RICHARDS AND ARCHIBALD. — GROWING CRYSTALS. 353 



ized light were used. Only substances with high melting points were ex- 

 amined, and the crystallization was always from aqueous solution. No 

 properly focused image on any of the plates seemed to be devoid of crys- 

 talline structure. The growth in diameter during the first second of the 

 crystal's life was found to be vastly greater than during the subsequent 

 period. Not the diameter itself, but a power of the diameter, was propor- 

 tional to the time under the conditions used in our experiments. This 

 exceedingly rapid initial diametric growth accounts for a lack of definition 

 noticed in the first images, — a lack of definition sufficient to have misled 

 the eye, but not enough wholly to obscure the photographic evidence of 

 crystalline structure. 



Hence we may conclude that whatever theoretical reason there may be 

 for believing that crystals always develop from a transitory liquid phase, 

 the present experimental evidence is inadequate to prove that these 

 globules attain a size visible in the microscope, except in the case of 

 substances which melt at temperatures not far from the temperature of 

 crystallization. The present paper is to be regarded rather as the sug- 

 gestion of a mode of study than as a finished treatment of the subject, 

 however. 



The apparatus might be used to obtain a series of kinetoscopic pictures 

 of insects or other small animals or plants, and is now being used for the 

 study of the change in structure of steel at high temperatures. 



Cambridge, Mass., October, 1898, to October, 1900. 



vol. xxxvi. — 23 



