Arsenious acid, Arsenic blanc, Arsenic oxide, Flowers of Arsenic (AsO_3) is commonly used as the only preparation in which it could be assimilated. In the Solutio Fowleri we find a combination with Kali carbonicum e Tartaro, a combination which allows to the Arsenious acid its full destructive power. Now comes Spiritus Angelicæ comp. and the pure chemical preparation smells like Theriac, but it ought hardly ever be allowed to add something to a pure chemical preparation in order to give it taste, color, and use. This Spir. Angel. comp. is made up of Anglica, Siordium, Juniper berries, Valerian, Camphor, and Alcohol, and Solutio Fowleri is prepared even to this day in the same manner, and ought therefore be expelled from every pharmacopoeia, especially as it is sure to spoil in the pharmacies if kept too long on the shelves. Looking, therefore, for a better preparation, I prescribe now for the last decade: [Symbol: Rx]. Arsen. albi. depurat. pulv., Kali carb. e Tartar. [=a][=a] [Latin: ezh]j., coque cum Aqua destill. lb 1/2 ad perfect. solutionem, refriger., adde aqua destil. q. s. ut fiat solutio [Latin: ezh]xii., Dein adde Brom. pur. [Latin: ezh]ii. This solution, which during first eight days is frequently shaken, becomes colorless in the fourth week, and is then ready for use. It must be kept in a dark, cool place. I will now give my reason for choosing Bromine as a combination. The study of mineral waters is an old pet of mine; many of them contain Arsenic in combination with Bromine, and are all well known for their roborating and alterating qualities. I begun, therefore, my experiments with minute doses of _Brom. arsen._; gradually these were increased, and I felt astonished what large doses were well borne, and how long I could use this preparation without injurious consequences. After a few drops of my solution I could prove Arsenic in all secretions, an experiment easily made by Marsh's test. Experiments on animals with toxic doses of either solution (Clemens and Fowler) showed that the same quantity _Arsenicum brom._ is less poisonous (one has to be careful with the selection of animals, as many of them, especially ruminants, bear very large doses of Arsenic without injury). My preparation gives a rapid, not destructive, but roborating action on every part of the body.