226 IIO\V TO WORK 



will be better understood by a description of the spectrum of clc 

 oxidised hrematin. 



~ 



6 >_: 



"S -2 c - 



o" cq -~ w 



&J ^ ^ -s 







~I> 



O 



r^- 



2 



o > 'u 'S C u 



4l : -5 S3----6-J 9 io--- ii - 



The following examples will show how simple or more com- 

 plicated spectra may thus readily be printed and compared. I have 

 chosen solutions of similar tint, in order to show that the spectra of 

 those of nearly the same colour may be very different, or, if analogous. 

 may differ in details, easily expressed by the symbols. The colour 

 of each is given after the name. Nos. i, 8, 9, io, n, 12, and 13 

 can be kept for a long time, sealed up in tubes, and the rest are 

 easily prepared. In each case the spectra are those seen with 

 solutions of such a strength as gives the most decided results, and 

 shows the presence or absence of absorption bands to the greatest 

 advantage. 



1. Cudbear in alum (/"/';//') 3 ..... 3 i: . - 



2. Colour of elder berries with 1 , q 



citric acid. (Red Pink] J 



3. Brazil wood, with bicarbonate ~| # 



of ammonia. (Pink) / 4^ 5% ...... 8 



4. Logwood, with bicarbonate of "1 * 



ammonia. (Pink] J 3^ 5} ..... 7 



The next four are spectra of blood, produced by the successive 

 addition of the various reagents, as in detecting fresh stains. 



* * 



5. Fresh blood. (Pale Scarlcf) 3^43 4* 5f 7 8 - - 9 



6. Citric acid then added. 1 



(Pale Brown) J if ... 2$ 4 ... 8 ... 9 - - io 



7. Ammonia then added. I * * 



(Pale Brown) J 3| . . . 4| 4| . . . 5| 7 . . S - - - io 



8. Deoxidised hrematin, from ~| # 



blood stain 2 yrs. old. (Pink) J 4] 5 5i . '. . C4 9 . . io - - - 1 1 



