Continuing with Turner’s watercolors, the book above mentions the substances found on Turner’s surviving watercolor palettes for binding the pigment:
various gum mixtures that generally tragacanth, arabic, cherry or sarcocolla, and traces of added sugar. Turner seems to have preferred hard watercolors rather than the soft ones. The hard watercolors don’t have the ease of use of the soft watercolors commercially available, which dissolve immediately with the addition of water. Reviving hard watercolors takes more time. I like to use both myself, depending on what I’m trying to do.
There’s a nice picture of a period watercolor box made by Reeves and Sons. It doesn’t say if it was used by Turner, but you can read the colors in the box: Prussian Blue, Indigo, Crimson Lake, Indian Red, Vermillion, Gamboge, Burnt Sienna, Yellow Ochre, Van (Dyck?) Brown, Burnt Umber.