Natural History. 193 



watered on the 5th of May with two ounces of water, containing 

 twelve grains of corrosive sublimate. Next day they looked un- 

 healthy ; the leaves had drooped, and the stalk had become of a 

 yellow brown colour ; an equal quantity of the same solution was 

 added to them. On the 7th of May the plants were quite dead ; the 

 stems were yellow, and the leaves dry and faded. The leaves, put 

 into water, gave a solution containing mercury. 



A branch of a rose-tree, with two or three half-expanded roses, 

 had its extremity immersed in a similar solution of corrosive sub- 

 limate. On the second day, the leaves became discoloured here 

 and there, the external petals had faded, but the flower had opened 

 a little more ; twenty-four grains of solution had been absorbed. 

 Next day, the discoloration was more extensive, and the leaves 

 seemed very unhealthy ; on the fourth day the discoloration of 

 the leaves was almost complete, and the branch was dry ; the cen- 

 tral petals were deepened a little in colour, but had not faded. 

 Thirty-two grains of solution, or half a grain of the poison, had 

 been absorbed. 



On the 1 Oth of May, a hole was made in a cherry-tree, penetrat- 

 ing to its pith ; a few globules of mercury were introduced, and 

 the hole closed up, so that air or water could not enter. The 

 tree was perfectly healthy on the 10th March, 1825*, not having 

 suffered in the slightest manner. 



Tin. — April 13th, a branch of a rose-tree, with two or three 

 half-expanded flowers, was put into a solution of muriate of tin, 

 of similar strength with the preceding solutions ; on the 1 5th, 

 striae of a yellow brown colour had appeared along the fibres of 

 the leaves ; on the 16th, the leaves were yellow, and the branch 

 dead. The leaves, steeped in water, gave a solution containing 

 tin. Muriate of tin affected bean plants in the same manner as 

 muriate of mercury. 



Copper. — The roots of a bean plant were withdrawn from the 

 earth, and placed in a vessel containing a solution of sulphate of 

 copper, in the proportion of the former solutions ; in twenty-four 

 hours the leaves of the plant had faded entirely. Reference is 

 made to an experiment by Mr. Phillips (Annals of Philosophy, 

 xviii. 76), in which a young poplar was killed by watering it with 

 solution of copper. A knife, employed to cut a branch off this 

 tree, had the copper precipitated on its surface. 



Lead. — The roots of bean plants were introduced into solution 

 of acetate of lead, of the preceding strength ; on the second day, 

 the lower leaves faded ; on the third day, the plant was dead. 



The same result was obtained with muriate of baryta. 



Bean plants, introduced into solution of sulphuric acid, in three 

 times its weight of water, began to droop in a few hours, and in 

 twenty-four hours were entirely faded. 



* Probably some mistake. The paper was read 16th Dec. 1824. 

 Vol. XX. O 



