130 FRAGMENTS OF SCIENCE 



eye. Thus, without solution of continuity, we start with 

 matter in the atom, and end with matter in the mass; 

 sky-matter being the middle term of the series of trans- 

 formations. 



Instead of sulphurous acid, we might choose a dozen 

 other substances, and produce the same effect with all of 

 them. In the case of some probably in the case of all 

 it is possible to preserve matter in the firmamental condi- 

 tion for fifteen or twenty minutes under the continual 

 operation of the light. During these fifteen or twenty 

 minutes the particles constantly grow larger, without ever 

 exceeding the size requisite to the production of the celes- 

 tial blue. Now when two vessels are placed before us, 

 each containing sky -matter, it is possible to state with 

 great distinctness which vessel contains the largest par- 

 ticles. The eye is very sensitive to differences of light, 

 when, as in our experiments, it is placed in comparative 

 darkness, and the wave -motion thrown against the retina 

 is small. The larger particles declare themselves by the 

 greater whiteness of their scattered light. Call now to 

 mind the observation, or effort at observation, made by 

 our President, when he failed to distinguish the particles 

 of mastic in Briicke's medium, and when you have done 

 this, please follow me. A beam of light is permitted to 

 act upon a certain vapor. In two minutes the azure ap- 

 pears, but at the end of fifteen minutes it has not ceased 

 to be azure. After fifteen minutes its color, and some 

 other phenomena, pronounce it to be a blue of distinctly 

 smaller particles than those sought for in vain by Mr. 

 Huxley. These particles, as already stated, must have 

 been less -than -j-^Vusth of an inch in diameter. And now 

 I want you to consider the following question: Here are 



