presence of potassium and sodium, and only the last one found present. Another part of the original so-called "citrate-of-magnesia solution" was now tested in regard to the acids that might be combined with the sodium, and it was ascertained that, besides a little sulphuric acid, no other acid besides tartaric was in the liquid. The so-called solution of citrate of magnesia" was, therefore, nothing but a solution of sodium tartrate, and it could now at once be explained why this solution always keeps well, and never forms a deposit.-New Remedies.

ON THE PURITY OF COMMERCIAL IODIDE OF POTASSIUM.

BY 0. KASPAR.

THE method which is employed by the author to determine the per-centage of pure iodide is very simple, and has the additional advantage that it is not interfered with by the presence of carbonate, bromide and chloride. It depends upon the following reaction :

HgCl,+4KI = 2KCl+HgI,.2KI.

Four molecules of iodide of potassium are, therefore, exactly decomposed by 1 molecule of corrosive sublimate, so as to form a soluble double salt. If, now, an excess of corrosive sublimate is added, the double salt is again decomposed and mercuric iodide is separated.

HgCl,+HgI,.2KI = 2KCl+2HgI ̧.

As soon as this separation begins, the reaction is terminated.

The normal solution of corrosive sublimate is prepared by dissolving 2:71 grams of the salt in sufficient water and diluting to 100 cubic centimetres. 1 cc. of the solution, according to the above equation, indicates 0.06643 gram of iodide of potassium. When using the process, 10 grams of the iodide of potassium are dissolved in 50 grams of water, and 5 cubic centimetres of this solution are used at a time for trituration. This quantity is run into a beaker, placed on a sheet of white paper, and the above volumetric solution is allowed to flow in from a burette divided in ', until a permanent reddish yellow opalescence ensues. Just before this occurs, the liquid itself assumes a reddish-yellow colour, which may be regarded as a sign of the approaching end of the reaction. It is best to prepare the solution of the sublimate each time fresh.

The author has examined many commercial samples of iodide of potassium by this method and has found the per-centage of the true salt to vary between 88 and 99.6 per cent. He considers that the commercial salt should contain at least 96 to 97 per cent. of pure salt.-Schweiz. Woch. f. Pharm.

LEAD IN BROMIDE OF POTASSIUM.

MASCHKE has found bromide of potassium in the market which is contaminated with lead. It is soluble to a clear liquid only after addition of an acid; the larger crystals are remarkable by their transparency and their form, being a compound of octoëders and cubes. In testing for lead, sulphuric acid cannot be used, since the resulting sulphate of lead is soluble in bromide of potassium. But if hydrosulphuric acid or sulphide of ammonium is used, no doubt can arise.-Pharm. Zeit.

THE ADULTERATION OF BALSAM OF PERU.

BY ALFRED SENIOR, M.D., F.C.S.

THE adulteration of balsam of Peru has been practised to a large extent and with some degree of success, for several years past, principally in the north of Germany. The adulterants employed are rosin, gum benzoin liquefied with a little alcohol, storax, copaiba, and in some cases castor oil. In a communication to the Pharmaceutische Zeitung (xxx., 222,) Prof. Flückiger deals with the problem of the examination of Peru Balsam for impurities. Pure balsam of Peru is a mixture of about two-thirds, as a maximum, of benzyl cinnamate or cinnameni, and one-third, as a minimum, of a brownish black resin; it also contains about four per cent. of cinnamic acid, besides small quantities of other substances. The specific gravity determined at 15° C. varies from 1∙138 (minimum) to 1·147 (maximum), and inasmuch as all the adulterants are lighter than the pure balsam, the specific gravity of the sample is an important item. Samples should be regarded with suspicion when the specific gravity is below 1.14, or perhaps as the extreme limit, 1,138. Among other physical characteristics, the consistency of the specimen is important; adulterated samples usually yield "thick, thread-like attenuated drops."

