The Optical Magic Lantern Journal (November 1891)

The Optical Magio Lantern Journal and Photographic Enlarger. 163. after which it is quickly cooled. The mass is then pulverised and treated with hydrochloric acid, which leaves the silica in an insoluble state. After this it is necessary to get rid of the iron from the zirconia. This may be done by taking the solution just mentioned and mixing with it carbonate of soda and hyposulphite of soda. After prolonged boiling, the iron is reduced to the state of protosalt and the zirconia precipitated. This precipitate is washed and dried, and is then ready for making up into cylinders, which is effected by compression. Some years ago, patents for the preparation and compression of zirconia were obtained by M. Tessie du Mothay. In the specification he says; ‘Zirconia ...can be agglomerated by compression into sticks, discs, cylinders, or other forms, suitable for being exposed to the flame of mixtures of oxygen and hydrogen without undergoing fusion or other alteration. Ofall the known terrous oxides, it is the only one which remains unaltered when submitted to the action of the blow-pipe, fed by oxygen and hydrogen, or mixtures of oxygen with gaseous or liquid carbonated hydrogens. Zirconia is also, of all the terrous oxides, that which, when introduced into into an oxy-hydrogen flame, develops the most intense and the most fixed light. To obtain zirconia in a commercial state, I extract it from its native ores, by transforming, by the action of chlorine, in the presence of coal or charcoal, the silicate of zirconium, and of silicium. The chloride of silicium, which is more volatile than the chloride of ziconium, is separated from the latter by the action of heat; the chloride of zirconium remaining is afterwards converted to the state of oxide by any of the methods now used in chemistry. The zirconia thus obtained is first calcined, then moistened and submitted in moulds to the action of a press, with or without the intervention of agglutinant substances, such as borax, boracic acid, or clay. Thesticks, cylinders, discs, or other forms thus agglomerated are thus brought to a high temperature, and thus receive a kind of tempering or preparing, the effect of which is to increase their density and molecular compactness. I can also compress in moulds, shaped for the purpose, a small quantity of zirconium capable of forming a cylinder or piece of little thickness, which may be united by compression in the same mould to other refractory earths, such as magnesia or clay.” During the early part of 1869 the Court of the Tuilleries was illuminated by the zirconia light on an extensive scale, by the Oxy-hydrogen Company, whose aim was to employ this light for illuminating buildings, cities, &c., and with such limited uses as optical lanterns, they did not concern themselves to any extent. Numerous experiments, however, were tried with this form of light for lantern purposes, the result of which may be summed up in a few words. Compared with lime, the zirconia gave a light which was slightly reddish, whilst that from lime was of pearly appearance. The cost of a cylinder of zirconia is very great when contrasted with one of lime, but whilst the latter has a very short existence, the former is supposed to be practically indestructible. For class and other demonstrations, when the lantern may be required at a moment’s notice, zirconia is particularly convenient, as the apparatus can be kept in readiness, so that all that is necessary is to turn on the gases and apply a light ; but for general exhibitions, and particularly for long range, it cannot be said to supplant the lime as at present used. Moreover, it appears to be a difficult matter to obtain suitable pieces ; for in zirconia there is, like in the majority of things—quality and quality. . ~»a TABLE for Ascertaining the Quantity of Gas in Cylinders from the Indication of Gauges showing Atmospheres. ATMOSPHER rd INDICATED ON! Sizes or Gas BOTTLES. | GAUGE. 12 Feet. 40 Feet. 15 Feet. | 20 Feet. 6 Feet 10 Feet. ! —_—---— { | 20 oes avis! 4O . «+ 2 Cubic Feet) 3) 4, 4, i 4 55 60 sore see 3 ” ” 3, ” ” 6 ” 80 4 ” ” 6% ” ” 8 ” 100 e354 | 85 5, 9 TO oy 120 | 6 MO yg: yp. “ER. ay t Cubic Foot] 1}CubicFeet: 2 Cubic Feet} 24 CubicFeet’ 3 Cubic Feet! ? 2 1 6 CubicFeet ” 3 5B] ” 4 ” ” 124 ” ” ” 7% ” ” 10 ” ” '20 ” ” ” pee ” ” 125 F) yy 125 ” ” EZ op » 16% 4, yy ARR yy ogy .B} iS ”) ” 20 a} 7 40 ” ”