Silver White is one of the names for Lead White, PW1. In the letters of Vincent Van Gogh, he mentions Silver White, or Blanc d'Argent. Cameo describes Silver White as a, " very pure basic lead carbonate imported from Paris". Over the ages, especially when lead white was one of the main whites, there have been different names for the locales of its manufacture (such as Venetian White, which was also a pure lead carbonate in its time). Cameo notes that in England Silver White was sometimes used as a name for zinc white as well as lead white, so it is best to double check historical sources if you come across this name.
A fuller discussion of lead white is found on the page for PW1, Lead White.
