26 



MATTER'AND ITS PHYSICAL PROPERTIES. 



deprived of all food, their condition becomes reduced ; they regain their spirit S 

 and activity, and amuse themselves in the pursuit of the more minute animals C 

 which are supplied to them ; they swallow these without depriving them of > 

 life, for, by the aid of the microscope, the one has been observed moving within I 

 the body of the other. These singular appearances are not matters of idle and > 

 curious observation. They lead us to inquire what parts are necessary to pro- * 

 duce such results. Must we not conclude that these creatures have heart, 

 arteries, veins, muscles, sinews, tendons, nerves, circulating fluids, and all the 

 concomitant apparatus of a living organized body ? And if so, how inconceiv- 

 ably minute must not those parts be ! If a globule of their blood bears the same 

 proportion to their whole bulk as a globule of our blood bears to our magnitude, 

 what powers of calculation can give an adequate notion of its minuteness ? 



These and many other phenomena observed in the immediate productions 

 of nature, or developed by mechanical and chemical processes, prove that the 

 materials of which bodies are formed are susceptible of minuteness which infi- 

 nitely exceeds the powers of sensible observation, even when those powers 

 have been extended by all the aids of science. Shall we, then, conclude that 

 matter is infinitely divisible, and that there are no original constituent atoms of 

 determinate magnitude and figure at which all subdivision must cease ? Such 

 an inference would be unwarranted, even had we no other means of judging 

 the question except those of direct observation ; for it would be imposing 

 that limit on the works of nature which she has placed upon our powers of 

 observing them. Aided by reason, however, and a due consideration of certain 

 phenomena which come within our immediate powers of observation, we are 

 frequently able to determine other phenomena which are beyond those powers. 

 The diurnal motion of the earth is not perceived by us, because all things I 

 around us participate in it, preserve their relative position, and appear to be at / 

 rest. But reason tells us that such a motion must produce the alternations of S 

 day and night, and the rising and setting of all the heavenly bodies — appear- / 

 ances which are plainly observable, and which betray the cause from which s 

 they arise. Again, we cannot place ourselves at a distance from the earth, ) 

 and behold the axis on which it revolves, and observe its peculiar obliquity to s 

 the orbit in which the earth moves ; but we see and feel the vicissitudes of the / 

 seasons, an effect which is the immediate consequence of that inclination, and J 

 by which we are able to detect it. 5 



So it is in the present case. Although we are unable by direct observation s 

 to prove the existence of constituent material atoms of determinate figure, yet / 

 there are many observable phenomena which render their existence in the s 

 highest degree probable, if not morally certain. The most remarkable of this / 

 class of effects is observed in the crystallization of salts. When salt is dis- ( 

 solved in a sufficient quantity of pure water, it mixes with the water in such a / 

 manner as wholly to disappear to the sight and touch, the mixture being one J 

 uniform transparent liquid like the water itself before its union with the salt. / 

 The presence of the salt in the water may, however, be ascertained by weigh- \ 

 ing the mixture, which will be found to exceed the original weight of the / 

 water by the exact amount of the weight of the salt. It is a well-known fact < 

 that a certain degree of heat will convert water into vapor, and that the same J 

 degree of heat does not effect any change in the form of salt. The mixture of J 

 salt and water being exposed to this temperature, the water will gradually / 

 evaporate, disengaging itself from the salt with which it has been combined, s 

 When so much of the water has evaporated that what remains is insufficient to / 

 keep in solution the whole of the salt, a part of it thus disengaged from the S 

 water will return to the solid state. The saline particles will not in this case / 

 collect in irregular solid molecules, but will exhibit themselves in regular fig- i 



