Jo6 An EJfay on Ekaching. 



alfo for bleaching raw cotton or cotton thread. Thbngh the 

 difpofitions which we have recently made prefent great ad- 

 vantages, yet as this new art is, as we may fay, only in its 

 infancy, we {hall defcribe, in the words of Chaptal, an ap- 

 paratus fimilar to that which C. Bawens has cauled to be 

 conltrucled. 



" At about. the diflance of fixteen inches from the grate 

 of a common furnace, heated by pit-coal, is placed a copper 

 boiler of a round form, four feet in diameter and eighteen 

 inches in depth. The edges of this boiler, which are about 

 feven inches in breadth, and turned backwards, reft on the 

 lateral edges of the brick-work of the furnace. The re- 

 mainder of the furnace is of cut (lone, and forms an oval 

 boiler, the height of which is fix feet, and the breadth, mea- 

 sured at the centre, five feet. The upper part of the boiler 

 forms a round aperture,, the diameter of which is eighteen 

 inches. This aperture may be {hut by a fort of moveable 

 {tone, or a copper lid fitted to it. On the edge of the copper 

 boiler, which forms the bottom of this kind of digefler, is 

 placed a grating formed of wooden bars, fo clofe to each other 

 that the cotton laid upon it cannot fall through between 

 them, and flrong enough to fuftain the weight of about 

 1600 pounds." 



In the apparatus of C. Bawens, the mode of heating em- 

 ployed in Count Rumford's furnaces has been adopted in 

 order to fave fuel. The heat of the chimney is applied to 

 heat a veflel containing diluted fulphuric acid. (See the three 

 uppermoft figures of Plate IV.) 



The apparatus propofed in other countries afforded the 

 advantage of being able to wind up the cloth in the infide : 

 it was, as we may fay, the boiler of a fleam-engine, with 

 its tubes, fafety-valves, and leather collars; but it was ne- 

 ceffary to introduce the ftuffs at the top, which is very in- 

 convenient. 



With thefe data, and after having maturely reflected on 

 the means of improving this apparatus, I invented feveral 

 kinds proper for being applied to different kinds of goods. 



The firft, which I propofed to be executed at Jouy, re- 

 prefented a chamber, arched with cut Hone, fix feet eight 

 inches in length, three feet ten inches broad, and three feet 

 and a half in height above the level of the wooden grate. 

 (See Plate V. fig. 1.) At one of its extremities was a door, K, 

 two feet in height and three feet long, covered with a plate 

 of caft iron, in which was a hole for introducing a conic 

 valve, kept in its place by a very powerful f'crew and fpring. 

 The object of this valve was to guard againft an explofion, 



which 



