Page images
PDF
EPUB

chloric acid may be used, or oil of vitriol mixed with nine times its bulk of water. I do not state that these preparations are absolutely necessary, but they are convenient, the requisite condition being, that the acids be not concentrated nitric or sulphuric acid; since these acids, when concentrated, destroy the alliole in proportion to the quantity in which they are used. I agitate the aliole with the acid in a suitable vessel, which should be nearly closed, or so constructed as to prevent evaporization of the spirituous substance for a length of time, which will vary with the quantity of spirituous substance which is under treatment; all that is necessary being to keep the acid and spirituous substance in a state of intimate mixture for a sufficient time, to enable the acid to form salts with the ammonia and oily alkaloids, which accompany the crude alliole; I then allow the vessel to stand undisturbed, till the two fluids bave separated; I then draw off the acid liquor, and wash the alliole by agitating it with about its bulk of clean water in the same manner as with the acids. The alliole, if then allowed to separate from the water and drawn off

, is fit for use. But it is convenient sometimes to rectify it again, and to allow it to stand for some time, after careful separation from any water that may accompany it, upon fresh-burnt lime, which will remove any acid and water that may still adhere to it.

The spirituous substance so obtained will be found to have a slightly alliacious odor, somewhat resembling that of bisulphuret of carbon, to be extremely volatile, and if placed in a retort and distilled, should begin to boil about ti5 degs. or 70 degs.; and the greatest portion of its bulk should distil over before the temperature from the retort arrives at 80 degs., and the temperature should then rise very fast, and the retort should be dry at about 90 degs. or a little above. This spirituous substance will be found to be an excellent solvent of caoutchouc, gutta-percha, and many of the resios; it will mix with pyroxylic spirit in equal proportions, if the spirit be not too much diluted with water, and may be used when so mixed for dissolving shell-lac, or shell-lac and guttapercha, or caoutchouc mixed, though it will not lissolve lac in sufficiently large quantities when alone, or it may be mixed with a solution of lac in pyroxylic spirit in similar proportions. And the proportions in which it may be mixed with any sample of pyroxylic spirit may be readily ascertained, by putting a known quantity of the alliole into a graduated glass

, and pouring it into the pyroxylic spirit, at the same time shaking the mixture until the whole of the alliole is dissolved, and a clear transparent mixture results, which shows no streaks of milkiness when the surface in an open glass is slightly blown upon. The proportion or quantity of spirit which has been added to the alliole which was in the glass, shows the proportions in which they may be mixed. Alliole so prepared also yields a brilliant light when burned by the aid of a current of air. Next of the purification of benzole

prepared from coal tar or the products of coal tar. If this be not required perfectly free from the odor of alliole, and if moderate purity be only required, I treat this spirit in the same manner which I have described for the treatment of alliole; and if it be required for burning with the aid of a current of air, as hereinafter described, I prefer to treat it in this manner, by which all the spirituous substance is preserved intact, while the picoline and other basic or alkaline substances, which chiefly cause the disagreeable smell of the naphtha, are removed; and I consider it sufficiently pure for this purpose when a piece of white deal, dip. ped first into the benzole and then into hydrochloric acid, does not acquire a red or pink color. If, however, a volatile substance be required as a solvent, or for any other purpose where freedom from an unpleasant odor is necessary, the treatment is different. Instead of agitating the benzole with dilute acid, I agitate it with concentrated sulphuric acid, in the proportion of about one half pound of acid to a gallon of the benzole, which destroys the alliole, at the same time that it removes the basic oils, and oxidizes any of the brown forming substance which may be present; and I prefer to add with the sulphuric acid a small portion of the nitrate of potash, or nitrate of soda, about one ounce to half a pound of sulphuric acid, or nitric acid, or nitrous acid, or aqnafortis of specific gravity about 1.30, in the proportion of one fluid ounce to half a pound of sulphuric acid; the addition of nitric acid tends greatly to bring out the pleasant smell of the benzole from the more perfect oxidation of oxidable substances which are present, and from the formation of a small quantity of the sweet-smelling compound, of which I have already spoken, which, when the benzole is rectified, is separated in the residue; or instead of sulphuric acid, mixed with nitric acid or its salis, I use nitric acid, nitronis acid, or aquafortis alone, of spicitic gravity about 1.30 or 1.40, or nitric acid mixed with hydrochloric acid, or nitro-muriatic acid, in the proportion of half a pound of the acid to a gallon of the benzole, or instead of the nitrate of potash or soda, I use a similar proportion of bichromate of potash. I then, after agitation, allow the mixture to settle, and then draw off the benzole from the thickened acid. I then sometimes add to the benzole a small quantity of the chloride of lime and some moderately strong acid, and stir the mixture, but this further deoxidizing process is seldom necessary. And whether this last process be used or not, I now agitate the benzule with water and complete its purification in the same manner as the alliole is purified. The spirituous substance so obtained will be found 10 be very volatile; if placed in a retort, it should commence to boil at 30 degs., and the largest portion of it should come over before the temperature in the retort reaches 85 degs., and the retort should be dry at 100 degs. without leaving any residue. If subjected to a temperature of 20 deg. below ( degs. (--20 degs.) it should de

