2 POROSITY OF GASES. DIVISIBILITY. 



al Isolid and liquid bodies, may be compressed into 

 a smaller space by adequate pressure; hence they all 

 possess pores. It will be shown hereafter, in the 

 chapter on Heat, that the volume of bodies may be 

 diminished even more easily by cooling than by 

 pressure. 



6. Divisibility. -^A\\ bodies may, by proper means 

 (for instance, by cutting, pounding, etc.), be divided 

 into smaller and smaller parts. The divisibility of 

 bodies which are soluble in liquids may be carried very 

 far by diluting their solution. As 'has been mentioned 

 previously, one cubic centimetre of the red an line 

 solution, which contains 0*02 gramme of colouring 

 matter, will give a beautiful red colour to 2 litres cf 

 water ; one cubic centimetre of this water will therefore 

 contain (since one litre is equal to 1000) the ^oVoth- 

 part of 0'02 gramme, that is, the one hundred thousandth 

 part of a gramme of aniline red, and a whole cubic centi- 

 metre is by no means required to show distinctly the 

 red colour. A piece of a fine glass tube, about 10 mm 

 long, and l min wide, may be filled with the liquid by 

 immersing it into it; if held against the light, the liquid 

 in the tube appears very distinctly red. Now a cyl- 

 inder of l mm in diameter, or having a radius of 0'5 mm 

 and a length of 10 mm , has a volume of 0'5 x O5 x 

 3-1416 x 10 = 7-854 cubic millimetres. 



The quantity of liquid in the tube is therefore not 

 quite thc. y i f th part of a cubic centimetre, (for 1 

 cubic centimetre = 1000 cubic millimetres, and 



~ 127*32366), and since one cubic centimetre of 

 the liquid does not contain more than -nn?,Tnnr * a 



