GAS-LIGHT.

117

WASTE

WATER

BOX

v ariation of the water levels within such narrow limits, that the measurement may beConsidered perfectly just on all occasions.

The last patent by Mr. Edge is for an improvedindex, which is composed of a series of movingdials, with 10 figures upon each, one figure only ap-pearing of each series at a time.

This contrivance is very ingenious, and will nodoubt be applied to other machines, where indexes.( indices ) of quantity are required.

Recurring to Mr. Clegg, he is also the inventorof an instrument of great value—appropriatelycalled a “ governor.” Its purpose is to renderequal the height of flame of the several burners inany house or establishment, and to keep them so,notwithstanding any, and whatever alteration maybe made in the pressure at the works or elsewhere.This instrument is perfected, and successfully ap-plied, though it is not so generally in use as itought to be. By the use of this instrument a lightonce set at the height desired will maintain thatheight uniformly, and without the least variationthe whole evening; and continue to do so tillaltered.

Without this instrument, it is necessary to payattention to the burning of gas-lights, as theirheights are frequently affected by the most triflingcircumstance, such, for example, as their extinctionat the hour of closing the shops, which makes a sen-sible difference in the neighborhood.jjAjl these works have prodigiously increased in the quantity of gas made and sup-Since the account in the former edition of this work, large additional manufac-•K le s have been erected by new companies, and great additions made by the old ones.2 jj ere are now in the metropolis alone 15 public gas companies, having among themsn *’ a ? establishments. The quantity of gas manufactured by these 23 gas-works, and0 j,Pplied to the public was during the past year three thousand one hundred millions■lOn^le teet S as > an d the coa * used to produce this quantity of gas was at the leastg°00 tons!

c <il a ^ e< ^ c ^ r re torts are very generally used in Scotland , and found to be most economi-cs regards wear and tear; in London , however, they are mostly of cast iron.

Loon G P ressure upon the retorts is caused principally by the use of wet lime, used inIVf, , 011 ’ because the process is less expensive and less cumbersome than dry lime.

A lime can not be used with clay retorts, owing to this excess of pressure,j^nerit is due, for enlarging the capacities of double gas-holders, to the late{j ' Joshua Horton, of West Bromwich, near Birmingham ; and to Mr. Stephens lic c binson, engineer of the New London Gas-Works, Vauxhall, where they were first8 *»ftlly introduced, and manufactured by Mr. Horton. They have now come very»tau rall y iui 0 use throughout the kingdom and are manufactured by all gas-holderg e ts.

UsgfPauate gas-holders are advisable and advantageous, but they are not generally-j, > except in Glasgow, Manchester, Birmingham , Sheffield, and a few other places.ai »tn 6 annexec l drawing represents Mr. Croll’s vessels for the purification of gas fromden °ui a , which is effected by means >of dilute sulphuric acid applied between the con-a hd w db the ordinary lime purifiers. The vessels are made of either wood or iron,w db l ea d 1 have a wash-plate similar to the wet lime purifiers. The radi-Sup® bottom formed of wooden bars, as shown in the drawing, is for the purpose ofporting the wash-plate and distributing the gas.

a, is the inlet pipe; b, the outlet pipe; c, c, the tube with funnel foru< r‘ng the sulphuric acid; d, the first purifying vat; e, the second ditto, boththe w Wltl1 ^ eat *> anl * w hich are filled up to the dotted line with the dilute acid; /,/,a ter supply-pipe ; g, g, the discharging cocks.h°tt c °' 68 represents a ground-plan of the vats, each 10 feet in diameter; A, theIn p f the uuddle ; B, the inlet of the gas; C, the outlet of ditto.

>H the ° mmencin g the process, these vessels are charged with water and sulphuric acid,Vine Proportion of seven pounds, or thereabouts, of the latter, to '300 gallons of thel hr 0 ^' As the acid is neutralized by the ammonia contained in the gas passing'tf°pp?b the vessels, the above proportion, as near as may be, is kept up by a continuouswn g or running of acid, regulated according to the quantity of ammonia contained