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



it was the biniodide therefore; with 380 grs. of the protochloride of tin and 150 grs. 

 of iodine, a precipitate was obtained, which was found to yield — 



Per cent. 

 Iodine 67/8 



Tin 31-67 



99-45 

 it was therefore protiodide of tin. 



The solution remaining after the precipitation of the protiodide was evaporated at 

 a gentle heat, until sufficiently concentrated, and allowed to cool; some crystals 

 were thus obtained which were freed as much as possible from the mother-liquor, by 

 pressure in bibulous paper, but on attempting to purify them for analysis by redis- 

 solving them in water, they were immediately decomposed, giving a scarlet crystal- 

 line precipitate of protiodide of tin, while chloride of tin remained in solution ; they 

 were therefore pressed as dry as possible in bibulous paper, and afterwards retained 

 in vacuo over sulphuric acid for some hours. 



10 grs. were then treated with a solution of pure carbonate of potash, evaporated 

 to dryness, redissolved in cold water and separated from the protoxide of tin by fil- 

 tration ; the solution acidulated with nitric acid, and the iodine precipitated by nitrate 

 of palladium while hot, the precipitate washed, dried, and ignited, left 1*94 gr. of 

 metallic palladium =4*586 grs. iodine. The chlorine was afterwards precipitated by 

 nitrate of silver; the precipitate, washed, dried, and fused, weighed 5*22 grs. ; upon 

 dissolving the chloride of silver in ammonia O'l gr. of metallic palladium was sepa- 

 rated, which had subsided with the chloride of silver as a subsalt ; this leaves 5-12 

 for the true weight of the chloride of silver =1*263 chlorine ; 5 grs. decomposed with 

 nitric acid in excess, evaporated to dryness and ignited, gave 2-68 grs. peroxide of tin 

 =2-108 of metallic tin. 



This gives in 100 parts — 



Theory. Per cent. Experiment. 



One atom chlorine = 35-4 or 1267 12*63 



One atom iodine =126 or 45*10 45*86 



Two atoms tin. .=118 or 42*23 42*16 



279*4 100-00 100-65 



It is therefore a compound of one atom of protochloride of tin, and one atom of prot- 

 iodide of tin. 



The excess in the quantity of iodine in the above analysis, is probably owing to the 

 tendency of the protonitrate of palladium to subside as a basic salt in company 

 with precipitates, which is a great objection to its employment in analysis. 



As the protochloride of tin is stated by Gmelin*, on the authority of Berzelius, 

 to contain one atom of water of crystallization, while the late Dr. Turner, in the last 

 edition of his Elements, published during his life-f-, states that it contains three atoms 



* Handbuch, vol. iii. 4^ Edit. y. p. 550. 



