NATURAL PHILOSOPHY. 113 



in size and weight. We shall have one substance and one common 

 atom. With the atom at rest, the uniformity of matter would be per- 

 fect; but the atom always possesses more or less motion due, it must 

 be assumed, to a primordial impulse. This motion gives rise to vol- 

 ume. The more rapid this movement, the greater the space occupied 

 by the atom, somewhat as the orbit of a planet widens with the degree 

 of projectile velocity. Matter is thus made to differ only in being 

 lighter or denser matter. The specific motion of an atoni being in- 

 alienable, light matter is no longer convertible into heavy matter. 

 In short, matter of different density forms different substances, differ- 

 ent incontrovertible elements, as they have been considered." " This 

 is not meant to be applied to the gaseous volumes which we have oc- 

 casion to measure and deal with practically, but to a lower order of 

 molecules or atoms. The gaseous molecule must itself be viewed as 

 composed of a group or system of the above-mentioned inferior 

 atoms, following as a unit, but similar to those which regulate its 

 constituent atom." We must refer our readers for details and for 

 the results of M. Graham's interesting speculations, merely adding 

 another expression of his hypothesis : "As in the theory of light we 

 h^ve the alternative hypothesis of emission and undulation, so in mo- 

 lecular mobility the motion may be assumed to reside either in sep- 

 arate atoms and molecules or in a fluid medium caused to undulate. 

 A special rate of vibration, or pulsation, originally imparted to a por- 

 tion of the fluid medium enlivens that portion of matter with an indi- 

 vidual existence and constitutes it a distinct substance or element. 



* 



THE TRANSITIONS OF MATTER. 



From a discourse recently delivered before the New York Academy 

 of Medicine, by that eminent scientist Dr. John W. Draper, we make 

 the following interesting and suggestive extract : 



f^ *TD *J 



No one can devote himself to the study of physical science and 

 especially of Chemistry without experiencing at once what might seem. 

 to be contradictory sentiments, pride and self-humiliation. Pride, 

 that he has been permitted to see so far as he does into the great 

 scheme of the universe ; humiliation, in recognizing how frail and insig- 

 nificant he is. 



What, then, are some of the latest truths that these physical senses 

 teach? They show us how transitory, how dependent we are. There 

 is a constant wear and tear of the human system. Particles that served 

 the purpose of forming it accomplish their office and die, and are 

 replaced in due succession by others. In this respect life is the result 

 of an aggregate of deaths. The atmospheric air into which all this 

 dismissed material eventually finds its way, is thus the cemetery of 

 animal substance, of things that have once been organized, but that 

 have lost their force, and lapsed into an inorganic, a lifeless state. 

 From this inorganic, this lifeless state, such substances are destined 

 to be recalled ; for, under the influence of the rays of the sun, car- 

 bonic acid and water and ammonia are decomposed, and taking the 

 products that arise from that operation, plants group them into organ- 

 ize;! portions a^.iin, and use t h n in t!i3 construction of their various 

 parts, leaves, ilovvers, stem?, fruits. Plants thus constitute the forma- 

 tive agents of the world of life. Animals are the destroyers. They 

 10* 



