ticularly as that operation as conducted in the ordinary process of the manufacture of gas for lighting. Now, the object of this part of my invention is to resolve the whole or the greater part of this nitrogen into cyanogen compounds, by the following methods of operating upon coal, or the gases or vapours produced by the distillation of coal. When the coal operated upon is distilled to produce gas for illumination, I proceed by one or other of the following methods:-First. When it is desired that the coal to be distilled shall yield its coke as usual, but it is not essential that the tar produced shall be collected, and when the process resorted to for the production of the cyanogen must be such as shall not interfere with the manufacture of the coke, I then proceed as follows:From the retort in which the coal is distilled as usual, the whole of the gaseous or volatile products of its distillation are passed into and through another retort or cylinder of iron or fire clay (the latter being preferable), containing a mixture of charcoal and alkali. If the heat be strong enough, the result is, the separation from these products of all those matters which are considered as impurities when existing in coal gas intended for the purpose of illumination, and the formation of a cyanide of the kind of alkali used, accompanied generally with sulphuret and some other compounds. The cyanide is the product of most value, and it is afterwards treated in the usual way for its separation from the other cognate products, and its transformation (if required) into other compounds, the means of doing which being well known, need not be here particularly described. The gas which has passed on through the second or decomposing retort, will be found to be a tolerably pure illuminating gas, containing the usual elements of that product, but free, or nearly so, from nitrogen, ammonia, cyanogen, or sulphur compounds, all, or nearly all of which will be found to have been absorbed by the alkali. If it be desired that both the tar and the coke shall be preserved as usual in the distillation of the coal, then the decomposing retort must be interposed at a point beyond the position of the tar-condenser, and the operation in all other respects conducted as last before described. The decomposing retort is so arranged that it can be charged readily with fresh alkalized carbon, as that material becomes saturated with the formation of the cyanide,

sulphuret, &c.; and this arrangement may be such that a constant current or stream of the alkalized carbon may be made to flow through the decomposing retort, so that the process may not be interrupted in the intervals. of charging or replenishing, as shown in fig. 2, and hereinbefore described. And in like manner I cause the coal itself to be supplied, by causing a continual stream or current of small coal to be passed through the retort, by the use of an apparatus of the description shown in the drawing, fig. 10. Here, A, represents the decomposing cylinder, containing a screw revolving on its axis, being supported through each end of the cylinder, and moved by any suitable machinery connected with the toothed wheel, B. c, is an opening through which the charge of small coal or other material is gradually introduced. D, D, D, are vertical pipes, connecting the cylinder with a common main-pipe, E, which serves to carry off the gaseous or volatile products of the distillation of the coal, &c. Upon motion being given to the screw, the charge is progressively moved forward in the direction of the arrows, giving off its volatile products in its passage, and being finally ejected through the opening, s. To the outlet, G, may be appended a decomposing apparatus, such as represented in figs. 1, and 2, 4, and 5, and the products operated upon therein by any of the other inodes of treatment herein described. To s, may be connected the chamber, D, fig. 2, or R, fig. 4, for the reception of the products from A. When it is not material or not desired that the coke from the coal shall be obtained as usual, then I proceed as follows:-I mix with the coal itself a certain proportion of any alkali, say carbonate of soda or of potash, and distil the mixture in the retorts in the same manner as when coal only is distilled; or pass this mixture through the screw cylinder or retort apparatus already described, and seen in fig. 10. The result is, that after all gases and vapours have been expelled in the act of distilling this mixture, the nitrogen and sulphur of the coal are retained, either mostly or entirely, by the alkali, in the form of cyanide and sulphuret. This residual mixture from the retorts may be used for manure, or a variety of other purposes; or it may be treated for the formation, from its cyanide, &c., of other cyanogen products, by the application of well known methods of operating. Again, in place of

mixing the alkali along with the coal in the same retort, a second retort may be attached, containing a mixture of alkali and carbon, in the form of charcoal or coal, through which, when also strongly heated, the gaseous and volatile products from the first retort may be passed, or the same retort may be in one portion filled with the coal to be distilled, and in another portion with the alkalized carbon through which the gaseous products from the coal must be made to pass, as generated by the action of the heat upon it, as shown in fig. 9. In this figure, A, B, is the retort, having doors at both the ends, A, and B, of the construction usual in gas retorts. c, is the outlet for the gaseous and other volatile products. D, is the fire-place, E, the ash-pit.

