The Structure of Coloured Bodies. 193 



Colour and its relation to the Structure of Coloured 

 Bodies; being an investigation into the Physical 

 Cause of Colour in natural and artificial bodies, 

 and the Nature of the Structure producing it. 

 By Alexander Hodgkinson, M.B., B.Sc. 



{Received April 8th, iSSg.) 



Introduction. 



Colour has always been to me a subject of special in- 

 terest, and as far back as I can remember I began to collect 

 objects characterised by striking colour effects or possessing 

 some peculiarity of appearance produced under varying 

 conditions of illumination. In the course of years my col- 

 lection became extensive, and a voyage round the world 

 some twelve years ago enabled me not only to add to my 

 collection, but also gave me the opportunity of personally 

 obser\ang many natural objects of great beauty not to be 

 seen under the same favourable conditions away from their 

 native habitats. 



With the object of ascertaining the cause of the colour 

 of these various bodies — animal, vegetable, and mineral — 

 they have been submitted to different methods of examina- 

 tion. Miscroscopic investigation is, of course, essential for 

 discriminating the different parts of such structures ; but 

 alone, and as a mere amplifying appliance, the microscope 

 is inadequate for revealing the structural cause of colour in 

 most of the objects under consideration. Nor is this to be 

 wondered at, since the colours of all objects, whether 

 natural or artificial, are due to the suppression of certain of 

 the rays of light received from the source of illumination, 

 and such suppression is due either to so-called absorption 

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