GAS. MANUFACTURE OF. 



GAS, MANUFACTURE OF. 



M 



basis for much specuUtion, and many patent* embodying thoM 

 method* hire been taken out For tome purpoaei it is mifficient to 

 add hydrochloric or sulphuric acid* to the crude pic-liquor, to well 

 agitate the mixture, allow impurities to nibiide, concentrate to the 

 CTTstallisingpoint, and expose the crystals to a slightly elevated tem- 

 perature. The resulting salt it still of course very impure, but serves 

 lor the preparation of carbonate of ammonia by sublimation with 

 chalk ; or certain portion* of the impure chloride alone may be farther 

 purified by sublimation. For purposes in which purer ammoniacal 

 salta are desired, the ammonia is displaced from its combinations in 

 gat-liquor by a stronger base, usually lime ; it is separated from the 

 resulting lime-salts and impurities by distillatory processes, and its 

 vapour condensed in water containing the acidr with which it IB wished 

 to unite it From these solutions the salts are obtained by evaporation 

 and crystallisation. 



For a list of, and details concerning the various patented processes 

 for "the manufacture of ammonia and ammouiacal salts from the 

 ammoniacal waters of coal gas-works," see ' Pharmaceutical Journal,' 

 vol. ziii., first series, pp. 63 and 118. 



GAS, MANUFACTURE OF. There are few more remarkable illus- 

 trations of the occasional stagnation of human invention for long periods, 

 and of its subsequent feverish activity, than may be discovered in the 

 history of artificial lighting. It is true that from a passage in Ammianus 

 MarcellinuB, in which he speaks of the towns in the time of Constantius, 

 A.D. S53, and says that it was easy for conspirators to carry on their 

 treason in them, " ubi pernoctantium luminum claritudo ilk-rum solet 

 imitare fulgorem," it may be supposed that the ancients paid nome 

 attention to the lighting of their streets, but the most elaborate critical 

 investigations, and the most careful observations upon the remains of 

 antiquity, have failed to discover traces of any other system of lighting 

 amongst the Greeks or Romans, than very rude oil lamps without 

 chimnies, candles of very imperfect manufacture, torches, or open coal 

 fires. The same methods of public and of private lighting were 

 retained, without improvement, throughout the middle ages ; nor was 

 it indeed until about the end of the 17th century that anything like 

 , a regular system of public lighting was attempted in any of the capitals 

 of Europe. The first decided steps towards the improvement of this 

 important detail of domestic comfort and public security, seems to 

 have been taken under the guidance of M. de Sartineg ; for under his 

 protection Laugrin introduced the reflector lamps, which were subse- 

 quently improved by Quinquet ; and finally Argancl perfected the 

 ordinary oil lamps, by the introduction of the cylindrical wick and 

 chimney, with a double current of air. Letters patent for this inven- 

 tion were granted on 5th January, 1787, but they were abolished during 

 the French revolution of 1798. 



Whilst the methods of artificial lighting were thus slowly progressing 

 in the beaten track, Mr. Murdoch was engaged in experiments on the 

 combustion of coal gas ; and in 1792 he lighted his house and offices at 

 Redruth in Cornwall, by that means. In 1798, Murdoch also lighted 

 the shops of Messrs. Bolton and Watt at Soho with " inflammable gas ; " 

 and in 1802 it appears that a M. Lebon proposed to light a portion of 

 Paris in a similar manner. The Jesuits' College at Stony hurst, was 

 amongst the earliest public institutions to adopt the " new light ; " and 

 it was in the course of executing this work that Mr. Clegg introduced 

 the method of purifying the gas by passing it through lime water ; 

 this took place about 1807. In the same year Mr. Winner, who had 

 taken a very conspicuous part in diffusing the knowledge of the new 

 method of lighting, obtained permission to apply his apparatus to a 

 few lamps in Pall Mall. The first act for the establishment of a gas 

 company was ]ssed in 1810, and under its powers the Chartered Gas 

 Company commenced operations, in spite of the sneers of scientific 

 men and the opposition of practical ones. It was not until the 31st of 

 December, 1813, that gas lighting was employed on a large scale in 

 streets, by the lighting of Westminster Bridge ; and on April 1st, 

 1814, the parish of St. Margaret's Westminster substituted gas for oil 

 throughout their district. About the beginning of the year 1820 

 Paris imitated the example thus set ; and subsequently to that period 

 almost every city of importance in England, and on the continent, has 

 adopted the use of gas. The meter, for registering the consumption of 

 gas, was invented in the year 1815 by Mr. Crosley, and since that 

 period gas has been commonly applied in lighting private houses. It 

 may convey some idea of the importance of the gas manufacture of 

 London to state here that there are no less than nineteen companies 

 established for this purpose, with a paid up capital of nearly six 

 millions sterling. 



