398 Prof. Bunsen on Cacodyl Cojnpoiinds containhig Platinum. 



These analyses conduct to the following formula for chlo- 

 ride of cacoplatyl : — 



3209-0 100-00 100-00 



The agreement between the carbon, hydrogen, and chlorine 

 found, and the numbers obtained by calculation, proves with- 

 out doubt that the following empirical formula, C4 H- As., Pt 

 CI Oo, is correct. It appears certain that this compound con- 

 tains an atom of water, not as water of crystallization, but in 

 another form, for the compound may be heated to 164° C. 

 without decomposition. At that temperature the colour is 

 changed to a citron yellow, and an atom of water is given oW, 

 which however is reacquired when the substance is boiled with 

 watei'. 0-9767 loses, by 210° C, 0-037, and no more, although 

 the temperature is raised to 240° C. The compound con- 

 tains therefore 3-79 per cent, of water, which corresponds to 

 1 atom, and can be replaced by I atom of ammonia. 



Bromide of Cacoplatyl. 

 This compound is formed when a hot solution of the chlo- 

 ride of cacoplatyl is mixed with bromide of potassium; the 

 crystals obtained are redissolved and recrystallized twice. 

 They possess great similarity to the chlorine combination, 

 and form small yellow needles by the quick cooling of the 

 aqueous solution; but when the solution is allowed to cool 

 oradually, the crystals formed are large, well-shaped, and co- 

 lourless. They are pretty soluble in hot, but only sparingly 

 soluble in cold water. They have a feeble acid reaction, are 

 inodorous, but possess a decidedly disagreeable arsenical 

 taste, which is bitter and astringent, and remains long on the 

 palate, suggesting alcarsin. At 120° C. they lose their water 

 and become yellow. At 240° C. this compound begins to be 

 decomposed, becoming gray at that temperature; and when 

 the heat is increased to 246° C. it melts into a black foetid 

 mass. At a higher temperature it takes fire in the air, and 

 burns like tinder, leaving the arseniuret of platinum in shining 

 scales. The analysis of this compound is equally simple with 

 that of the preceding chlorine compound, and is made by 

 combustion with oxide of copper; the anterior part of the 

 tube being filled with copper turnings. 