In working the retort for the purpose herein described, the portion of the retort between A, and x, is charged with coal, and that between x, and B, is charged with alkalized charcoal or other substance, as hereinbefore described. The gaseous and volatile products from the coal are thus made to pass through the heated alkalized carbon, and so to produce a cyanide, &c., of the alkali present, whilst the remaining gaseous products are discharged through c. I do not in this part of my invention confine myself to any particular proportions, but I find that from five to ten parts of alkali to one hundred parts of coal, are economical proportions to be used. The alkali may in a dry state be ground up along with the small coal, or the coal may be drenched with a solution of the alkali, and again dried before it is used. When the manufacture of coal into coke is the main object, instead of allowing the incidental and residual products to go to waste as heretofore, I attach a decomposing tube or cylinder, or retort, charged with the alkalized carbon, to the ordinary ovens. or other apparatus employed in making the coke, and cause the gaseous and volatile products evolved to be drawn or forced through the decomposing tube or retort. The resulting products are then treated in all respects in the manner already described. With regard to the kind of alkalized carbon to be used in the operations last described, it may be wood charcoal, containing from five to twenty per cent. of alkali; or it may be one or other of certain mixtures described in the specification of former letters patent granted to me, of date the 7th April, 1845, "for the

application and use as manure of certain substances or compounds not hitherto so employed, and for improvements in manufacturing such compounds." I do not, under this head of my invention, claim the producing of cyanogen or its compounds from coal in the act of distilling or coking it, for that such compounds are so formed is well known. But I do claim as my invention the particular accessory methods and processes as herein described, whereby the quantity of these products is greatly increased, or, in other words, whereby the whole or the principal part of the nitrogen existing in the coal is converted into cyanogen or its compounds, instead of into ammonia or its compounds, as heretofore.

As to the fourth part of my invention. Through a vessel-an earthenware retort or cylinder being preferred -containing carbon in the form of wood, charcoal, or coke, closed from the air and intensely heated, I pass dry nitrogen gas; and I collect the cyanogen formed by the mutual action and reaction of those substances in water, or in alkaline or metallic solutions. I am aware that it has been proposed to form cyanogen by passing nitrogen gas through a mixture of carbon and alkali intensely heated in a retort, thereby producing a cyanide of the kind of alkaline metal employed; but my process is distinguishable from that referred to in this,-that I neither seek to induce the formation of the cyanide by the presence of the alkali, nor to form the cyanide as the immediate product, for, contrary to all existing theory which leads to the employment of the alkali along with the carbon and nitrogen as a thing essential to the formation of the cyanogen, I have ascertained that the cyanogen is readily produced by the direct action of nitrogen upon heated carbon. The cyanogen so formed I collect, and afterwards treat for the formation from it of other compounds, by the application of methods which are well known, and need not here be described. Again, pass into heated carbon, contained in an earthenware retort or any other suitable vessel, a mixture of atmospheric air and steam, and I so apportion the relative quantities of carbon and the other elements, that is, by having the carbon greatly in excess, that the resulting product is cyanogen or hydrocyanic acid, or hydrocyanate of ammonia, or mixtures thereof. This product I collect in water, or in an aqueous solution of some alkali or

I

metallic salt, for the formation of other cyanogen compounds, and by the application to them of well known methods of treatment. I am aware that it has been proposed to pass steam and atmospheric air through ignited charcoal in order to form ammonia, but neither my object nor the result of this part of my invention, is the formation of ammonia, but not of cyanogen or hydrocyanic acid, or hydrocyanate of ammonia; and if the mass of heated carbon be so great compared with the quantity of air and steam brought to act upon it, or their relative proportions be such that the carbon is always greatly in excess, the result is the formation of these compounds, and not of ammonia. And I do not collect or fix the cyanogen so formed by means of the presence of an alkaline substance, but collect or fix it by drawing or forcing the resulting gases or vapours through water, or solutions containing alkaline or metallic salts; as, for example, a salt of iron and solution of potash. The subsequent processes are well known, and need not, therefore, be here detailed.

What I claim under this fourth head of my invention is,

Firstly, the production of cyanogen by the direct and simple action of nitrogen gas and carbon, under the influence of a high temperature, as before described; and,

Secondly, the method of collecting cyanogen and hydrocyanic acid produced by the action of heated air, steam, and carbon, in aqueous alkaline or metallic solutions, as before described.

As to the fifth part of my invention. In the manufacture of ferrocyanide from the crude cyanides existing in what is technically called the "metals" of prussiate makers, or in any other form of cyanide, I proceed as follows:-In lixiviating the metal or other crude cyanide, it is broken into small lumps, and packed round about the flanges of the lixiviating vat (hereinafter described, and shown in fig. 11). This vat is then filled with water, and the steam put on and continued till the whole "metal" or crude cyanide is lixiviated and transformed into ferrocyanide. As a convenient and valuable source of the iron required to be supplied in this operation, I use the reduced or spongy iron, obtained by acting upon heated oxides of iron by means of hydrogen gas or car