1 10 W. West on a remarkable Analogy between 



while. Apple trees and Peaches remain green very late, often 

 till the end of November. Young Beeches never cast their 

 leaves till spring, — till the new leaves sprout and push them 

 off': in the autumn the beechen leaves turn of a deep chest- 

 nut colour. Tall Beeches cast their leaves about the end of 

 October."] 



But it is worth while to state that there grows with us (at 

 Naples) an exotic tree which preserves its deciduous leaves 

 almost to the end of the appearance of the new ones, and 

 consequently seems to confound itself with evergreen trees. 

 This species is the Salix babylonica, commonly called Salcio 

 piangente, or Weeping Willow. 



[I will now conclude this memoir in again endeavouring to 

 impress strongly upon the minds of my readers the great be- 

 nefits that may ultimately be bestowed on science by institut- 

 ing careful inquiries into the changes and periods of vegeta- 

 tion in different situations both at home and abroad, and by 

 comparing the results of their labours in various parts of the 

 globe ; and finally, in recalling their attention to the following 

 memorable words of the illustrious Swede : 



" Calendaria Florae quotannis conficienda sunt in quavis 

 provincial, secundum [Germinationem^Frondescentiam, [Efflo- 

 rescentiam,~] Fructescentiam, Defoliationem, observato simul 

 Climate, ut inde constet diversitas regionum inter se."] 



XVIII. On a remarkable Analogy between 'ponderable Bodies, 



and Caloric and Electricity. By William West.* 

 COME years have elapsed since the attention of chemists 

 *? was called, by Dulong and Petit, to the relation between 

 the specific heats and the atomic weights of simple bodies. 

 Their experiments and conclusions, though at first called in 

 question, have since been confirmed and extended by others. 

 The relation which they discovered has been variously ex- 

 pressed ; it was thus announced by themselves : " The specific 

 caloric of simple bodies is inversely as their atomic weights." 

 It has since been thus stated : " A given quantity of heat will 

 elevate the same number of degrees a portion of every simple 

 substance represented by its atomic weight." A third mode 

 is: " The specific heats multiplied by the atomic weights give 

 a constant quantity." This variety of expression deserves 

 notice, because it may have tended to obscure, if not to con- 

 ceal, the analogy between caloric and ponderable bodies, which 

 it is my purpose to point out. The analogy in question is 

 this : The quantity of caloric separable from, or combining 



* Communicated by the Author. 



