MR. HENRY ON THE COMPOUNDS OF TIN AND IODINE. 367 



of water of crystallization, and several works of character do not give the composi- 

 tion of the crystallized salt at all, it became necessary to analyse the salt used in the 

 above experiments ; it was obtained by digesting strong hydrochloric acid with tin 

 in excess at a moderate heat, and when a tolerably concentrated solution was ob- 

 tained, decanting it and setting it aside to crystallize ; the strongly acid mother-liquor 

 was again digested with the tin and took up a fresh portion (it appears impossible to 

 saturate hydrochloric acid with tin at once). The salt was in small prismatic crystals 

 and dissolved in water, after drying on blotting-paper, forming a perfectly clear solu- 

 tion, and producing a great degree of cold ; 700 grs. dissolved in 3oz. of water re- 

 duced the temperature from 58° to 27° Fahr. 



The crystals were coarsely powdered and pressed as dry as possible in bibulous 

 paper; 25 grs. were dissolved in water acidulated by sulphuric acid, and the tin pre- 

 cipitated by sulphuretted hydrogen, the protosulphuret washed and dried, weighed 

 17*23 grs. ; 16*2 of these were ignited in a porcelain crucible, and the ignition, repeated 

 with a little carbonate of ammonia, gave 15-6 grs. of peroxide ; this corresponds to 

 16-59 on the total quantity of sulphuret, which is equivalent to 1309 of metal. 



The excess of sulphuretted hydrogen was removed by a little sulphate of copper, 

 and the chlorine, precipitated by nitrate of silver, gave 30-94 grs. of fused chloride of 

 silver =7'72 chlorine. 



To determine the water, 23*58 grains were retained in vacuo over sulphuric acid 

 for twenty-four hours, and were found to have lost 3-87 grains = 16-41 per cent. ; we 

 have therefore — 



99-65 100-00 112-4 



The following table contains the principal analytical results of this communica- 

 tion : — 



Protiodide of tin . . . SnI, solid and fixed, sparingly soluble. 

 Periodide of tin ... Snig, solid, volatile, decomposed by water. 

 Chloriodide of tin . . . SnCl, SnI, solid, fixed, decomposed by water. 



March 28, 1845. 



MDCCCXLV. 3 C 



