160 
Mr Levy , Some New Platinocyanides. 
Urcmyl Platinocyanide. 
Most uranyl salts and most platinocyanides are fluorescent. 
Uranium compounds, being radio-active, emit radiations which are 
capable of making platinocyanides fluoresce. Uranyl platino- 
cyanide should therefore prove interesting for a double reason. 
The salt was prepared by double decomposition between the 
calculated quantities of uranyl sulphate and barium platino- 
cyanide. After filtering off the precipitated barium sulphate, a 
green solution remained which gave the reactions for uranyl and 
platinocyanide ions. On allowing this solution to evaporate in 
a desiccator at ordinary temperatures, red crystals with strong 
green metallic reflexion are obtained. If the solution is evapo- 
rated on a water bath imperfect crystals of a yellow colour are 
left. This yellow form, when cooled, passes into the red-green 
form. These two forms may therefore be enantiotropic modifica- 
tions of the same substance or they may be differently hydrated 
forms. In view of the great tendency of many platinocyanides to 
form several brightly-coloured hydrates (cf. magnesium, hydroxyl- 
amine and hydrazine salts), the latter explanation is probably the 
correct one. 
The red-green modification is transformed into the yellow form 
at a temperature of 39° C. On passing a current of dry C0 2 over 
the powdered red-green modification the colour changes to 
greyish-black and no further change takes place. The loss of 
weight is very small. This grey powder still turns yellow on 
warming. I intend the further investigation of this salt and hope 
to publish the results in a subsequent communication. 
