GAS, COAL 



585 



by a cast-iron plate K, through which the axle c passes : the latter communicates a ro- 

 tary motion to the cylinder and cone A and A'. It is inclined 8 from the perpendicular, 

 and rests upon the steel point of the centre pin b', whilst at top it carries a pulley by 

 which a circular motion is communicated to it. a a are a series of metal discs which 

 stand vertically to the inner surface of the cone A', with spaces of about one inch 

 between them. The discs are arranged concentrically, and have spaces correspond- 

 ing to the quantity of gas which has to pass through them. They are from 6 to 7 

 inches long. As the axle c and cylinder A are not vertical, but somewhat inclined, one 

 side of the cone A' will, during the revolution, be in a nearly horizontal position, 

 whilst the opposite side will be immersed in the liquid to the extent of about 16. 

 The whole of this mechanism is enclosed in a sheet-iron lid B. The centre pin b is 

 attached by a cross bar to the lower edge of B, whilst the axle c is supported by d, 

 which is also attached to B. d' d' is a water-joint permitting of the free motion of c. 

 The lid B thus contains the whole of the washing apparatus, and it is held in its proper 

 position in the trough c by lateral attachments. D is the inlet pipe opening into the 

 cylinder A, from which it has to make its way through the discs a a to the outlet E. 

 This apparatus gives no sensible pressure, and requires a very small motive power. 



Fig. 1045 represents an arrangement of four of the dry purifiers shown in fig. 1041, 

 worked by a central valve, as used at the present time in most large gas works ; it is 

 the invention of Mr. Malam, and is described in Mr. Peckston's treatise. A, B, c, D, 



are the four purifiers connected with 

 , , r , . 



the central valve E in such a way as 



to permit of three of them being at 

 work whilst the fourth is emptied 

 and re-charged. The outer case of 

 the central valve E, is a cylinder of 

 cast or wrought iron, 5 to 6 feet in 

 diameter and 3 to 4 feet deep. Its 

 floor receives the open ends of 10 

 pipes conducting the gas from the 

 condenser or exhauster to the diffe- 

 rent purifiers, and then to the gas- 

 holders; the ends of these pipes 

 project upwards to the height of 14 

 inches, and the vessel E is filled with 

 water to the height of 12 inches, 

 thus leaving the orifice of the pipes 

 2 inches above the water-level. This 

 cylinder has a cover which consists 

 of a smaller cylinder, open below 

 and closed above, fitting into E so as 

 to form a water-lute. Its interior is 

 divided into 5 chambers, as shown 

 in Jig. 1046 ; and when the cover is 

 so far lowered into E as to immerse 

 the edges of these chambers into the 

 water, they each connect together a 

 pair of pipes as shown in fig. 1045, 

 at E, which exhibits a horizontal 

 section through these chambers. 

 The chambered cover being placed 

 in the position shown in fig. 1045, 

 the gas takes the following course : it enters the chamber a' by the pipe a a, passes 

 through the pipe marked 1, into the bottom of the purifier c, and after traversing the 

 layers of purifying material in c, it returns to chamber e of the central valve by the 

 pipe 2 ; thence by pipe 3, it enters the purifier D, and returns to chamber d of the 

 valve by pipe No. 4. From this chamber it can only make its exit by pipe No. 5, 

 which conducts it into B, whence it returns to chamber 6, by pipe No. 6, and from this 

 chamber it finally passes to the gasholder through the exit pipe b b. Thus the purifier 

 A is left out of the circuit for the purpose of re-charging or revivification ; but when 

 the material in c has become exhausted, it can be replaced in the circuit by A, by 

 slightly raising the cover of E, and turning it round so as to bring the chamber a' over 

 pipe 3, and again depressing it to its former position l by this arrangement D, B and 

 A become the working purifiers, whilst c will be thrown out of the circuit. Thus, by 

 the action of the central valve E, each of the four purifiers can in turn be excluded 

 from the circuit, and recharged or revivified. 



