Cuar. VIL] SALTS OF POTASSIUM. 147 
Potassium, Sulphate of.—Balf-minims of a solution of one part to 
437 of water were placed on the discs of six leaves. After 20 hrs. 80 m. 
no effect was produced; after an additional 24 hrs. three remained 
quite unaffected; two seemed injured, and the sixth seemed almost 
dead, with its tentacles inflected. Nevertheless, after two additional 
days, all six leaves recovered. The immersion of three leaves for 24 
hrs., each in thirty minims of a solution of one part to 875 of water, 
produced no apparent effect. They were then treated with the same 
solution of carbonate of ammonia, with the same result as in the case 
of the nitrate of potash. 
Potassium, Phosphate of.—Half-minims of a solution of one part to 
437 of water were placed on the discs of six leaves, which were observed 
during three days; but no effect was produced. The partial drying up 
of the fluid on the disc slightly drew together the tentacles on it, as 
often occurs in experiments of this kind. ‘he leaves on the third day 
appeared quite healthy. 
Potassium, Citrate of —Half-ninims of a solution of one part to 437 
of water, left on the discs of six leaves for three days, and the immer- 
sion of three leaves for 9 hrs., each in 80 minims of a solution of one 
part to 875 of water, did not produce the least etfect. 
Potassium, Oxalate of.—Half-minims were placed on different occ2- 
sions on the discs of seventeen leaves; and the results perplexed me 
much, as they still do. Inflection supervened very slowly. After 24 
hrs. four leaves out of the seventeen were well inflected, together with 
the blades of two; six were slightly affected, and seven not at all. 
Three leaves of one lot were observed for five days, and all died; but 
in another lot of six all excepting one looked healthy after four days. 
Three leaves were immersed during 9 hrs., each in 30 minims of a 
solution of one part to 875 of water, and were not in the least affected ; 
but they ought to have been observed jor a longer time. 
Potassium, Chloride of.—Neither half-minims of a solution of one 
part to 437 of water, left on the discs of six leaves for three days, nor 
the immersion of three leaves during 25 hrs., in 80 minims of a solution 
of one part to 875 of water, produced the least effect. The immersed 
leaves were then treated with carbonate of ammonia, as described 
under nitrate of potash, and with the same result. 
Potassium, Iodide of.—Halt-minims of a solution of one part to 437 
of water were placed on the discs of seven leaves. In 30 m. one leaf 
had the blade inflected; after some hours three leaves had most of 
their submarginal tentacles moderately inflected ; the remaining three 
being very slightly affected. Hardly any of these leaves had their 
outer tentactes inflected. After 21 hrs, all re-expanded, excepting two 
which still had a few submarginal tentacles inflected. Three leaves 
were next immersed for 8 hrs. 40 m., each in 30 minims of a solution 
of one part to 875 of water, and were not in the least affected. I do 
not know what to conclude from this conflicting evidence; but it is 
clear that the iodide of potassium does not generally produce any 
marked effect. 
L 2 
