274 CAPTAIN W. DE W. ABNEY ON THE COLOUE 



Similarly the following equations were found : 



329 RS GS V 



(23) 100 = 18-8 + 45-3 -f 35'9. 



339-6 ES GS V 



At 380 the violet was of the same hue as further in the spectrum. 



This completes the observations made in the spectrum with the provisional violet 

 sensation. It now remains to show how the composition of the violet was 

 determined. 



(XVIII.) Determination of the Composition of the Violet. 



A slit was placed at SSN 205 and another at SSN 345, and mixture made to 

 match a violet at SSN 400, to which white was added. 

 The equation was 



B R V W 



33 + 15-2 = 21-2+ 27, 



V E BS 



21-2 = 15-2 + 6, 

 or 



V ES BS 



(28) 100 = 717 + 28-3. 



Other equations made at 230, 235, 240, 250, gave the following : 



V RS BS 



(29) 100 = 70 + 30. 



V ES BS 



(30) 100 = 72 + 28. 



V RS BS 



(31) 100 = 74-5 + 25-5. 



V RS BS 



(32) 100 = 73-5 + 26-5. 



