About four grams of these crystals were dried in a glass-stoppered flask under a rapid stream of dry hydrobromic acid at a temperature varying between 100° and 120°. The average temperature was about 110, and the drying lasted continuously through three and a half days. After cooling, perfectly dry air was drawn through the flask for a little over ten minutes. This was supposed to be but was not long enough as the analysis showed that all the free hydrobromic acid had not been removed. It requires at least thirty minutes for thorough removal. The substance dried down to a hard, white, crystalline solid which was quite soluble in water. The composition of this salt was as

It is evident that the assignment of such a formula is largely guess work, but the cost in time and materials was too great for us to repeat the experiment.

Another experiment was carried out as follows:

One hundred cc. of forty-eight per cent. hydrobromic acid. solution were saturated with wet Zr(OH), by continuous boiling. The solution was never perfectly clear until it was twice filtered through compact filter-paper doubly folded. The clear yellow solution was concentrated by evaporation on the waterbath. The more concentrated it became the redder it was; finally the color was so deep that it appeared almost black. This was due to decomposition of the hydrobromic acid.

After concentration the liquid was cooled and white crystals separated out. On allowing it to stand twenty-four hours, or always when made too concentrated by further evaporation, a red jelly separated on top of these crystals. In trying to wash this jelly from around the crystals, for it was very soluble in water, the crystals were also dissolved. The whole was therefore redissolved and after several attempts a set of prismatic needles one to two mm. in length separated free from the jelly. This jelly was not silicic acid as feared. The mother-liquor was poured off, the crystals quickly washed three times with small amounts of water, dried between filter-paper, and analyzed:

The solution was further evaporated and another crop of needle crystals similar to, but much smaller than, the above obtained. They were washed four times in cold water, dried to a powder between filter-paper and analyzed :

An investigation of the gelatinous oxybromide of zirconium showed that it was a hydrogele.

On dialysis the small amount

of crystalline oxybromide present passed through the membrane. At the same time the gelatinous compound, if it may be so termed, slowly decomposed into zirconium hydroxide and hydrobromic acid, the latter gradually passing through the septum while the former remained behind.

III. ZIRCONIUM OXYIODIDES.

According to Melliss, zirconium oxyiodide is not formed by dissolving Zr(OH), in hydriodic acid. Hinzberg' secured an oxyiodide by precipitating a solution of zirconium sulphate with barium iodide in equivalent amounts. The solution was evaporated over sulphuric acid and the crystals washed with carbon bisulphide. The analysis gave ZrI(OH),.3H2O.

In our experiments we found that zirconium hydroxide, when precipitated cold, was soluble to a small extent in strong aqueous hydriodic acid or could be dissolved by passing hydrogen iodide into water in which the zirconium hydroxide was suspended. Evaporation of this solution over sulphuric acid or calcium chloride gave needle-like crystals strongly colored with iodine and very hygroscopic. Every attempt failed at getting these freed from excess of iodine and properly dried. Washing with ether or with carbon bisulphide was ineffective. A hydrogele was gotten by acting upon zirconium hydroxide with hydrogen iodide, which formed on drying a hard, horn-like, colored mass insoluble in water and acids. This contained: 1 Ann. Chem. (Liebig), 239, 253.

It lost only 11.07 per cent. of its weight after three hours' heating at 100°-120°.

UNIVERSITY OF NORTH CAROLINA.

ATROPINE PERIODIDES AND IODOMERCURATES.

BY H. M. GORDIN AND A. B. PRESCOTT.1

Received March 12, 1898.

I. ATROPINE ENNEAIODIDE.

T has been known for a long time that in solutions of atropine salts, as in those of the salts of most other alkaloids, a solution of iodine in potassium iodide gives an insoluble precipitate. The nature of this precipitate has so far as we know not been thoroughly investigated. Jörgensen has obtained and described two periodides of atropine: a triiodide and a pentaiodide. Our experience has taught us that in aqueous solutions the capacity of atropine for combining with iodine varies very widely, and the quantities taken up seem to depend upon the concentration of the liquids and even the order of mixing them.

The highest number of iodine atoms which a molecule of atropine can combine with, seems to be nine; between this and the above-mentioned triiodide lie the other compounds of atropine with iodine which are formed in aqueous solution. The same is true when chloroform is used as a solvent. We reserve for a later date a report upon the exact conditions which are necessary for the formation of any particular periodide of atropine. For the present we wish to say that under the conditions described below we were able to obtain the enneaiodide of atropine, C,,H,,NO,.HI.I,, as the sole combination of all the alkaloid, and sufficiently stable.

