[ 426 ] 



LXXL On the Action of Iodine and Fluosilicic Acid. Bi/ 

 M. Varvinsky, Engifieer in the Russian Mines*. 



IT appeared to me probable that action would occur be- 

 tween iodine and fluosilicic acid gas, on account of the 

 weakness of the affinities of the elements of the gas for each 

 other; and I imagined that some new compound would be 

 formed by these two bodies. I connnunicated this idea to 

 Dr. Ure of Glasgow, and he kindl}^ allowed me to verify it 

 by experiment in his laboratory ; the results of these trials 

 were as follows: on causing fluosilicic acid gas, evolved from 

 a retort, to mix with the vapour of iodine which was formed 

 in the receiver adapted to the retort, 1 observed that the re- 

 ceiver became lined with a white crust. When the action had 

 evidently ceased, I took off" the receiver and poured water into 

 it; a portion of silica was immediately precipitated in a ge- 

 latinous state, and I obtained a yellowish solution, the colour 

 of which was attributable to an excess of iodine, for by eva- 

 poration it became perfectly colourless. The solution was fil- 

 tered, and being strongly acid it was saturated by the addition 

 of carbonate of ammonia ; carbonic acid was liberated with ef- 

 fervescence, and at the same time silica was deposited. I took 

 the precaution of adding excess of carbonate of ammonia, so 

 that on filtering the liquor it was found to be alkahne (A). 

 On evaporating this solution in a platina crucible to the con- 

 sistence of a syrup, 1 saw with surprise that it not only gra- 

 dually lost its alkalinity, but that although it originally re- 

 stored blue colours which had been reddened, it became even- 

 tually perfectly acid. Lastly, on carrying the evaporation still 

 further, I obtained some beautiful small crystals, or rather 

 plates, of a bright golden yellow colour. The crystals pos- 

 sessed the property of an acid, for they reddened blue vege- 

 table colours; they were more soluble in hot than in cold 

 water, and with a strong solution of potash they formed a ge- 

 latinous salt of a very disagreeable taste. 



In order to determine whether fluoric and iodic acids were 

 present in these crystals, I treated a solution of them with ni- 

 trate of barytes; this salt produces a precipitate with difli- 

 culty, and not without the assistance of heat. Solution of 

 starch mixed with another portion of the solution, produced 

 no chann-e in It, unless sulphuric acid was added ; in this case 

 the blue colour denoted the presence of the iodine. 



May it not be concluded from these experiments, that fluoric 

 and iodic acids are both contained in these crystals, and that 



* Communicated by the Author. 



they 



