AND VOLATILIZATION OF PLATINUM. 101 



course be easily understood by every one, who is acquainted 

 with those machines. The pneumatic tub is necessarily fa- 

 miliar to every chemist; and for an explanation of the hy- 

 drostatic blowpipe, I beg leave to refer to my memoir before 

 mentioned. 



There is a transparent representation of the apparatus at 

 Fig. 1, Plate, III. It consists of an oblong tub A, contain- 

 ing two chests B, C, which arc open at bottom, and complete- 

 ly air-tight every where else. One of these chests B, is dou- 

 ble the size of the other; and is divided by the air-tight par- 

 tition K K, into two compartments. Thus three air-cells arc 

 formed, one by the smaller chest C, and two by the larger one 

 B. These last mentioned cells communicate with the open 

 air by means of cocks and pipes a, b, The other cell com- 

 municates with the air by means of the cock c. — At D, E, F, 

 three circular bellows may be observed, each furnished with 

 a suction-pipe, and pipe of emission. The suction-pipes may 

 be observed at d e, f g, h i, severally entering their respective 

 bellows; and the pipes of emission may be seen at k 1, m n, o p, 

 each issuing from the bottom of the bellows to which it ap- 

 pertains. The orifices of the pipes of emission k, m, p, under 

 the air-cells, and those of the suction-pipes within the bellows, 

 at e, g, i, are furnished with valves opening upwards. The 

 bodies of the bellows consist of hose-leather sewed water- 

 tight, and distended by iron rings. They are nailed to the 

 bottom of the tub, and to circular pieces of wood, which 

 constitute the tops of the bellows. These tops are loaded with 

 several pounds of lead, which keeps them depressed, when 

 they are not elevated by means of the handles and rods. The 

 table is affixed to the tub, by means of hooks and staples, 

 so that it may be removed at pleasure. 



At GHI, HI, pipes of delivery may be observed. These 

 are furnished with cocks at H H, and conical mouths at I I. 

 which last, are calculated for the insertion of an adjutage, for 

 the purposes of an ordinary blow-pipe; or for the reception of 

 the compound blowpipe at Fig. L l. 



In order to prepare this apparatus for use, let the cock of 

 the air-cell behind the partition K K, be closed, and let all 



