566 



if its previous history (chilling, slowly cooling etc.) had any influence 

 on the density of zinc. These investigations are not exact enough 

 to yield a definite conclusion. Rammelsberg, summing up his measu- 

 rements, says: "Nach dem Gesagten handelt es sich hier nicht um 

 molekulare Modifikationen. Wir finden nur, dass der schnelle Ueber- 

 gang aus dem flüssigen in den festen Zustand die Sprödigkeit des 

 Metalls erliöht . . ." It will be pi'oved here that this conclusion does 

 not agree with the facts. 



We thought it necessary to carry out fresh experiments on this 

 subject. Considering the results of our investigations on tin, bismuth ^) 

 and cadmium^), and in view of the existence of a transitionpoint 

 at 350° it might be expected that the metal, which has been called 

 "zinc" until now, might be a metd.stable system, containing two or 

 more allotropic modifications of this metal. 



The following experiments prove that such is really the case. We 

 melted one kilo of the metal (Zink-"KAHLBAUM"; we were not able 

 to detect any impurity in 100 grams of the material). It was then 

 poured out into a cylinder made of asbestos-paper, which was placed 

 in a glass beaker. The beaker was filled up with solid carbon-dioxyde 

 and alcohol. In this way the melted metal was chilled very quickly. 

 The cylinder of zinc formed in this way, was turned into small 

 pieces on a lathe; the outer layer was not used in the following 

 experiments. The metal was washed with ether: after this we carefully 



determined its density I c? — 3— I, using a pycnoraeter contammg 2i) cc. 



The material was divided into two parts {Zni and Znjj), which were 



manipulated separately. 



In this way we found (21 hours after having chilled the metal) 



25°.0 

 d — ^ Ziij 7.130 Zuff 7.129. 



We then brought the samples (weighing each 35 grams) into a 

 Jena glass flask, into which was poured so much of a solution of 

 zincsulphate, (saturated at 15°) that the metal was covered by the 

 solution. The whole was then heated at 100° for a long time. 



At different intervals of time we took the metal out of the flasks 

 washed it with dilute hydrochloric acid and water (until the reactions 

 for SO4 and CI had disappeared), alcohol and ether. It was then 

 dried in vacuo, using sulphuric acid as a drying agent. After these 

 operations the density of the two samples was determined again, 

 using the whole mass (35 grams) in the pycnometer. 



1) Zeitschr. fur physik Chemie 85, 419 (1913j. 



2) Proceedings 16, 485 (1913). 



