Serpentaria (Virginia Snakeroot). Note our remarks under Senega and

Jeffersonia.

Senecio (Life Root.) We mention this because of the fact that the common name leads to the impression that the root of the plant is the part used in medicine. The evident intent of the devisors of the name is to remind one of The Root of Life as applied to the excellence of its qualities. The herb is used in making the Eclectic preparations, and it should be fresh. Solanum (Bittersweet). Note our remarks under Celastrus Scan

dens.

Solomon's Seal. This is not likely to be mixed with or substituted for other drugs, but, through deterioration from age, and the attacks of insects and worms, it is likely to be absolutely worthless. A short time only is necessary for this sugar-bearing drug to become alive within itself, and it should never be carried over to the second season. (See phytolacca, parsley, etc.)

Statice Caroliniana (Marsh Rosemary). We include this drug because of its historical record. When Samuel Thomson was tried for murder, the charge being that he had killed one or more persons with a violent drug, Lobelia, he declared that the preparation employed was not Lobelia, but Marsh Rosemary. Experts testified to the contrary, but Manasseh Cutler settled the matter in Thomson's favor by identifying the substance under consideration as Statice, or Marsh Rosemary, which testimony secured Thomson's freedom.

Trilliium (Birthroot or bethroot). Many are the species and varieties of Trillium found in the section of the country that furnishes the drug, and all are gathered indiscriminately and sold under the name Trillium trifolium. Few who read this article would be willing to attempt to differentiate in any way between these various Trillium roots which are used indiscriminately by the majority of consumers and dealers.

Viburnum (High Cranberry). Note our remarks on Eupatorium, which apply alike to the Viburnums. Viburnum Opulus was employed long before Viburnum prunifolium was introduced, and came to be known under the name Viburnum. The introduction of prunifolium complicated the matter, and in order that there might be no confusion, we determined to use the name Black Haw for Viburnum prunifolium. This overcame the aforenamed confusion.

Viburnum prunifolium (Black Haw). The bark of all species of Wild Haw native to the country that supplies the drug for the market, is collected by root diggers, and sold under the name Black Haw.

An Expeditious Method for the Determination
of Arsenic Trioxide.*

By Charles E. Caspari and Leo R. A Suppan.

The usual method recommended for the determination of arsenic trioxide consists in dissolving the material under examination in water with the aid of sodium bicarbonate and from the amount of iodine required to oxidize the sodium arsenite to arsenate, calculating how much arsenic trioxide was present. This method is recommended by the United States Pharmacopoeia of 1890 and also by the 8th Revision and as it stands in these two books, it is open to two objections. In the first place it requires a very long time to dissolve 0.1 gram of arsenic trioxide in water with the help of 1 gram of sodium bicarbonate, ten hours being frequently required even with the aid of gentle heat and then some of the bicarbonate is converted into carbonate which reacts with iodine, producing high results for the amount of arsenic trioxide present. In the second place if solution be accelerated by using a higher temperature, more carbonate is formed and the same difficulties are encountered.

We have had frequent occasion to determine arsenic trioxide and it seemed to us desirable to have a rapid method which was at the same time accurate. The results in this paper will show whether we have succeeded. It has been suggested that the arsenic trioxide be dissolved in sodium hyroxide, in which solution takes place very readily that then carbon dioxide be passed into the solution until all the sodium hydroxide has been converted into sodium bicarbonate. Theoretically this is a good solution of the problem, but practically it is tedious because it requires much time to convert the last trace of hydroxide into bicarbonate. For this reason, then, this method is rejected.

