3SQ USEFUL fftODUCTS FROM COAE. 



be ufeed, the cock may be turned, a"nd prevent Stiy gas hcfm 

 passing from the reservoir, and by opening the cock E on 

 the top of the purifier, and firing it, all the gas which is 

 made more than is wanted for use may be burnt away. If 

 this was not done, the gas would continue to find its way 

 into the reservoir K, which would overflow and produce a 

 disagreeable smell, which this simple way of burning it 

 away as fast as it is made when not wanted, prevents. 

 Receptacle for It may in some measure happen, that, although the gas 

 in^hepurmerf ^'^^ passed through the purifier C, a small portion of tar 

 will pass along with it, and would either clog the pipe S, or 

 accumulate in the reservoir. To avoid this, there is placed 

 at the bottom of the pipe S and G, before it rises into the 

 reservoir, ajar, into which a pipe, made as shown in the 

 drawing, conducts the tar; this collects all that passes 

 through the purifier ; it is filled with water, over which the 

 gas passes up into the reservoir, but the tar drains down 

 this lead pipe and deposits itself in the jar of water. The 

 longer this pipe S is, the better, as it serves as a refrigitory. 

 Receptacle for H is a plain cask, made to any proper size, and filled with 

 Seaas'^^'"™^ water, with a cock to draw off the water when it becomes 

 foul. The upper vessel K is made of sheet iron, rivetted 

 together in the nanner engine-boilers are made. If it is only 

 from five hundred to one thousand gallons in size, it will 

 require only two cross iron bars at top, and four ribs down 

 the sides to keep it in form, with a strong ring at top ; and 

 as there is no stress on this vessel, it will ascend and descend 

 easily without any other support or framing, the plain sheet 

 iron sides being rivetted to the four ribs, and it is quite open 

 at the bottom. A strong rope runs over the pullies L L, 

 with a weight M to balance the vessel K, and.^ssist it in 

 rising and falling. The pipe J is that through which the 

 gas passes from the reservoir or gazometer, and rising 

 through the pipe T, is conveyed to all parts to be lighted. 

 Method of pre- There is also another drain-pipe at N, for, after all the 

 venting the -yvashine &c., a very small portion of tar and moisture may 



pipes from o 7 j r ..,, 



being clogged, rise into the pipes, and perhaps in time clog them, but bj 

 laying all the pipes in the first, second, and third stories on 

 a small descent, if any tar or moisture should rise, it will 

 drain down all the pipes from top to bottom, and be depo- 

 sited 



