384 



Of four others : 



Transpiration time. Boiling-point. 



Formic ether 0'51 1 55'5 



Acetic ether 0'553 74 ! 



Butyric ether 0'750 



Valerianic ether 0'827 133'5 



Judging from these last observations, the order of succession of in- 

 dividual substances in any natural series will be indicated by the in- 

 dividual transpirability of these substances, as clearly as it is by their 

 comparative volatility. Transpiration and boiling-point observations 

 may come thus to claim an equal interest. In carrying out the in- 

 quiry, it will probably be found advantageous to transpire the liquids 

 at a fixed temperature which is somewhat elevated. A large number 

 of substances are liquid at 1 00 C., of which the transpiration times 

 could easily be obtained. Slow transpiration and low volatility ap- 

 pear to go together, and both to be connected in a general way with 

 a heavy molecule. So also the annexation of constitutional water to 

 the hydrated acids and alcohols appears to impede the transpiration 

 of these substances. 



XX. " Electro-Physiological Researches. Eleventh Series. On 

 the Secondary Electromotor Power of Nerves, and its 

 Application to the Explanation of certain Electro-Physio- 

 logical Phenomena." By Professor C. MATTEUCCI. Com- 

 municated by General SABINE, Treas. and V.P.R.S. 

 Received June 2, 1861. 



(Abstract.) 



The object of this paper is to show by experiment that when a 

 . nerve is traversed by an electric current, it acquires in all its points 

 a secondary electromotor power, and consequently becomes capable 

 of producing in a conducting homogeneous circuit, whose extremities 

 touch any two points of that nerve, an electric current in an opposite 

 direction to that of the original current. This result is independent 

 of the vital properties of the nerves, but is affected in greater or less 

 degree by their physical condition. A similar effect indeed is pro- 

 duced by the passage of an electric current in all porous substances 



