402 GAS MANUFACTURE 



ture. The solid bodies in the room however are not raised in temperature to the same 

 extent, with the result that a sensation of chill is experienced by a person sitting near a wall, 

 owing to the heat of the body passing by radiation to the wall. 



In the modern gas fire a large percentage of the heat is converted into radiant heat, and 

 the convection heat is reduced to a minimum, whilst the efficiency has been so improved 

 that a large proportion of the heat in the gas is utilised. Provided that the stove be fitted 

 in a proper manner the ventilation of the room is effected quite as thoroughly as with open 

 coal fire, but to do this the space between the stove and the fireplace must not be filled in 

 with a sheet of metal, as was the old accepted procedure, but the exit pipe should be carried 

 for some little distance up the chimney, when the outrush of hot gases will be drawn up with 

 them, by a sort of injector action, and nearly as large a volume of air can be withdrawn from 

 the room as with an open fire. 



Hygienic Effect of Gas Heating. Careful researches have demonstrated that the use of 

 gas in incandescent burners and stoves is by no means detrimental to health, but is a valu- 

 able adjunct to ventilation, owing to increased circulation of the air. 



I n the old forms of gas stove convected heat was relied on for raising the temperature of 

 a room, but this decreased the percentage of humidity to such an extent as to produce rapid 

 evaporation from the plants and occupants in the room, the results being drooping in the 

 former and discomfort to the latter. This is always the case where convected heat is the 

 sole method of warming, but if a combination of the two systems be adopted it will be found 

 very useful in the case of large spaces where enough radiant heat could not be given by an 

 open grate, or gas stove. With a factory or schoolroom, for instance, radiators or hot water 

 pipes could be fixed below the windows and inlet ventilators, and in this way the entering 

 current of air would be warmed up two or three degrees, and the fire would then be able to 

 complete its work of warming the solids in the room by radiation in a much shorter time. 



(VIVIAN B. LEWES.) 



In no large industry have such fundamental changes taken place during the past few 

 years as in coal gas manufacture, a complete revolution of the old ideas upon the carbon- 

 isation of coal having led to the introduction in Great Britain of vertical retort processes, 

 while on the European Continent and in America carbonisation in bulk or chamber 

 processes have made rapid headway. 



The beginning of the present form of vertical retort, in which gravity is brought into 

 full play to aid the filling and discharging of the retort, was in 1902, when at the Exeter 

 gasworks a retort on this principle was erected and worked by T. Settle and 

 retorts. W. A. Padfield, and in the same year vertical retorts began to be experi- 



mented on in Germany, by Dr. J. Bueb who by 1904 had got a good-sized 

 installation at Mariendorf working successfully. In July 1003 however Messrs. H. W. 

 Woodall and A. M. Duckham had patented in England a form of vertical retort on a 

 totally different principle to the German retort, inasmuch as they embodied the principle 

 of working continuously, so rendering possible the uniform treatment of coal during 

 carbonisation, instead of putting in a full charge of coal, carbonising, drawing the coke 

 and recharging, as is done in the Continental type of vertical. 



Messrs. William Young and S. Glover in 1905 patented a continuous vertical process, 

 which differed from the Woodall-Duckham. In the latter the principle is adopted of a 

 continuous column of carbonising material, the inlet of fresh coal at the top being 

 dependent on the withdrawal of coke from the bottom, the retort being so proportioned 

 with regard to time and temperature that the carbonisation of the coal was completed 

 by the time the bottom was reached; whilst in the Young and Glover system the dis- 

 charge of coke was independent of the coke feed, and a space was left in the top of the 

 retort above the coal so as to form a chamber in passing through which tar vapour might 

 be gasified and fixed by radiant heat: in this respect resembling the procedure adopted 

 by Settle and Padfield. 



In 1909 the Glover-West retort took the place of the Young and Glover, a cooling 

 chamber for the coke being constructed at the bottom of the retort, and the heat utilised 

 for raising the temperature of the secondary air supply to the flues, whilst the empty 

 space at the top of the retort was done away with, and the coke- withdrawal made to 

 govern the feed, thus reverting to the principle introduced by Woodall and Duckham. 



1 See E. B. xi, 483 et seq. 



