290 Anali/ses of Booh. [April, 



thin layers from two (o four inches in Jhickness, is to obtain the greatest quantity 

 of gas from a given qviniility of coal at the least expense. 



Mr. Cle^g uas (he first person who poitiled out to the public (he aiivanta^es that 

 must accrue from ibis mode of operating, and to him we arc indebted for the con- 

 struction of an a|)pnratus, the great ii;^ciiuily and superiority of which entitles 

 what is called (he horizontal ro(ary re(ort, (o all (he merit and "praise that belongs 

 to the ciiaracter of an original inven(?on. 



The numerous and great advantages of this distillatory apparatus, the rapidly 

 increasing adoption of it,* and the almost certain pr.spect which exists of (heir ul(i- 

 niately superseding all former methods uf decomposing coal, make it proper that I 

 should lay before the reader as full an account as my limits will permit, of the 

 C(-instruction and operation of this reiort, and tlie mode of ajjplyingit; and this 

 becomes the more necessary on account of t!ie many important iniprovBmen(s 

 which the ajtparatus liar undergone since i.s fir.-t adoption, + and of which no descrip- 

 tion has yet been laid before the public. 



Tiie fidlowing account will render the construction of this retort siifficienlly 

 obvious : 



Description of the Horizontal Rotttry Bitorts at the Roijal Mint.X 



^ The horizontal rotary retor(s at the Royal Miirt are hollow cylinders, eight feet 

 six inches in diameter, and 15 inches high, arched a !t((le at (he lop. They are 

 made of wronght-iran plates, half an inch ihi' k, rivelted together in t.ie manner of 

 a Sleair.-eigine boiler. A, A, A, fig. I, Pl.ilc CUI. exhibits a perpendicular sec- 

 tion of llie rolary reiort. In fig. 2, ihe reiort is seen fixed in the brick-work; 

 n, fig. 2, shows the mouth of (he retort, through which the coals are introduced, 

 and from whence the coke is withdrawn. It is also shown in perspective at 

 B, H, 15, fig. 6. Tiie month is closed with a ca:(-iron door fi(ted on alr-(ight by 

 grinding. 



Tile door is connected at its upper and lower exlremidcs, wilh a frame and 

 adjusting rod, see Jj, B, fig. 2, by means of which it m;iy readily be slided down 

 helotv tlie mouth of (he re(or(, when (he coals are (o be introduced, or coke is (o 

 be w ididrawn. To (he iipjacr extremity of (he rod B, fig. 2, is fixed a lever, 

 loaded \> i:h a coun(crpoise wriglK C, (o balance the door, and to render the open- 

 ing and closing of it ca«y and expeditions. 



The iiiondt-piece and its door is (hree feet long, and nine inches wide-; it pro- 

 jcc(s nine inches beyond (he biick-work or furnace in which the retort is fixed, as 

 may be seen a( a, fig. 2. 



The fire-place, which is on (he op])o?i;e >ide (o (hat of (he mou(h of the relorf, 

 heats only onc-lhird part of Ihe whole capacity of the retort to that degree which 

 is proper for the complele and rapid decomposition of Ihe coal ; while the remain- 

 ing parts, which are not over (he fire-place, and (o which the fire jBues do not 

 extend, are kept at a lower temperature. 



The tiues are direc(ed under about one-third of the area of the boKoni of (he re- 

 tort, and yf(er having passed over one-(i)ird par( of the area of the lop of tiie retort, 

 they pa-s in(o the chimney. Fig. .5, exhibits ihe direction of ihe flues ; A, A, the 

 flues and the fire-place. The w hole relori is guarded from the contnct of (he fire, 

 which would soon destroy i(. by fire-bricks; it notwithstanding speedily receives 

 the full elfccl of the heat, and rclains its temperature wh-?n once healed for a long 

 time. Fig. 2, cxhihits one of (he re(orts fixed in its fiirnace. A perspective view 

 of three retorts may be seen in fig. 6. ^ 



Through (he centre of the retort passes perpendicularly an iron shaft, D, as 

 fhown in the teclinn of the rc!or(, fig. 1, and also in fig. 2. The lower ex(remi(y 

 of the shaft revolves upon (he boltom of the retort, in a cup-shaped cavity, while 

 its upper e.xtremily passes through the roof of the retort, where ihe lalter is made 

 air-tight by means of a pipe, E, fig. 2, awd E, fig. 1, closed at the lop and sur- 

 rounding ihe shaft ; and hence Iheshaft must always preserve its centie. 



* Reiorls of (his description have be n lately adopted in the gas works at Bris- 

 tol, Birmingliam, Chester, Kidderminster, and at many other provincial gas esta- 

 blishmenl^. 



t An account of iheoiiginal construction of (lie rolary re(ort may beseen in the 

 liepository of Arts, No. CLXXVI. 1S16, p. I ; and aho in the Journal of Science, 

 vol. ii. p. 133. 



.j: Thj retorts lalcly erected at the gas work; at Birmingham, Cliestcr, Bri:toI, 

 &c. are similar to tiioseat (he Mint. 



