The operation of this lime machine is obvious. The gas first passes into the lowermost chamber of the cylinder h, where it comes in contact with the purifying mixture and passes through the fluid to the top of the same chamber, and thence through the pipe b, into the cylinder above it which communicates with the lower chamber, where it is acted on again by the lime and water, and bubbles up through the fluid to the top of the chamber. From this compartment the gas passes into the third cylinder, where it bubbles up and passes through the lime and water; and lastly it makes its exit through the pipe K, into the gasholder or vessel destined to receive it.
When the mixture of quick-lime and water in the compartments a, a, a, of the machine, requires to be renewed, it is let off by the stop-cock at the bottom of the lowermost vessel into the reservoir e. The fluid contained in the upper chamber may be discharged into the chamber below it, and so on with the chambers below it, care being taken to close the stop-cock of the lower vessel. The machine may be recharged at the uppermost chamber with the purifying mixture. Fig. 5, exhibits the plan of the machine. b, b, b, the tubes connecting the chambers. B, the flanch of the cylinder h.
This machine has in part remedied the inconveniences stated [pages 141], [142], but the increase in the quantity of the purifying materials which the apparatus requires, is of itself productive of most serious disadvantages.
The greater accumulation of waste lime which such a practice occasions, renders it necessary that capacious reservoirs and sewers should be constructed to receive and carry off the refuse materials, and where an outlet by such means cannot be obtained, the carting away the increased quantities of waste matter adds greatly to the cost of the gas.
If attempts are made to convey the waste substances into the common sewers or drains of the neighbourhood, the proprietors of gas works are exposed to indictments for a nuisance at the suit of the inhabitants, and when the near proximity of any river or lake induces an attempt to convey the waste materials thither, the most serious injury may be done to the water, which becoming impregnated with hydrosulphuret of lime is rendered unfit not only for domestic but for many manufacturing purposes. The latter evil indeed is one which operates also in a greater or lesser degree, even when the fœtid refuse or hydrosulphuret is discharged into the common sewers, all of which ultimately empty themselves into some water course, rivulet or lake. I would here beg to suggest, that considering how rapidly the new mode of procuring light is extending throughout Britain,[37] and how much the waters of the country are liable to be contaminated, from discharging into them the noxious refuse from the process of purifying coal gas, so as to be rendered proportionably unfit for the various purposes of domestic and manufacturing economy, it is well deserving the attention of the legislature, whether such contamination ought not to be guarded against by prohibiting enactments.
[37] The Towns of Edinburgh, Glasgow, Liverpool, Bristol, Bath, Cheltenham, Birmingham, Leeds, Manchester, Exeter, Macclesfield, Kidderminster, Preston, Waterford, Rochester, Chatham and several others, have been lighted with gas within these few years.
It appears to me that it would be a wise exertion of authority, to insert in every act of Parliament granted for incorporating Gas-light Companies, a clause prohibiting the proprietors from ever conveying the waste material, or any other produce from the manufacture of coal gas, either directly or indirectly into the common sewers, drains or water courses, or into rivers and lakes adjacent. The salubrity of the water we use is of as much consequence to us, as any superior excellence or saving of cost in our light can possibly be, and we ought to take care that in profiting by an improvement which science and art have discovered, we do not unnecessarily depreciate one of those primary blessings we owe to the bounty of nature.
Lime Machine lately adopted.
In the improved purifying apparatus[38] lately brought into use, of which we shall now give an account, a shaft or axis furnished with teeth or claws, is applied within the interior of the vessel, and made to act in such a manner as to scrape out the openings or slits through which the gas has to pass every time the axis is moved round, and by which regular clearance all chance of stoppage is avoided without any augmentation of the purifying mixture.
[38] This machine has been adopted at the gas works at Chester, Birmingham, Kidderminster, Bristol, and in many other provincial Gas Establishments.