l6 Upon ilie variegated Colours of Bodies^ cj'c 



fluence than that of any humid matter, all of them nearly 

 in an equal degree, the concentraled acid however excepted^ 

 which gave some difference ; but all these effects ceased al- 

 most in the same manner upon drying. 



When the exterior orbit of the eye was moistened, its yel- 

 lowish colour became of a lively blood red colour, and the 

 reflection, primitively green in consequence of its obliquity, 

 ■was almost extinct. If we moistened the green space withm 

 the circle, it was the violet reflection which this time disap- 

 peared. Lastly, by the smoking muriatic acid, this same 

 green space gave perpendicularly a yellow colour strongly 

 inclining to the red, and the oblique reflection at first a 

 green and afterwards a violet colour: at no time did any q£ 

 these alterations continue. 



Upon also moistening the extremity of the tail feathers 

 of a turkey, J obtained some new and very lively colours, ' 

 which we could not previously see in the same direction, 

 but the existence of which was indicated to me by certain 

 reflections against the light, analogous to what I have men- 

 tioned w hen speaking of the feathers of the duck. 



It was impossible for me, after all these particularities, 

 to persist in ranging, under one and the same system, the 

 chanffi^ablc colours of the feather and those of the coloured 

 rings of pellicle?. An examination of the latter, several 

 times repeated, induced me to think that tliey might proceed 

 from the super- position of several coloured matters, some- 

 times of two only, or of three or any greater number, nearly 

 as if, wishing to paint a body of several colours, we should 

 cover it successively with a coat of each of the proposed in-r 

 gredients. 



This supposition, properly adapted to each pert of Ijie fea- 

 thers, accounts very feasibly for all the appearances we ob* 

 serve in them. 



In short, if, for example, upon a coat of painting, formed 

 upon a green substance, we spread in a thin coat a violet 

 colour not very abundant, it will be evident that upon look- 

 ing perpendicularly at the painted surface it will appear al- 

 most uniformly green, while upon lowering the eye to ren^ 

 der the visual rays more and more strong, the colour will 



become 



