GAS AND OIL LIGHTING 407 



The incandescent gas mantle, both in its upright and inverted forms, has made 

 steady headway during the past few years, and the great increase in light that can be 

 obtained by increase of the pressure under which the gas is supplied to the burner has 

 been taken advantage of in constructing lamps for the illumination of large spaces. 



The most important outcome of the last few years with regard to gas lighting is the 

 change of opinion that is gradually taking place with regard to its hygienic effect on the 

 air of enclosed spaces. When the electric light was first introduced as a domestic 

 illuminant, the fact that it took no oxygen from the air and gave off no products of com- 

 bustion led to the assumption that it must be more healthful in a dwelling room than 

 gas, which not only abstracted oxygen but evolved as products of combustion water 

 vapour and carbon dioxide, the amount of which latter gas in the air of a room had al- 

 ways been taken by the sanitary authorities as an indication of its hygienic condition. 

 The researches of Dr. S. Rideal and others have shown conclusively however that the 

 air in the breathing zone of an inhabited room lighted by the incandescent gas mantle 

 is always fresher and less oppressive than with electric incandescent burners, and that 

 the increase in carbon dioxide and humidity which one would expect is not to be found, 

 whilst a large decrease in the organic matter takes place. This is explained by the fact 

 that the uprush of heated air and products from the 'burner draws up the emanations 

 from the skin and lungs of the occupants, charring and sterilising any germs and organic 

 matter that are present, and, reaching the ceiling at a temperature 12 C. higher than 

 when electric light is used, diffuses so rapidly through the plaster as to draw in fresh air 

 below the door of the room, and whilst so diffusing filters off the carbonised organic mat- 

 ter and dust on the surface of the plaster, so giving the blackening that is always found 

 above a gas burner, which is often erroneously attributed to imperfect combustion. 



Air movement, coolness, humidity, and reduction in the mass action of pathogenic 

 bacteria, are now recognised as being of far greater importance to health than the 

 chemical purity of the air, and the convection currents and change of air set up by the 

 heat of the incandescent gas burner lead, it is held, to a fulfilment of these requirements 

 far better than the electric light. (VIVIAN B. LEWES.) 



OIL LIGHTING 2 



There has been but little change in either the construction of oil lamps or the use of 

 oil for lighting during the past few years, and the production of a successful lamp using 

 ordinary lamp oil and an incandescent mantle still awaits solution. 



In lighting by oil gas a marked improvement has been made by Messrs. Pintsch in 

 railway carriage lamps. Attempts were made for many years to devise oil gas burners 

 fitted for use with incandescent mantles, but whilst upright mantles only were available 

 no great success was achieved, as the shaking of the train rapidly destroyed them, and 

 no and- vibration device seemed to have any effect in preventing this. When however 

 the inverted mantle was introduced, it was found that the method of suspending it by 

 its steatite base from lugs on the burner nozzle rendered it far more resistant to shock, 

 whilst in case of the mantle breaking the fabric was suspended in a fine platinum wire 

 basket, which kept it in position until it could be renewed. Using the ordinary Pintsch 

 compressed oil gas in small inverted atmospheric burners, a consumption of 0.6 of a 

 cubic foot per hour gives with the mantle a light of 24 candle power, or three times the 

 amount of light for half the gas consumption with small flat flame burners. 



An interesting development of compressed oil gas for portable use, buoys, motor 

 lamps, etc., is the introduction on the European continent of what is known as ".Blau 

 gas." When ordinary oil gas is compressed, as in a Pintsch cylinder, a considerable 

 amount of liquid hydrocarbons, which were present in the gas as vapours, separate out, 

 the liquid consisting of benzene, toluene, hexane, heptane, etc., and the gas suffers 

 considerable reduction in illuminating power. The gas thus freed from vapours con- 

 tains hydrogen, methane of little or no illuminating power, and the higher gaseous 



1 See E. B. xvi, 655 et seq. ~ See E. B. xvi, 651 el seq. 



