GAS VENTILATION. ] 



UNDULATORY FORCES. LIGHT. 



133 



These results indicate, that the most easy way of 

 destroying the inflammability of coal gas, is that of 

 mixing it with a large proportion of atmospheric air; 

 and hence the necessity for good and effective ventilation 

 wherever there is an escape of gas. We can recognise 

 the odour of gas long before the mixture acquires ex- 

 plosive properties. Dr. Alfred Taylor states, that the 

 inell of gas is perceptible when it is mixed with five 

 hundred parts of atmospheric air; and that it is very 

 manifest when it forms one part in a hundred and fifty 

 of air. We have, therefore, a ready means of discovering 

 the danger ; and, indeed, the offensive odour of coal gas 

 is one of its most valuable properties ; for if it were to be 

 ; deprived entirely of its odour, accidents would be far 

 more frequent than they are at present. 



As gas is lighter than atmospheric air, it is always 

 disposed to accumulate in the upper part of the room ; 

 and here it is that ventilation will be most effective. 

 Still, however, there is a strong diffusive power possessed 

 by all gases, by virtue of which they rapidly commingle ; and 

 hence the necessity fora complete displacement of all the 

 atmosphere of a room in which coal gas has been escaping. 



Dr. Taylor attaches importance to the poisonous pro- 

 perties of coal gas ; saying that there are reports of six 

 deaths on record, where persons have l>etn killed by 

 Bleeping in rooms near to which there was a leakage of 

 gas. M. Tourdes found, that an atmosphere containing 

 one- thirtieth, or even one-fiftieth, part of coal gas seriously 

 affected animals. It cannot, therefore, be too strongly 

 impr-iMed upon the minds of those who use gas in 

 d.\e ig-honseu, that where a smell is perceptible, the 

 defet should be immediately found out and remedied. 

 When the leakage U comparatively slight it may endanger 

 the lives of those who sleep in or near the spot ; and 

 when it has reached a higher point, it may lead to a 

 serious accident by explosion. The effects which it 

 produces on thp human system are those of depression, 

 headache, sickness, and general prostration of the vital 

 powers, followed by deep coma. 



Qai Ventilation. It has been already stated that the 

 products of gas combustion are very pernicious that 

 they not only cause discomfort to the feelings, and 

 perhaps injury to the health of those who inhale them, 

 but they are also very destnictive to property ; besides 

 which, the high temperature which is produced in rooms 

 where gas is burnt in a wasteful manner, is very objec- 

 tionable. All these circumstances render it necessary 

 that the products of combustion, as well as the heated 

 atmosphere, should be removed as speedily as possible. 

 In fact, it is of the greatest importance that gas should 

 be consumed in such a manner as not to affect the atmo- 

 sphere of the room at all. Several contrivances have 

 been suggested for the purpose of effecting this. 



Man}- years ago, when the books in the library of the 

 Athemeuin Club-house were found to have been impaired 

 by the gas used in the building, Professor Faraday in- 

 vented an apparatus which was found to remedy the evil. 

 It consists of an ordinary bat's- wing, or fish-tail burner, 

 enclosed in a globe or bell-glass, closed at the top with 

 mica ; the interior of the globe communicates with a tube, 

 which surrounds the gas-fitting, and passes away through 

 a c<ii; ., to a ventilating shaft. The tubes 



are so arranged as not to be visible, and the burners are 

 suspended in the ordinary way from a chandelier. By 

 this contrivance the gas burns in a closed chamber, and 

 the products of combustion are at once carried away. 

 This plan of consuming gas is practised at the club-house 

 before mentioned, and also at Buckingham anil Winds. .r 

 palaces; but the great objection to it is the frequent 

 break in:,' of the glasses, and the necessity for a venti- 

 lating shaft with a strong upward current. 



The ' I,I,,,,.T has already been described, and so 

 lias the ventilating burner of Mr. Carter.* Messrs. 

