Schnee als kristallines Aggregat

Summary The newly fallen snow exhibits in its large variety of form all the changes in the atmospheric conditions (temperature, moisture, wind), and is a divided, labile matter. After the deposit, the cubic weight increases through the dead weight and the intercrystalline forces. These latter are closely connected with the metamorphosis of the crystals of newly fallen snow, basing on a stability of form. It appears that the snow crystal is covered with a superficial layer of fluid-like properties, and that the surface expansion is responsible for the first phase of the transformation. For the further change into the coarse grained old snow temporal and local differences are necessary. This has been found by observation of nature and of laboratory experiments, and in both cases were the results the same. The snow aggregate possesses, as a whole, a remarkable plasticity; the relations of this latter to the crystal plasticity is, at present, being examined by means of deformation tests. Of the characteristics of the plasticity of crystals a certain firmness and recovery can be observed partly, however, obscured by an elastic after-effect up till now never observed in snow. Of a slow limit there is only a suggestion. Besides mechanical mensurations, microscopic tests are being made on thin grinding plates to get at the individual proceedings.