567 



In this way we found : 



Density d 



25°.0 



4°. 



Specimen Znj Specimen Ziijj 



After 24 hours 7.124 7.128 



72 „ 7.114 7.121 



„ 192 „ 7.116 7.112 



„ 386 „ 7.102 7.109 



In comparing these vahies with the original one, it will be seen 

 that the density has decreased at least 24 units of the third decimal 

 place and that this decrease was a continuous one during the whole 

 experiment. 



Now there exists full agreement between these results and that 

 of Kahlbaum and his collaborators, described in the paper mentioned 

 above. In the distillation of zinc in a porcelain tube in vacuo they 

 determined the place where the metal was deposited in the inner 

 side of the tube by photographing it by means of RöNTGEN-rays. In 

 this way they found (the photo is reproduced in their paper), that 

 the zinc was deposited at a small distance from the hottest part of 

 the tube. Consequently the metal has been able to remain during 

 the cooling in the condition which corresponded to its temperature. 

 In full agreement with this manner of cooling the density of the 



/ 20° \ 



metal was found to be very low I a . —^ 6.922 1 . This value probably 



lies very near to the density of pure «-zinc. 



Our experiments prove that we have to consider "zinc" as a 

 metastable system. The moditication formed at high temperatures, 

 only very slowly changes into that which is the stable one at 100° 

 (at ordinary temperature). In this way we find (as in the case of 

 tin, bismuth and cadmium), that our "zinc world" is in a metastable 

 condition. 



As there exists a e;reat difference between the specific volume of 

 the modifications of zinc, all objects made from this metal will 

 disintegrate in the long run. 



In conclusion the following facts may be pointed out : 



Quite recently M. U. Schoop invented a method of coverirlg 

 any object with a layer of metal. In order to do so (the operation 

 is called "schopieren") the metal (in the form of a wire) is mechan- 

 ically moved through an oxy-hydrogen flame. A strong current of 

 nitrogen "atomizes" the metal which immediatelj' covers the object 

 which is held before the burner. Evidently this device forms an 



