investigated in its Optical Relations. 285 



The crystals were discovered, exhibited, optically investigated, 

 and described by Herapath ; and indeed it was their having, by 

 transmitted light, a greater polarizing power than Wtbest tour- 

 maline, which principally claimed his attention. 1^ crystals 

 can easily be procured in the following manner. 



The disulphate of quinine of commerce is dissolved in hot 

 acetic acid, in the proportion of about ten grains to one. or two 

 cubic inches, and when the solution is cooled somewhat, a few 

 drops of a spirituous solution of iodine are added drop by drop ; 

 it is then allowed to remain some hours to get quite cold and to 

 crystallize. The crystals are then transferred in some of the 

 fluid upon glass, and are thus ready for examination as soon as 

 they are dried. In a later communication, Herapath gives the 

 formula (C 20 H 12 NO 2 + I) + SO 3 + 6HO. 



The results of two analyses A and B, and of the calculation C, 

 were — 



A. B. C. Atom. 



Iodine . . . 32-6092 31*453 124 3263 1 



Sulphuric acid 10*612 10-844 40 10-52 1 



Alkaloid . . 42-692 ... 162 quinine 42-63 1 



Water . . . 14-1764 ... 54 142152 6 



100-0896 380 99*9952 



As, however, the disulphate of the alkaloid obtained from the 

 dichromatic crystals by a later process had not quite the same 

 properties as the originally employed disulphate of quinine, 

 Herapath considers the basis not directly as true quinine, nor 

 yet /3-quinine or quinidine, since it approaches nearer to what 

 has been lately called 7-quinine ; three bodies, of which a-qui- 

 nine is a trihydrate, jS-quinine a bihydrate, and 7-quinine a 

 monohydrate of the radical C 20 H 12 NO 2 . 



As a somewhat complex expression would be needful for a 

 perfectly clear verbal description of the crystals of the new com- 

 pound of iodo-quinine now under discussion, I propose as a short, 

 easily used expression, the name Herapathite, in remembrance of 

 the discoverer, who also was the first to give an optical descrip- 

 tion of them. I follow in this the principle of specific nomen- 

 clature, which slowly but certainly will be extended and esta- 

 blished. In the present case, a simple specific name, and indeed 

 this very one, is still more desirable, since Dr. Herapath has 

 succeeded in applying crystal plates of the new body as " arti- 

 ficial tourmalines" between the eye and the eye-piece of the 

 microscope, an application which must certainly be called a real 

 addition to optical apparatus. 



In its optical relations, though mention is made of the metallic 

 green surface colour, like the elytra of cantharides, or murexide, 

 yet it was chiefly the phenomena of the dichroism by trans- 

 mitted light, or of the different absorptions, which were investi- 



