26 



NATURE 



[Nov. II, 1880 



This heating arrangement is not however essentially 

 necessary ; in several of the grates which I have 

 altered for gas I have simply closed up the space below 

 the bottom bar by means of a close-fitting ash-pan, 

 and introduced the gaspipe behind the lower bar, an 

 alteration which can be effected at very trifling expense, 

 and presents the advantage of great cleanliness, the ash- 

 pan being withdrawn only at intervals of several days for 

 emptying. The appearance of the fire however is in that 

 case much less brilliant than when the hot-air arrangement 

 is added. 



In order to test the question of economy I have passed 

 the gas consumed in the grate through a Parkinson's 10- 

 light dry gas-meter supplied to me by the Woolwich, 



■ Plumstead, and Charlton Consumer's Gas Company ; the 



j coke used is also carefully weighed. 



The result of one day's campaign of nine hours is a 



I consumption of 62 cubic feet of gas and 22 lb. of coke (the 

 coke remaining in the grate being in each case put to the 

 debit of the following day). Taking the gas at the average 

 London price of 3^'. 6d. per 1000 cubic feet and the coke 



I at \%s. a ton, the account stands thus for nine hours : — 



, Copper plate \ inch thick and lo inches wide 

 trap-doo: 



for removing ashes ',/i gas-pipe 



d. 



62 cubic feet of gas at 3^. 6(/. per thousand ... 2*604 

 22 lb. coke at iSx. a ton 2'I2I 



Total ... 4725 

 or at the rate of o'^z\d. per hour. In its former condition 

 as a coal-grate the consumption exceeded generally two 

 and a half large scuttles a day, weighing 19 lb. each, or 

 47 lb. of coal, which at zy. a ton equals 5 ■jd. for nine 

 hours, being o'633rt'. per hour. This result shows that the 

 co'^e-gas fire, as here described, is not only a warmer but 



back of grate ; ^, frill of copper ^ inch thick : c, iron dead plate riveted to plate a ; d, angle plate with 

 '5 inch diameter with holes | inch apart. 



a cheaper fire than its predecessor, with the advantages in 

 its favour that it is thoroughly smokeless, that it can be 

 put off or on at any moment (which in most cases means 

 considerable economy), that it is lit without the trouble of 

 laying the fire, as it is called, and keeps alight without 

 requiring to be stirred. 



It may appear strange at first that the use of the sepa- 

 rated coke and gas to produce a given effect should be 

 fully as cheap as using the raw material combining the 

 two constituents, but the solution may be found in the 



