CHAP. II. FUNCTION OP NUTRITION. 197 



" pure colour." But as the colours in contiguous com- 

 partments will differ less and less from each other as 

 we extend our circles, it will not be necessary that we 

 should proceed further than we are able readily to ap- 

 preciate their difference. Now it is considered that 

 the third circle of twelve colours will satisfy the re- 

 quired purpose, and these we name the fundamental or 

 " basial " colours of our scheme. Their composition 

 is expressed in our diagram (fig. 154.), and the usual 

 names employed to designate them would be 



B. Blue. 



2 B + R. Bluish Purple, or Purplish Blue. 

 B + R. Purple. 

 2 R + B. Reddish Purple, or Purplish Red. 



R. Red. 



2 R + Y. Reddish Orange, or Orange Red. 

 R + Y. Orange. 

 2 Y + R. Yellowish Orange, or Orange Yellow. 



Y. Yellow. 



2 Y + B. Greenish Yellow, or Yellowish Green. 

 Y + B. Green. 

 2 B + Y. Bluish Green. 



(184.) Pure Colours. It may be here observed 

 that if the three colours purple, orange, and green, 

 or any other three taken at equal intervals round a cir- 

 cle constructed on the above principle, had been assumed 

 as our three primaries, and these had been combined 

 two and two, we should have obtained all the pure 

 colours as before, and among them the three former 

 primaries (blue, red, and yellow) under the character 

 of binary compounds. This will be apparent when we 

 recollect that the union of three primaries in equal pro- 

 portions forms white light with the colours of the 

 spectrum, and a grey or neutral tint (N), when ma- 

 terial colours are employed. 



Now, Green + Orange=(B + 



Orange -t-Purple=(R+Y) + (B+-R) = (B + R + Y) + R=N+ R. 

 Green+ Purple=i;B+ Y; + (B-t- R}= (B + R + Y) + B = N + B. 



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