MOLECULAR DYNAMICS. 373 



stroyed ; if the characteristic manifestations of life have disappeared, 

 it is not because they are really extinguished, but because they have 

 been one after another turned back by the paralyzing action of the 

 poison. In that motionless body, back of that lack-lustre eye, with all 

 these semblances of death, sensibility and mind still persist intact ; 

 what looks to be a dead carcass hears and knows all that goes on 

 around it ; it feels pain when its body is pinched or burned; it still 

 has feelinsr and will, but it has lost the instrument needed for mani- 

 festing them. The movements which are most expressive are the ear- 

 liest to disappear — first voice, then the movements of the limbs, those 

 of the face and the thorax, and lastly the movements of the eyes. 



Is it possible to conceive a more dreadful torture than that endured 

 by a mind which thus witnesses the privation of its organs one after 

 another, and shut up, as it were, in the fullness of life within a corpse? 



MOLECULAE DYNAMICS. 



By L. E. CUETISS. 



DYNAMICS refers to force or power. It deals with the primary 

 conceptions of energy in its relations to subjects that are suscep- 

 tible of numerical estimation, such as time, space, and velocity. Or, 

 again, dynamics is that branch of science which measures the energies 

 producing motion as Avell as those produced by motion, and is divided 

 into two parts — kinematics, which pertains to motion without regard to 

 the bodies acted upon ; and kinetics, which refers to the cause of ener- 

 gies whereby motion is given to bodies, each of which is the antithesis 

 of static energy or energy at rest. Molecular dj^namics has for its 

 domain the actual working forces inherent in the atoms and molecules 

 of matter. This branch of the subject bears the same relation to phys- 

 ics as the differential calculus does to mathematics, and by thus dealing 

 with the physical molecules and atoms we are enabled to extend the 

 kinetic chain of causation down toward the infinitely small with a cer- 

 tainty almost parallel to the accuracy with which the integral calculus 

 defines the motion of the planets. 



The text-books teach us that one of the properties of matter is iner- 

 tia, including both that of rest and that of motion, the former being 

 defined as the passive condition of bodies Avhen at rest. This definition 

 refers to matter as a mass. The new philosophy, however, teaches 

 that, since molecular motion refers to the invisible movements of the 

 particles of the mass, there is no such thing as complete rest of the 

 ultimate particles of matter short of absolute zero of temperature, which, 

 if universal, means total frigidity of every sun and orb in the universe. 



The current of scientific thought tends to demonstrate that all the 



