Zinc chloride

“ The common use of disinfecting fluids containing zinc chloride, such as Burnett’s fluid, leads to more accidents in England than in any other European country. Of twenty-six cases of poisoning by this agent, twenty-four occurred in England, and only two on the Continent. Death may follow the external use of zinc chloride. Some years ago, a quack at Barnstaple, Devon, applied zinc chloride to a cancerous breast; the woman died with all the [660] general symptoms of poisoning by zinc, and that metal was found in the liver and other organs. ”

“ The method has since chiefly been applied to the treatment of copper ores and products, but has also been used for the recovery of nickel, gold, zinc, &c. The production of electrolytic zinc from solutions has been encouraged as a result of the shortage of pure zinc for war purposes, and several processes have been developed. In these processes the solution used consists either of zinc sulphate or of zinc chloride, the anodes consisting of metallic lead or of carbon, and the cathodes of pure zinc sheets. ”

“ Huebner’s Cement.—Zinc oxide, 500.0 parts; powdered manganese, 1.5 parts; yellow ocher, powdered, 1.5–4.0 parts; powdered borax, 10.0 parts; powdered glass, 100.0 parts.
As a binding liquid it is well to use acid-free zinc chloride, which can be prepared by dissolving pure zinc, free from iron, in concentrated, pure, hydrochloric acid, in such a manner that zinc is always in excess. When no more hydrogen is evolved the zinc in excess is still left in the solution for some time. The latter is filtered and boiled down to the consistency of syrup. ”

“ Zinc oxide, ZnO, is a white powder, almost insoluble [40] in water, [2] like magnesia, from which, however, it is distinguished by its solubility in solutions of sodium and potassium hydroxides. [3] Zinc chloride [4] is decomposed by water, combines with ammonium [41] chloride, potassium chloride, &c., just like magnesium chloride, forms an oxychloride, and also combines with zinc oxide. [4 bis]
Zinc, like many heavy metals, is often found in nature in combination [42] with sulphur, forming the so-called zinc blende, [5] ZnS. It sometimes occurs in large masses, often crystallised in cubes ”

“ The reducing agents available are zinc, sulphurous acid, or sulphureted hydrogen. Stannous chloride may also be used when the titration is made in the presence of hydrochloric acid. Since the excess of both the gaseous reducing agents can only be expelled by boiling, with consequent uncertainty regarding both the removal of the excess and the reoxidation of the iron, zinc or stannous chlorides are the most satisfactory agents. For prompt and complete reduction it is essential that the iron solution should be brought into ultimate contact with the zinc. ”

“ This, if left on the outside, would prevent the passage of electricity almost entirely; so lateral holes are drilled into the carbon before the cap is finally cast on. The action that takes place in the Leclanché cell may be summarised as follows:—
When the zinc, Zn, is acted on by the ammonium chloride, 2NH4Cl, the zinc seizes the chlorine and forms with it zinc chloride, ZnCl2, while the ammonium, 2NH4, is liberated. But this ammonium, 2NH4, does not escape. ”

“ Dissolve the sal ammoniac in the water thoroughly. Let stand twenty-four hours. Then add the zinc chloride, and when cool, will be ready for use.
When you have your zinc cup ready, pour a little wax in the bottom, to insulate; place a piece of blotting-paper inside cup and laying tight against the zinc, about three turns. The negative element is prepared as follows: One pound pure carbon, powdered; one pound black oxide manganese; mix thoroughly. Then add sufficient of above solution to hold it together without being plastic, as that would be too wet to tamp. ”

“ At a red heat, zinc inflames, and the product of combustion is the white oxide of zinc, or flowers. The oxide of zinc is reduced by mixing it with charcoal, and exposing the mixture to a strong heat in close vessels.
Zinc will burn in chlorine gas, and forms a chloride of zinc. If the perchloride of mercury and zinc-filings be heated together, the same compound will result. This chloride melts at 212°, and rises, in the gaseous form, at a heat much below ignition. It was formerly called the butter of zinc, and muriate of zinc. With iodine, zinc forms a compound, called iodide of zinc. ”

