967 
Evidently the silver of the underground is due to evaporation 
and the larger particles proceeded from atomizing. 
Consequently evaporation produced a much finer deposit than 
atomizing. 
The results which H. Frirze*) obtained with cathode-atomizing of 
silver agree with this statement. For he explicitly states that the 
colour of his deposits was never yellow, though he devoted much 
attention to the exhausting and the removing of vapour of water 
and other gases absorbed by the bulb. As a rule the deposit was 
blue, with a decrease of thickness it became red, while finally with 
still thinner layers, no distinct colour can be identified, it results in 
‘jede Andeutung einer ausgeprägten Farbtönung zu verlieren”. 
Such a vague, non-characteristie colour as indicated by Fritze 
may also. be found in the film proceeding from the effect of 
air on our thin greenish-yellow silver-deposits. It is, as we have 
seen, distinctly heterogeneous and much coarser of granule than the 
greenish-yellow layer formed by slow sublimation. 
Tungsten. Again the colour of the film was black, like that 
obtained by evaporation. It appeared ultramicroscopically that by 
rapid atomizing very course particles were formed (2 to 5 u dia- 
meter); by slow atomizing small particles arose, radiant without 
colour and — also with an extremely thin black deposit — so 
numerous that they filled the whole field. So here again it appears 
that coarser particles are obtained by cathode atomizing than by 
evaporation *). 
SUMMARY. 
1. The clear, colourless condensate of rock-salt that settles on 
the bulb during evaporation in high vacuum is, also under ultra- 
microscopic investigation, optically homogeneous and must be con- 
sidered as a salt in the amorphous-vitreous state. 
2. The opalizing, which this deposit undergoes, by the influence 
of moist air, originates in the formation of separate crystals, whose 
growth could be followed ultramicroscopically. 
1) Ann. der Physik (4) 47, 763 (1915). 
2) Of course, the coarseness of the particles in cathode-atomizing depends on 
the temperature the material attains during the process. When the temperature 
is high coarser particles are torn off than when the cathode-atomizing is conducted 
in such a manner (e.g. by repeated rests) that the temperature of the material 
remains lower, 
