Reaction before Complete Equilibrium* 61 



perature read on the small thermometer, while tbe solidifying 

 mass is passing its bulb), then the ri«e of temperature of the 

 liquid from its initial temperature Tb — T' is found to be =40' 

 per cent, and more of the total value Tb — T . The investigation 

 was carried out as near to the melting-point as possible 

 (i. e. as far as the abnormalities in the crystallization, which 

 appear near the freezing-point, did not hinder the investi- 

 gation), and again, so far from the melting-point, until 

 spontaneous crystallization set in ; in other words, the whole- 

 length of the curve accessible for the investigation has been 

 studied. If the undercoolings T — T (as read on the small 

 thermometer) be taken as the abscissae, and the velocities of 

 crystallization (or the reciprocal Aalues of time which are 

 necessary for the solidifying mass to pass from the lower end 

 of the platinum tube to its upper end) as ordinates, straight 

 lines are obtained, which on continuation pass the freezing- 

 point. If, on the contrary, I calculate my results so that 

 I assume the temperature of the liquid at the surface of 

 contact with the solid to be that of the surrounding bath, the 

 curves become less regular, and on continuation they cut the 

 abscissae, not at the freezing-point, but considerably below it, 

 since a shifting of all the points of the curve by about 

 40 per cent, is thus caused. This leads either to the im- 

 possible conclusion that overcooled liquids cannot freeze 

 below the freezing-point, or to the result that the other- 

 wise more or less straight lines finish up irregularly on 

 approaching the freezing-point. The obtained result is,. 



therefore, ~r = C(T — T), where t is the time, T the 



melting-point, T the temperature of the liquid in contact 

 with the solid while the reaction is going on. 



No capillary tubes were used for the investigation since I 

 found in my investigation of mercury thermometers that the 

 velocity with which the mercury thread moves in the capillary 

 tube, when the thermometer assumes the temperature of a 

 liquid, is about 40 per cent, greater when it rises than when 

 it falls. Consequently there is no free movement of the 

 liquid in a capillary tube, even when this liquid is mercury,, 

 and still more in the case of other liquids which adhere to- 

 the glass or platinum when they are crystallizing out. 



A tube of very thin platinum was used instead of a glass 

 tube, as it is necessary that the heat capacity of the mass of 

 the tube should be so very small in comparison with that of 

 the liquid that it may be neglected, and also that the con- 

 ductivity for heat of the tube should be very great. We 

 must otherwise take into consideration the tube as well. In 



