268 LIFE AND DEATH. ' 



movement is extremely rapid, and can only occasion- 

 ally be perceived. It is probable that it would be 

 still more accelerated in smaller objects; but the latter 

 will always escape our observation. 



Its Independence of the Nature of the Bodies and of the 

 Environment. — M. Gouy remarked that the move- 

 ment depends neither on the nature nor on the form 

 of the particles. Even the nature of the liquid has 

 but little effect. Its degree of viscosity alone comes 

 into play. The movements are, indeed, more lively 

 in alcohol or ether, which are very mobile liquids ; 

 they are slow in sulphuric acid and in glycerine. In 

 water, a grain one two-thousandth of a millimetre in 

 diameter traverses, in a second, ten or twelve times its 

 own length. 



The fact that the Brownian movement is seen in 

 liquors which have been boiled, in acids and in 

 concentrated alkalies, in toxic solutions of all degrees 

 of temperature, shows conclusively that the pheno- 

 menon has no vital significance ; that it is in no way 

 connected with vital activity so called. 



Its Indefinite Duration. — The most remarkable char- 

 acter of this phenomenon is its permanence, its 

 indefinite duration. The movement never ceases, 

 the particles never attain repose and equilibrium. 

 Granitic rocks contain quartz crystals which, at the 

 moment of their formation, include within a closed 

 cavity a drop of water containing a bubble of gas. 

 These bubbles, contemporary with the Plutonian age 

 of the globe, have never since their formation ceased 

 to manifest the Brownian movement. 



Its Independence of External Conditions. — What is 

 the cause of this eternal oscillation ? Is it a tremor 

 of the earth ? No ! M. Gouy saw the Brownian 



