PHILOSOPHICAL INSTITUTE.

Globe, Volume XX, Issue 1640, 23 May 1879, Page 3

PHILOSOPHICAL INSTITUTE.

! ♦ ARTIFICIAL ILLUMINATION. The first of a course of scientific lectures in connection with the Philosophical Institute was delivered last night by Professor Bickerton in the Science Theatre of the College. There was anunnsally large attendance, many ladies being present, and members of the institute. The subject chosen was Artificial Illumination, and Professor Bickerton commenced by stating that the lecture of the evening was only a species of stop gap, preparatory to the commencement of the regular series. Ho had not had much time to prepare a sot lecture, but at least it was one that would not involve much thinking. Commencing with the simplest form of illumination, the lecturer explained the principle of the burning of an ordinary candle. Ho explained that the luminosity of the lighted candle was occasioned by the combination of hydrogen and carbon, the former liberating the latter. s?he fiame vas hohow, any its centre contained gas which could bo drawn off by a tube, and lighted at its extremity. Any solid particles introduced or dusted into the hollow of the llamo would not burn, but would give light. This bo illustrated by dusting spores of lycopodium into the flame. Of all particles for rendering a flame luminous nothing was so effective as the introduction of the solid particles of magnesium. Therefore, solid carbon was the essential principle in producing light. The lecturer proceeded to explain the elements necessary for producing flame. These consisted of oxygen, hydrogen, and carbon, the light varying with the amount of the individual constituents. It was the hydrogen that burnt, and the amount of the carbon introduced determined the luminosity of the fcme. Professor Bickerton then illustrated with experiments, the difference between burning a Vamp with or without a glass chimney. The g»aB&, he explained, produced a etrong updraught, liberating the carbon which burnt at the top, and more air was drawn into the apparatus at the bottom to supply the oxygon. The Budo lamp was the first that produced any great amount <i brilliancy. This invent!jn was simply the argand or solar lamp intensified by introducing oxygen into the centre of the flannel The best condition for obtaining the finest quality of coal gas was by evenly balancing the proportion Qf nitrogen and

carbon, and in proportion to the predominance or diminution of the latter the flame would be j ure and luminous, or impure with a largo quantity of smoke tiuowu off. The light given by the combustion of the magnesium wire was next illustrated. The difference m the color of the sodium light and that produced by the magnesium wire was also shown, as illustrative of the fact that the quality of artificial light produced was a more important condition than its quantity for the purpose of illumination. The concentric argand burner the lecturer stated, was the one wiiieh seemed to be the light which would for the future bo used for the purposes of public illumination. The system was simply a number of concentric rings one within the other inside the burner. The method of instantaneously lighting a number of gas jots by electricity was next shown, and the lecturer proceeded to elucidate the principle of Foucault’s magnificent electric lamp, the experiments with this unique apparatus being extremely interesting and beautiful. The brilliancy given by this lamp was duo to the enormous amount of heat concentrated in one little place, and the subdivision of this light was the desideratum to render the invention practically useful. In conclusion, Professor Bickerton showed the difference between the electric light, a powerful argand lamp burning coal gas, and the magnesium light. Before dispersing Professor Bickerton invited those present to stroll through the laboratory, while a series of experiments wonld be gone through. Ho also expressed a hope that such members of the institute ns possessed valuable microscopic apparatus, or choice dissolving views, would kindly place them at his disposal to render future similar gatherings more interesting and enjoyable. Ho also said that they would be gratified to hear that the third lecture of the series woidd bo delivered by Mr Hobson, C.E. After partaking of refreshments and visiting the several departments of the laboratory, the visitors dispersed after passing a very pleasant evening.