Clegg'i /Ipparalus for producing Coal Gas. 14 i 



forms a cylindrical dish, nearly of the same diameter as the re- 

 tort. On the ii|)per part of the retort, and adjoining the door, 

 I place a hopper, sufficiently large to contain coal for twelve 

 hours' consumption. The coal is previously screened, and all 

 lumps excluded, larger than the required thickness of the strata 

 to be laid in the dish. The lid of the hopper is kept tight by 

 means of an hydraulic joint. To that part of the hopper where 

 the coal is discharged, is attached a cone, the difference of the 

 diameters of whose ends is in exact proportion to the difference 

 of the space described in their revolutions by the parts of the dish 

 over which it is placed. On the surface of this cone, a number 

 of thin bars are fixed longitudinally ; each about the depth of 

 the stratum of coal to be applied. The cone is made to revolve 

 upon its horizontal axis, at the same time that the dish revolves 

 horizontally; and by varying their relative velocities, the thickness 

 of tiie stratum may be varied ad i/rfinitum*. 



"The products arising from the coal thus introduced, are con- 

 veyed bv a pipe to the condenser, which condenser forms the prin- 

 cipals for supporting the roof over the retorts. From the condenser 

 all the fluids are conveyed back by a pipe to the retort, drop by 

 drop, as they are condensed ; and as these drops fall upon the red- 

 hot coke as it revolves, they are all completely decomposed f. 



" The lime machine is constructed upon the same principle as 

 that described in Accum's last Treatise, but much simplified and 

 impro'. ed. By using lime and water in a semi-fluid state, a smaller 

 quantity of lime is required for absorbing the sulphuretted hydro- 

 gen gas I, while, at the same time, lime of this consistence is as 

 <-otni)!ete!v free from the obnoxious fluid produced by lime-water, 

 as if dry lime had been used. As the tjuantity of gas absorbed 

 in the process of purifying is proportioned to the bulk of water 

 employed, it is obviously more oeconomical to use lime and water 

 iu a semi-fluid state; to which it maybe added, that gas purified 

 IjV this mode possesses higher illuminating power. In proof of 

 these assertions, I refer to a paper in the Philosophical Magazine 

 for September 1S19, by Dr. Henry, pp. 164-1G6. 



" From the lime machine the gas is conveyed to the large 

 nu'ter§, where every foot is registered, and finally into the col- 

 lapsing gas-holder, a machine preferable to any now used, and 

 constructed at half the expense ||. 



* When the stratum of coul is about half an inch in thickness the cylin- 

 <lrical (iish makes one revolution in forty minutes, tlie-velocity varying with 

 tile thickness of the stratum. 



f This is u more a?conomical and certain method of decomposing oil, tar, 

 &c., than any which has hcc-n offered to the notice of the public'. 



I For the purity of the jjas, after having passed through cream of lime, 

 *e'the Philosophical Magazine for February 1811), p. 138, No. 250. 



§ The utility of this machine is illustrated in Accum's Treatise onCJas Light, 

 art. Gat'Meter. \\ See A<Tum'.s Treatise, art. Collupsing GiiU'hoUk'i-, 



