In these wholesale samples, therefore, the percentage of mercury varied from 31 to 36 per cent. Traces of mercurous oxide occurred in 25 per cent. of the samples, and a trace of mercuric oxide in 8.3 per cent. of samples.

Mr. R. R. BENNETT said he was rather surprised that Mr. Simpson had made no mention in his paper of the hypophosphorous acid method of determining the percentage of mercury in the pharmacopoeial pill. It is generally admitted that this method is much easier of application than the old-fashioned combustion method, and is equally accurate. Mr. Bennett outlined the hypophosphorous method, which was originally published in The Pharmaceutical Journal.

Mr. F. H. ALCOCK asked the author of this paper what time was required for the complete performance of his method, for, whilst not doubting the accuracy of it, he was sure the hypophosphorous acid method suggested some years ago, and now referred to by Mr. Bennett, was certainly much more expeditious, and was quite safe in the hands of a novice, as he had recently proved, and the results when the process was properly conducted were more applicable to the needs of the busy pharmacist. There was no fear of explosions, to which reference had been made; there would not be waste of costly material, such as alcohol and ether; nor would so much attention and time be required. If the author was a retail pharmacist and used this process, he might have to leave it at a critical moment to serve some customer, especially if he happened to be singlehanded, as many are perforce now obliged to be.

Mr. DAVID ANDERSON remarked that he was surprised that so small a proportion of the samples examined contained traces of mercuric oxides, and since Dr. Attfield had stated that the therapeutical value of mercury pill was most probably due to the

traces of oxides present, it would be interesting to know which of the samples were the more active therapeutically.

Mr. D. MITCHELL asked if the author could suggest some other excipient to replace the confection of roses in this pill. He noticed that the majority of samples examined by Mr. Simpson were either hard or stiff, and only one sticky. His experience, on the other hand, was that the majority of the masses of Pil. Hydrarg. met with in commerce was too soft, and generally hygroscopic.

Mr. COWIE said, having had a little experience of this method of examination, he considered that Mr. Simpson had taken the safer but more laborious method. He never obtained really good concordant results with the hypophosphorous acid method, which was greatly improved by using an alkali hypophosphite and HCl instead of hypophosphorous acid. He considered the iodine absorption process superior to both in point of accuracy and time required. The difficulty in obtaining a uniform consistency of mass could easily be overcome by drying the confection of roses at a suitable temperature.

Mr. SIMPSON said, in reply to Mr. Bennett, that he had tried the hypophosphorous acid method for mercury and found it satisfactory with Hydrargyrum c. Creta or mercuric salts, but for galenicals containing such organic matter as Pilula Hydrargyri it gave very varying results. Mr. Alcock inquired what time the analysis took. He might say that he could comfortably carry out two determinations in three hours. With regard to the expense, that, where definite results were aimed at, was a detail even in Aberdeen. Further, his paper aimed at determining the quality of Pil. Hydrarg. and did not suggest a method of assay. Mr. Anderson suggest ed that the small number of samples containing Hg,O was rather curious. He knew it was supposed that the therapeutic value of this pill was due to traces of mercurous oxide, but in the former analyses of blue pill recorded they would find even fewer samples containing Hg2O. He had never had the temerity to resort to the practical method of discovering which of the samples was the most active therapeutically. In reply to Mr. Mitchell, he certainly considered that confection of roses and liquorice powder were very satisfactory excipients, and he could not suggest any more suitable. In an emergency he would suggest, where a certain weight of pill was wanted-the weight, the whole weight, and nothing but the weight-that if the

original mass be too soft it might be hardened with Hyd. c. Creta, which contained the same percentage of Hg.

THE ASSAY AND EXAMINATION OF COMMERCIAL SAMPLES OF MERCURIAL OINTMENT.

BY PHILIP H. CREWE.

The method generally employed for the assay of mercurial ointment consists in extracting the fatty base by repeated treatment with ether or some other suitable solvent, removing any soluble impurities by warming with dilute hydrochloric acid, and finally drying and weighing the residual mercury.

This method, which is now included in the United States Pharmacopoeia, gives satisfactory results, but it is ofttimes difficult to obtain the mercury in the globular form, on account of certain insoluble impurities preventing the coalescence of the finely divided metal. In the following process the ointment is warmed with an alcoholic solution of potassium hydroxide, and the saponified fat is removed by treatment with hot water. The results agree with those obtained by extraction with ether, the method is simpler, and the mercury is obtained in a more satisfactory form. The details of the method are as follows: About 20 grammes of the ointment are weighed into a beaker having a capacity of 300 mils; 10 grammes of potassium hydroxide and about 100 mils of methylated spirit are added, and the whole is warmed on a water-bath until the mercury collects in globules. Hot water is next added, and the solution of soap is carefully decanted from the mercury, which is then washed several times with hot water. The metal is washed with alcohol and then with a little ether, which is allowed to evaporate before weighing the mercury. If the globule be not quite bright, it should be treated with a little warm dilute hydrochloric acid in order to remove any impurities. The solvent action of alcoholic potash on mercury was determined by warming 11-019 grammes of the pure metal, to which had been added some lard, with a solution of potassium hydroxide, as described above. The loss in weight amounted to only 8 milligrammes, which calculates to less than a tenth of 1 per cent.

Tests were made of a number of samples of mercurial oint

ment in order to compare the article supplied by the wholesale houses with that obtained from retail chemists in different parts of the country. The author regrets that, owing to his unavoidable absence from the laboratory, a number of samples could not be assayed, but trusts that the results tabulated below may prove of interest to the members of the Conference. The majority of wholesale ointments were assayed both by the ether extraction and the saponification methods.

With the exception of Nos. 1 and 4, the wholesale samples may all be said to answer the requirements of the British Pharmacopoeia. Sample No. 1 was different in appearance from the other ointments; it was very much softer, and at a temperature of 75° F. could readily be poured from one vessel to another. Its behaviour with alcoholic potash suggested that the ointment had a petroleum base, and a subsequent examination confirmed this belief. The saponification value of the base was found to be about 11; and, taking that of lard as 190, there was a deficiency of fatty matter amounting to at least 94 per cent. As before stated, this ointment had a low melting point; the low percentage of mercury may possibly be explained by the fact that it was purchased during the prolonged spell of hot weather in July.

When purchasing samples Nos. 14 to 28 the official ointment was specified, and with the exception of Nos. 18 and 28, and possibly No. 15, they may be said to contain a satisfactory percentage of mercury. Two other samples, i.e., Nos. 29 and 30, were ordered simply as Ung. Hydrarg., and whereas in one case the B.P. ointment was supplied, the percentage of metal in the other was only one-third of that required by the official formula. Whilst not wishing to criticize the action of the pharmacist in supplying the dilute article when mercurial ointment was requested, it must be pointed out that the B.P. ointment only is recognized by the authorities responsible for the administration of the Foods and Drugs Act. This point has been further emphasized by the many prosecutions which have taken place under this Act during recent years. In order to protect himself, the chemist is required to state verbally, as well as on the label, when supplying the dilute ointment. It will be observed that of the four samples purchased as mercurial ointment not one is of B.P. strength; two of these were without labels, and a third did not specify the strength. In no instance was any