_The eleventh_ Experiment, _about the Blackness of the Skin, and Hair of_ Negroes, _and Inhabitants of Hot Climates. Several Objections are made, and the whole Matter more fully discours'd and stated from several notable Histories and Observations_ (from the 151 to the 167.) _The twelfth_ Experiment, _of the white Powders, afforded by Precipitating several Bodies, as Crabs Eyes, Minium, Coral, Silver, Lead, Tin, Quick-silver, Tin-glass, Antimony, Benzoin, and Resinous Gumms out of Spirit of Wine_, &c. _but this is not Universal, since other Bodies, as Gold, Antimony, Quick-silver_, &c. _may be Precipitated of other Colours_ (168, 169, 170.) _The thirteenth_ Experiment, _of Changing the Blackness of some Bodies into other Colours_ (171, 172.) _and of Whitening what would be Minium, and Copper, with Tin, and of Copper with Arsnick, which with Coppilling again Vanishes; of covering the Colour of that of_ 1/3 _of Gold with_ 2/3 _of Silver melted in a Mass together_ (173, 174) _The fourteenth_ Experiment, _of turning the black Body of Horn into a White immediately with Scraping, without changing the Substantial form, or without the Intervention of Salt, Sulphur, or Mercury_ (176.) _The fifteenth_ Experiment, _contains several Instances against the Opinion of the_ Chymists _that Sulphur_ Adust _is the cause of Blackness, and the whole Matter is fully discuss'd and stated_ (from 176 to 184) Part the Third. _Concerning Promiscuous Experiments about Colours_. Experiment the First. _IN confirmation of a former Conjecture about the Generation of Colours from diversity of Reflections are set down several Observations made in a Darkned room_ (186, 187.) Experiment _the second, That white Linnen seem'd Ting'd with the Red of Silk plac'd near it in a light Room_ (188,189.) Experiment _the third, Of the Trajection of Light through Colour'd Papers_ (189, 190.) Experiment _the fourth, Observations of a Prism in a dark Room_ (191, 192.) Experiment _the fifth, Of the Refracting and Reflecting Prismatical Colours in a light Room_ (193.) Experiment _the sixth, On the Vanishing of the_ Iris _of the Prism, upon the access of a greater adventitious Light_ (194.) Experiment _the seventh, Of the appearances of the same Colour'd Papers by Candle-light_ (195, 196). Experiment _the eighth, Of the Yellowness of the Flame of a Candle_ (197). Experiment _the ninth, Of the Greenish Blew transparency of Leaf Gold_ (198). Experiment _the tenth, Of the curious Tinctures afforded by_ Lignum Nephriticum (from 199 to 203). _Several trials for the Investigation of the Nature of it_ (from 204 to 206.) Kircher's _relation of this Wood set down, and examin'd_ (from 206 to 212). _A Corollary on this tenth_ Experiment, _shewing how it may be applicable for the Discovering, whether any Salt be of an Acid, or a Sulphureous, and Alcalizate Nature_ (from 213 to 216).