1894.] MICHOSCOPICAL JOURNAL. 253 



well, those of terrestrial gravity, are so masked as not to be at 

 all perceptible. Now, when we consider how minute all of these 

 particles are, and yet that they move apparently unhindered 

 with such constancy and force, it ought to be apparent that 

 they have no self-motive power. However erratic the paths of 

 individual particles may be, the likeness among the movements 

 is extraordinary, so almost identical in every case, varying in 

 greatness of range and rapidity only in inverse ratio to the size 

 of the particle, that we cannot conceive of self-actuated par- 

 ticles so behaving ; for relative greatness of size in self-actuated 

 particles ought to coincide with relatively greater, not relatively 

 less, energy of movement ; whereas, here the case is reversed. 

 But there are other facts that I have observed through exper- 

 iment, which also prove what I say. In alcohol, and as far 

 as my experiments go, in fixed and volatile oils, the Brownian 

 movements are not observable, and yet the microscope plainly 

 reveals that the movements of foreign bodies in all these is as 

 free as in aqueous solutions, and I think more so. So molecu- 

 lar movements of solid particles in suspension in aqueous fluids 

 must take place perforce of the constant repulsions of the con- 

 stituent molecules of the particular liquid present — water." 



" I have shown that the molecular motion, called Brownian, 

 taking place under all conditions imposable, is a property of wa- 

 ter and of water only, and that light and heat have naught to do 

 with producing it, although, as I have admitted, they may pos- 

 sibly act in intensifying it. All that I may claim to have de- 

 tected is a phenomenon which reverts to the molecular consti- 

 tution of water, as to which the moving, solid particles in it 

 concerned in the brownian movement have no more to do than 

 has a current-metre to do with the flow of the stream the swift- 

 ness of which it measures." 



Attention is thus fully called at this time to the latest explan- 

 ations of the Brownian movements, in order that they may be 

 considered in connection with the ver}' interesting paper of Mr. 

 Cunningham upon the movements of diatoms. 



^A^ashing Diatoms. — To avoid the use of acid in clearing 

 diatoms a correspondent of a country publication says, put it in 

 ajar of water and shake it for an hour. Evidently the time of 

 this man is of little value and the space of the editor equally so. 



