Sympathetic ink

The best is a solution of muriate of cobalt. Printer’s ink. See this article. By decomposing vanadate of ammonia with infusion of galls, a liquid is obtained of a perfectly black hue, which flows freely from the pen, is rendered blue by acids, is insoluble in dilute alkalis, and resists the action of chlorine. Whenever the metal vanadium shall become more abundant, as it probably may ere long, we shall po e the means of making an ink, at a moderate price, much superior to the tannate and gallate of iron. To prepare the above vanadic salt cheaply, the cinder or hammerschlag obtained from the iron made at Ekersholm, in Sweden, or other iron which contains vanadium, being reduced to a fine powder, is to be mixed with two thirds of its weight of nitre, and one third of effloresced soda. The mixture is to be ignited in a crucible; cooled and lixiviated, whereby solutions of the vanadates of potash and soda are obtained, not pure, indeed, but sufficiently so for being decomposed, by means of sal ammoniac, into a vanadate of ammonia. This being rendered nearly neutral with any acid, constitutes an excellent indelible ink. INULINE; (Eng. and Fr.) is a substance first extracted from the root of the Inula-Hellenium , or Elecampane. It is white and pulverulent like starch; and differs from this substance chiefly because its solution, when it cools, lets fall the inuline unchanged in powder, whereas starch remains di olved in the cold, as a jelly or paste. Inuline is obtained by boiling the root sliced in 3 or 4 times its weight of water, and setting the strained decoction aside till it cools, when the pulverulent inuline precipitates. It exists also in the roots of colchicum, and pellitory. IODINE; ( Iode , Fr.; Iod , Germ.) is one of the archæal unde compounded chemical bodies, which was discovered accidentally in 1812 by M. Cour to is, a manufacturer of saltpetre, in the mother-waters of that salt. Its affinities for other substances are so powerful as to prevent it from existing in an insulated state. It occurs combined with pota ium and sodium in many mineral waters, such as the brine spring of Ashby-de-la-Zouche, and other strongly saline springs. This combination exists sparingly in sea-water, abundantly in many species of fucus or sea-weed, and in the kelp made from them; in sponges; in several marine molluscæ , such as the doris , the venus , oysters, .; in several polyparies, and sea plants, as the gorgon i a , the zoster a marina , .; particularly in the mother-waters of the salt works upon the Mediterranean sea; and it has been found in combination with silver, in some ores brought from the neighbourhood of Mexico. Iodine is most economically procured from the mother-water of kelp, as furnished by those manufacturers of soap in Scotland and elsewhere who employ this crude alkaline matter. By pouring an exce of sulphuric acid upon that liquid, and exposing the mixture to heat in a retort, iodine rises in violet vapours (whence its name), and condenses in the receiver into black, brilliant, soft, scaly crystals, resembling graphite or plumbago. An addition of the peroxide of manganese to the above mixture, favours the production of iodine. Soubeiran has proposed, as a means of extracting it in greater abundance from a given quantity of the said mother-waters, to transform the iodide of potash or soda, present, into an insoluble iodide of copper, by pouring into them solution of sulphate of copper, which precipitates first of all one half of the iodine. He then decants the supernatant liquor, and adds to it a fresh quantity of the sulphate along with some iron filings. The latter metal seizes the oxygen and sulphuric acid of the cupreous salt, sets the copper free, which then seizes the other half of the iodine. To separate this iodide from the remaining iron filings, he agitates the whole with water, and decants the liquor. The filings immediately subside, but the iodide of copper remains for some time in a state of suspension. This compound, separated by a filter cloth, is to be mixed with twice its weight of the black peroxide of manganese, and as much sulphuric acid as will make the mixture into a paste; which mixture being introduced into a retort, and distilled, the iodine comes over in its characteristic violet vapours, which are condensed into the glistening black substance in the receiver. Iodine is always solid at atmospheric temperatures, though it slowly flies off with a peculiar offensive penetrating odour somewhat like chlorine. Its specific gravity is 4·946 at the temperature of 58° Fahr. Its prime equivalent, according to Berzelius, is 63·283, one volume of hydrogen being 1·000; but 126·566, if two volumes of hydrogen be reckoned unity, as most British chemists estimate it, from the composition of water. It po e es in a high degree electro-negative properties, like oxygen and chlorine; and therefore makes its appearance at the positive pole, when its compounds are placed in the voltaic circuit. It stains the skin yellow; and if applied for some time to it, is apt to produce painful ulcerations. Iodine melts only at about 390° Fahr.; but with the vapour of water it volatilizes at 212°. It has a great affinity for hydrogen, and constitutes by that union hydriodic acid; a compound resembling in some respects muriatic or hydrochloric acid. It also can be combined with oxygen, and forms thereby iodic acid. Its compounds with carbon, phosphorus, sulphur, chlorine, azote, and many metals have not been applied to any manufacturing purpose, and therefore need not be described here. The chief application of iodine in the arts, is for the detection of starch, which its watery solution, though containing only one part in 5000, does readily, by the production of a deep purple colour; this vanishes by exposing the starch to the air for some time, or more quickly by heating it. As a medicine, iodine and its compounds, such as the iodides of pota ium and iron, are supposed to po e great powers in resolving glandular swellings. The periodide of mercury is a brilliant red pigment, but somewhat evanescent. Chlorine, bromine, and iodine are frequently a ociated; and it has hitherto been reckoned a difficult problem to separate them from one another. The following plan is proposed by M. Lövig. Heat the mixture of the dried chloride and bromide (or chloride and iodide) while a current of chlorine is made to pa over it, till no more bromine is carried off by the chlorine. Receive the gases in a solution of potash; saturate this fluid mixture of the chloride of pota ium, and the chlorate and bromate of potash with nitric acid, adding afterwards nitrate of silver. A mixture of bromate and chloride of silver will precipitate. Dry the precipitate, calcine it, and calculate the proportion of bromine from the volume of oxygen gas now disengaged. It would be preferable to digest in a phial, the precipitate while moist, along with water of baryta, which decomposes the bromate of silver without acting upon the chloride. The exce of baryta being thrown down by carbonic acid, and the liquid being evaporated, a bromate of baryta is obtained, which may be washed with alcohol of 0·840. The solution of bromate of baryta may also be neutralized by nitric acid, and the bromic acid may be precipitated by nitrate of silver. The same method is applicable to the separation of iodine from chlorine. After throwing down the solution of the mixed salts by nitrate of silver, Berzelius digests the washed precipitate in a closed bottle of water of baryta; whence results bromate of baryta without any chloride of barium. On evaporating the liquor we obtain crystallized bromate of baryta, which may be freed from a small accidental quantity of chloride, by washing with alcohol at 0·840. By calcination we then obtain bromide of barium, which being distilled with sulphuric acid and peroxide of manganese, affords bromine.