Fittig and Wurster, who discovered atrolactic acid, C_{2}H_{10}O_{3}, an isomer of tropic acid, gives tropic acid the second formula, while Burgheimar and myself have shown that it is the true formula of atrolactic acid. Lately we have succeeded in performing the complete synthesis of atropic acid, and the artificial preparation of atropine has been greatly facilitated since I have shown that we can easily reconstruct atropine by starting from its products of decomposition, tropic acid, and tropine. Before my researches nothing was known of the constitution of tropine. New unpublished researches into this problem have shown that it closely resembles neurine,[1] a body which I hope will speedily lead us to the complete synthesis of atropine. [Footnote 1: As we shall probably hear a great deal about this alkaloid, it may be as well to state that, although found in the brain and liver, it may be prepared synthetically by the action of ethylene oxide, (CH_{2})_{2}O, water, H_{2}O, and trimethyiamine, N(CH_{3})_{3}. Its constitution is that of trimethyl-ethylene-hydrate-ammonic-hydrate, and has the following constitutional formula: { (CH_{2})_{2}OH { CH_{3} N { CH_{3} { CH_{3} { OH or in other words, it is the hydrate of trimethyl-hydrethylene-ammonium.] The fusing point of atropine is not 194° F., as stated by Planta, but 237° F. Crystallized from not too dilute alcohol it forms crystals which are aggregations of prisms. Toluene, alcohol, and chloroform all dissolve atropine readily. Its double gold salt is very characteristic. It is generally precipitated in the form of an oil which solidifies rapidly and may be crystallized from hot water after the addition of a little hydrochloric acid. This clouds in cooling, and after a certain time it separates in small crystals of indeterminate form which unite in warty concretions. After drying the salt forms a dull powder, melting between 275° F. and 280° F. It also melts in boiling water, and its aqueous solution exposed to the light is partially reduced, 100 grammes of water acidulated with 10 cubic centimeters of 1.190° solution of hydrochloric acid dissolves 0.137 gramme of the gold salt at 136° F. to 140° F. I should fancy that the above particulars are sufficent to completely differentiate atropine from all the other mydriatic alkaloids. II.--THE ATROPINE OF DATURA STRAMONIUM.