Manufacturer and builder 8, 1874
By Lewis Feuchtwanger.
IV.
Read before the Polytechnic Club of the American Institute, April 9th, 1874.
Carbonic Oxid.
If an iron tube,ftilled with fragments of charcoal, is heated to redness in a furnace, and carbonic acid gas is transmitted through it, the resulting gas at the other extremity of the tube, the properties of carbonic acid gas, will be so touch changed that a taper will burn with a beautiful blue flame. The carbonic acid by this operation yields half of its oxygen to the charcoal, both becoming converted into carbonic oxid. It inflames when it meets with the oxygen in the air, and occupies twice the volume of the carbonic acid from which it was produced. It is in all its characters different from carbonic acid; it is a permanent gas and nearly insoluble in water; it is lighter than air, having a specific gravity of 0.967, and has neither acid nor basic properties it is very poisonous, one volume diffused through list volumes of air makes it totally unfit to sustain life, and we have daily proofs of this fact by the many accidents occurring from burning charcoal or coke in close rooms, in which the amount of oxygen diffused through the air becomes insufficient in many cases to convert the carbonic oxid into carbonic acid. Nevertheless the carbonic oxid is proposed as an illuminating agent; it is effected by passing it through a wide tube containing a little cotton moistened with benzole, there by producing a very luminous flame. The gas is obtained by passing steam over red hot coke or charcoal Instead of benzole, another method may be adopted, for the reason that the gas obtained contained the carbonic acid, carbonic oxid, and hydrogen; the two latter however do not burn with a luminous flame, and if the gas so obtained is next passed into a vessel containing redhot coke, over which melted rosin was allowed to trickle, the vapors thereby arising are similar to that of the benzoic, and confer considerable illuminating power upon the gas.
One peculiar character of the carbonic oxid having great attraction for oxygen is made use of in metallurgy for separating the latter from its combustion in iron ores.
Carbon and Hydrogen.
It is undeniable that there are no two elements known to no which are capable of combining in so many forms as carbon and hydrogen. They are called hydro-carbons, and include most of the inflammatile gases, many essential oils, naphthas, and other similar substances. It is supposed that they claim their derivation from vegetable sources, although some of them are only traceable to the mineral kingdom; hot for the better understanding of their mutual relations, or metamorphoses of these two important elements, they have been classed with the organic chemistry.
Carbon and Nitrogen.
The boundary between organic and inorganic chemistry is comprised in the compound of carbon and nitrogen, known as cyanogen. The origin and chemical properties of a large number of its compounds entitle it to be ranked among organic substances.
Prussian blue is considered the type of cyanogen compounds. As early as 1724 it was prepared by calcining dried animal matters with carbonates of potash and mixing the aqueous solution of the calcined mass first with sulphate of iron and afterward with hydrochloric acid; and Scheele first prepared the hydro-cyanic acid in 1782, while Gay Lussac obtained the pure cyanogen from the combination of Prussian blue with red oxid of mercury in the gaseous form in 1815. The cyanid of mercury is the material front which pure hydro-cyanic acid is prepared, and from which the cyanids are the most useful combinations. Foremost is the cyanid of potassium, as it is extensively employed in electro-plating and gilding. This salt is obtained by passing air over red-hot charcoal which has been previously soaked in a strong solution of carbonate of potash and dried, when the nitrogen requisite for the formation of the cyanid is absorbed from the air, and carbonic oxid is disengaged. Cyanid of potassium is frequently produced in the blast furnaces in which iron ores are reduced, the potash being derived front the ash of the fuel. For practical use, the cyanid of potassium is prepared from ferro-cyanid, conurionly called yellow prussiate of potash, which is resolved by a very high temperature into cyanid of potassium and carbonate of iron with evolution of nitrogen. To make the commercial cyanid, it is usual to mix three parts of dry carbonate of potash with seven parts of dry ferro-cyanid and fusing the same in a covered earthen crucible and occasionally stirring until gas ceases to be evolved; the crucible is then removed from the fire, allowed to stand for a minute or two, so as to allow the iron to subside, when the clear fixed cyanid is poured out on a stone; and this, the common preparation, is used in the trade, but is not pure. It deliquesces when exposed to the stir, and emits the odor of hydro-cyanic acid and also ammonia. In order to obtain it chemically pure, it is necessary to pass the vapor of hydro-cyanic acid into an alcoholic solution of potash, or by boiling the common cyanid with alcohol and filtering while hot, when the cyanid crystallizes out as the solution cools.
The yellow ferro-cyanid is prepared on a large scale in Scotland and imported into the United States; and so is the ferri-cyanid, the red phosphate, prepared front chlorine. If chlorine gas is passed into a solution of ferro-cyanid of potassium, the liquid assumes a brown color; and when evaporated deposits beautiful red rhombic prisms, called the red prussiate of potash, much used in dyeing, for if a piece of cloth is heated in a solution of the red salt acidulated with asetic acid, a blue compound similar to Prussian blue is deposited in the fiber. It is also the base of a blue pigment called Turnbull's blue. In calico printing it is employed as a discharge four indigo, as it acts as a powerful bleaching agent in consequence of its tendency to impart oxygen, whereby the ferricyanid is converted into the ferro-cyanid.
The fulminates are compounds of cyanogen and some metals, such as mercury and silver, used as explosive compounds. The fulminate of mercury, which is so largely employed for the manufacture of percussion caps, is prepared by the action of alcohol upon a solution of mercury, in excess of nitric acid, and care must be taken to avoid an explosion. The fulminate is separated during this process its fine; needl-elike errs tabs. Moderate friction or percussion will cause the same to detonate violently, it is therefore usually preserved in a sect state with about one-fifth its weight of water. For the use of fulminate of mercury in the cap composition it is mixed with nitrate or chlorate of potash. The oxidizing property of these salts is preferable to insure the ignition of the cartridge. Chlorate of potash and powdered glass are generally added to increase the sensibility of the mixture to explosion by percussion.
Fulminate of Silver is prepared in a manner similar to that of mercury, but its explosive properties are far more violent, and can only be revered in small guantities; but the pyrotechnists consume much fulminating silver in the manufacture of torpedoes. Their method is to dissolve ten grains of pure silver in a liquid consisting of 1½ drachms of strong nitric acid and 1 drachm of water at a gentle heat, and as meet as it is dissolved ½ ounce of alcohol is added, and the fulminate of silver will soon be deposited in minute needles. They may be washed and dried very cautiously and kept in small quantities in paper. The violence of its explosion renders it useless for percussion caps.
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