Page:Micrographia - or some physiological descriptions of minute bodies made by magnifying glasses with observations and inquiries thereupon.djvu/367

Rh hardning and tempering of Steel, endeavour'd to be shewn and explicated by several Reasons and Experiments: the reason of the colours on ''Lead, Brass, Copper, Silver, &c. other'' Instances of such colour'd bodies in animal substances: several other distinguishing Observations. Des Cartes Hypothesis of Colours examin'd. An Hypothesis for the explication of light by motion, indeavoured to be explicated and determined by several Reasons and Experiments: three distinguishing Properties of the motion ''of light. The distinguishing Properties'' of a trasparent Medium [that there seems to be no Experiment that proves the Instantaneous motion of light] the manner of the propagation ''of light through them. Of the'' homogeniety and heterogeniety of transparent Mediums, and what effects they cause on the Rayes of light, explicated by a Figure: an Examination of the refraction of the Rays by a plain Surface, which causes Colours. An Examination of the like effects produced by a spherical Surface: the use that may be made of these Experiments, for the examination of several Hypotheses of Colours. Des Cartes Hypothesis examin'd. Some ''Difficulties taken notice of in it. What'' seems most likely to be the cause of colour: that propriety is indeavoured 62 [sic]to be shewn in a Glass ball: that the reflection is not necessary to produce Colours nor a double refraction: the Hypothesis further examined, both in the pellucid Medium and in the Eye. The definitions of Colours; and a further explication and examination of the Proprieties of laminated Bodies; by what means they conduce to the production of Colours.

Observ. 10. Of Metalline Colours.

That all Colours seem to be caus'd by ''refraction. An Hypothesis consonant'' ''hereunto, explicated by Figures. How'' several Experiments, of the sudden changing of Colours by Chymical Liquors may be hereby explicated: how many wayes such Chymical Liquors may alter the colours of Bodies. Objections made against this Hypothesis of two colours only, indeavoured to be answer'd, by several Reasons ''and Experiments. The reason why'' some Colours are capable of being diluted, others not: what those are: that probably the particles of most metalline Colours are transparent; for this several Arguments and Observations are recited: how Colours become incapable of diluting, explicated by a ''Similitude. An Instrument, by which'' one and the same coloured Liquor at once exhibited all the degrees of colours between the palest yellow and deepest red: as likewise another that exhibited all varieties of blues: several Experiments try'd with these ''Boxes. An Objection drawn from the'' nature of Painters colours answered: that diluting and whitening a colour are different operations; as are deepening and blackening: why some may be diluted by grinding, and some other by being tempered with Oyl: several Experiments for the explicating of some former Assertions: why Painters are forced to make use of many colours: what those colours are: ''and how mixt. The conclusion, that'' most coloured Bodies seem to consist of transparent particles: that all colours dissoluble in Liquors are capable of diluting: some of mixing, what a strange variety may thereby be produc'd.

Observ. 11. Of the Figures of Sand.

Of the substances and shapes of Rh