174 



THE CIVIL ENGINEER AND ARCHITECT'S JOURNAL. 



[JUKB, 



boa in the retorts, and extra labour was necessary for agitating tlie 

 liquid lime and for conveying the refuse liquor to be evporated. This 

 being effected in pans, placed under the retort furnaces, the sulphur 

 given off tended to destroy very rapidly the iron retorts, which were 

 exposed to the action of the flame. The wet lime purified the gas 

 from the sulphuretted hydrogen, a great portion of the hydro-3ul- 

 phuret of ammonia, the sulpho-cyanuret of ammonia, and the carbonic 

 acid ; but it still allowed a considerable quantity of ammonia and its 

 compounds, to pass into consumption with the gas. The dry Ume 

 purifiers used without this process, presented some advantages to the 

 gas companies, over the plan of purifying with wot lime ; but it was 

 only in open places in the country that the dry lime could be used, 

 without the works becoming a public nuisance. The objection to 

 dry lime purifiers arose from this cause : the hydro-sulphuret cf am- 

 monia, which is generated with carburetted hydrogen gas, is highly 

 volatile, and that portion which is extracted hy the lime, having no 

 chemical affinity for lime, but being merely held in mechanical com- 

 bination, had a strong tendency to fly off. The hydro-sulphuret of 

 lime, is formed in the dry lime purifier, from the sulphuretted hydro- 

 gen of the gas; ou the opening of the vessel, it rapidly combines with 

 the oxygen of the atmosphere, and becomes converted into sulphate 

 of lime. During that conversion, heat is rapidly evolved, which ren- 

 ders the hydro-sulphuret of ammonia, extracted from the gas by the 

 lime purification, more volatile than ever, and the most offensive 

 stench is the consequence. Besides, so noxious is this gas, that a 

 comparatively small portion of it, in a given volume of atmospheric 

 air, would render it destructive to animal life. 



These obstacles would warrant the almost universal abandonment 

 of dry lime purifiers ; now, however, in connexion with this process of 

 purifying gas from ammonia, the dry lime purifier will, it is antici- 

 pated, become the only system used for the abstraction of the sul- 

 phuretted hydrogen. The gas purified from all ammonia, by passing 

 over the solution of sulphuric acid, has only to be freed by the dry 

 lime purifier, from the sulphuretted hydrogen, the sulpho-cyanuret, 

 and the carbonic acid, which form in chemical combination with the 

 lime, the hydro-sulphuret of lime, cyanuret of lime, and carbonate of 

 lime, neither of which are volatile, but are highly valuable for agri- 

 cultural purposes. 



Appliction of the Products to Agriculture. 



In those instances, in which the localities have permitted gas com- 

 panies to continue the use of dry lime purifiers, the value of the pro- 

 ducts as manure, has been so well understood, that the refuse lime has 

 been bought up as fast as it was produced; and an impression having 

 prevailed, that this refuse lime owed its value to the presence of 

 ammonia, some of the contractors of such gas-works have expressed 

 an apprehension that the adoption of this process, by previously ab- 

 stracting the ammonia, would destroy the valuable properties of this 

 lime. It is evident, that this is entirely a misapprehension. The 

 chemical causes before detailed will have shown, that the hydro-sul- 

 phuret of ammonia, which had been extracted from the gas, in the dry 

 lime purifiers, having been volatilized and lost, long before the refuse 

 lime (then become sulphate of lime), could have been taken from the 

 works ; the value of the lime really consisted in the fertilizing power 

 of the sulphate of lime and of the cyanuret of lime. This power will 

 still exist in the same products, concurrently with the use of this pro- 

 cess, while the noxious exhalations, which formerly occurred on the 

 opening of dry lime purifiers, wUI be absent. 



In manual labour alone, the Chartered Gas Company have effected 

 a saving, at their Brick-lane station, of between 400/. and 500/. a-year, 

 by the use of dry lime instead of wet lime purifiers. 



In addition to the advantages arising from the use of the dry lime 

 in place of the wot lime purifiers, which this process renders every- 

 where possible, the saving which will accrue upon the meters and 

 fittings of the Chartered Gas Company, by the abstraction of the am- 

 monia from the gas, will amount to a considerable sum annually. 



At the Brick-lane station the number of meters requiring repair, 

 has already been reduced by one-half, and those annually condemned 

 have been two-thirds less, since this process h:is been adopted, al- 

 though an incre^ise of meters has taken place. The public lamp fit- 

 tings reqiiiring repair, since its adoption, have also been two-thirds 

 less in number than previously. A large saving in wear and tear has 

 thus been effected by the plan. In addition to the above, the illumi- 

 nating power of the gas has been increased upwards of 5 per cent., 

 by its freedom from ammonia, and it may now be consumed in the 

 drawing-room or bed-chamber, with as little inconvenience or effluvium 

 as a wax candle. In addition to the advantages already enumerated, 

 this process comprises another, fully equal if not superior to all the 

 rest. This consists in fixing and neutralizing the ammonia in com- 

 bination with sulphuric acid, and making it available, iu the htm of 



the valuable product of sulphate of ammonia. Already many tons are 

 produced weekly from the works which have adopted this process, 

 and the purity of the product has been sufficiently attested. It is un- 

 necessary to enumerate the various manufactures and arts, in which 

 sulphate of ammonia is useful or necessary ; but the author draws at- 

 tention to its value for agricultural purposes, a subject upon which 

 many men of science, education, and capital, have for several years 

 past bestowed so much attention. 



