1858 Mayne Expos. Lex. ,Platinoso-, a prefix employed by Berzelius in compound terms or epithets of double salts which result from the combination of a platinous salt with another metallic salt, as Platinoso-ammonicus, etc. 
1866 Watts Dict. Chem. IV. 667A dark brown solution supposed by Magnus to contain platinoso-platinic chloride. 
platinoso-
Prefix
- chemistry platinous