THE CONSTITUTION OF MATTER. 5 



comparatively unmeaning." And, to give an idea of the 

 minuteness of these particles, Tyndall adds that they might 

 be condensed till they would all go into a lady's traveling- 

 bag. Manifestly these particles escape any kind of direct 

 measurement arid observation. Their objective reality can 

 no more be demonstrated than that of the particles of ether 

 can be made evident. Yet there are certain facts which 

 aid us to form a clear conception of them. Let us dissolve 

 a gramme of resin in a hundred times its weight of alcohol, 

 then pour the clear solution into a large flask full of pure 

 water, and shake it briskly. The resin is precipitated in 

 the form of an impalpable and invisible powder, which does 

 not perceptibly cloud the fluid. If, now, we place a black 

 surface behind the flask, and let the light strike it either 

 from above or in front, the liquid appears sky-blue. Yet, if 

 this mixture of water and alcohol filled with resinous dust 

 is examined with the strongest microscope, nothing is seen. 

 The size of the grains of this dust is much less than the ten- 

 thousandth part of ^g- of an inch. Morren makes another 

 experiment, proving in a still more surprising way the ex- 

 treme divisibility of matter : Sulphur and oxygen form a 

 close combination, called by chemists sulphuric-acid gas. 

 It is that colorless and suffocating vapor thrown off when a 

 sulphur-match is burned. Morren confines a certain quan- 

 tity of this gas in a receiver, places the whole in a dark 

 medium, and sends a bright ray of light through it. At 

 first nothing is visible. But very soon in the path of the 

 luminous ray we perceive a delicate blue color. It is be- 

 cause the gas is decomposed by the luminous waves, and 

 the invisible particles of sulphur set free decompose the 

 light in turn. The blue of the vapor deepens, then it turns 

 whitish, and at last a white cloud is produced. The par- 

 ticles composing this cloud are still each by itself invisible, 

 even under strong microscopes, and yet they are infinitely 

 more coarse than the primitive atoms that occasioned the 



