P Salt could be a trademarked name.
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Azotyn amonianu platyny (2+) (1: 2: 2) Nr CAS: 14286-02-3
Nazwa: Amonian azotynu platyny (2+) (1: 2: 2)
Nr CAS: 14286-02-3
EINECS: 238-203-3
http://pl.alfachemsp.com/metal-catalysts/platinum-2-nitrite-...cccc
Platinum P Salt in ammonia
The system produces bright and adherent deposits of low stress.
Platinum P SALTTM is available as a solution in ammonia, which is then mixed with diammonium and disodium hydrogen phosphates to provide the plating bath.
https://matthey.com/en/products-and-services/precious-metal-...