April 20, J 888.] 



SCIENTIFIC NE^A/^S. 



379 



of gases are calculated at normal temperature and 



pressure. 



Amount of Oxygen removed from the air, i 

 IVater Vapour generated to give an illu 

 power, {The amount of light required i 



vid Carbonic Acid Gas and 

 nination equal to 32 candle 

 room 16 by 12 by 10.) 



From these data it appears that according to the rules 

 laid down in sanitary science, by which the degree of 

 vitiation of the air in any confined space is measured by 

 the amount of oxygen removed and carbonic acid formed, 

 candles are the worst offenders against health and 

 comfort, and gas the least, an assumption which 

 practical experience does not bear out, the feeling of 

 oppression being distinctly less in a room lighted by 

 candles or oil than in one lighted by any of the older 

 forms of gas-burner. The explanation of this is that 

 when we use candles or lamps we are contented with a 

 smallerand more local illumination than when gas is used ; 

 also more water vapour is given off during the combus- 

 tion of gas ; and this absorbs radiant heat, and heats the 

 atmosphere, whilst the air being charged with moisture, 

 evaporation from the skin is checked. 



Still more important reasons are that, even in the 

 highly-purified London gas, small quantities of impurities 

 are present which give products of combustion more 

 deleterious to health than carbonic acid; whilst bad forms 

 of burners cause incomplete combustion, giving rise to 

 carbonic oxide, which, even in small traces, is highly 

 poisonous ; and finally all the products of combustion, 

 being at a higher temperature than the air of the room, 

 rise to the ceiling, and collect there, and the exhalations 

 from respiration, and the skin being at a lower tempera- 

 ture, cannot rise through them, so that the ceiling is 

 practically lowered to the level of the gas-burners. 



All these considerations bring us to the conviction that 

 for the health of ourselves and our families we must 

 have adequate ventilation specially provided to remove 

 the products of combustion given off by illuminants from 

 our dwelling-rooms. 



If we use candles or oil-lamps, all we can do is to 

 secure the ventilation of the room by the ordinary 

 methods, as the conditions under which these sources of 

 light are employed prevent their being used as a venti- 

 lating power; but with gas this is not the case. Attempts 

 have been made from time to time to provide special 

 ventilation and the removal of the products of combus- 

 tion ; but, with the exception of " Sun-burners " for large 

 halls and places of public entertainment, none have met 

 with any degree of success, owing to the unsightly tubes 

 needed to convey away the heated gases ; but with the 

 new era of regenerative gas-lamps this trouble disappears, 

 and gas can now be made not only the best and most 

 convenient means of illumination, but also a powerful 

 engine for ventilation. 



Of the various forms of regenerative lamps now in the 

 market, the " Wenham " is the one most suitable for this 

 purpose, as the shortness of chimney required and com- 

 pactness of the regenerative portions of the lamp, enable 



it to be fixed with the burner within fifteen inches of the 

 ceiling, and sufficiently far above the head to prevent 

 any sensation of radiant heat from it, whilst the air 

 supply to the flame is so arranged as to be undisturbed 

 by the up-draught created in the flue attached to the lamp. 

 In order to convert the lamp into an efficient ventilating 

 agent, it is set in an ornamental metal box, which fits 

 into the ceiling space, and has its lower portion, with the 

 lamp attached, projecting downwards into the room ; and 

 this part is provided with openings into the room. The 

 upper portion of the box in the ceiling space has a flat 

 rectangular flue attached to it, which passes alongside the 

 joists, and is led into the flue of the room illuminated by 

 the lamp, or into a special flue fitted in the chimney 

 stack. Under these conditions a No. 4 Wenham lamp, 

 consuming from 20 to 24 cubic feet of gas per hour gave, 

 as an average of illuminating power from 120 candles in 

 a horizontal plane to 280 in a vertical, whilst a current 

 was created in a flue with a velocity of 12-5 feet per 

 second, and the area of the tube being 6 inches by 4 

 inches, this was equal to 7,498 cubic feet per hour. The 

 temperature of the gases in the flue 4 inches from 

 burner was 276° F. , but the air in the room was at 60° 

 F.; and reducing the volume to this temperature, and 

 deducting the air used by the lamp, we have 5,160 cubic 

 feet of air over and above that required by the lamp, 

 removed from the upper part of the room to be replaced 

 by cool fresh air, whilst none of the products of combus- 

 tion are allowed to find their way into the room. With 

 a No. 2 lamp, burning 10 cubic feet per hour, 2,000 

 cubic feet of air per hour was withdrawn from the room. 

 In order to fully realise the importance of these results 

 as bearing upon ventilation, one must remember that 

 nearly all the impurities in the air emanate either from 

 the body or from the combustibles used, and are there- 

 fore, at a higher temperature than the normal air of the 

 room, with the result that, being expanded by heat, they 

 are lighter and rise to the ceihng, so that the air with- 

 drawn by the burner is not the ordinary air of the room, 

 but the foulest air in the room. 



In order to test the safety of the flues passing through 

 the ceihng space a number of experiments were made as 

 to temperatures of the products of combustion and the 

 exterior surface of the flues. 



The metal box containing the lamp is double-jacketed 

 with i| inches of "silicate wool," which, being fire-proof 

 and a non-conductor of heat, prevents the escape of heat 

 anywhere near the lamp, the highest temperature ever 

 reached being 90° F. The flue which conveys the mixed 

 products of combustion and air from the lamp casing to 

 the chimney were jacketed with | inch of silicate wool, 

 in the hottest part rarely reaches 100° F., whilst if the 

 flue be packed round with loose silicate wool, kept in 

 position by a layer of loose slates placed on it, no heat 

 at all escapes. 



As regards the heating effects of regenerative burners 

 on the air of a room, the kind of heat given out is almost 

 entirely radiant heat, which does not heat the air directly, 

 but heats the walls and furniture in the room, and these 

 in turn heat the air, whilst in the old forms of burner the 

 air is rapidly heated by convection, radiation playing but 

 a small part in the heating of the room. In the first 

 instance, you have warm walls and furniture with cool 

 air, which are undoubtedly the conditions best suited for 

 health and comfort ; whilst, in the second case, you have 

 warm vitiated air with cold walls : a state of affairs which 

 lead to chills and discomfort to the system. 



