[551.] Definitio 3.

[552.] Experimentum 1.

[553.] Experimentum 2.

[554.] Experimentum 3.

[555.] Experimentum 4.

[556.] Experimentum 5.

[557.] CAPUT XIX. De Radiorum Coloribus & horum immutabilitate.

[558.] Definitio 1.

[559.] Definitio 2.

[560.] Experimentum 1.

[561.] Experimentum 2.

[562.] Experimentum 3.

[563.] Experimentum 4.

[564.] Experimentum 5.

[565.] Experimentum 6.

[566.] Experimentum 7.

[567.] CAPUT XX. De Colorum permixtione, ubi de Albore.

[568.] Experimentum 1.

[569.] Experimentum 2.

[570.] Experimentum 3.

[571.] Experimentum 4.

[572.] Experimentum 5.

[573.] Experimentum. 6.

[574.] Experimentum 7.

[575.] CAPUT XXI. De Iride.

[576.] J, R:: CL, CM:: C l, C m:: CL--C l = L l, CM--C m = M n.

[577.] BC, BL:: B b, B o. BC, BM:: B b, B p.

[578.] BL, BM:: J, 2 R.

[579.] Experimentum I.

[580.] BCq, BLq:: 8 Rq, Jq-Rq