The: Ff ae pi 
| 4 52 hardning and tempering of Steel, 
: endeavour d to be hewn andexplica- 
ted by feveral Reafons and Experi- 
ments: the yeafon of the colours:on 
i | 5 3 Lead, Brafs, Copper, Silver, Ke..other. 
Inflances of fuch colour'd-bodies ix 
animal fubftances: feveral other di- 
—sftinguifhing Obfervations. Des Cartes 
54 Hypothefis of Colours examin'd.: An 
Hypothefis for the explication, of 
light by motion, indeavoured tobe 
a explicated and determined by.feve- 
«+55 ral Reafons and Experiments : three 
_ diftingnifhing Properties of the moti- 
56 Of light. Tbe dijtinguifbing Broper= 
ties of a trafparent Medium {that 
there feems to be no Experiment that 
"proves the. Infiantancows motion. of 
7 light | the manner of the propagati- 
on of light through them. Of the ho- 
-omogeniety avd heterogeniety of 
tranfparent Mediums , and what ef- 
fe&s they canfeon the Rayes of light, 
58 nation of ‘ther cfrattion of the Rays 
by a plain Surface, which caufes.Co- 
lours, An Examination of the like ef- 
feEs produced by a fpherical Surface : 
the ufe that may be wade of thefe Ex- 
periments , for the examination of 
feveral Hypotheles of Colours. Des 
60 Cartes Hypothefis examin'd. Some 
61 Difficulties taken notice of in it. What 
feenes moft likely ta be the a of ¢o- 
“fours that propriety 7s indeavoured 
92 10 be hewn ina Glafs ball: that the 
reflection is not neceffary to produce 
63 Colours nor adouble refrattion : the 
: is er examined,both in 
64 the pellucid Medium aud in the Eye. 
‘The definitions of Colours;and a fur- 
65 ther explication and examination if 
66 the Proprieties of Jaminated Bodies 5 
67 by what means they conduce to the 
produttion of Colours. 
Obferv. 10. Of Metalline Colours. 
63 © That all Colours feem tobe cans d by 
refradion. .AnHypothelis confonaut.. 
hereunto,explicated by Figures. How 69 
Jeveral Experiments, of the fudden 
changing of Colours by Chymical Lim - 
quors, may be hereby explicated : how 70 
many twayes fuch Chymical. Liguers 
may alter the colours of Bodies; © 
Objettions made againft this Aypo=7t 
thefis of two colours only,indeavour- 
ed t0 be: anfirer'd, by fever al Reafons) 
and Experiments. The reafon why 72 
fome Colours are capable of beingdi- 
luted,others not : what thofe ares that 
probably the particles of moft, metal- 
Line Colours are tran{parent 5 for this. 
Several Arguments.and Obfervations, 
are recited : how Colours become in-.73 
capable of diluting, explicated by.a 
Similitude, An Inftrument, by which 74 
one andthe fame coloured Liquor. at 
once exhibited all the degrees of co- 
lours. between the paleft, yellow and 
| deepal eda. Leif another that. 
explicat ed bya Figure: .an-Exami- | exbi 
ibited all varieties of blues: fe- 
veral Experiments try d with the ba 
Boxes, An Objedion drawn from the 75 
| nature of Painters colours anfwered: 
that diluting and whitening a colour 
are different operations 3 as are 
deepening and blackening: why fome 
may be diluted by grinding, and fome 
orher by being tempered with Oylr 
feveral Experiments for the explica- 76 
ting of fome former Affertions : why 77 
Painters are forced to make ufe of ~ 
colours : what thofe colours are : 
and how mixt. The conclufion, that 78 
moft coloured Bodies feem to confift 
of tran{parent particles : that allco- 79 
lours diffoluble in Liquors are capa- | 
a ftrange variety may thereby be pro- 
Obferv. 11. OF 
"pe ha lanes “ahi 
of pipers : 
Shapes. of 8a 
COMMON — 
- 
