YEAR-BOOK OF PHARMACY.

PART I.

CHEMISTRY.

Preparation of Hydrogen and of Carbonic Oxide by means of Zinc-Dust. H. Schwarz. (Ber. der deutsch. chem. Ges., xix. 1140.) Pure hydrogen may be conveniently obtained by heating a mixture of 20 grams of zinc-dust with 22.8 grams of calcium hydrate in a combustion tube. If in the place of the calcium hydrate 30 grams of calcium carbonate are used, the resulting gas is carbonic oxide.

Combustion of Carbonic Oxide. L. Meyer. (Ber. der deutsch. chem. Ges., xix. 1099.) The author confirms Dixon's observation that a well dried mixture of carbonic oxide and oxygen requires a powerful spark and a tolerably high gas pressure for its explosion.

The Purification of Water by Alum. P. T. Austin. (Chemical News, July 23, 1886.) The author has further extended his experiments with this method of purification, and feels justified in very strongly recommending it. On an average two grains of alum to each gallon of water will efficiently clarify it by allowing the water thus treated to stand for forty-eight hours. The proportion of alum and the time for standing vary, however, with different waters, but may be easily determined for any particular case which may arise.

Action of Water on Lead. (Pharm. Journ., 3rd series, xvii. 269.) In a report on the action of drinking water on lead, presented by Messrs. Crookes, Odling, and Tidy, to the Chemical Section of the British Association, it is stated that of a large number of first-class soft waters, all those which took up lead in passing through the service pipes contained less than two-tenths of a grain of silica per gallon, while those containing half a grain

or more per gallon did not take up any lead. This observation agrees with results obtained with soft water to which dialysed silica had been added. The reporters therefore believe that artificial silication would minimise to the utmost, and practically prevent, the action of the water on lead pipes, and thus effect a real hygienic improvement. The plan adopted in the Huddersfield works is to pass the water through tanks containing crushed flint, sand, and limestone, the surface of these materials being equal to one foot for every fifty-four gallons of water passing through per hour. Examination shows that considerable solvent action is exercised upon the flint, whilst the undesired action of the water upon the lead service pipes is prevented.

Occurrence of Free Iodine in a Mineral Water. J. A. Wanklyn. (Chemical News, liv. 300.) It has been known for many years that the water of the Woodhall Spa, near Lincoln, is exceptionally rich in bromides and iodides. In the course of an investigation, the author has made the observation that there is free iodine in this water sufficient to impart to it a brown colour of considerable depth of tint.

Upon shaking this water with bisulphide of carbon, the latter assumes the characteristic deep violet coloration.

The Woodhall Spa is known as a remedy in skin diseases. Periodates. C. W. Kimmins. (Proc. Chem. Soc., February 17, 1887.) The author, at the suggestion of Mr. Pattison Muir, has re-examined certain periodates of potassium, silver, and sodium, with the object of explaining the discordant results of various observers.

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Besides the salt, Na H, IO, described by Langlois, he has obtained a sodium periodate of the formula Nag H, IO; he also describes a potassium periodate K, HI, O,. He has prepared and analysed the following silver salts :—

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Presence of Potassium Chlorate in Commercial Potassium Nitrate. H. Beckurts. (Arch. der Pharm. [3], xxiv. 333–337.) The author has noticed the presence of traces of potassium chlorate or perchlorate in nearly all samples of nitrate examined by him. The quantity of this impurity may be deduced from the difference in weight of silver chloride precipitated before and after ignition of the nitrate.

Potassium Manganite. M. Gläser. (Monatsh. Chem., vii. 651-654.) The author has studied the action of potassium permanganate on sodium hyposulphite, and states that the potassium manganite formed in this reaction is a stable compound, which is not decomposed by cold or hot water. Numerous analyses confirm the correctness of the formula K H, Mn4 010

Compounds of Sodium and Potassium Hydrates with Water. C. Göttig. (Ber. der deutsch. chem. Ges., xx. 543, 544, and 10941096.) The author describes compounds of the formulæ, Na HO+ 2 H2 0; 2KHO+9 H2O; and 2 K HO+5 H, O, which he has obtained from concentrated alcoholic solutions of the alkaline hydrates. For particulars as to their formation and properties, reference should be made to the above sources.

Explosive Properties of Sodium Hypophosphite. A. Cavazzi. (Gazzetta chim. Ital., xvi. 172.) Sodium hypophosphite, when mixed with an equal quantity of sodium nitrate, forms a highly explosive mixture. The reaction probably takes place in accordance with the following equation: Na H, PO2+2 Na N 0 ̧= Nag PO4 + H2O + NO2+NO.

Sodium Ferrocyanide. L. Pebal. (Liebig's Annalen, ccxxxiii. 165.) The author finds that this salt contains 10 molecules of water of crystallization, and not 12 as hitherto supposed.

