392 Mr. C. A. Schunck. A Photographic Investigation 



teristic of each were then selected and photographed together as 

 depicted in the plates. In no case on dilation were any further 

 bands observable, and in all I find this particular distinctive absorp- 

 tion situated between the lines F and L in chrysophyll, carotin, and 

 chlorophyll, and in the other derivatives between the lines Gr and L, 

 the mean position of the bands being situated at the K/a line, varying 

 sometimes slightly towards red and in others towards the violet. 

 The main difference in my procedure to that of Tschirch is that I 

 have made use of artificial light in the place of direct sunlight. By 

 this means I have been able to reproduce the bands as regards their 

 definition and their relative intensity in a far more distinct manner, 

 and though my photos, do not extend so far as his, mine going to Q 

 and his to S, yet as the cha.racteristic absorption does not extend 

 further than M this is not of great consequence. 



Chlorophyll, Chrysophyll and Carotin. 



The chlorophyll solution was prepared in the usual way. Fresh 

 leaves were extracted with boiling alcohol, and the solution filtered 

 off from the fatty deposit which usually forms on standing. When 

 the solution is diluted so that in the normal chlorophyll spectrum of 

 four bands only the characteristic one in the red is visible when 

 received by the spectroscope, and a photograph is now taken, three 

 bands are found lying between the lines F and K/s (Plate 3, figs. 

 1 and 2). The first two bands are the bands usually numbered 

 5 and 6 of the normal chlorophyll spectrum, and can be seen on 

 dilution by the eye when sunlight is used, and the first one, 5, when 

 artificial light is used. But the third band in the violet, having its 

 centre situated about the line h, has not, I believe, been observed 

 before. In weaker solutions still, one only gets a general absorption 

 in the ultra-violet, no further bands being discernible. As is well 

 known, chlorophyll solutions prepared from the leaves of different 

 plants vary slightly in their absorption spectra, which depends 

 upon the amount of acid present in the leaf. In the spectrum of 

 the purest chlorophyll solutions, the fourth band situated about the 

 line E is extremely faint ; the purer the solution the fainter it it 

 but where the least trace of an acid is present this band appeal 

 darker than the third, situated between the lines D and E, and 01 

 the solutions standing becomes darker still, while the third become 

 fainter, and has moved further away from the red end. If, how- 

 ever, a chlorophyll solution be exposed to the action of dim 

 sunlight for a few hours until the colour has become brown, or if 

 few drops of a strong acid, as hydrochloric, be added, and the solutioi 

 be allowed to stand for a few days, a further change in the spectral 

 takes place, by the formation of a fifth band situated between the lin< 