posit so large a quantity of crystalline matter as to become almost entirely solid. It should have a smell somewhat like that of almonds. It will be found to be an excellent solvent for the same purposes as alliole, being very useful for making many kinds of varnishes. If a solution of gutta-percha be made in benzole, and the solution be spread as a varnish on a smooth surface, such as glass or porcelain, the spirituous parts will rapidly evaporate, and will leave the gutta-percha in a tough film on the surface, which must be peeled off

, and in this way, by properly adjusting the surface and carefully peeling off the varnish, artificial membranes applicable to many useful purposes may be made, or by spreading the solution on the surface of the human body, an excellent plaster or artificial skin may be obtained in cases in which protection is desirable. This benzole is an excellent sol. vent for camphor, essential oils, fats, wax, and many other substances. It

may be used as a substitute for spirits of wine in some of the arts, and for oil of turpentine in most of the purposes to which that hydrocarbon is applied, having the property of far greater volatility than the latter substance, which in many instances would be an advantage. Benzole admits, however, of yet further purification, which for some purposes it is desirable to effect, and this is accomplished by freezing. But since for those purposes for which it would be required to be so highly rectified, it would probably be required to be as free as possible from all foreign oily matters, I recommend that it be again treated with sulphuric acid, with or without the addition of saltpetre or nitric acid, or with nitric acid alone, or with nitro-muriatic acid, as above described, or that it be distilled with about one quarter its bulk of a mixture of two parts concentrated sulphuric acid and one part of a concentrated aqueous solution of bichromate of potash, or with a small quantity of chromic acid; and I recommend that such treatment be repeated until the benzole, on being agitated with cold oil of vitriol, no longer confers a dark color upon the acid; but strong nitric or nitro-muriatic acids must not be used in so large proportion as sulphuric acid may be used, since the benzole

may be decomposed by the former acids, though not by the sulphuric acids.

When this further treatment with acid has been used, I wash the benzole well with water or with lime-water to remove the acid, and distil it either with or without the addition of some lime, and I prefer to insert a thermometer in the retort, and to receive for refrigeration what comes over, while the temperature in the retort is between 79 degs. and 88 degs. What comes over beyond may be mixed with some of the crude spirituous substances, reserved as purified toluole, of which it will partly consist. The benzole may be further rectified by distillation any number of times, and that portion of the distillate should always in that case be reserved separately for purification, which comes over between 80 degs. and 85 degs.