Three different methods suggested themselves to us. All of these were tried and all gave the same results. First, the arsenic trioxide

Read before the Scientific Section of the Atlantic City meeting of the A. Ph. A.

is dissolved with the aid of heat in dilute hydrochloric acid, to the solution a slight excess of sodium hydroxide is added, the excess of sodium hydroxide neutralized with sulphuric acid and an excess of a saturated solution of sodium bicarbonate added. The solution is then titrated with a standardized solution of iodine. Second, the arsenic trioxide is dissolved in a dilute solution of sodium hydoxide with the aid of heat, the solution is cooled and neutralized with sulphuric acid, an excess of a saturated solution of sodium bicarbonate is added and then the solution is titrated as usual. Third, the arsenic trioxide is dissolved in a saturated solution of sodium bicarbonate at the boiling temperature, the solution is cooled and any carbonate which may have been formed is converted into bicarbonate by sulphuric acid, an excess of the saturated solution of sodium bicarbonate is added and the titration with the solution of iodine effected as usual. The determinations according to each of these methods were made on the same sample of arsenic trioxide with practically identical results. These results with more details concerning the methods follow.

It was our desire to experiment on a sample of arsenic trioxide of high purity and this was kindly given us by the J. T. Baker Chemical Co. of Easton, Pa., whom we take this opportunity of thanking for their kindness and courtesy.

Two gravimetric determinations were made of the purity of this sample in order that we might have a standard by which to judge the results of our methods. The gravimetric method was the usual one, that is the arsenic was precipated as sulphide, washed with pure carbon disulphide, dried and weighed. 0.5002 gms. of the sample yielded 0.6188 gms. of arsenic trisulphide, corresponding to 99.49% of arsenic trioxide.

0.5100 gms. of the sample yielded 0.6313 gms. of arsenic trisulphide, corresponding to 99.55% of arsenic trioxide.

The mean of these two results showed that the sample on which we were working contained 99.52% arsenic trioxide.

By our first method a weighed quantity of the sample is dissolved in 20 c. c. of a 10% solution of hydrochloric acid and 20 e. c. of distilled water by heating on a hot plate, care being taken to avoid boiling, which would entail a loss, as at that temperature arsenous chloride which is present in the solution is volatile. As soon as solution has been effected and the solution has cooled, a

few drops of phenolphalein are added and enough of a ten per cent. solution of sodium hydroxide is added to produce a distinct alkaline reaction. The color of the solution is just discharged with sulphuric acid. Now, there are present in the solution sodium arsenite, sodium chloride, a little sodium sulphate and a small quantity of sodium bicarbonate formed from the carbonate that was contained in the sodium hydroxide. To the solution are added 20 c. c. of a saturated solution of sodium bicarbonate, and it is then titrated with a standardized iodine solution. The standard solution of iodine used for all the determinations contained in this paper was of such a strength that 1 c. c. was equivalent to 0.00499 gms. of arsenic trioxide. The following are the results of ten determinations by the above method:

It will be observed that the maximum and minimum results obtained are 99.74% and 99.58% respectively, the difference being 0.16%.

By our second method a weighed quantity of the sample mixed with 20 c. c. of distilled water is heated almost to boiling on the hot plate and while still hot small portions of a ten per cent. solution of sodium hydroxide are added until solution of the trioxide is effected. By operating in this way any bumping incident to the boiling of the sodium hydroxide is avoided. After cooling, the alkaline solution is neutralized with sulphuric acid, using phenolphthalein as an indicator. After adding 20 c. c. of a saturated solution of sodium bicarbonate, the solution is ready to be titrated in the usual manner. Ten determinations by this method yielded the following results:

The maximum and minimum results are 99.72% and 99.58% respectively and the difference is 0.14%. The average of these determinations is identical with that of the ten determinations made according to the first method.

The third method consists in dissolving a weighed quantity of the sample in 20 c. c. of a saturated solution of sodium bicarbonate at the boiling temperature, cooling the solution, neutralizing it with sulphuric acid, using phenolphthalein as an indicator, adding 10 c. c. of the saturated solution of sodium bicarbonate and titrating as usual. This method yielded the following results in ten determinations:

The maximum and minimum results are 99.73% and 99.54% respectively and the difference between them is 0.19%.