“ Very large doses of zinc chloride have been recovered from, e.g., a man had taken a solution equivalent to about 13 grms. (200 grains) of the solid chloride. Vomiting came on immediately, and there was collapse, but he recovered in sixteen days. On the other hand, ·38 grm. (6 grains) has destroyed life after several weeks’ illness.
§ 866. Post-mortem Appearances.—In poisoning by sulphate of zinc, the appearances usually seen are inflammation, more or less intense, of the mucous membrane of the stomach and bowels. ”

“ Reduction is carried out in the Belgian or Silesian process by strongly heating calcined matte with coal in retorts. The zinc as it distils is caught in special condensing receptacles (prolongs) . After distillation is complete the residue is raked out of the muffle and the furnace charged afresh. As zinc ores generally contain much lead, the work-zinc is therefore refined [126] by remelting in a reverberatory furnace, during which process the impurities collect on the zinc as dross and are removed by agitation with sal-ammoniac or magnesium chloride. ”

“ Preparation of pure Oxide of Zinc, by M. Hermann.—It is by no means easy to obtain this substance perfectly pure; the following is M. Hermann’s process: Oxide of zinc, or metallic zinc, is to be dissolved in excess of sulphuric acid, and the solution being filtered, sulphuretted hydrogen is to be passed through, so long as a brown or yellow precipitate is formed. Cadmium, lead, or copper, being thus separated, and the solution filtered, it is to be treated with solution of the chloride of lime, (bleaching powder,) by which the iron and manganese will be separated. ”

“ Now, in an alkaline solution, zinc-ion is converted into zincate-ion (Zn2+ + 4 HO− ⇄ ZnO22− + 2 HOH) and a large concentration of zinc-ion cannot accumulate. The consequence is that zinc liberates hydrogen freely even from alkaline solutions, for instance from molar solutions of potassium hydroxide, in which the concentration of hydrogen-ion, roughly 10−14, is very much smaller than that calculated for the benzene solution of hydrogen chloride (namely, 10−9) . ”

“ Billion used here to mean one million million, and trillion to mean one million billion.
We have temporarily restricted ourselves to the electrolysis of hydrogen chloride. Let us now assume that we have chloride of zinc (ZnCl2) , which, by electrolysis, is separated into chlorine and zinc. Each atom of chlorine will, as before, carry 4·77 × 10−10 units of negative electricity to the anode; but since zinc is divalent (cf. p. 17) and one atom of zinc is joined to two of chlorine, therefore one atom of zinc must carry a charge of 2 × 4·77 × 10−10 units of positive electricity to the cathode. ”

“ These impurities are determined by well-known methods; sulphur is oxidized and precipitated with barium chloride, lead by sulphuric acid and alcohol. The examination of zinc dust, when used for the regeneration of metal, determines the quantity of zinc resident therein, and employed as reducing agent, the quantity of metal which causes the generation of hydrogen. Cadmium, showing the same deportment, must also be considered as well as lead and arsenic. ”

“ Chlorine is as effective, but is so destructive that it can only be used in empty rooms. It requires about a tablespoonful of alcohol to light a pound of sulphur. Sulphur (roll-brimstone) , 10 cents a pound.
Thymol. See Carbolic Acid.
Zinc Salts.—The sulphate and the chloride of zinc are excellent disinfectants. They are colorless, and can therefore be used on clothing. They form, with albuminous matters, extremely insoluble compounds, and also absorb gases from putrefying material. They are the best disinfectants of their class. ”

“ The sulphate is cheaper, but the chloride more efficient. Sulphate of zinc, 10 cents an ounce; chloride of zinc, 20 cents an ounce.
It is better and cheaper to buy and mix one’s own disinfectants. The many proprietary articles are no more efficient, and are very expensive. The composition of some of those most in use is here [Pg 97] given. (Analyses by Waller, of the New York City Health Department.)
The first column gives parts in 100, and the second, ounces in a gallon in the case of liquids, and ounces in a pound in case of powders.
Bromo-chloralum (Tilden & Co.) , 50 cents a pint. ”

