78 



GAS PATENTS. 



[1852. 



by reiuoviuir tliese so-called b3'drocai'bons from the mixtm-e. 

 Ill 1826, Faraday discovered various compouuds of tbis nature 

 iu tbe liquid obtained by compressing oil gas, aud among otbers 

 a substance wbicb was afterwards formed by Mitscberlicb from 

 tbe decomposition of benzoic acid, viz., benzine. This substance 

 was proved by Hoffmann to be present (mixed with a variety of 

 bodies of a similar nature) in common naptba or coal tar oil, 

 wbicb is obtained in large quantities during the distillation of tar, 

 and it has lately been obtained from that source iu large quanti- 

 ties by Mansfield. This body possesses iu an eminent degree the 

 illuminating power when burnt in a good draught, and as it is a 

 very volatile substance, it would be better fitted for " napthalizing" 

 the o-as than any of the other hydrocarbons with which it is 

 associated. On account of ecouoiu}-, however, the rectified coal 

 tar oil is used without further purification. The process of nap- 

 thalizing consists simply in saturating the purified coal gas with 

 the vapoui-s of some of those substances from which it had been 

 freed in a previous part of the process, and this is eftected either 

 by filling the meter by which the gas is measured with the uaptha, 

 or by passing it through a kind of closat containing shelves, on 

 which are placed pieces of sponge or of pumice stone soaked in 

 that liquid. In one contri\-ance the gas is freed from ammonia 

 by passing over pumice stone soaked in sulphuric acid, contained 

 in one-half of the apparatus, aud is then napthalked by being 

 carried thi'ough the other half filled with sponge or pumice stone 

 saturated w-ith coal tar oil. 



An apphcation of tbis napthahzing process has been made in 

 a plan for preparing gas, which has attracted a good deal of 

 attention in the States of late yeai-s ; \iz., Paine's process for 

 preparino- gas fitted for illumination from water. Paine claims 

 to have discovered a method by means of a magneto-electric 

 machine, of converting water entirely into oxygen or hydrogen 

 by merely changing the electrical poles. No one would have 

 been astonished if such a statement had been made in the times 

 of Geber or Albertus Magnus, but that the possibility of such a 

 convereiou of elements should for one moment be entertained at 

 tbe present day, seems rather curious. The water having by 

 this incredible process been converted into hydrogen, a gas which 

 gives out little or no light in burning, is then endowed -mth 

 illuminatino- powers by a process little less incredible. The gas 

 is ijassed through oil of turpentine and becomes, as Paine says, 

 caialized, the applicability of which term, derived from a Greek 

 word, signifying to loosen or dissolve, seems niore than doubtful. 

 By this process, without taking up any turpentine, although it 

 acquires its smell, the gas is said to become capable of emitting 

 a powerful light on combustion. According to the best informa- 

 tion that we as yet possess on the subject, the ■whole invention 

 mav be designated as humbug. 



Another plan in which water is employed is more feasible, viz., 

 that invented by Gilliard, which depends upon the intense light 

 emitted by platin um rendered incandescent in the flame of hydrogen. 



The hydrogen is obtained by parsing the vapour of water over 

 heated coke, by which means a mixture of hydrogen, carbonic 

 acid carbonic oxide, with a small trace of carburctted hydrogen, 

 is produced. By the ordinary lime purifiers it is freed from 

 carbonic acid, and is burnt in jets, over which are suspended 

 cages of platinum wire. There can be no doubt of the brilliancy 

 of the li""ht emitted, but the .safety of the process seems some- 

 what doubtful, when we consider the explosive qualities of 

 Lvdrofen when mixed with air, and the remarkable ease and 

 rapidity with which this gas escapes through tiie finest crevices, 

 and when under pressure through tissues, which to other gases 

 are ti>t;illy impervious. This gas has also been applied to heating 

 motalUc plates placed in a grate so as to replace burning coals, 

 and ay>)iari'ntly with some success. 



Ill til'- foniif-r paper a plan was iiifiitioncl In- wlii-li water was 



resolved into its elements by passing through one-half of a retort 

 filled with incandescent coke, aud a modification of this process 

 seems to be that adopted at the Astor House in New York, and 

 alluded to iu the Annual of Scientific Discovery for 1851. It is 

 clear that the process is incorrectly described in that work, but it 

 seems to consist of a combination of the water-decomposing 

 process by means of hot coke, and the production of ordinary 

 gas by the destructive distillation of melted rosin. 



Various substances of a nature similar to rosin, such as asj^halt- 

 bituminous slate, oils, fat«, (fee. have been employed at times for 

 the preparation of gas, but although each may be more particu- 

 larly applicable in certain localities and under peculiar circum- 

 stances, yet, as a general means of preparing gas they cannot 

 compete with coal. 



Since writing the first part of this paper I have found that a pro- 

 cess for making gas from wood has been invented by Pettenhofer, 

 and is being extensively employed in various parts of Germany 



The gases evolved from the destructive destination of an}' 

 animal or vegetable substance \vill always be essentially the same, 

 diftering in the relative proportions of the gases, and in those 

 compounds which are formed in small quantities during the pro- 

 cess, and are either mixed with the gas or deposited with the tar. 

 The general process for purifying and collecting remains the same 

 as abo\e described. 



A few words might be said in reference to the uses of the 

 different substances produced during the formation of gas, as 

 some which were formerly considered as useless have lately been 

 proved to be of considerable value. 



The coke which remains behind is exceedingly valuable as a 

 fuel, from the fact of its having been deprived of all volatile 

 ingredients, and therefore forming little or no smoke when bm'ut. 

 In England large quantities of the best canuel coal are coked 

 without collecting the gas for the use of the railroad locomotives. 



The tar is frequently returned into the retorts or else employed 

 in keeping up the fire, the coking furnaces mentioned in the last 

 paragraph are sometimes fed by means of it. When distilled it 

 yields a residue of pitch and a volatile liquid called naptba, from 

 its resemblance to mineral naptba. This substance is a mixture 

 of a variety of interesting chemical compounds, and is applied to 

 several useful purposes in the arts; such as the solution of caout> 

 chouc and gutta percba. The gas liquor, which is the aqueous por- 

 tion of the contents of the hydraulic main, contains a variety of coiu- 

 pioimds, and possesses a most disagreeable odour, it was formerly 

 thrown awa}', and often allowed to run into rivere to the destruc- 

 tion of fish and the entire deterioration of the water for domestic 

 purposes. Even at the present day this nuisance exists to a certain 

 extent in London. The greater portion of it, however, is employed 

 in the manufacture of sal ammoniac. The gas hquor of itself con- 

 tains a considerable quantity of this salt, but a much larger propor- 

 tion is obtained by the addition of muriatic acid, evaporation, heat- 

 ing until charring commences, and resolution in water, crysfaliza- 

 tion or sublimation. Iodine and Bromine ha\e lately been discov- 

 ered in the gas liquor, and \\ hetlier these ^•aluable medicinal bodies 

 can be economically obtained from it, remains yet to be pro\'ed. 



The refuse lime from ,the purifiere is used for agricultural 

 purposes, and in some instances has been found eflicacious in the 

 destruction of the \virewori\i; it must, however, be employed 

 with caution. By exposing it to the air for some time, a largo 

 quantity of a peculiar salt, the hyposulphite of lime, is generated, 

 from which may bo iire]iared the corresponding compound of 

 soda, a substance wbicb finds rather an extensive use iu Photo- 

 graphy and the preparation of Daguei-reotypes. 



The separation of ammonia from tbe g.aseous mixture h.as been 

 .alreadv described. 