These conditions are the following: The concentration of the aqueous solution of the atropine salt should not exceed fivetenths per cent.; that of the iodine solution must not exceed one

1 In the work of Research Committee D, Section 2, Committee on Revision of the Pharmacopeia of the United States.

21. prakt. Chem. [2]. 3, 329.

per cent.; the latter has to be acidulated with some sulphuric or hydrochloric acid; the atropine solution must be added to the iodine solution and not vice versa, and this addition must take place in small portions at a time, shaking the mixture thoroughly after each addition. At first the liquid becomes very turbid and particles of iodine are seen to be floating upon its surface : on continued addition of the atropine solution and shaking, the iodine-colored turbidity disappears, a dark granular precipitate falls out, and the supernatant liquid becomes perfectly transparent but is still dark-colored. If the addition of the atropine be stopped at this stage, i. e., while the supernatant liquid has a very dark red color, the composition of the precipitate will be found to be that of the enneaiodide C,,H,,NO,HI.I.

Whether additional quantities of atropine will make the precipitate take up more atropine and become a lower periodide we shall try to determine by later experiments. On the other hand when the order is reversed and the iodine solution is added to the atropine solution, it is always a lower periodide that is formed; but whether on continued addition of the iodine the precipitate will take up more of it and become a higher periodide, we cannot say as yet.

The enneaiodide, obtained as described, being unstable while moist and when removed from its mother-liquor, the precipitate has to be collected quickly by means of a pump, washed a few times with cold water and dried first on porous plates and then in vacuum over sulphuric acid. As thus obtained it is a very dark brown almost black powder, quite permanent in dry air and has only a slight odor of iodine. It is very difficultly soluble in ether, chloroform, benzene, or carbon disulphide, but is soluble in alcohol, very freely when hot. In cold water it is insoluble; hot water decomposes it quickly; it is also decomposed by concentrated solutions of potassium iodide. At 90° C. it commences to give up iodine vapors and at 140° C. melts to a dark liquid.

To obtain it in crystalline form it is first washed with a little cold alcohol to remove traces of free iodine and then dissolved in warm alcohol. On cooling it crystallizes out in dark-green prisms and leaflets, having the same properties as the noncrystallized body.

In this enneaiodide one-ninth of the total iodine is firmly combined just as in normal hydriodides, while eight-ninths is easily removed by reducing agents, such as sulphur dioxide and sodium thiosulphate. The compound therefore may be considered an atropine hydriodide octaiodide.

The additive iodine we estimated volumetrically and the total iodine both gravimetrically and volumetrically.

To estimate the additive iodine a small quantity of the enneaiodide is dissolved in very little alcohol, an excess of a standardized solution of sodium thiosulphate added and the excess titrated back with a standard solution of iodine using starch as the indicator.

For total iodine the substance is covered with an excess of powdered metallic zinc and some water and then boiled gently for ten or fifteen minutes, taking care to prevent loss by spurting; the mixture is then thrown upon a filter, and the containing flask and the filter thoroughly washed with hot water. The iodine in the zinc iodide thus formed can either be estimated by precipitation with silver nitrate and nitric acid and weighing as silver iodide, or it is precipitated with an excess of a standardized solution of silver nitrate and the excess titrated back with a standard solution of ammonium thiocyanate, using ferric nitrate as indicator.

Having obtained the enneaiodide of atropine it was natural to suppose the existence of a heptaiodide, with probability of a complete series from the triiodide to the enneaiodide.

fact in the course of our work we once obtained this heptaiodide. But our efforts to determine the exact conditions necessary for the formation of this body have so far not been successful.

The easiest way to obtain the periodides of atropine is to use chloroform as a solvent. On adding twenty grams atropine to a warm solution of thirty grams iodine in chloroform (500 cc.) the enneaiodide crystallizes out very soon in the shape of small, shining, dark green crystals. If these be removed by filtration, the mother-liquor will give several successive crops of the dark blue pentaiodide and at last a crop of the brownish-red triiodide.

II. ATROPINE MERCURIC IODIDES.

The periodides of atropine, like those of many other alkaloids,