The reduction of benzole to a state of further purity, depends upon the property which it possesses and which distinguishes it from coal naphtha, and from all the other hydrocarbons contained in the naphtha, viz., that of becoming solid when exposed to a low temperature, and of melting again when pure at a temperature a little above that at which ice melts. The degree of cold requisite to solidify the fluid will vary inversely with the degree of purity which it has previously attained by distillation. If nearly pure it will solidity at u deg., if about half the fluid be benzole, and the rest the other hydrocarbons of the naphtha, which distil over with it, the benzole will crystallize out of the solution, when exposed to a temperature of 20 degs. And I may state that, generally, if the crude benzole obtained by once distilling the first runnings of the coal naphtha, or the whole light oil, or the rectified naphtha, as described in the first part of my invention, viz., from a boiler surmounted by a head surrounded with water, which is allowed to become heated to ebullition, be again rectified in a similar apparatus, and the first portion of the distillate equal to one-third the quantity placed in the retort (especially if the very first one-sixteenth portion be set aside separately as alliole, which does not solidify at 0 deg.), or if that portion which comes over while the temperature in the retort is rising from 80 degs. to 90 degs. be reserved as benzole, that portion so received on the second distillation will, if submitted to a temperature of —20 degrees, become in great part solid, depositing crystalline matter equal to at least half its bulk. By further rectification both of the mother liquor of the solid portion (that is, of that portion of the spirituvus substance which is separated as fluid from the solid benzole after refrigeration), and also of the rest of the distillate on this second rectification, a further portion of spirituous substance may be obtained which will solidify at —20 degs. I now expose the benzole which has been prepared for refrigeration to a low temperature in a suitable vessel, and for the production of this low temperature I use, if it be necessary, a freezing mixture. When the benzole has been so congealed, I expose it to a powerful pressure, and the more powerful the pressure by which this separation is effected the purer will be the result, and the lower the temperature at which the operation of pressure is conducted, the larger will be the produce. The fluid pressed out is set aside, and after further rectification, if required, will yield another portion of solid matter by refrigeration.

The purification may be carried still further, either by again pressing at a temperature of 0 deg. the mass obtained by a first pressure, or by placing the mass in a funnel, and allowing it to melt slowly in the air, with the bulb of a thermometer immersed in the mass, reserving as pure that which remains solid when the temperature of the mass has risen to 0 deg. I call the substance so produced absolute benzole. It will be found to boil constantly

at 80 degs. or 81 degs. It will produce a state of intoxication if inhaled in the manner in wbich ether is used. It is an excellent substitute for ether, in many uses to which ether is applied, as for the solution of iodine, quinine, wax, and fatty and volatile oils. The next spirituous substance, or toluole, which when pure boils at about 110 deg., and which may be obtained in a state of partial purity by reserving the last portions which come over in the rectification of benzole, and the first which come over in the rectification of camphole, is purified by treatment with acids in the same manner as the benzole, but not by refrigeration. And I wish it to be understood, that by purified toluole, I do not mean a chemically pure hydrocarbon having a fixed boiling point, but I mean an oily or spirituous substance obtained from the coal naphtha, which will boil chiefly between 100 degs. and 130 degs. being so much of the naphtha as remains after separating on the one hand as much as possible of the spirituous substances that will yield a white flame with a current of air passed through them, and on the other hand as much as possible of the oily substances which will not take fire on the surface on the application of a lighted match, both being understood of the fluids at the ordinary temperature of the air.

Since all that applies to toluole as regards its purification, is also applicable to coinmon naphtha, and to other bituminous and empyreumatic oils, such as petroleum, or native naphtha, the oil distilled from bituminous schist, &c., I will here state my method of purification as applied to coal naphtha, generally observing, however, that in the application of concentrated sulphuric acid to common coal naphtha, a certain proportion of oil is lost by the destruction of much of the cumole by the acid, I add to the baphtha, or toluole separated as above described, concentrated sulphuric acid in the proportion of about three quarters of a pound, and nitric acid or aquafortis in the proportion of about a quarter of a pound to a gallon of the naphtha or toluole, which has been previously carefully separated from water. I then agitate them well together in a suitable leaden or other vessel. The nitric acid need not be the strongest, that of specific gravity between 1.30 and 1.40 is suitable, and it need not be pure; the crude acid, known as nitrous acid, or the acid called single aquafortis, may be used.

I do not confine myself exactly to the proportions here given, or I use a mixture of nitric and hydrochloric acids, or nitromuriatic acid, or nitrate of potash or of soda, instead of nitric acid, in about the same proportions, with or without the addition of an equal proportion of bichromate of potash, or bichromate of potash without the nitrates; but if I use these salts instead of . nitric acid, I prefer to use a rather larger proportion of sulphuric acid. Since the object is not to form definite chemical compounds, exact proportions are unnecessary; all that is requisite is to have

« PreviousContinue »