Another form of moulding machine is shown in Fig. 470. It is manufactured by Galabrun Freres, of Paris, and ie in general favour on the Continent ; it is said to be capable of turning out 200 candlee per half hour ; but it ia only suitable for stearic acid, or bimilarly hard material.
When moulded and cold, the candles are taken to little tables, fitted with circular knives re volving at high speed. Here the butt ends are trimmed, and the length of the candles is ad justed to the weight. Some of the superior kinds of candle undergo a special polishing operation, performed by sub jecting them to the friction of felt and other substances. In Fig. 471 is seen a trimming, washing, and polishing machine combined, as made by Gala brun Freres.
Modifications of Candle Manu facture. — a. Double wicks.— Some very thick candles, such as the so-called " police-lights," and others, used in ships' lanterns, &c., are made with double wicks. Ordinary frames cannot be used in this case. The wick is threaded on a kind of metallic skewer, which is thrust into the centre of the candle mould. When the candle has partially cooled, the skewer ie withdrawn, and the wick is left behind. The space left vaca,nt by the extraction of the skewer is filled up with candle material.
b. Fancy patterne.—Instead of the plain cylindrical form, candles are sometimes made in a variety of fancy patterns—spiral or ropelike, with figures to indicate the hours, &c. These require special moulds.
c. Self-fitting ende.—Many candles are now moulded with conic,a1 bases, so as to fit any holder.
For these, a little tin mould is fixed above the ordinary frame mould.
d. Coloured candles.—For colouring candles, vegetable dyes are almost solely used. In tlivse extravagant days, candle-makers are often required to supply an article of a tint which will match some particular ceiling or wall paper, and no little ingenuity is required to ensure such tints being permanent.
As an illustration of the demands made by fashion, it may be mentioned that Price's Candle Company keep 300 varieties of candle always in stock, and are open to make 1000 different kinds (including size, colour, and material) in case of need.
Though electric lighting has emerged from embryotic obscurity into a palpable, tully-developed fact, much to the consternation of the gas companies, there is no reason to suspect that it will, within a proximate date, at all displace candles. With abundant evidence that the antiquated rushlight is still an article of domestic use—Messrs. Haynes supply between three and four tons annually, prin cipally to the University towns,—there is safety in predicting a long life for paraffin, stearine, and composite candles, and even for the humble " dip."
Bluminating Value.—lt is somewhat remarkable that the public, in judging of the value of a candle, are entirely guided by its mere appearance, and more particularly by its colour. The primary object of a candle is to give light. In estimating the value of any light-giving material, three factors have to be ta,keu into account, viz. :—(1), the cost of the material ; (2), the rate of its consumption ; (3), the luminous intensity produced. In practice, a sperm candle burning at the rate of 120 gr. an hour, is taken as the standard light with which all others are compared. This is the explanation of the phrases "sixteen-candle gas," electric light of so many thousand " candle power," and so on. Such a standard, however, is unsatisfactory at best, since very slight in equalities in the wick, or changes of its curve in the candle flame, materially affect the luminous intensity, without appreciably altering the amount of sperm consumed. Various other standards have been proposed, but none are thoroughly reliable. (See Photometry.) The following tables are the result of experiments by Dr. Franklaud, F.R.S., as to the luminous intensity, cost, &c., of various sources of light :— I. Quantities of different substances required to produce the same amount of light.
Although it is impossible to avoid the inference from the above figures, that candles in any form are very expensive illuminating agents, compared either with coal gas, or paraffin oil (or any of its numerous modifications), nevertheless, the numerous advantages which they possess render it exceedingly unlikely that they will, to a greater extent than at present, be superseded by either of the two cheaper methods of illumination. Neither coal gas nor paraffin oil can be employed except at what are, for all practical purposes, stationary points; they cannot be carried about, while evolving light, from one place to another, and are altogether destitute of that element of portability, which reuders the candle so valuable. Further, except in so far as a fire may result from actual contact between a candle flame and any inflammable substance, candles are absolutely safe illuminating agents, and persons burning them are not liable to the alarming explosions and fires which result from the careless use of gas, or of paraffin lamps.