10 Introduction. 



flask. Pour out half the colored water and fill to 500 

 cu. in. again. Repeat this operation as long as the eye 

 can with certainty detect the color in the water. As many 

 as nine divisions may be made and the eye detect the color 

 when looking down through 12 inches of the water poured 

 into a long glass tube held over white paper, using a sim- 

 ilar tube with clear water as a standard for comparison. 



If the division of the aniline is carried to this extent 

 there will be in the last 500 cubic inches of water only 



512 of 155 = lOlO of a S ram of aniline - 



It is reasonable to suppose that in the last 500 cubic 

 inches of water there was at least one molecule of aniline 

 in each cube of water .01 of an inch on a side, and if this 

 is true there must ha.ve been at least 



100 X 100 x 100 X 500 = 500,000,000 



molecules of aniline in the last vessel of water. Since at 

 least this number of molecules is found in TS^-S of a 

 gram of aniline one gram would contain not less than 



10, 240 X 500, 000, 000 = 5, 120, 000, 000, 000 molecules. 



It is plain, therefore, from this straightforward line of 

 observation and simple calculation that molecules of ani- 

 line at least must be very small and that a pound of the 

 material would contain an enormous number. 



From another line of observation Maxwell has computed 

 that the molecules of hydrogen, oxygen and carbon dioxide 

 are so small that the numbers in the table below are re- 

 quired to weigh one gram. 



Number of molecules in one gram of 



Hydrogen Oxygen Carbon dioxide 



2,174(10)" 1,359(10)" 9,881(10) 8 ' 



That is to say, the number of molecules is so large in ono 

 gram of these three substances that 2,174, 1,359 and 9,381 



