Car. VILL] THE EFFECTS OF ACIDS. 159 
Nitric Acid.—Four leaves were placed, each in thirty minims of one 
part by weight of the acid to 437 of water, so that each reccived >}, of 
a grain, or 4°048 mg. This strength was chosen for this and most of 
the following experiments, as it is the same as that of most of the 
foregoing saline solutions. In 2 hrs. 30 m. some of the leaves were 
considerably, and in 6 hrs. 30 m. all were immensely, inflected, as were 
their blades. ‘The surrounding fluid was slightly coloured pink, which 
always shows that the leaves have been injured. ‘They were then left 
in water for three days; but they remained inflected and were evidently 
killed. Most of the glands had become colourless. Two leaves were 
then immersed, each in thirty minims of one part to 1000 of water; in 
a few hours there was some inflection; and after 24 hrs. both leaves 
had almost all their tentacles and blades inflected; they were left in 
water for three days, and one partially re-expanded and recovered. 
Two leaves were next immersed, each in thirty minims of one part to 
‘2000 of water; this produced very little effect, except that most of the 
tentacles close to the summit of the petiole were inflected, as if the acid 
had been absorbed by the cut-off end. 
Hydrochloric Acid.—One part to 437 of water; four leaves were 
immersed as before, each in thirty minims. After 6 hrs. only one leaf 
was considerably inflected. After 8 hrs. 15 m. one had its tentacles 
and blade well inflected; the other three were moderately inflected, 
and the blade of one slightly. The surrounding fluid was not coloured 
at all pink. After 25 hrs. three of these four leaves began to re- 
expand, but their glands were of a pink instead of a red colour; after 
two more days they fully re-expanded; but the fourth leaf remained 
inflected, and seemed much injured or killed, with its glands white. 
Four leaves were then treated, each with thirty minims of one part to 
875 of water; after 21 hrs. they were moderately inflected; and, on 
being transferred to water, fully re-expanded in two days, and seemed 
quite healthy. 
Hydriodic Acid.—One to 437 of water; three leaves were immersed 
as before, each in thirty minims. After 45 m. the glands were dis- 
coloured, and the surrounding fluid became pinkish, but there was no 
inflection. After 5 hrs. all the tentacles were closely inflected ; and an 
immense amount of mucus was secreted, so that the fluid could be 
‘drawn out into long ropes. The leaves were then placed in water, but 
never re-expanded, and were evidently killed. Four leaves were next 
immersed in one part to 875 of water; the action was now slower, but 
after 22 hrs. all four leaves were closely inflected, and were affected in 
other respects as above described. These leaves did not re-expand, 
though left for four days in water. This acid acts far more powerfully 
than hydrochloric, and is poisonous. 
lodic Acid.—One to 437 of water; three leaves were immersed, each 
in thirty minims; after 3 hrs. strong inflection; after 4 hrs. glands 
dark brown; after 8 hrs. 30 m. close inflection, and the leaves had 
become flaccid; surrounding fluid not coloured pink. These leaves 
were then placed in water, and next day were evidently dead. 