“ Tin gives beautiful results. If zinc be placed in a solution of stannous chloride it is quickly surrounded with a growth of prolonged octohedra, and as these advance into the liquid it is easy to observe that the additions of new metal commence at the apex, and that the wave of chemical change proceeds down the lateral edge, occupying some seconds of time in depositing the new layer of material. Frequently, also, there is a luxuriant growth of large, flat leaflets, or symmetrical structures resembling fern-leaves, but with the fronds arranged at right Fig. ”

“ Filter from the bismuth hydrate, and if copper is present, add potassium cyanide till the colour is destroyed, then pass sulphuretted hydrogen, and cadmium is precipitated as the yellow sulphide. If copper is absent, then sulphuretted hydrogen can be passed directly into the solution.
The next group precipitate may contain the white gelatinous aluminium hydroxide, the greenish chromium hydroxide, reddish ferric hydroxide, and possibly zinc and manganese hydroxides. Treatment with casutic soda dissolves out aluminium hydroxide, which is reprecipitated by the addition of ammonium chloride. ”

“ No zinc is used, only care in washing out, drying out, and managing the water." This is the evidence of an engineer with a large number of vessels in his charge. On the other hand, some of the most prominent Liverpool engineers always use zinc, and take care to apply it most strictly. The evidence of one of them is as follows: "We always fix slabs of zinc to most boilers, exposing not less than a surface of one square foot for every twenty indicated horse-power, and distributed throughout the boiler. This zinc we find to be in a state of oxide and crumbling away in about three months. ”

“ Its soluble neutral salts, when dissolved in water, change blue litmus paper to red. Its salts, with organic acids, are decomposed by ignition, and the carbonate of zinc remains.
The oxide of zinc turns yellow by being ignited in the oxidation flame, but it is only visible by daylight; this color changes to white when cold. It does not melt, but produces a strong light, and it is not volatile.
It disappears gradually in the flame of reduction, while a white smoke sublimates upon the charcoal. This sublimate is yellow while hot, but changes to white when cold. ”

“ Zinc itself is readily soluble in dilute acids; any residue which is left after boiling with dilute hydrochloric or sulphuric acid consists simply of the impurities of the metal; this is generally lead.
All zinc compounds are either soluble in, or are decomposed by, boiling with acids, the zinc going into solution. Zinc forms only one series of salts, and these are colourless. Their chief characteristic is solubility in an alkaline solution, from which sulphuretted hydrogen produces a white precipitate of zinc sulphide. ”

“ Plates of platinum and pure or amalgamated zinc are separated by a porous pot, and each surrounded by some of the same solution of a salt of a metal more oxidizable than zinc, such as potassium. When the plates are connected together by means of a wire, no current flows, and no appreciable amount of zinc dissolves, for the dissolution of zinc would involve the separation of potassium and a gain in available energy. If sulphuric acid be added to the vessel containing the zinc, these conditions are unaltered and still no zinc is dissolved. ”

“ Zinc dust contains both metals and their oxides, and methods which, from the volume of hydrogen generated, determine indirectly the percentage of metallic zinc do not give the real composition of the zinc dust. For the determination of the metallic components the material is digested with a solution of copper sulphate, which dissolves zinc and cadmium; the liquid is filtered, acidified, and decomposed with hydrogen sulphide, or treated with a solution of ammonium carbonate. ”

“ Zinc is detected by dissolving the substance in hydrochloric or nitric acid, boiling, and adding sodic hydrate in excess, filtering, and adding ammonic sulphide to the filtrate. The precipitate contains the zinc, which can be dissolved out by boiling with dilute sulphuric acid, and detected by the formation of a white precipitate on the addition of potassic ferrocyanide.
The dry assay of zinc can only be made indirectly, and is unsatisfactory. Zinc is volatile, and at the temperature of its reduction is a gas. ”

“ It is generally held that zinc chlorid solutions which possess a strength of from 1 to 200 up to 1 to 500 exercise a weak antiseptic action. The strength of zinc chlorid in Lavoris is approximately 1 to 1,000. The directions for its use recommend that Lavoris should be diluted. A dilution of 1 to 4 is recommended for a variety of mouth conditions while for cystitis irrigations and as a vaginal douche, it is recommended that one tablespoonful be added to a quart of warm water or salt solution. The strength of zinc chlorid in the last suggested dilution would approximate 1 to 64,000. ”