GAS LIGHT. 



37J 



A A represents an outside cast metal case of a flat 

 cylindrical form. Into the back of this casing a pipe 

 is led from the gasometer, the opening of which turns 

 up within the case. On the knee of this point a 

 pivot is fixed exactly opposite to another fastened 

 into the front face of the case, on which pivots a sort 

 of drum, C C C C, revolves. This drum carries 

 vanes, which open at the circumference, as may be 

 seen in the figure. The instrument is filled with 

 water up to the height marked by the dotted line, 

 through an orifice in the side of the vessel, in which 

 a plug is fitted. The gas enters by the pipe A, and 

 fills the cavity above with gas, causing the drum, 

 C C C C, to revolve from right to left, while the gas 

 escapes from an orifice on the other side into the 

 pipes to be consumed. By means of a train of wheel 

 work fixed upon the axis of the drum, an index is 

 turned, which points out on an index-plate how many 

 cubic feet have passed through the meter. Should 

 there be too much water in the meter, it is clear that 

 the index will point out falsely, as there will be less 

 consumed than is registered. 



The principles of the distribution of gas are exhi- 

 bited in the following table given by Mr Peckston. 

 The gas-holder is worked at a pressure of one verti- 

 cal inch of water, and each argand burner consumes 

 five cubic feet per hour. 



The number of candles equivalent to produce an 

 equal quantity of light, may be found by multiplying 

 the last column in the table by 4. 



The area of the pipes which lead from the retort, 

 must be equal to the sum of the area of all the pipes 

 to which they transmit the gas for consumption. 

 The main pipes are usually made of cast metal, and 

 those which are led from them to the jets, are com- 

 monly formed of tinned iron plate. The diameter of 

 the bore of gas burners varies from one-fortieth to one- 

 sixtieth of an inch. 



It has been found that one pound of cannel coal, 

 decomposed on the small scale, will yield 5 cubic feet 

 of gas, but in large manufactories only about 3 

 feet, and the quantity of tar from one ton of coal is 

 usually about 11 ale gallons ; and, according to Mr 

 Murdoch 1 10 tons of coal will yield about 40 tons of 

 coke. The quantity of coal for furnaces used with 



the tar and coke is about twenty-six tons for seven- 

 teen of the retort coal, and the quantity of lime for 

 purifying, varies from five to ten per cent, of the 

 weight of the retort coal. 3500 cubic feet of gas 

 may be obtained from 1120 Ibs. of cannel coal, but 

 only 3000 from the same quantity of Clifton coals. 

 Dr Henry states that 100 measures of oil gas is 

 composed of 



Olefiant gas, . . 



Azote, 



Carburetted hydrogen, 



Carbonic oxide, 



Hydrogen, . 



38 

 3-1 

 6'54 

 93 

 31 



The specific gravity being -906, air=l: then will 

 100 measures of coal gas be found to be composed of 



Olefiant gas, ... 13 

 Carburetted hydrogen, . 82-2 

 Carbonic oxide, . . . '.',!> 



Azote, 1-3 



The specific gravity being 0-650, and the hydrogen in a 

 condensed state of the olefiant gas. 



We shall not enter here into the process of oil gas 

 manufacture, as it has not, upon trial, been found to 

 possess all the advantages which its advocates would 

 have had the public to believe. Its production is 

 much more expensive than that of coal gas, and its 

 tendency to explode, when ignited in combination 

 with 1 common air, is also much greater than the gas 

 obtained from pit coal, but, at the same time, its illu- 

 minating power is to that of coal gas as 16 to 10. 



The formation of oil gas is much more simple 

 than that of coal, nothing more being necessary than 

 decomposing the oil in retorts moderately heated, 

 and allowing the gas which rises to bubble 

 through a vessel of water for its purification, before 

 it passes into the gasometer. It contains more car- 

 buretted hydrogen than coal gas, in the proportion 

 of 75 to 40, in equal volumes. It may be obtained 

 from oil of very inferior quality, and is destitute of 

 the disagreeble odour of coal gas, nor does it injure 

 the metallic pipes through which it is conveyed. The 

 peculiar smell of coal gas may be regarded as an 

 advantage, since it warns the consumer of its escape. 



The following statements may be interesting to 

 the reader. A manufactory near Glasgow using 

 460 common gas burners or jets, during all the dark 

 hours from six hi the morning till eight at night, 

 from September 16, 1833, till April 12, 1834, is 

 supplied with gas from two retorts, each ' having 

 an elliptical cross section, the greater diameter 

 of which is one foot six inches, and the lesser 

 eight inches, the length being sixty-two inches ; 

 thirty-six tons of Jordanhill coalfor the retorts, forty 

 tons of dross for the furnaces, used along with the 

 tar and coke produced during the process. The 

 coal is changed in the retort once in six hours, and 

 the lime in the purifiers is changed once in three 

 days. The cost of the whole apparatus amounted to 

 400, and j60 per annum are required for its main- 

 tenance, of which lQ go to pay the attendant ; 

 18 for gas coal ; 10 for furnace coal ; 2 for 

 lime, and the rest for repairs, &c. ; the price of light 

 ibr one jet being thus .0 4s. 6jd. 



In a larger factory, in the same city, using 837 jets 

 during the same hours as the factory alluded to in 

 the foregoing statement, the following quantities of 

 coal were consumed each successive fortnight, from 

 the 1st of September 1833, to March 28, 1834. 



Tons. Cwts. Qrs. 

 1 6 1 



161 

 252 

 302 

 531 

 631 



IS II 



2A2 