The benzyllic cinnamate is easily extracted from the balsam by shaking with three times its weight of carbon disulphide, the solution, which, if the balsam be pure, is nearly colourless, being evaporated and the residue weighed. The quantitative determination of this constituent is not always of much value, owing to the varying amount of this substance contained in different specimens of balsam: in some cases, however, it is valuable, the effect of adulterants being to increase the weight of what ought to be nearly pure benzyllic cinnamate. The substance remaining after the treatment with carbon disulphide is the rosin, the weight of which should be nearly two-fifths, or at any rate exceed one-third, of the original weight of the balsam operated upon. If adulterants have been added, the weight will be less than this. For the estimation of the cinnamic acid, the author proposes the following method: fifty parts of balsam are boiled with a mixture of twenty parts of lime and five hundred parts of water, for two hours, care being taken to replace any water which evaporates during the process. At the end of this time the boiling solution is filtered, the substance remaining on the filter being twice washed with two successive two hundred parts of boiling water. In this way all the cinnamic acid is obtained in solution as calcium cinnamate. The filtrate and washings are now evaporated to two hundred parts, treated with excess of hydrochloric acid and allowed to stand for some time. The cinnamic acid which will have separated in crystals, is collected, and after pressing between bibulous paper, dried partially by exposure to the air and finally on the water-bath. The weight ought to equal from three to four per cent. of the original sample. The determination of this constituent, however, is only of importance when considered in relation to the amounts of the other substances present. After the above treatment there remains upon the filter a mixture, the condition of which affords an important indication of the purity of the balsam-pure samples yield a soft, pliable mass; when adulterated the mass is more or less hard. So important does Prof. Flückiger consider this indication that he proposes a special test based upon it, for the determination of the general purity of balsam of Peru. If two parts of the balsam are triturated with one part of slacked lime a or somewhat pliable, tenderly divisible mass is obtained if the balsam

66

soft,

kneadable

is pure; in fact

the mass presents exactly the characteristics that one would expect from such a mixture. Where, however, storax, alcoholic extract of gum benzoin, rosin or copaiba were added to the extent of ten per cent., the mass became solid, hard and unkneadable. If this test is found by other experimenters to answer with all genuine specimens of balsam of Peru, Prof. Flückiger suggests that as a test of purity, it should be ordered that "ten drops of Peru balsam shall furnish with four grammes of slacked lime a mixture which remains soft." The only case where this test could not be applied is when castor or other fatty oils have been used as adulterants. These substances, however, would be revealed by heating the lime mixture, when they would be rendered evident by their odour and would also be detected by the treatment with carbon disulphide.

GERMLESS MAIZE.

THE importance of maize to the distiller and to the brewer is becoming generally recognised in this country, but it requires to be degerminated to be used to the highest advantage. The removal of the germ greatly enhances the value of the maize for the purposes of the distiller, and the degerminating process promises to be exceedingly valuable as a means of preparing the grain in question. By degermination its value is increased, by increasing the proportion of starch, so as to yield, it is said, 5-26 lbs. more of proof spirit for every 100 lb. of maize employed. By the reduction of the proportion of oil to something like that contained in barley malt, and by reducing to some extent the amount of nitrogenous compounds, the spirit from germless maize is, it is found, not only larger in quantity, but better in quality than that from the whole grain, while the extracted germs, though detrimental in distilling, are, it is said, more valuable for feeding purposes than the article in a whole state. The germs contain a larger amount of oil than linseed cake, while the nitrogenous matter, so valuable as a flesh-former, is largely increased by the degerminating process. Messrs. Muir and Son are said to be working the process upon a large scale, and to the entire satisfaction of distillers, brewers, and starch makers, who are their largest customers. As an article of feed for horses, when reduced with hay, chaff, or straw, the germ, as extracted by the process of the Messrs. Muir, we understand, commands a high price, ratifying the statement made by Mr. Gladstone in his budget speech respecting the enhanced value of the cereal in its degermed state for distilling, brewing, starch-making, and for feeding purposes. Distillers as a class are not less alive to their interests than any other class of manufacturers, and there may be a good future in store for the Muir process. -Miller.

DISPLACEMENT OF THE SODIUM BASE IN SODIUM CHLORIDE BY COPPER HYDRATE.Copper hydrate in a moist state possesses the singular property of liberating a certain quantity of alkali, if it is brought in contact with certain saline solutions, such as sodium and potassium chloride, potassium bromide, sodium sulphate, &c. The displacement of the alkali takes place even at temperatures as low as 4° and 5° C. If copper hydrate, well washed and moist, is added to a solution of sodium chloride of 10 per cent., the liquid in a few minutes acquires an alkaline reaction, which increases on standing. Meantime the hydrate is converted into a pale green powder containing chlorine. Moist copper carbonate acts in a similar manner.- Comptes Rend.

SOCIETY OF PUBLIC ANALYSTS.

Analyses of English Public Water Supplies in October, 1881.

All results are expressed in GRAINS PER GALLON.

SOCIETY OF PUBLIC ANALYSTS.

Analyses of English Public Water Supplies in October, 1881.

0840 20.0° 10.0° 22:40 veg. debris, desmids, diat.
2.5°
3.0°
3.50
23.0° 7.0° 25.00
12.6°
0040 1.5°

Abbreviations:-c., clear; f., faint; h., heavy; p., pale; v. h., very heavy; v. 8., very slight.

ERRATA. In the September Table the Nottingham Chlorine should have been 1.49 instead of 149; Reading Chlorine should have been 1.10 instead of .11.