Dr. Herapath on the Cinchona Alkaloids. 221 



class of salts produced by ethyle-quinine and ethyle-quiuidine, but 

 optically distinct from tbose of quinine and quinidine. He has already 

 produced three salts from ethyle-quinine, having optical characters 

 different from any previously described. 



I St. A deep purple-red salt by transmitted light, in thicker plates 

 or aciculse quite impervious to light. This salt occurs as very slender 

 acicular prisms ; it has a brilliant metallic-green reflected tint, but 

 very little double absorption. 



2nd. There is a foliaccous salt, having a plate-like form, a deep 

 red or orange-red colour, transmitting an orange-yellow, having only 

 slight optical powers. 



3rd. A salt having many of the characters of the new quinidine 

 salt when first produced, viz. the optical characters and the a-form ; 

 but on attempting to recrystallize it, the orange-red plates just de- 

 scribed are alone produced. 



The only salt yet produced from ethyle-quinidine is one very similar 

 to the red salt described above, but it has only been very partially 

 examined. The iodide ethyle-quinidine is a very beautiful silky salt, 

 less soluble than the iodide ethyle-quinine. The author is not aware 

 that it has yet been described. It is readil)' made by mixing an 

 alcoholic solution of quinidine with an etherial solution of iodide- 

 ethyle; on repose, the new iodide ethyle-quinidine separates in long, 

 slender, silky aciculse; and further crops can be repeatedly pro- 

 duced by diluting the original solution with water until precipitation 

 bee/ins to follow ; on long repose, the iodide crystallizes and may be 

 removed by filtration, and washed with dilute spirit. 



Note. — In reference to the rotatory power of the cinchona alkaloids, 

 the calculation of the molecular rotation gives an excellent plan of 

 deciding on the purity of the alkaloid employed ; for if the absolute 

 molecular rotation be obtained precisely identical with those given 

 by other optical chemists, the purity may be inferred as proved. 

 But it is possible for a large quantity of two alkaloids to be present 

 in solution, one dextro-, the other levo-gyrate, and in such propor- 

 tions that the polariscope shall give no indication of the presence of 

 either. 



Thus a highly concentrated solution of the acid sulphate of quinine, 

 marking a left-handed rotation of 57°*^^, was mixed with rather more 

 than double its bulk of a similar solution of quinidine marking 2\°^. 

 The resultant solution gave no rotation at all, the one eff'ect perfectly 

 neutralizing the other. 



In experimenting upon «OM-^More«eeM# solutions of quinine or qui- 

 nidine in the polariscope, it was found that these solutions were still 

 possessed of their original molecular rotation upon ])lane-polarized 

 light, even undiminished, if care were taken not to dilute the fluid 

 when destroying the fluorescence by the soluble chloride, &c., which 

 was always done by adding it in the solid state. 



" Sur la Relation entre les Courants induits et le Pouvoir Moteur 

 de I'Electricitc." By Professor Carlo Matteucci of Pisa. 



