Brilliancy of the Diamond.
The cause of the wonderful Brilliancy of the Diamond is not popularly known. It has no inherent luminous power; it is simply transparent, like common glass, and yet, if the latter were cut into the form of a brilliant, it could no more be mistaken for a real one than for a sapphire or an emerald. The secret, therefore, of the brilliancy of the diamond must lie in something other than its clearness or its transparency. It is owing to its great refractive power. When rays of white light pass through transparent substances they are refracted, or bent out of their former course, and under certain circumstances are separated into their constituent elements, and dispersed in the form of the well-known prismatic colours. The cut drops of glass chandeliers show a familiar example of these properties. Now, the degree in which this effect is produced by any substance depends on the refractive power it possesses, and it so happens that the diamond has this power in an extraordinarily high degree, its index of refraction being 2·47, while that of glass, or rock crystal, is only about 1·6, and of water 1·3. The effect of this great refractive capability, particularly when aided by judicious cutting, is, instead of allowing the light to pass through, to throw it about, backwards and forwards in the body of the stone, and ultimately to dart it out again in all sorts of directions, and in the most brilliant array of mingled colours; and this is the marvellous effect that meets the eye. Sir David Brewster has shown that the play of colours is enhanced by the small dispersive power of the diamond, in comparison with its refractive properties.
The general value of diamonds has been rising of late years; for, though the production is not scanty, the demand, owing to general prosperity, and the extension of ornament to wider classes in society, is largely on the increase.—Mr. Pole; Macmillan’s Magazine.
Philosophy of Gunpowder.
It may be well to have one word, as transmutation, to indicate chemical molecular change, and another, as transformation, to indicate mechanical molecular change; but, as industrialists, we must hesitate to marvel more at the one than the other. How cheerfully they labour to a common end, like twin brother and sister; the one strong by measurable strength, the other by immeasurable fascinating power, we see in the case of that great world-changer, that emblem of war, and minister of peace, Gunpowder. It needs the strong brother to fell the oaks, and with a hint from his twin to burn them into charcoal. It needs his stout arms to quarry the sulphur, and bring the saltpetre from India; to crush them into grains, and grind them together. But it also needs his weird sister, in whose palm he lays the innocent dust, to breathe upon it before the Alps are tunnelled, or Sebastopol lies in ruins.—Prof. George Wilson.
New Pear-flavouring.
The new Pear-flavouring is derived from an alcoholic solution of pure acetate of amyloxide, considerable quantities of which are manufactured by some distillers, and sold to confectioners, who employ it chiefly in making Pear-drops, which are merely barley-sugar, flavoured with this oil. There is, also, an Apple-oil, which, according to analysis, is nothing but valerianate of amyloxide.
Methylated Spirit.
Methylene is a highly volatile and inflammable liquid produced from the destructive distillation of wood; whence Methylated Spirit, or wood spirit. It is permitted to be used, duty free, in arts and manufactures. Hitherto, no effort to obtain a potable spirit from methylated alcohol has succeeded. A patent has been granted for a process which professes not only to accomplish this object, but to render wood spirit itself potable, and that, too, at a cost almost nominal; and it has afforded matter for earnest discussion among some of our leading pharmacologists, who, anxious to preserve the integrity of medicinal preparations, have not unreasonably been alarmed by the assertion that wood spirit can be so far defecated as to render it almost indistinguishable from vinous alcohol, and by the exhibition of specimens of such spirit which might be used, instead of spirits of wine, for pharmaceutical purposes. But after a series of experiments, Mr. Phillips, of the Revenue Laboratory, has not been able by the process indicated to render either methylated or wood spirit potable, although it was submitted to numerous successive distillations, which from their costliness could not be applied profitably on a commercial scale.
One of the latest Acts passed, Session 1863, was to reduce the duty on rum. It recites that by the Act 18th and 19th Victoria, cap. 38, spirit of wine was allowed to be methylated duty free; and that it is expedient to allow foreign and colonial rum to be methylated, on payment of reduced duty. Rum may now be “methylated” in the Customs’ warehouse; but the wood naphtha, or methylic alcohol, or other article to be mixed with the rum, is to be provided by the Inland Revenue Commissioners; and the mixture is to be denominated “methylated spirits,” and such spirits may be exported.