610 GAS, WATER 



chamber, thus forcing the disc back to its original position, and expelling 1! 

 portion of gas through tho pipes of distribution. Each motion of tho disc thus evi- 

 dently corresponds to a given volume of gas, and being registered by clockwork, in- 

 dicates the consumption upon tho usual dial plates. 



Dry gas-meters are generally preferred, and consequently they havo come into 

 general use. 



To the present system of registering the quantity of gas burnt by tho consumer, 

 many honest objections may be raised. Whichever meter may be used, tho record 

 of gas passing through it is entirely removed from the inspection of tho consumer. 

 The quantity is registered by a servant of the gas company supplying tho meter, and 

 whatever may be the number of cubic foot returned by him, for that is the consumer 

 charged and obliged to pay. It seldom happens that the gas companies admit that 

 any error can occur which tells against themselves, but they frequently discover errors 

 in the other direction. Presuming that honesty of purpose actuates equally tho 

 supplier and the consumer of gas, it would be perfectly easy to arrange the dials of 

 our domestic gas-meters so that the consumer might note the quantity indicated at 

 any time, and from his knowledge of tho number of burners used by him, within any 

 given week or month, be enabled to toll if, as compared with any other period, the 

 indicated result was near to, or far from, the truth, and direct the attention of the 

 servant of the gas company to tho circumstance. 



GAS, WATER. Various methods have been from time to time introduced for 

 decomposing water, and for employing the hydrogen liberated therefrom for the purposes 

 of heating and lighting. Recently (1874) this ' water-gas' has been introduced to the 

 public under the name of the ' New Gas.' 



The possibility, without any great amount of trouble, of obtaining a quantity of 

 hydrogen gas from water has always been a favourite theme with inventors, and many 

 schemes for its practical utilisation have been introduced ; and a patent has been 

 obtained for the carbonisation of this gas with some light hydrocarbon liquid, so as to 

 give it a high illuminating power. 



The process is dependent upon the decomposition of steam by red-hot coal, coke, or 

 metal. Hydrogen, carbonic oxide, and carbonic acid are produced. An analysis of 

 the gas obtained by passing steam over red-hot charcoal for some hours gave as a 

 mean : carbonic acid, 20 per cent. ; carbonic oxide, 20 per cent. ; hydrogen, 60 per 

 cent. Any form of carbon is capable of effecting this decomposition if a metal, such 

 as iron, be present ; it adds to the quantity of hydrogen obtained according to the 

 following action : 



4HO + 3Fe = Fe 3 0* + 4H (4H 2 O + 3Pe = Pe 3 O 4 + 4H 2 ). 



This mixture of gases is inflammable, and burns with a non-luminous but hot flame, 

 the heat of which would be increased if the carbonic acid were previously removed, 

 the flame of hydrogen having a temperature of 3,776 Fahr. This heat of the flamo 

 is an undoubted advantage when the gas is carburetted, as the particles of carbon are 

 thereby heated to whiteness ; but, on the other hand, the presence in the gas of a 

 quantity of carbonic oxide is as great a disadvantage, on account of its injurious and 

 exceedingly harmful character. Carbonic acid is an injurious gas, but its action upon 

 the system is not that of an active poison, but rather that of preventing the necessary 

 amount of oxygen from entering tho lungs, and hence death from its effect will bo 

 death from suffocation. On the other hand, carbonic oxide is an active poison, and 

 recovery from its effect is much more doubtful ; indeed, it is calculated that 2 per 

 cent, in an atmosphere would prove fatal, a result that should cause great caul ion in 

 tho use of a gas containing it in any quantity. 



It is thought it will bo possible to utilise this gas by itself, as a heating ga:- : but 

 its chief use is for illumination, and the illuminating power is obtained in the samo 

 manner as with air-gas, the hydrogen gas obtained by any of tho methods named 

 being caused to bubble through some light spirit, any reduction of temperature by 

 tho rapid evaporation being avoided by maintaining tho vessel containing it at a 

 constant temperature by means of a steam-pipe. The illuminating power of the gas 

 so obtained is equal to about sixteen or seventeen candles ; and its permanent cha- 

 racter is declared to be, and no doubt is, sufficient to render it of practical utility 

 under some peculiar conditions. 



A company, called tho ' New Gas Company,' has been formed for working :\ patented 

 process, the invention of Mr. Ruck. Instead of manufacturing -ras by the dis; illation 

 of coal, Mr. Ruck first obtains his hydrogen by the decomposition of water, and then 

 charges it with tho carbon necessary for illuminating purposes by passing it t! 

 a petroleum spirit of specific gravity 0*680. In the first part of tho process, super- 

 heated steam is conveyed into retorts containing ir n ami coke raised to 

 temperature. The steam is decomposod ; tlio resulting oxygen combines with the 



