pure; and from the great simplicity of the process, it was offered at a lower price than that made in the usual way; but a prejudice existed in the market in favour of sublimate in lump, which, notwithstanding its higher price, and the trouble and expense of reducing it to a state of powder for use was more generally employed, while that made by his process, being in minute crystals, scarcely required powdering at all.

A paper was next read

ON A MODE OF ANALYZING SODA-WATER
AND OTHER AËRATED WATERS.

BY ANDREW URE, M.D., F.R.S., &C.

Hon. Member of the Pharmaceutical Societies of Great Britain and North Germany.

THERE is perhaps no article extensively sold by the Chemist and Confectioner, which varies so much in quality and composition as soda-water. A great deal of what passes under this name hardly deserves it, since it contains so small a proportion of the alkali, as to possess little or none of its antacid and renal operation.

The examination of such a water for its alkaline and saline constituents offers no difficulty to the analytical chemist. For determining the quantity of soda, L employ an alkalimeter of a peculiar construction, composed of a test nitric acid, having a definite density, adjusted by means of a glass bead, so nicely, that half a degree of difference in the temperature by Fahrenheit's scale, either raises the bead to the top or sinks it to the bottom of the liquid. Nitric acid is diluted with distilled water till the adjusted bead floats in its middle at 60° Fahr. This mode of preparing the normal test liquor is both much more ready and precise than that by one of the ordinary instruments for taking specific gravity. An assortment of such beads made with extreme care, is admirably adapted to the preparation of an assortment of normal test liquids for my rapid system of general analysis.

The test liquor is in each case poured out by a glass apparatus so mounted as to permit of introducing it either in a continuous stream of any tenuity, or in fractions of a drop, at pleasure. I intend to publish a particular description of this, and several other pieces of new apparatus, for facilitating analysis, in my forthcoming work on Chemistry.

It is no mean advantage derived from the employment of dilute nitric acid in alkalimetry, that it allows the neutralized liquid to be examined directly, for its sulphuric, hydrochloric, phosphoric and most other saline combinations, which could not without complexity be done, were dilute sulphuric acid used for the alkalimeter, as is the common practice. By means of a normal test liquor, made and applied with such nicety, aided by

rightly tinted litmus paper, it is possible to determine in the course of a few minutes the quantity of potash, soda, or ammonia, without calculation, by inspection of the graduated scale on the glass, to one part in 10,000.

In this way I have found that much of the soda-water now on sale in London contains no more than one grain of carbonate of soda in each bottle, diffused, on an average, through 4000 grainmeasures of water, or 4998 of a pint imperial. One sample which was sent to me from Sheffield for examination, contains from six to seven grains of carbonate of soda. One or two other samples have afforded me a somewhat larger proportion of soda.

The method which I employ to determine the quantity of carbonic acid gas present in the said water is peculiarly simple and sufficiently precise. I fasten in the hole of the head of one of Mohr's cork-borers a bit of stiff iron wire, an inch long, to serve as a handle to turn it by. I now force the borer half through the cork of the soda-water bottle, without loosening its wire fastening, then pass over it a soft flaccid ox bladder, and after expelling all its air, I bind the mouth of the bladder firmly round the neck of the bottle with twine. I next work the borer down through the cork into the bottle, and then draw it back into the cavity of the bladder. In this operation the carbonic acid gas rushes into the bladder with explosive violence, and inflates it more or less. The bottle with the bladder held above it is now plunged into cold water, contained in a suitable vessel, and heated up to the boiling temperature. This must be done somewhat slowly, otherwise the thick glass of the bottle will be apt to crack. Whenever the whole of the carbonic acid gas has been expelled from the water, the neck of the bladder is to be tied tightly round above the cork, and its mouth may then be disengaged from the bottle. The bladder is now to be placed in a jar, and water at 60° F. poured over it, till its surface is level with the lip of the jar, the bladder being kept immersed by means of a slender rod. On opening the mouth of the bladder, the gas is expelled by the water pressure, and the level of the water falls. Water out of a graduated cylinder is poured into the jar till it rises to the brim, the quantity of which is the measure of the gas contained in the soda-water.

