298 Progress of Foreign Science. 



with small portions of an alcoholic solution of caustic potash, 

 there was instantly formed a very abundant yellowish, curdy 

 precipitate, composed of a mixture of hydrochlorate and acid 

 iodate of potash. The acid iodate, it ought to be observed, 

 exists only at the commencement. The saturation being con- 

 tinued and pushed to a slight alkaline excess, the liquid, which 

 was strongly coloured at a certain period of the saturation, 

 by the separation of the iodine of the sub-chloride, appeared 

 after some moments of repose above the saline deposit, 

 of a lemon-yellow colour, having the saccharine taste given to 

 it by the hydriodide of carbon, which it holds in solution, along 

 with the hydriodate of potash. We decant and wash the salts 

 several times with alcohol, to carry oiF the whole of the 

 hydriodide ; which is indicated by the alcohol ceasing to be 

 coloured. The salts are set to drain on a filter, and the liquid 

 is united to the other portions, after filtration. We evaporate 

 the liquid at a gentle heat ; the hydriodide crystallizes ; and 

 we separate it before the entire evaporation of the liquid, by 

 throwing it on a filter and washing it with cold water, till this 

 be no longer affected by nitrate of silver; a proof that the 

 hydriodide is freed from the hydriodate of potash which it 

 might have retained. We separate afterwards, by solution and 

 crystallization, the hydrochlorate from the iodate, which we 

 make use of, converting it into an iodide by fusion. 



M. Serullas afterwards contrived the following modification 

 of the process : Into alcohol of the above strength, mixed with 

 much more iodine than it could dissolve, he passed a current 

 of chlorine, which made the colour of the iodine speedily dis- 

 appear, whose solution was meanwhile aided by agitation with 

 a glass tube. The stream of gas having been continued some 

 instants after the disappearance of the iodine, the yellowish 

 liquor, considered to be then an alcoholic solution of chloride 

 and sub-chloride of iodine, was saturated in the same way as 

 the other, by an alcoholic solution of caustic potash, which 

 immediately determined the formation of the same yellow curdy 

 precipitate containing the same substances ; iodate, hydro- 

 chlorate of potash, and hydriodide of carbon in solution ; the 

 last in as large a proportion as by the process of mingling 

 alcohol with the chloride of iodine separately prepared. The 

 acid-iodate of potasli, which instantly falls down, from its inso- 

 lubility in alcohol, has, like iodic acid, a sharp and astringent, 

 but less intense taste than that of iodic acid. Its solution 

 merely reddens, without destroying, tincture of litmus. This 

 salt is less soluble than the neutral iodate of the same base ; 

 and its crystals, wlien slowly formed, present truncated pyra- 

 mids, whose base is a rectangular parallelogram, or small 

 prisms, with four very transparent faces, terminated by 

 pyramid of four faces. 



