An antiseptic, being a derivative of toluene, capable of generating chlorine.

The parent group of dyes formed from chromophores by substitution in hydrocarbons, and when, in addition, a strong basic or acid group is also present, dyes are obtained.

An essential oil used in medicine which is obtained in India by distillation with water of the leaves of the Melaleuca leticcdendron L. It is of light green colour, soluble in alcohol and ether, containing cineol and terpinol. Sp. gr., 092 optical rotation, io degrees to 40; refractive index. i46o to i466.

Occurs naturally in many fruits, including lemons, citrons, oranges, and red bilberries, and associated with malic acid in gooseberries. It is also found as caicium citrate in potatoes, beetroot, etc. Lemonjuice is the material from which it is usually made, and when pure it crystallizes in large, colourless, rhombic prisms, which melt at 153 degrees C. and are readily soluble in water. Citric acid and its salts are used in medicine, in the preparation of summer drinks, and extensively in dyeing and calicoprinting. Citric acid is also used as a remedy for scurvy.

There is a fundamental difference between a mere mixture and a chemical compound. If some lead shots be mixed with some powdered sulphur ever so carefully, they can be easily separated again. For instance, the sulphur can be blown away from the mixture by the use of a bellows, or all the shots can be picked out and removed one by one. Hut if, instead of removing the shots, the mixture is subjected to strong heat, both the lead and the sulphur disappear as such. They enter into combination with each other in a chemical sense, and a new substance or chemical compound is formed, named lead sulphide, which has properties or qualities quite different from those of its constituents. The tarnish which forms on articles of silver when exposed to the air of towns is also a chemical combination of silver and sulphur due to the presence of traces of a compound of sulphur in the air. Iron filings may be mixed ever so carefully with sand; but tnis, again, is a mere mixture, and all the iron filings may be separated or withdrawn from the mixture by means of a magnet, which attracts the iron and not the sand, showing that they are not in chemical combination, but only mechanically admixed. Gunpowder is only a mechanical admixture of nitre, charcoal, and sulphur, and their separate respective particles can be seen ly;ng apart from each other by means of the microscope. As a further instance of the difference between a mere mixture and a chemical compound it may be mentioned that when quicksilver is heatted and exposed to the air, it becomes changed into a yellow powder, which is a chemical compound of the mercury and atmospheric oxygen, and by no mere mechanical process can the mercury and the oxygen of which it is compounded be separated from each other, showing that it is not a mere mixture of the two things. Chemical combination always takes place in equivalent weights, or socalled combining proportions of the elements concerned, and the combining weights are the smallest which will combine with one part of hydrogen. Lead, for example, has an atomic weight of 207, so that when it enters into chemical combination with sulphur, which has an atomic weight of 32, 207 parts by weight of lead combine with 32 parts by weight of sulphur, and yield 239 parts of the chemical compound sulphide of lead. Salt is a chemical combination of 23 parts by weight of the metal sodium and 35 parts by weight of the gas chlorine, or, in oiher words, a combination of one atom of each of these two elements. The two atoms thus combined make up a molecule, so that the molecular weight of the compound is that of the two added togethernamely, 58J. When salt is decomposed that is, split up by chemical means into its two constituent elements58J parts by weight always yieid 23 parts by weight of sod

The particular atomic groupings characteristic of coloured organic compounds, such as.N: N and N02.

A new proprietary nonferrous alloy, stated to be very efficient for making machinetools, containing zirconium, molybdenum, tungsten, silicon, and aluminium; iron being replaced by nickel as a basic constituent for tool production.

The volatile oil contained in balsam of copaiba to the extent of some 30 to 60 per cent. It belongs to the class of terpenes; is colourless or pale yellow, of aromatic odour, is soluble in alcohol, ether, etc., and finds some use in medicinal practice. Sp. gr., 0885 to 0*918; refractive index, 1493 to 1502 optical rotation 40 to 35 degrees, accord ing to variety.

2NII, the:inide of diphenyl, is a constituent of coaltar and crude anthracene. It is a white, crystalline substance which melts at 23d0 C., is readily sublimable, and can be formed by passing the vapour of diphenylamine through redhot tubes. A recently patented process for its manufacture consists in heating the crude article with an alkali metal or hydroxide in the presence of an indifferent solvent, such as naphthalene or toluol, under pressure, and at a temperature below the meltingpoint of the alkaline carbonate. The solvent is subsequently removed, and the alkaliearbazole decomposed by boiling with water. Carbazole is soluble in alcohol and ether, but insoluble in water, and is used in the manufacture of dyestuffs.

A proprietary liquid disinfectant containing sodium permanganate.