Fine metal crystallites with diameters 200∼2000 Å made by evaporating a metal in an atmosphere of an inactive gas were studied by electron microscopy. It is found that the crystal habit common to Be, Cr, Mn and Fe, which are bcc just below the melting point, is rhombic dodecahedra truncated by {100}. Fcc metals show six different types of crystal habit. However,only one, viz. octahedra truncated by {100}, is a single crystal and all the others have twins. Various degrees of truncation were found both for rhombic dodecahedra and octahedra. Crystallites with certain degrees of truncation are possibly Wulff polyhedra.

Twinned particles of magnesium prepared using the gas evaporation technique were studied using electron microscopy. Particles with (10.1), (10.3), (11.1) and (11.2) twin planes were found in the smoke outer zone. Their external faces were the same as those of single crystal particles, i.e. {10.0} and (00.1). The growth of the (10.1) twinned particle was more pronounced than that of the other three kinds of twinned particles and from this it was deduced that the twin formation occurs at the nucleation stage.

Aluminium smokes in He, Ar and Xe at various pressures were studied. Their macroscopic shapes were roughly the same in 200 Torr He, 10 Torr Ar and l Torr Xe. Under these conditions the particle size in the inner zone of a smoke decreased with the molecular weight of the gas. In the course of the experiment, several electron micrographs showing the intermediate stages of particle coalescence in the smoke were obtained. When an inactive gas contained oxygen, the smoke particles were almost perfectly oxidized in the outer zone of the smoke, while the oxidation was slight in the inner zone.

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The crystal structure and habit of small particles of iron-nickel alloys prepared by the gas-evaporation technique were studied by electron microscopy. Most of the particles grown from Fe-36 at.%Ni foil consisted of a single phase of ferrite or austenite, and they formed alternating long chains.