410 THE LIFE OF MATTER. 



The inovomciits uro, indeed, more lively in alcohol or eth(M'. which are 

 very mo))ile liquids. They are slow in sulphuric acid and o'lyccrin. 

 In water, a j^rain one two-thousandth of a inilliineter in diameter tra\ - 

 erses, in a second, ten or twelve times its own lenuth. 



The fact that the Brownian movement is seen in liquors which have 

 been boiled, in acids and in concentrated alkalis, in toxic solutions of 

 all degrees of temperature, shows conclusively that the phenomenon 

 has no vital significance; that it is in no wa>^ connected with vital 

 activity so (tailed. 



Its indefinite duration. — The most remarkable character of this 

 phenomenon is its permanence, its indefinite duration. The move- 

 ment never ceases, the particle never arrives at repose and equilib- 

 rium. Granitic rocks contain quartz crystals which at the moment of 

 their formation included within a closed cavity a drop of water which 

 contained a ))u))l)le of gas. These bubbles, contemporar}^ with the 

 Plutonian age of the globe, have never from that time ceased to mani- 

 fest 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 siw 

 the Brownian movement exist far from cities, where the mercurial 

 mirror of a seismograph showed no subterranean vibration. It did 

 not increase when these vibrations appeared and became quite appre- 

 ciable. Neither is it changed by variation in light, magnetism, or 

 electric influence«; in a word, by external occurrences. The result of 

 observation is to place before us the paradox of a phenomenon wdiich 

 is kept up and indefinitely perpetuated in the interior of a body with- 

 out known exterior cause. 



The Brovminn movetnent mast he the p'r.st st(/(/r of moJecidar inove- 

 nu'tit. — When we take in our hands a shcM't of (luartz which contains 

 a gaseous inclusion we seem to ))e holding a pm'fecth^ inert object. 

 When we have placed it upon the stage of the microscope and have 

 d(Mnonstrated the agitation of the bul)blc wc mi"c (•()n\inccd that this 

 seeming inertia is merely an illusion. 



The repose exists only in the limitations of our vision, ^\'e s(>e the 

 objects as we see from afar a crowd of peo})le; we perceive them as 

 a whole, without being able to discern the individuals or their move- 

 ments. A visible object is, in the same way. a mass of i)articles. It 

 is a molecular ci-owd. It gives us the iiupi'ession of an indivisible 

 mass, of a block in repose; but as soon as a lens l)rings us nc^ar to this 

 crowd, as soon as the microscope enlarges for us the minute elements 

 of the ])rutebody, then it appears to us, and we ])erceive the contiiuial 

 agitation of those who are at least four one-thousandths of a millimeter 

 in diameter. The smaller the particles under consideration, the more 

 lively are their movements. From this we infer that if we could per- 

 ceive molecules whose probable dimensions are about one thousand 



