GAS. 



373 



is charged directly into them, thus not only 

 saving that amount of heat, which is less than 

 might be imagined, but also saving the labor of 

 again handling the coke. In one of the large 

 works of this city, where it has not yet been 

 deemed advisable to introduce the new fur- 

 naces, an economy of labor and fuel is secured 

 by charging the old style of furnaces with hot 

 coke as it comes from the retort. It is drawn 

 into a peculiarly shaped iron barrow, which is 

 then wheeled in front of the furnace-door, and 

 the coke is pushed in. 



Retort-Charging. Many efforts have been made 

 here and abroad to do away with the laborious 

 hand-charging. Apparatus has been tried by 

 which a scoop of the length of a retort was 

 introduced by machinery into the retort, and 

 was then inverted, opened, or had its bottom 

 withdrawn, dropping the charge of coal upon 

 the bottom of the retort. These machines are 

 preceded by another one which draws the coke 

 from the retort. In all cases they work on the 

 principle of the old-fashioned " drawing-rake." 

 The coke is raked or hoed out of the retort, 

 exactly as in the old hand -process. A very 

 ingenious machine has recently been intro- 

 duced for charging retorts, in which a jet of 

 steam is made to drive the coal before it into 

 the retort. As may be surmised, this is of 

 extremely simple construction. A steam noz- 

 zle is arranged with a quick- opening valve 

 so that a sudden puff of steam can be dis- 

 charged. A scoop or pipe leads the coal down 

 in front of the nozzle, and, by a succession of 

 openings of the valve, the coal is driven in two 

 or three installments into the retort. By grad- 

 uating the force of the jets of steam, the coal 

 can be deposited with great regularity along 

 the entire length of the retort. An unsuccess- 

 ful attempt has been made to use the same 

 principle in discharging retorts. 



The great objection to the mechanical stokers 

 was their size, complexity, and consequent ex- 

 pense. By the use of the steam-jet these ob- 

 jectionable features, at least, were to a great 

 extent obviated. 



Scrubbers. It is surprising how long it took 

 gas- engineers to learn to wash the ammonia 

 out of gas. For years, hardly an attempt was 

 made to remove the ammonia economically 

 and thoroughly. William Mann, of England, 

 was one of the earliest to enter the field. He 

 introduced his coke-scrubbers at many English 

 works, where they met with complete success. 

 Their construction is very simple, their effi- 

 ciency being due to their size. They are iron 

 towers, sometimes sixty or seventy feet high, 

 which are filled with coke, and supplied with 

 water at the top ; this, trickling down through 

 the coke, effectually absorbs the ammonia from 

 the gas, which is driven up through the mass. 

 Less than a gallon of water suffices for each 

 thousand cubic feet of gas. Ammoniacal 

 liquor of improved quality and high commer- 

 cial value is also thus obtained. Another form 

 of scrubber contains a series of vertical re- 



volving disks, perforated with many holes, 

 whose lower areas dip into water. The gas 

 passes through these disks and is thereby very 

 efficiently washed. The water is so distributed 

 that the first disk is moistened with clean wa- 

 ter, the next with the weakest ammoniacal 

 liquor, and so on, the water regularly passing 

 from end to end of the scrubber, against the 

 current of the gas. 



Other Improvements. In the purification of 

 gas the general practice has adhered to lime. 

 Some very remarkable results have been 

 achieved with bone-black, but they have led 

 to no extensive practical use. Heating the 

 gas with a small percentage of air before puri- 

 fication has also been tried, but with only ex- 

 perimental results. A new method of work- 

 ing purifiers has been introduced. Purifiers 

 are arranged universally in sets of four, with 

 center seal arranged to keep three of them 

 continuously working, and one of the set al- 

 ways off for cleaning and refilling. By the 

 new system either three or four purifiers can 

 be kept in operation. Three are used while 

 the fourth is being replenished, after which 

 four are put to work, and kept so until the 

 third purifier stains lead-paper, then the center 

 seal is turned so as to reduce the working 

 number to three, while the other one is cleaned 

 out and refilled. A double center seal of pe- 

 culiar construction is required for this process. 

 The general idea is to keep four purifiers at 

 work whenever possible, only reducing to three 

 when one is to be cleaned out. 



Water-Gas. In this subject we meet with a 

 genuine revolution. For many years it was 

 the dream of engineers to obtain its hydrogen 

 from water and utilize it for gas. Patent after 

 patent has been taken out for hydrogen pro- 

 cesses, which generally were based on two 

 principles reduction of steam by heated car- 

 bon, or by heated iron. In the first process, 

 a mixture of carbonic oxide and hydrogen, 

 theoretically in equal volumes, is produced. 

 In the second process hydrogen only is gener- 

 ated, in volume three fourths that of the car- 

 bon gases. As carbon, molecule for molecule, 

 is far cheaper than iron, and as it produces a 

 greater volume of gas per molecule, it is uni- 

 versally used for the production of the hydro- 

 gen. The only departure from this rule is 

 where a balloon is to be inflated ; then iron 

 may be used to decompose the steam, as it 

 gives a far lighter gas. Thus the hydrogen- 

 gas, so often named by the water-gas engineer, 

 is really a mixture, containing only 50 per cent, 

 of its name-giving element. 



The flame of this "hydrogen," as we shall 

 call it, is blue, and practically non-luminous. 

 It resembles the lambent flame seen on the 

 upper surface of a hard-coal fire, its blue color 

 being due to the carbonic oxide it contains. 

 To be of use in gas-lighting, it must be made 

 luminous. It is not easy to say what is in the 

 future, but to-day, whether it be electric light 

 or gaslight, candles or oil, the source of all 