A chemical analysis of the sulphate of ammonia, produced by the 

 evaporation of the saturate-sulphate liquor, before described, as drawn 

 oft' from the purifying vessels, shows it to be of great purity, as it 

 affords in 100 parts, nearly 30 parts of ammonia, after deducting water 

 and sulphuric acid, equivalent to about 24 parts of nitrogen. This 

 shows a fertilizing power two or threefold greater than any other 

 manure. Actual experiments have corroborated the conclusions of the 

 analytical chemist, and some of the most accurate of these are re- 

 corded by Mr. W. M. F. Chatterley, at the Manor Farm, Havering- 

 atte-Bovver, in Essex, occupied by CollinsonjHall, Esq. These were 

 made in 1842, a season which, like the present, (1844,) was, from its 

 dryness, by no means favourable to top dressings.— It will be remarked, 

 that the weight of the wheat, the grand test of its quality, was in- 

 creased by the use of sulphate of ammonia, and this alone would add 

 at least Id. arid, per bushel to the selling price. Other experiments 

 might be detailed, but they have all shown very similar results. 200 

 lb. of sulphate of ammonia applied iu 1843 to poor grass land, by Mr. 

 Bower, of West Dean House, produced an increase of 10 cwt. of hay 

 per acre. — The result of all the experiments, however, seems to show, 

 that 1 cwt. of sulphate of ammonia per acre, whether applied to grain 

 or to grass crops, gives a maximum of profit for the outlay. 



The total yearly quantity of coal gas made in London, has been 

 estimated at 2,400,000,000 of cubic feet ; whence some idea may be 

 formed of the amount of sulphate of ammonia, which this process may 

 render available for the purposes of agriculture. It should be ob- 

 served also, that this quantity is over and above that ammonia which 

 was, and still is, obtained from the common ammoniacal liquors of the 

 gas-works, and that the process which enables such agricultural bene- 

 fits to be secured, efi'ects at the same time, a considerable saving in 

 the manufacture of gas by the companies which have adopted it, 

 while the use of coal-gas for the purpose of illumination, from its being 

 rendered more agreeable and healthy, will be greatly extended in all 

 private families. 



Rem.^rks. 



After the paper was read, Mr. Lowe confirmed the statements 

 therein, relative to the advantages of the new system. Formerly, 

 when the dry lime purifiers were used at the Brick-lane Gas Station, 

 the health of the men suffered, and the complaints by the neighbour- 

 hood, of the nuisance when the lime was changed, were so constant, 

 that the system was abandoned ; at present, although ten times the 

 quantity of gas was purified, theie was not any nuisance, either in the 

 works, or in the neighbourhood. It had been stated, that the system 

 had been used in other places, and that the credit of the invention was 

 not due to Mr. Croll. Although it was not the province of the Insti- 

 tution to enter into such an inquiry, he might perhaps be allowed to 

 state, that a similar plan had been tried at Bristol, at the suggestion 

 of Mr. Herapath, the chemist; the idea had originated in the same 

 chemical facts, which had induced Mr. Croll's attention to the sub- 

 ject, but the modus operandi was essentially different. In Mr. Hera- 

 path's plan there was not any continuous supply of acid ; no valuable 

 product was obtained; it was troublesome and expensive, hence it 

 was not successful, and the plan was ahandoned. Mr. Croll had en- 

 tered upon the subject, with perhaps more practical skill, which, joined 

 to his chemical knowledge, had enabled him to attain the success 

 which attended the present system. The economy of the process, 

 the diminution of the destructive effects of the purified gas upon the 

 apparatus and the fittings, its increased illuminating power, and its 

 greater fitness for combustion in dwelling houses, with other advan- 

 tages, had been fully and fairly stated in the paper. — The chemical 

 products obtained froin the process, deserved very careful atteution, 

 and their adoption for agricultural purposes was important. The 

 effect of sulphate of ammonia, in assisting vegetation, was remarkable, 

 and it was already extensively used in agriculture. It also revivfied 

 cut flowers, when they were apparently withered and dying. Flowers, 

 whose stems were cut diagonally, so that their capillary tubes were 

 not bruised or torn, on being put into a solution of 8 grains of sulphate 

 of ammonia to 1 pint of water, would be speedily restored to vigour, 

 if somewhat faded, and they might be kept fresh by this means for a 

 long period. 



Professor Graham bore testimony to the efficacy of Mr. Croll's pro- 

 cess. In the first step of the purification, namely, the proper cooling 



