. The oil which distils over during the operation of calcining is known in commerce as "Dippel's animal oil;" it contains aniline and several other basic bodies, and can be employed for the production of colouring matters in the same way as coal-tar.

The subject of artificial manure is one which has received great attention of late years. Chemists have discovered that the earthy constituents of bones form one of the most valuable foods of plants, and to supply the soil of England with the earthy phosphates which are annually removed from it by cereals and other crops, manufacturers now not only make use of recent bones, but avail themselves of the rich store of phosphatic wealth existing in the fossilized remains of extinct animals. The so-called superphosphate of lime consists of calcined bones, or coprolites,* which have been reduced to fine powder and then treated with sulphuric acid; part of the lime is removed by this process and the remaining superphosphate is obtained in a form which is readily assimilated by plants.

The manufacture of phosphorus-"that dark, unctuous, daubing mass,"-which has now become so important and universal an agent of civilization, is the last product from bones which claims our attention. It is prepared from the phosphoric acid contained in bones by heating it to a very high temperature with charcoal. The five equivalents of oxygen contained in the phosphoric acid are removed by the charcoal, and the phosphorus distils over. The crude product is afterwards purified by distillation and squeezing through chamois

*Coprolites are supposed to be the petrified dung of reptiles.

THE EXHIBITION OF 1862.

leather. One of the largest firms for the preparation of this element, Messrs. Albright and Wilson, of Oldbury, exhibit a most interesting case illustrating this manufacture, the beautiful semi-transparent, wax-like appearance and the large blocks in which it is produced are very accurately illustrated (phosphorus itself being inadmissible in the building).

The great consumption of phosphorus is of course in the manufacture of lucifer matches; in this, two difficulties have to be contended with, phosphorus being the most inflammable body known, and also one of the most poisonous.. Numerous had been the attempts to overcome these difficulties in the manufacture of this useful though humble commodity, but the liability to explosion, and the terrible disease to which the workmen who inhale the phosphuretted vapours are subject, seemed scarcely capable of being obviated, when Professor Schrötter, by one of the most remarkable discoveries in modern chemistry, effected an entire revolution in the manufacture. He discovered that when common phosphorus was heated for some time in a close vessel to a temperature of 470° F., it underwent a complete alteration in the whole of its physical characters. From a white, waxy, crystalline body, soft and flexible as lead, it became a deep red, amorphous, opaque mass, hard and brittle as glass. The white phosphorus quickly ignites by mere exposure to the air; the red phosphorus will not ignite spontaneously, and may be packed up in boxes, in the dry state, without any danger. The white phosphorus is as poisonous as arsenic, and has a strong garlicky smell, whilst the red is without odour, and has no poisonous properties. The former is luminous in the dark, and melts at 108° F., whilst the latter is perfectly illuminous, and requires a temperature above 500° F. to melt it. Lastly, the white is freely soluble in various liquids, whilst scarcely any known solvent will touch the red modification. In spite of these striking differences, the red phosphorus answers quite as well for match may making as the common sort, and as the transformation effected with very little trouble, there is no doubt that the harmless variety will, in course of time, entirely supersede the dangerous variety.

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Considering the frightful disease which attacks and destroys the jawbones of the workpeople employed in making common matches, and at the same time their highly poisonous properties, we think it the duty of every person to encourage to the utmost the manufacture of matches made from red or allotropic phosphorus. Of these, two varieties are at present before the public. One kind is exactly like the ordinary match in which the oxidizing material and the red phosphorus are mixed tegether, and put on the tips of the splints, differing there