I have found that the average volume of gas is 12,000 grainmeasures in a bottle containing on an average 4000 grain-measures of water, that is, thrice the volume of the water, or two volumes by condensation with the pump, in addition to the one volume which the water absorbs without pressure. One sample of sodawater afforded 13,500 grain measures of gas.

The Chairman then drew the attention of the meeting to a specimen of

PRESENTED BY JOSEPH HOULTON, M.D.

Who thus describes the plant :

I send for the museum a specimen of Melilotus Cærulea-the Trifolium odoratum of the old botanists. This elegant plant, which is a hardy annual, was well known to the herbalists in the days of Gerard, but it has for very many years been a scarce plant. It is a native of Germany, but was cultivated in this country as an ornamental and a medicinal plant, and known by the herb women in Cheapside by the name of Garden Balsam. It was esteemed on account of its styptic properties. Cases of bloody urine from violent contusions are said to have been wonderfully relieved by the internal use of its juice. It is said to be cultivated in Switzerland, and used there to give the peculiar flavour to cheese; and that it is employed as tea in Silesia. The whole plant, when dry, is very fragrant, and has been used to keep moths from the drawers in which it is placed; it will retain its odour for some years. From this property, perhaps, it is named in France Le Trefle Musqué. I obtained the seed, from which I raised the plant, from D. Price Esq., Surgeon, at Margate, who first directed my attention to it. I have had no experience of its medicinal properties, but think it deserves a fair trial. It is still used by one house in London, in the preparation of an oily remedy for burns.

87, Lisson Grove.-August 8, 1842.

Melilotus Cærulea, or Trifolium Odoratum.

A drawing of

COLCHICUM AUTUMNALE*

Was exhibited, with the following remarks,

BY JOSEPH HOULTON, M.D.:

I beg leave to show to the meeting of the members of the PHARMACEUTICAL SOCIETY a drawing of colchicum autumnale. The drawing is a faithful portrait of a specimen that was gathered by my friend and late pupil Frederick Barham, Esq., now of Osnaburg Street, a gentleman well versed in medical botany. He gathered the plant at Fressingfield, in Suffolk, where it grows spontaneously, and in great abundance. The specimen, with several others, came packed in wet moss, and arrived in town in a very fresh state, and the drawing was taken on the same day, May 30, 1831, by E. J. Pasquier, under my direction. The upright leaf was traced upon the paper. I do not know that we have a published figure of the plant at this period of its duration.+ The old cormus is seen in a shrivelled state; its coat is carried quite away from it, and is on the outside of the base of the new plant, which part is seen to be protuberant with the new cormus.

87, Lisson Grove, 8th August, 1842.

Mr. Payne thought it right, before the meeting adjourned, to make an allusion to the School of Pharmacy, which would open again in October. As no Pharmaceutical Meeting would take place next month, he took the present opportunity of expressing a hope that the lectures would be well attended. The meeting had heard Dr. Thomson's favourable report of the attendance at the Botanical Lectures, but he hoped that during the ensuing session the number of pupils would be more than doubled. This, he said, was not too much to expect, when the importance of the subject is considered, and also the number of Associates and Ap prentices who reside within reach of the School. He would particularly allude to the lectures on Practical Pharmacy, a subject of great importance to the Pharmaceutical Chemist, and one. which he believed had not hitherto been taught in this country in a separate course of lectures. Mr. Payne had pleasure in giving notice that Dr. Lankester would deliver a lecture on Botany, on August 24th.

The Chairman then adjourned the meeting until October 12th.

See Plate, page 130, fig. 1. The cormus in fig. 1 is smaller than the average size. Fig 2 represents a cormus also drawn from nature.-ED.

[In Brandt and Ratzeburg's Deutschlands Phancrogamische Giftgewächse is a beautiful coloured representation of the colchicum in fruit, as large as life, and a small woodcut of the same is given by Dr. Pereira, in his Elements of Materia Medica.-ED.]