60 P. T. CLEVE, 



a very deep purple. The crystalline form of the polyiodide seems, nevertheless, to be 

 that of a regular octahedron; at least sotne crystals, as large as a pin's head, had this 

 form. The polyiodide is dissolved by water with some difficulty, and the solution has 

 an intense purplish-red colour. 



Analysis: the compound dried at 100°. 



1. a. 0,4095 gr. gave 0,osoo gr. metallic platinum 



b. 0,3702 gr. gave 0,5120 gr. ioclide of silver =0,2767 gr. iodine 



c. 0,3208 gr. gave 0,4477 gr. iodide of silver =0,2420 gr. iodine. 



2. a. 0,5065 gr. gave 0,1015 gr. platinum 



b. 0,5560 gr. gave 14 C. C. nitrogen (temp of water 18°, Bar. 762 m. m.) = 0,01615 

 gr. nitrogen. 



c. 0,4940 gr. gave 0,6930 gr. iodide of silver =0,3745 gr. jodine. 



The formula requires: 



Theory 1 Experiment 1 



a b c a b c 



Platinum 197,88—19,91 19,52 20,03 — 



Iodine 762,00—76,67 74,75 75,45 — — 75,65 



Nitrogen 28,oo — 2,81 — — — — 2,90 — 



Hydrogen 6,oo — — — 



993,88 



If treated with alkaline lye the polyiodide first assumes a brownish colour, Avhich 

 is soon changed into cinnabar. When heated with the alkaline liquid it dissolves with 

 a considerable evolution of ammonia, and becomes yellow. On adding hydroiodic acid 

 to the alkaline solution a black voluminous precipitate is thrown down and afterwards 

 the polyiodide crystallises. 



I2HO 



4. Nitrate, PtsNH 3 ~NH 3 .o.N0 2 ? A nitrate, probably of this composition, was ob- 



tained by boiling the chloride with nitrate of silver. Chloride of silver is precipitated, 

 but not completely, and the tiltered solution gives chloride of silver by evaporation 

 and with the vapours of water also some nitric acid. The solution was evaporated to 

 dryness in the water-bath and the remaining yellow mäss treated with water, which 

 dissolved the nitrate, leaving the chloride of silver. When alcohol was added to the 

 solution a voluminous uncrystalline yellowish-white mäss was precipitated. It was dis- 

 solved without difficulty in water and the solution again evaporated in the water-bath. 

 An amber-yellow, gum-like matter, was then obtained. 



The mäss dried at 100° was subjected to the following analysis: 



a. 0,387o gr. gave 0,2J60 gr. platinum 



b. 0,3865 gr. gave 43 C. C. nitrogen (teinp. of water 12° Barm. 755 m. ra. t. 18) 

 = 0,0501 gr. nitrogen. 



