401 Mr. C. Tomlinson on some Phenomena connected with 



is remarkable that the flame of pure hydrogen jetted on the glass 

 rod and on the surface of the water had no effect in rendering 

 either inactive. The inactive condition of the rod is exchanged 

 for an active one by exposure to the air. 



A moderate elevation of the temperature of the water is suffi- 

 cient to produce this inactive surface. At 160 c F. there was no 

 adhesion ; the creosote slipped through the surface and formed 

 an inactive sphere at the bottom. At 110° the creosote was in- 

 active at the surface, and remained so during twenty-five minutes. 

 In another experiment an inactive lens on a surface of water at 

 114° became an active figure on pouring in cold water. 



If the creosote itself be heated instead of the water or the rod, 

 it forms inactive figures for a few seconds. Creosote raised to 

 120° was thus inactive. 



The surface of the water is also rendered more or less inactive 

 by heat for other substances as well as creosote. The well-de- 

 fined but rapid figures of carbolic and cresylic acids are delayed 

 on water at 120°: they first form clear cut disks, and continue 

 many seconds longer than on cold water. Ether becomes sphe- 

 roidal on water at 120°, and rolls about in the form of a sphere ; 

 or if the figure be formed, it is imperfect. The well-defined 

 figures of castor-oil and oil of lavender are either not produced 

 at all, or are greatly injured, on water at 120°. 



At lower temperatures than the above, the adhesion of the 

 surface is so far diminished as to exert a marked effect on the 

 duration of the creosote figure. With water at 98° the figure 

 was very active, but its duration was eighteen minutes instead of 

 five. In summer weather, when the air is at 70°, the figure 

 does not in general split up. 



This diminished force of adhesion consequent on a rise of 

 temperature seems to be the commencement of the condition 

 which finally ends in inactivity. There are not only fewer par- 

 ticles within a given area, but their attractive force is diminished 

 and the repulsive force increased. This is not like a case of in- 

 creased solubility from heat, as when a body dissolves more 

 freely in a hot than in a cold menstruum ; for in such case the 

 body is not only expanded by the heat, but currents are excited 

 in the liquid which are constantly bringing fresh particles to 

 act on it. But in the surface- action to which we refer, the cur- 

 rents, if any, are chiefly horizontal, and the first touch of the 

 creosote with the heated surface may saturate the exceedingly 

 thin upper liquid layer, where the adhesive force chiefly resides. 

 It is possible, too, that in some cases, when the disks are inac- 

 tive, the inactivity may be due to a spheroidal condition, although 

 this would not account for all the phenomena above noticed. 



In another experiment the active creosote figure was sur- 



