of definite geometrical form
Plate 17, Fig. 8
Air-pits on a glass-cast surface of cadmium. 1000 diameters, vertical light. The pits are surrounded by halos due to the absorption of smaller bubbles by the pits.
illustrating J(ames) A(lfred) Ewing (1855-1935 *) and Walter Rosenhain (1875-1934 * **). “The Crystalline Structure of Metals.” Philosophical Transactions (of the Royal Society of London), Series A Containing papers of a mathematical or physical character (1900) : 353-375
“During the crystalisation the crystalline elements have built themselves around the gas bubbles in regular orientation, finally leaving the pits as we see them... ¶ The characteristic of the pits is that they are similar and similarly oriented over any one grain, but on passing from one grain to another, across a boundary, the orientation of the pit is found to have changed.”
tags: cadmium; metallurgy; rounds; J. A. Ewing & W. Rosenhain, “Crystalline Structure” (1900)