OF ARTS AND SCIENCES. 91 



upon by dilute sulphuric acid, and then washed free from acid 

 and left in water, continued to evolve pure hydrogen for the 

 space of two months, at the ordinary temperature of the air ; 

 in considerable quantities, at the temperature of 60° or 70° 

 Fahr. ; and in lesser quantity, but without interruption, at 32°. 

 Professor Cooke conjectured that this was owing to the zinc 

 being thrown from the passive to an active state by the action 

 of the acid and of the antimony ; but Dr. W. F. Channing 

 attributed it to the galvanic action developed by the acid, in 

 partly detaching the crystals or particles of the antimony from 

 the zinc, so as to form galvanic circuits. 



Three hundred and ninety-sixth, meeting. 



March 14, 1854. — Semi-Monthly Meeting. 



The President in the chair. 



The Academy met at the house of George B. Emer- 

 son, Esq. 



The Corresponding Secretary laid before the Academy a 

 letter from Professor Peters, of Konigsberg, acknowledging 

 his election as Foreign Honorary Member of the Academy ; 

 a letter from the Museum of Practical Geology, London, ac- 

 knowledging the reception of the New Series of the Acade- 

 my's Memoirs to Vol. V. Part I., and Yols. I. and II. of the Pro- 

 ceedings ; letters from the Royal Institution, the British Mu- 

 seum, the Linneean Society, the Society of Antiquaries, and 

 Chevalier Bunsen, acknowledging the reception of Vol. V. 

 Part. I. of the Academy's Memoirs, and pp. 233 to 359 of 

 Vol. II. of the Proceedings ; and a letter from the Academy 

 of Natural Sciences, Philadelphia, acknowledging the recep- 

 tion of Vol. V. Part I. of the Academy's Memoirs. 



Professor Tread well made a communication " On the 

 Measure of Force." In the Newtonian theory, the measure 

 of force is the mass multiplied by the velocity, or as the mo- 



