59 



Chemistry. — ''The allotropii of Zinc ^ II. \\\ Prof. Eknst Cohkn 

 and W. I). Heldekman. 



(Communicated in the meeting of April 24, 1914). 



1. In our first paper on the allotropj of zinc ') we called attention 

 to the ''atomized" metals which may be prepared by the new method 

 of M. U. ScHOOP of Zurich. 



We then pointed out that this method forms an ideal way of 

 producing ciiilled metal. As a result of our investigations on the 

 metastability of the metals as a consequence of allotropy we may 

 expect that "atomized" zinc will contain two or more allotropic 

 forms at the same time. 



From a technical standpoint we thought it interesting to prove 

 this more directly : if the "atomized" metal really contains two or 

 more moditications at the same time, it will disintegrate in the long 

 run when stabilisation occurs. 



2. Mr. ScHOOP supplied us with one kilo of zinc, which had been 

 "atomized" in the way described in our first paper on the subject. 

 As the material is very finely divided one would expect that an 

 eventual change would proceed in such a way that it could be 

 measured easily. On the othei' hand much care must be taken to 

 remove air from the very finely divided material after having brought 

 it into the dilatometer. 



3. About 750 grams of the metal and a small quantity of glass- 

 beads which had been heated beforehand") were put into a dilato- 

 meter. The material kad not been in contact with an electrolyte. The 

 capillary (bore 1 mm.) was bent horizontally and put in coimection 

 with a Gaede pump. In order to remove the air as comjjletely as 

 possible the dilatometer remained in coiinection with the pump 

 for 1 — IV2 hours. After this the paraffin oil was filled in; it had 

 been carefully boiled on the pump at 200° in contact with some 

 "atomized" zinc. In this way the instrument was made perfectly 

 free of air as many experiments proved. 



4. In a preliminary experiment we found that a contraction 

 of the metal occurs at 25°. 0. We then carried out a fresh one, the 

 "atomized" metal having been kept at 15° in a dry slate for three 



1; These Proc. 16, 565 (1913). 



2) These Proc, 16, 485 (§ 10) [1913]. 



