348 PROCEEDINGS OP THE AMERICAN ACADEMY, 



indicate a solid. A globule of a new liquid phase, xoVir millimeter in 

 diameter, would have left an unmistakably circular image un the highly 

 magnified plate, for its index of refraction could not have been identical 

 with that of the aqueous solution. The fact that we could not find such 

 a globule of course does not prove that a globule cannot exist, either for 

 an infinitesimally brief period of time, or of an infinitesimal magnitude 

 beyond the reach of microscopic observation. Nevertheless, so many 

 scores of photographs were taken as to diminish considerably the proba- 

 bility that such globules can ever be seen with substances possessing a 

 high melting point. 



A striking fact to be noticed in nearly all the most highly magnified 

 records is the ill-defined appearance of the smallest crystals. This ap- 

 pears to be due, not to a lack of structure, but rather to the rapid growth 

 in diameter which is manifest in the young crystal. The initial rapidity 

 is so great that the fifth of a second appears to include several different 

 stages of growth, and hence a blurred impression results. It is easy to 

 obtain some idea of the rapidity of this initial growth by comparing the 

 sizes of the first two or three appearances of each crystal. 



With this object a few of the series were measured by means of an 

 accurate micrometer; but the conditions of the experiments are too un- 

 certain to give the very precise measurements much value. Perfect 

 constancy of temperature and evaporation, as well as in the rate of the 

 revolving shutter, involving grave complications in the apparatus, should 

 of course be maintained if great accuracy is attempted. Measurements 

 with a fine millimeter scale afford all the precision which it is worth 

 while to attain under present conditions. A typical case (Figure 9, largest 

 crystal) gave the following measurements in millimeters for tlie successive 

 longest diameters : 2.0 ; 2.6 ; 3.0 ; 3.2 ; 3.3 ; 3.5 ; 3.7 ; 3.9 ; 4.1 ; 4.2 ; 

 4.4. The actual sizes of the crystals were of course only a hundredth of 

 these measurements, since the enlargement was 100 diameters. 



In spite of the inexact nature of such measurements, it is possible to 

 use them as a means of defining approximately the law regulating the 

 changes in speed. The following table details six series of corresponding 

 diametric measurements of six crystals taken at random. The measure- 

 ments were taken directly from the photographs, in millimeters. 