The manufacture of gas is conducted upon rather different principles 

 in the Urge establishments of such a town as London, from those 

 observed in the majority of small country works ; and it will therefore 

 be desirable to notice in detail the various processes of the manufacture, 

 in order to explain some of the reasons for these particular variations. 

 In so doing, the system to be observed is that of the ordinary course of 

 manufacture ; or to discuss, 1st, the carbonisation and distillation of 

 the coal ; 2nd, the condensation and purification ; 3rd, the storage of 

 the gas ; 4th, the distribution, under the sub-divisions of the mains 

 and of the fittings; and 6th, the accessory buildings, or processes 

 employed. The conditions connected with the discharge of the public 

 service by private companies, or by municipal bodies, will form the 

 subject of a special article [PUBLIC LIUUTISO], on account of the 



warm discussions which have lately taken place, and of the singular 

 differences of system which prevail in the matter. 



1. The distillation of the coal, or the process by means of which the 

 illuminating gases are separated from the solid carbon of the coal, is 

 effected in close vessels known by the name of retorlt. These retort* 

 are at the present day long, closed, horizontal vessels of cast iron, or of 

 fire clay, or occasionally in large town-works they are built up with 

 fire bricks ; and, as might be expected, they are of every variety of 

 form and cubical capacity. Generally speaking, however, retorts of 

 cast iron are made of the shape of the letter D, and they are about 7 

 feet 6 inches long, by 20 inches wide, and 12 inches deep ; tin ir 

 capacity being such as to allow them to carbonise 120 Ibs of coal in 

 each charge. The clay retorts are sometimes made of the same form 

 and dimensions as the iron ones, but they are very frequently made 

 perfectly cylindrical ; or in large works they are made in lengths of 

 about 16 inches, joined together with fire clay, so as, in fact, to form 

 ovens about 7 feet long by 5 feet wide, and 18 inches high, as in some 

 of Mr. Grafton's works ; or, as in the case of the Phoenix Works, London, 

 they are put together in three pieces, making retorts of 20 feet long, 

 by 16 inches diameter. There are numerous descriptions of retort 

 ovens formed of fire tiles and bricks now in use in the London gas 

 factories, such as those for instance of the Westminster station of the 

 Chartered Company, which are about 22 feet clear length, by about 

 20 inches wide, and 13 high, and are fed from both ends; or again 

 in Paris, and at the London Gas Works, Vauxhall, a large oven is 

 occasionally used, capable of carbonising as much as six tons of coals 

 at a time, for the purpose of obtaining a description of coke adapted 

 for foundry, or other analogous purposes, at the same time that the 

 illuminating gases are secured. 



Q 



Now the differences we thus find to prevail in the shape, dimensions, 

 and materials of gas retorts, extend likewise to the manner of their 

 arrangement in the same bed, as the assemblage of retorts heated by 

 one furnace is called. According to the size of the locality to be 

 supplied, 1, 2, 3, 5, 7, or even as many as 12 retorts are fixed in the 

 same setting, though it is very questionable whether any real advantage 

 be gained by exceeding the number of 7 or 8. The advantage of 

 placing several retorts in one bed, being only that they require, under 

 such circumstances, less fuel to bring the coal to the required 

 temperature, there must be a point at which the increased cost of 

 labour, from the difficulty of droving (or removing the carbonised coal 

 from the upper retorts) must balance the economy of fuel. Assuming 

 then that seven or eight retorts in a bed are the most convenient and 

 economical arrangement in large works, the setting of the retorts in 

 small works would be regulated on the calculation that each ordinary 

 D retort will yield a fair working result of from 2500 to 2700 cubic feet 

 per day : and the number of such retorts in a bed must be regulated 

 according to the size of the town and it* consumption of gas, so as to 

 have the smallest possible number of furnaces alight at the same time. 

 The nature of the fuel burnt under the retorts may modify the 

 ordinary course of proceedings, however, and in some cases the 

 character of the foundations upon which the retort bods are placed 

 may render it unadvisable to concentrate a great weight in one spot. 



Whatever be the shape of the ordinary retorts (that is to say, of 

 those in which no attempt is made to obtain mctallurgic coke), the 

 exposed end of the retort bears a mouthpiece, to which is attached the 

 ruing or itand-pipe, or the pipe through which the crude gas puses 

 from the interior of the retort into the hydraulic main, to be described 

 hereafter. As this mouthpiece is frequently exposed to severe shocks, 

 it is made of cast iron, even when clay retorts are used ; and it bears 

 two ears which receive the ends of the lidt, or covering-plates, and the 

 crou-bart used for fastening the lid (by means of a strong square 

 threaded screw) to the mouthpiece. The imperviousness of the junc- 

 tion of the mouthpieces and lids is, moreover, assisted by covering the 

 bearing surface with a luting composed of the spent lime from the 

 purifiers (when that material is used) mixed with fire-clay. The stand- 

 pipe is usually formed in a separate casting from the mouthpiece, and 



