294 Mr F. Marcet on the Action of Poisons 



experiments on the action of arsenic upon vegetables ;* and 

 Mr C. J. Th. Becker, whose work we have noticed in this 

 Journal, vol. i. p. 376, performed some experiments on the ac- 

 tion of prussic fluid upon plants ; but these authors have 

 scarcely, if at all, anticipated the curious results which are to 

 be found in Mr Marcels Memoir. 



1. Metallic Poisons. 



The first series of Mr Marcet's experiments was made with 

 metallic poisons, such as arsenic, mercury, tin, copper, and 

 lead, and he, in general, administered them to robust plants of 

 the Phaseolus vulgaris, or French bean. 



ARSENIC. 



Exp. 1. — Two or three plants of the French bean were 

 watered with a solution of six grains of oxide of arsenic in an 

 ounce of water. By two ounces of the solution, the plants 

 were completely withered at the end of twenty-four or thirty- 

 six hours, the leaves faded, and some of them had even be- 

 come yellow : an appreciable quantity of arsenic was afterwards 

 discovered in the leaves and stalk of the plant. 



Exp. 2. — A branch of a rose tree, with a flower at its ex- 

 tremity, just beginning to blow, was introduced into a similar 

 solution of arsenic, on the 31st March. On the 1st April, the 

 exterior petals of the flower had become flabby, and of a 

 colour slightly purple. Some of the petals were covered with 

 deep purple spots, and the leaves had begun to fall. It had 

 now absorbed ^gdths of a grain of arsenic. 



On the 3d April, the petals were still more flabby, and 

 much withered, their colour was of a deeper purple, and the 

 external petals were covered with purple spots ; the flower had 

 lost a portion of its smell, and the leaves were quite withered. 

 The next day the branch was perfectly dead, the plant having 

 absorbed altogether the Jjf'th part of a grain of oxide of arsenic. 

 The purple colour of the petals was found to vary in intensi- 

 ty, as the primitive colour of the rose was more or less deep, 

 or the rose itself more or less blown. 



Exp. 3. — On the 1st June, M. Marcet made a cut about an 

 inch and a half long in a lilac tree, whose stalk was an inch in 



* " Dissertatio Inavgnralis dcqffictibus arsenic i in varios organismos." 



