840 PROFESSOR PIAZZI SMYTH ON COLOUR, 
4. Judson’s Dyes—PURPLE—continued. 
Solution= 5}, strength. 
Wave-number | Colour Region by 

Intensity. in Brit. inch. Wave-number. 
Light begins 0 34 626 | Crimson RED 
Maximum Rep Licgut 2 37 651 | ScaRLET 
Light ends 0 39 417 | OraNGE 
Light begins again 0 56 054 | BLUE 
Farnt Maximum BLuE 1 59 701 | VIOLET 
End all 0 61 935 | LAVENDER 
Solution=, strength. Shows one red band only. 
Light begins. ‘ ; : : . 0 25:26 34 095 | Crimson RED 
Maximum Rep LicHt ; 4 P : iL 25°43 36 456 | Rep 
Endall . ; ; : : : 0 25°53 37 779 | SCARLET 
5. DIDYMIUM NITRATE. 
Solution= 3. Like water; nearly colourless, or with only a pale pinkish hue ; Yet 
makes many notable black lines and bands in spectrum. 

ae ier te Wave-number | Colour Region by 
Tikes ne % in Brit. inch. | Wave-number. 
Light begins : : : : 0 a 25°01 30 883 | Crimson RED 
Dak badd Ist side. ; : Res ase 25°24 33 830 | Crimson RED 
2d side E Fe 3 25°30 34 626 | Crimson RED 
Light near this line : : sale 
Maximum Rep Licut . : : 5 ae 25°85 41 494 | AMBER 
Salt line, from illuminating flame . Ste a8 26°00 43 103 | YELLOW 
Faint shade begins ; 1 26°00 43 103 | YELLOW 
Stronger shade begins . 3 26°06 43 687 | YELLOW 
Central strong black line 5 26°10 44 072. | YELLow 
End of that line group : me 3 | 26:13 44 366 | YELLOW 
Maximum GREEN LicHtT , : 7 coe || eOue 44 743 | YELLOW 
: Istedge ‘ us. Bec, A” 265 48 567 | GREEN 
BEDS EOIN) Oa as 4 | 2657 | 48 733 | GREEN 
. Ist edge . es iat 26°65 49 407 | GREEN 
Very faint haze band | Balad Be i. Gane 
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