Before passing from the consideration of ice, I may note a new use of snow pointed out in an American paper-" All places where snow abounds are not, perhaps, aware of the value of the fleecy flakes in making light, delicious, and wholesome bread. There is no 'rising' in the world so perfectly physiological as good, fresh, sweet snow; it raises bread or cakes as beautifully as the best of yeast, or the purest acids and alkalies, while it leaves no taint or fermentation like the former, nor injurious neutral salt like the latter."

It is not improbable that the muriatic acid so incessantly wasted in our soda works may be used for purifying glass-makers' sand; at ordinary temperatures this would probably remove the oxide of iron, which imparts the green tinge to common glass, and it certainly would by the application of a little heat.

Attention has been drawn recently by Messrs. J. Townsend and J. Mather, to the utilization of the residues from the manufacture of soda and potash. The uses to which the hyposulphates and sulphates are proposed to be applied are-first, as antichlorines in the manufacture of paper, and the treatment of cotton and other tissues, after bleaching by chlorine and its combinations; secondly, as agents for bleaching wool and other animal products, also for straw, starch, oils, ivory, horn, hair, &c.; and thirdly, as a purifier and antiseptic in the manufacture of sugar.

Bromine is an elementary substance discovered in 1826 by Balard, of Montpellier, in the bittern or residual liquid left after the evaporation and crystal

lization of the salt from sea water. It occurs in small quantity also in most mineral waters, in many sea plants and sea animals, in some land plants, and in some minerals-especially the argentiferous ores of Mexico. In medicine, bromine is used for the same purposes as iodine, appearing to have the same therapeutical effects, and even greater activity. It is employed to some extent in photography, and has also been used in the form of bromide of potassium for the purpose of falsifying iodide of potassium. By the ordinary process of manufacture, two pounds and eight ounces of bromine are obtained from thirty gallons of the bittern. So much bromine is there in the western waters of America, that it will ultimately become a large manufacture where a sufficient demand shall have been created for this substance, which is sure to happen sooner or later, as new and important uses will inevitably be found for a substance of chemical characters and relations so peculiar and striking as those of bromine.

WASTE MINERAL SUBSTANCES.

FINALLY, I must add a few words on miscellaneous mineral substances.

Professor Crace Calvert, in a valuable paper (in the Journal of Society of Arts, Vol. iii., p. 17), went into the various new or residual products of coal, exclusive of coal gas, such as, firstly, the coke, next the liquid portion, which is bought by chemical manufacturers, who obtain from it sulphate of ammonia for agricul

tural purposes; and sal-ammoniac for soldering which is also used in calico and print works for producing the style of prints called "steam goods." And from these two salts is obtained hartshorn, extensively employed in pharmacy. Ordinary coal gas liquid is also often employed to obtain by distillation common ammonia, much used in dye works, and to produce with lichens the beautiful colouring matters called orchil and cudbear. Many hundreds of thousands of gallons of ammoniacal liquor are used in the preparation of ammoniacal alum. To obtain this and other refuse products of coal, aluminous shale comes largely into use.

Coal tar (of which about 300,000 tons are made yearly) furnishes a chief ingredient of printers' ink, in the shape of lamp black; it is also made into asphalt for pavements, and mixed with red-hot clay becomes a charcoal that acts as a powerful disinfectant; with coal-dust it forms, by pressure, an excellent and compact artificial fuel.

Carbolic acid possesses extraordinary antiseptic properties, and carbazotic acid gives magnificent straw-coloured yellow dyes on silk and woollen fabrics.

Crude naphtha, used for burning, benzine or benzole for removing grease spots, the heavy paraffin oil, extensively employed as a lubricator in the cotton mills, &c., are other commercial products, formerly waste or unapplied.

We may thus sum up the useful products of coal. They are, first, the refuse of combustion, such as ashes, clinker, soot, all of which are valuable for the making of roads, mortar, and manure. Secondly, products after distillation in the manufacture of gas, consisting

of light carburetted hydrogen, olefiant gas, the chief source of illumination; hydrogen, carbonic oxide, which impairs the luminosity; nitrogen, vapours of volatile hydrocarbons, and vapour of bisulphide of carbon, remarkable for its high refracting power, its great volatility, and highly solvent action on phosphorus, &c. Thirdly, matters separated by the condensation and purification of gas, as carbonic acid, sulphuretted hydrogen, hydrocyanic or prussic acid, sulphate of ammonia, chloride of ammonium, sulphide of ammonium, tar, and volatile oils. In connection with coal tar, we have coarse soaps and paints, as well as asphalte pavements. Further, by distillation at low heat, we obtain naphtha (not mineral properly so called), benzol or benzine Collas, benzoic acid, isomeric with hydrosalicylic, and oil of meadow sweet, benzoin, isomeric with oil of bitter almonds, nitro-benzol, smelling of the last, cyanide of benzoyle smelling like oil of cinnamon, formobenzoic acid, like oil of hawthorn, benzoyle, like oil of geranium. Then follow toluol, radicle of the balsam of tolu, cymol, base of oil of cinnamon, and a whole allied progeny. If the distillation be conducted at a higher temperature, we have paraffin oil, and petrolene, now so extensively coming into use. In addition to these, naphthalin in solid crystals, whose derivative, chloronaphthalic acid, produces beautifully-coloured compounds with the metallic oxides, and is nearly identical with alizarine, the basis of the madder dyes. We obtain, further, from the oleaginous results, the acid principle phenol, or carbolic acid, creosote, or phenyl-alchol, nitrophenesic, or picric acid, used in

dyeing, and producing salts of yellow or orange hues. Next come alkaline volatile principles, as picoline, leucoline, aniline. The latter, a thin oily liquid, may be obtained either from indigo or nitrobenzol, and indigo may be reproduced from it in turn. It has assumed immense importance from its application in the production of the favourite colour called mauve, which has had such a run of public favour of late. To obtain the colour, equivalent proportions of sulphate of aniline and bichromate of potash are dissolved in water, and the black precipitate filtered off. Dry and digest in coal tar naphtha, to remove a resin, and dissolve out the colouring matter in alcohol.

An immense amount of coal is wasted at coal mines by the process of breaking up the coal into the proper sizes for market. In this operation a large per centage of the coal is finely pulverised, and is thrown aside as unsaleable. This fine and wasted coal is of the purest quality. A correspondent of the New York World, writing from the Pennsylvania coal mines, states that at a single colliery doing a good business, four hundred tons of coal per day are made to pass through the machines for breaking up the lumps, and the waste is about 20 per cent., or eighty tons daily. All this amount has to be mined, brought to the breaker (two iron cylinders, with iron teeth, revolving in a horizontal position, panneled to each other, and about ten inches apart), and, after this process of destruction, has to be carried away and piled up. One will see at any colliery, of several years' standing, hundreds of thousands of this now worthless article, very pyramids. All this, except what little is made