OF THE SPECTRUM ON VEGETABLE JUICES. 
115 
which, under the green, yellow, and part of the orange rays, a narrow figure of very 
deep crimson was formed, and two rose-coloured spots appeared in a rose-coloured 
disc below the red. 
Dark orange-coloured nasturtium stained writing-paper the colour of prussian 
blue, the image impressed on which was a deeper shade of the same, extending from 
the lowest edge of the red to the end of the blue, while a still deeper tint appeared 
under the orange, yellow and green, with a point of maximum intensity in the lowest 
part of the yellow. There was a tendency to bleaching from the blue upwards, and 
below the other end of the spectrum two well-defined dark spots were surrounded 
by a paler blue penumbra (fig. 10.). 
The juice of the velvety petals of a scarlet geranium was very sensible to the ac- 
tion of light (fig. 11.), and stained white paper rose-colour. A deeper rose-coloured 
tint was impressed by the spectrum from the lowest edge of the red to the end of the 
blue, feeble in the red and deeper in the orange, while a crimson image extended 
from the zero point in the yellow to the end of the green ; the maximum of intensity 
was in the latter. Two crimson-coloured spots in a rose-coloured halo were strongly 
marked at some distance below the red. 
With the addition of acid this juice gave a scarlet tint to paper, and a darker 
scarlet image was formed from the middle of the yellow to the end of the indigo. 
Then a very dark scarlet oval appeared between the zero point and the upper edge of 
the blue, with a small point of maximum intensity on the upper part of the yellow. 
The orange and red rays had no effect, but a pale rose-coloured border surrounded 
the lower part of the figure, which became of a bluer tint and darker than the ground 
when dry. Two spots of scarlet were distinct at some distance below (fig. 12.). 
The juice of the petals of scarlet balsam in distilled water is another instance; it 
gave a pale scarlet tint to paper, and a lake-coloured image extended throughout the 
spectrum from a point considerably above the violet to below the spots, which were 
distinctly visible, though not sharp. The greatest intensity of colour and breadth 
were under the yellow and green. When a little sulphuric acid was added to the 
same liquid, the action was feeble above the blue rays, but a very broad dark image 
was formed under the orange, yellow and green rays ; possibly under part of the blue 
also, which gradually became nearly black, with a blackish red penumbra, surrounded 
by a broad border of bright scarlet of a deeper tint than the ground, passing under 
the blue and indigo at one end, and under the red at the other, while below the latter 
an indistinct appendage of a paler colour projected ; an insulated scarlet disc appeared 
still lower down, in which two spots were evident, though not sharply defined (fig. 13.). 
The breadth of the image was very remarkable, and it was so deeply impressed that 
there was little difference in its intensity on the two sides of the paper. On repeat- 
ing the experiment with a hot iron behind the paper, the figure was the same, only 
that the central part was brown and the border merely a paler shade of the same : a 
