CHEMICAL SCIENCE. 195 



munication of vibratory motion through the ether ; that, as upon that 

 theory, an incandescent body, maintained at incandescence, would 

 eventually compel a cold body in its presence to come up to its own 

 temperature, by making its particles execute movements like those of 

 its own, so the sunshine, or the flash of an electric spark, compels a 

 vibratory movement in the bodies on which its rays fall ; that these 

 movements are interfered with by cohesion in the case of solids, but 

 that they are instantly established and almost as instantly cease in the 

 case of gases and liquids ; that reducing the cohesion of a solid, by 

 raising its temperature, permits a resumption of the movement ; and 

 that the condition of opacity, either melantic or otherwise, is a bar to 

 the whole phenomenon. 



SULPHATE OF IODO-QUIXIXE. 



Ix March last, Dr. Herapath announced the discovery of a beautiful 

 crystalline compound, possessing the optical properties of the tourma- 

 line, and even in a superior degree to this mineral. It also, at certain 

 angles of rotation, would act as selenite, viz., depolarize a ray. 



This remarkable body was procured in the following way : About 

 10 grains of di-sulphate of quinine (ordinary sulphate of quinine) were 

 dissolved in half a fluid ounce of pure acetic acid, and gently warmed ; a 

 spirituous solution of iodine was then cautiously added, a few drops at 

 a time ; the whole again gently heated to dissolve the cinnamon- 

 brown precipitate first produced, and the mixture set aside for several 

 hours to crystallize. When these crystals were examined by reflected 

 light, they were found to possess a brilliant emerald-green color, 

 similar to murexide, or the fragments of the elytra of cantharides ; but 

 by transmitted light, they were almost colorless and transparent, 

 having a slight olive-green tint only. The forms of these crystals are 

 very various ; prismatic plates, parallelepipeds, rhomboidal parallelo- 

 grams, and hexagonal plates very perfect ; but by very careful mani- 

 pulation and slow crystallization, the author obtained large compound 

 plates composed of many flat prisms, joined edge to edge, and all in 

 the same plane ; by which means he was enabled to produce crystals 

 large enough to furnish his microscope with artificial tourmalines, and 

 to perform all the experiments usually exhibited by the polarizing 

 microscope. Upon submitting this substance to chemical analysis, he 

 discovered the fact of its being a compound of iodine, sulphuric acid, 

 and quinine ; many experiments prove that all these constituents are 

 absolutely essential to its production, and the removal of either will 

 destroy the compound. These crystals are exceedingly small and 

 delicate, requiring considerable magnifying to show their remarkable 

 optical character. When placed upon the selenite stage, or a thin 

 film of mica, in a beam of polarized light under the microscope, they 

 exhibit the most vivid and beautiful colors. Even without any polariz- 

 ing apparatus, they serve very well to demonstrate the phenomena of 

 polarization, for when two of the crystals are crossed, at right angles, 