 Whichcord and Rosser have also patented a con- 

 trivance for effecting the same purpose; it consists 

 of a ventilating -I..-!! and draught-tube placed over the 

 burner. If the boll is lowered so as to be a little below 

 the level of the glass chimney, and the whole surrounded 



* Set ante, p. 129; Fig. 131. 



by a glass globe which is open only at the top, a current 

 of atmospheric air passes down over tho tube and 

 chimney, and thence to the flame, where it is consumed, 

 after which it passes away through the draught-tube. 

 By this means the air is heated before it reaches the 

 flame, and therefore the intensity of light is augmented ; 

 besides which, the cooling influence of the air on the 

 draught-tube and chimney prevents the heat of the gas 

 from being communicated to the room. 



Another mode of effecting ventilation, is to place a 

 simple catch-tube, or funnel, over the gas, and thus to 

 carry away the products of combustion into a neigh- 

 bouring chimney, or to the outside of the house. The 

 draught-tube need not be very large, and it may be 

 hidden above the ceiling. When this plan is not 

 available, a less perfect mode of ventilation may be 

 adopted by boring a number of holes through the ceiling 

 immediately over the chandelier or burner. The holes 

 should be about half an inch in diameter, and they 

 should communicate with the space above the ceiling. 

 A few ventilating bricks should also be introduced into 

 the wall, bounding the space on each, side of the house, 

 so as to carry off the warm air. The holes in the ceiling 

 may be hidden from view by means of a perforated or 

 open rosette. 



Lastly, where gas can be burnt out of the room 

 altogether, it is of the greatest importance that no plan 

 of internal combustion should be adopted. Shop-windows, 

 for example, are best lighted by means of an external jet 

 with a reflector. On the continent this is the plan very 

 generally employed ; and it is found to produce a much 

 more pleasing effect, than when the burners are placed 

 on the inside of the windows. There is no reason why 

 gas may not be used in a somewhat similar way for 

 illuminating private rooms. At present we generally 

 receive the light from the ceiling, and the combustion 

 takes place in the atmosphere of the room ; but it is quite 

 possible to burn the gas in a closed chamber at the side 

 of the room ; cay, for instance, in a recess which might 

 be formed by removing a portion of the wall in some 

 convenient situation, as between tun uindows. This 

 recess might have a number of small gas-burners with 

 reflectors behind them ; and it might be covered in front 

 with ground glass, ornamented with some device. It 

 should, of course, communicate with the external atmo- 

 sphere, and be shut off from the room. By day it might 

 be covered by a mirror ; and at night the mirror might be 

 slid to one side, so as to form a shutter for a window. 

 Again, in some situations where the space between the 

 c-eiling and the upper floor is very considerable, a ring 

 of gas jets, or a sun-burner, might be introduced into a 

 closed chamber in the ceiling, and the light might be 

 reflected or diffused in a very agreeable manner. In 

 short, there are many plans which might be suggested 



j for a more perfect and wholesome mode of burning gas 

 for illuminating purposes than that which we generally 

 employ; and there is no doubt that if attention were 

 sufficiently aroused to the importance of this subject, 

 many improvements would be adopted. 



Vitiating Effects of Illuminating Agents. Although 

 gas is generally regarded as the most injurious of all 

 light-giving bodies, yet this is not true when we consume 

 it in moderation ; that is, when we burn it in such a 

 manner as to obtain the same amount of light as we are 

 accustomed to have from other agents. This will be 

 ni.irle evident from what follows. A very little con- 

 sideration will show that we have become exceedingly 

 wasteful in the use of gas, buming it in situations where 

 we obtain the least possible advantage from its luminous 

 effects, and demanding such a strong glare from it, that 

 there is a much larger consumption of the material than 

 need be ; and consequently there is a larger vitiation of 

 the atmosphere than would occur with any other illumi- 

 nating agent. Take the case of an ordinary sitting-room. 

 \\ r ii two candles on the table, at a distance of a foot 



, from the observer, he can see well enough to read, write, 

 or work. But suppose that ga& is introduced into the 

 room : it is placed in a chandelier four or five feet from 

 the table, and then, according to the law of intensity, it 