Solubility of Lithium Carbonate. M. Bèvade. (Bull. Soc. Chim., xliii. 123.) The author gives the following table, showing the solubility of lithium carbonate in 100 parts of water at different temperatures :

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Action of Sulphur upon Solution of Ammonia. J. B. Senderens. (Comptes Rendus, January 3, 1887.) Pure sulphur was digested with solution of ammonia in a closed vessel at about 12° C. three weeks the liquid began to show a slight yellow tint, which passed gradually into a reddish yellow, and finally to a decided red. This liquid contained an ammoniacal polysulphide and a hyposulphite. On exposure to the air sulphur was deposited.

Ammonium Vanadates. A. Ditte. (Comptes Rendus, cii. 918– 921.) In addition to the normal salt, (N H4)2 V2O6, the author fully describes the sesquivanadate, 3 V2 O., 2 (N H1), O, the bivana

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date, (NH4)2 O, 2 V2O,, and the trivanadate, (N H1), 0, 3 V1⁄2 05. For details, reference should be made to the original paper.

Compounds of Permanganates with Ammonia. T. Klobb. (Comptes Rendus, ciii. 384, 385.) Metallic permanganates form combinations with ammonia, from which the latter cannot be liberated by boiling with alkalies, owing to the formation of nitrites, unless the permanganate be first reduced by sulphurous acid. The silver salt, Ag Mn 04, 2 N Hg, is obtained by saturating a solution of potassium permanganate with ammonia, and then precipitating with silver nitrate. It is a crystalline powder, which explodes when struck, and is decomposed on heating. Copper, cadmium, nickel, zinc, and magnesium form similar double salts.

Note on Lime-Water. J. I. Fraser. (Pharm. Journ., 3rd series, xvii. 782.) The author obtained different results of estimations of lime in liq. calcis, prepared strictly according to the B. P. (by shaking the lime in a bottle, allowing it to subside, and siphoning off the clear liquid), and in that prepared in a jar by repeatedly stirring up the slaked lime with water, allowing it to subside, and filtering. The former showed an equivalent of 6·16 grains of Ca O in ten fluid ounces; the other, which had been filtered, 5.26 grains.

An examination of eighteen samples of lime-water, bought in the ordinary way, showed that 50 per cent. of them were below the standard of the Pharmacopoeia.

Remarkable Feature in the Specific Gravity of Lime-Water. J. A. Wanklyn. (Chemical News, May 13, 1887.) The author has recently had occasion to take the specific gravity of limewater, and has noticed an interesting peculiarity. According to determinations in his laboratory, a litre of lime-water contains 1:344 grams of Ca O, and the specific gravity of the lime-water reaches the extraordinary figure, 1002:35, compared with distilled water at the same temperature (13° C.), reckoned as 1000.00.

It follows from these observations that in the formation of limewater a most extraordinary contraction takes place.

which contract so as to occupy one litre.

The contraction is, therefore, equal to three times the volume of the lime passing into solution.

The purity of the lime-water was ascertained by exactly pre

cipitating the lime by means of its equivalent of oxalic acid, filtering, and evaporating the filtrate to dryness; the residue was so small as to be insignificant.

Action of Dry Carbonic Anhydride on the Alkaline Earths and their Hydrates. C. Scheibler. (Ber. der deutsch. chem. Ges., xix. 1973-1982.) Dry carbonic anhydride is without action on the dry oxides and monohydrates of the metals of the alkaline earths.

When dry carbonic anhydride is passed over the normal hydrates of these metals at 100°C. in the presence of moisture the excess of water present will be removed, and the gas thus moistened will act on the hydrate, with formation of carbonate. The hydrate is, however, not completely converted into carbonate, even when 8 molecules of H2O are present; and for this reason the use of the dry gas in removing water from alkaline earths and converting the latter into carbonates cannot be employed as an analytical method.

Ammonio-Ferrocyanides of Calcium and Magnesium. T. Salzer. (Ber. der deutsch. chem. Ges., xix. 1697.) Strong solutions of calcium chloride, containing a large proportion of ammonium chloride, form with potassium ferrocyanide a crystalline precipitate corresponding to the formula (N H4)2 Ca Fe Cy. Magnesium salts, under the same conditions, behave in a similar manner.

The Composition of Prussian Blue and Turnbull's Blue. E. F. Reynolds. (Proc. Chem. Soc., June 2, 1887.) These compounds are generally represented by the formula Fe, Cy18 and Fe, Cy12 ; but Reindel and others have conjectured that they are identical in composition. The author has carefully prepared Prussian blue from hydrogen ferrocyanide and ferric chloride, and Turnbull's blue from hydrogen ferricyanide and ferrous sulphate; his analyses of the products show that the above formulæ are correct expressions of their composition.

Chromates. A. Stanley. (Chemical News, liv. 194-196.) The salts described in this paper are sodium bichromate, sodium trichromate, magnesium sodium chromate, and a copper salt of the formula Na, Cr 04, Cu Cr2 O7, 2 Cu 0+4 H, O.

Solubility of Silver Chromate in Alkaline Nitrates. R. F. Carpenter. (Journ. Soc. Chem. Ind., v. 286.) The subjoined table gives the results of some experiments made to determine the relative solubility of silver chromate in cold and hot strong solutions of the nitrates of potassium, sodium, ammonium, and magnesium :-