on Vegetables, with reference to their Temperature. 11 



temperature radiation, and conduction of the soil. The or- 

 ganic molecule of plants is not a mere compound atom, for it 

 is beyond the art of the chemist to create it synthetically. 



But, further, to meet objections of this kind, and convince 

 ourselves of the influence exercised by evaporation upon the 

 temperature of vegetable substances, we resolved to have re- 

 course to experimental proof of a direct nature. For this 

 purpose an experiment made by Dr. Hales (Statical Essays, 

 exp. 30) upwards of a century ago, was repeated with such 

 modifications as to suit our purpose. 



A green apple, about l± inch in diameter with a cluster 

 of leaves, was plucked from the 

 tree; and the stem introduced 

 through a cork into a glass tube 

 filled with water, to the lower 

 end of which a smaller tube was 

 cemented, the extremity passing 

 downwards into a cistern of de- 

 coction of logwood ; the appa- 

 ratus being supported in the ver- 

 tical position by a retort-stand, 

 as represented in the sketch; 

 and being found air-tight, the fol- 

 lowing experiments were made. 

 The temperature of the apple 

 was estimated at given intervals 

 with the thermo-electric pair, at 

 the same time the drying power 

 and elevation of the coloured 

 fluid in the smaller tube was ex- 

 amined, and the measures tabulated for the purpose of ex- 

 amining the connexion of these phenomena at a coup d'ceil. 

 A further experiment was then made by covering the apple 

 and its leaves with a delicate caoutchouc bag, so as to arrest 

 evaporation, and after a given interval examining the tempe- 

 rature of the fruit and elevation of the coloured fluid. These 

 experiments were repeated many times, but it is unnecessary 

 to adduce more than two series in this place. 



Table H. 



June 14th. An apple with twelve leaves, examined imme- 

 diately after collection at l h 45' p.m 



