Chap. VIII.] THE EFFECTS OF ACIDS. 155 



Nitric Acid. Four leaves were placed, each in thirty minima 

 of one part by weight of the acid to 437 of water, so that each 

 received -^ oi & 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 hre. 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 b^n 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 al- 

 most 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 in- 

 flected, 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 moderate- 

 ly 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 

 M'ere moderately inflected; and, on being transferre<l to water, 

 fully re-expanded in two days, and seemed quite healthy. 



Hydriodic Acid. One to 437 of water; three leaves were im- 

 mersed as before, each in thirty minims. After 45 m. the glands 

 were discoloured, 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 hydro- 

 chloric, and is poisonous. 



Iodic 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 evident- 

 ly dead. - 



