AN EXPERIMENT OS HYDROSTATIC PRESSURE. 



351 



différence of potential between the two pôles is at least 9 or 10 volts. 

 That this settling is not due to coagulation is proved by the appearance 

 of the solution, as well as by the fact that on reversing the pôles, the 

 colloidal solution spreads upwards, and distributes itself uniformly 

 through the liquid, in opposition to gravitational attraction. The phe- 

 nomenon of sinking in a quicksand is also not comparable with the 

 phenomena discussed in this note ; for the particles of sand are rauch 

 too large to transmit bydrostatic pressure. It is probable that as liquids 

 containing more and more coarse-grained particles are tested by the hy- 

 drostatic balance, it will be found that the apparent density, as deter- 

 mined in this way will decrease, but to décide the question, further 

 experiments are acquired. 



The density of milk dépends, no doubt partly on the amount of dis- 

 solved salts and milk-sugar, etc.; but it must also be influenced by the 

 imparts on the lactometer of the fat-globules which are sufficiently 

 small to be in rapid pedetic motion; and the experiments alreadyrecorded 

 would show that the true mean density of the milk is thus determined, 

 and not merely the density of the solution of salts. 



I have to express my obligation to Mr. Senter for carrying out the 

 experiments described in this note. 



