SCIENCE-GOSSIP. 



279 



calcic oxide or lime, whilst the hydrogen unites 

 with the carbon of the calcic carbide to form 

 acetylene, the cost of the gas so produced bringing 

 it not only within the range of commercial 

 possibilities for use per se, but also the building up 

 from it of a host of other compounds, whilst the 

 production of the calcic carbide from chalk and 

 from any form of carbon, renders us practically 

 independent of coal and oil, and places in our 

 hands the prime factor by which Nature in all 

 probability produces those great underground 

 storehouses of liquid fuel upon which the world is 

 so largely drawing to-day. 



" Calcic carbide is a dark grey substance, having 

 a specific gravity of 2262, and, when pure, a pound 

 of it will yield on decomposition 53 cubic feet of 

 acetylene. Unless, however, it is quite fresh, or 

 means have been taken to carefully protect it from 

 air, the outer surface gets slightly acted upon by 

 atmospheric moisture, so that in practice the yield 

 would not exceed five cubic feet. The density and 

 hardness of the mass, however, protects it to a 

 great extent from atmospheric action, so that in 

 lumps it does not deteriorate as fast as would be 

 expected, but in the powdered condition it is rapidly 

 acted upon. 



" For commercial purposes the carbide will be 

 cast direct from the electric furnace into rods or 

 cylindrical cartridges, which, when twelve inches 

 long and one and a quarter inches in diameter, will 

 weigh one pound, and will give five cubic feet of gas. 



"The acetylene so made, when analysed by 

 absorption with bromine, the analysis being also 

 checked by determining the amount present by 

 precipitation of silver acetylide, gives ninety-eight 

 per cent, of acetylene, and two per cent, of air, and 

 traces of sulphuretted hydrogen, the presence of 

 this impurity being due to traces of sulphate of 

 lime— gypsum — in the chalk used for making it, 

 and to pyrites in the coal employed. 



"Acetylene is a clear, colourless gas with an 

 intensely penetrating odour which somewhat re- 

 sembles garlic, its strong smell being a very great 

 safeguard in its use, as the smallest leakage would 

 be at once detected ; indeed, so pungent is this 

 odour that it would be practically impossible to go 

 into a room which contained any dangerous 

 quantity of the gas. 



" This is an important point to remember, as the 

 researches of Bistrow and Liebreich show that the 

 gas is poisonous, combining with the haemoglobin 

 of the blood to form a compound similar to that 

 produced by carbon monoxide, whilst the great 

 danger of the latter gas is that having no smell, its 

 presence is not detected until symptoms of poison- 

 ing begin to show themselves, so that no fear need 

 be apprehended of danger from this source with 

 acetylene. 



"The flame of acetylene, in spite of its high 



illuminating value, is a distinctly cool flame, and in 

 experiments which I have made by means of the 

 Le Chatelier thermo-couple, the highest tempera- 

 ture in any part of the flame is a trace under 

 1,000 degrees C, whilst with coal-gas burning in 

 the same way in a flat-flame burner, the temperature 

 rises as high as 1,560 degrees C. If the heating 

 effect of the flames be contrasted for equal illumina- 

 tion, it will be seen that the acetylene flame has so 

 small a heating effect, considering its area, that it 

 would not be much greater than the ordinary 

 electric incandescent lamp. 



"The intensity of the light will make small 

 acetylene lamps of enormous value for lantern pro- 

 jection, for railway signals, and, coming down to 

 smaller things, bicycle lamps, whilst I should 

 imagine the ease of production specially adapts it 

 for such purposes as lighthouse illumination, or for 

 floating buoys, and the small cylinders can also be 

 arranged in the form of portable lamps, whilst for 

 use in the country, where no gas is available, a 

 large cylinder of the liquid gas placed in an out- 

 house would supply a country house with light for 

 a very long period ; and there is no doubt that 

 there is a very great field for it in this direction, 

 as by utilising suitable burners a consumption of 

 half a cubic foot an hour will give a light equal to 

 from twenty to twenty-five candles. 



" Perhaps the most valuable suggestion which 

 has been made with regard to the utilisation of 

 this remarkable method of making acetylene is, 

 that advantage should be taken of the method of 

 preparation to utilise the body of portable lamps 

 for dining and drawing-rooms in places where no 

 gas supply exists. To do this a strong steel 

 cylinder, four inches in diameter and sixteen inches 

 in length, is fitted, with an opening in the top of 

 such size that a pound cartridge or stick of the 

 calcic carbide can be passed through it. The 

 cylinder has a second opening at the bottom, closed 

 by a screw, for cleaning out the lime left by the 

 decomposition. The right proportion of water is 

 put into the cylinder, and the stick of carbide, 

 coated with a slowly soluble glaze, is inserted, and 

 the head of the lamp screwed on. This head 

 contains a double reducing pressure valve, 

 which brings down the pressure existing in the 

 cylinder to that necessary for the proper con- 

 sumption of the gas, it also being fitted with 

 a valve. The gas can then be burned from a 

 suitable jet at the rate of half a cubic foot 

 per hour, which will give a light of over 

 twenty candles for something like ten hours." 



In the discussion which followed the reading of 

 this paper, it was acknowledged this discovery was 

 of a most important character, and, as the chair- 

 man pointed out, after all, the best way of utilising 

 electricity for illumination would be to convert it 

 into light by the method exhibited by the lecturer. 



