Variation Of Internal Energy Research Articles

Systematics of defect structures in glasses with ionic substitutions

The effects of various ionic substitutions on defect structures in glass were investigated in soda-lime-silica systems. It is shown that detailed measurements of flaw characteristics provide a useful tool for investigating subtle internal energy variations in this solid. Influences of specific ions were quantitatively studied by determining the parameters of flaw length ( F 1), and flaw number ( F n ). Flaws produced on freshly broken surfaces under controlled loading conditions, were shown to be a direct indication of the stress response of the glass network. Relative bond strength and rigidity or brittleness of the structures varied with the ionic field strengths of added cations. Alkali ions in the form of oxides, were substituted for sodium and alkaline earth ions for calcium. Other additions and substitutional ions were also studied in detail. In general, the changes in flaw parameters were found to agree with theoretical predictions of internal energy changes based on the manner in which the ion entered the network, that is, as a lattice modifier, interstitial or network former. In specific systems, the variations in flaw length and flaw numbers were tentatively explained by changes in defect concentration and free volume as the ions were substituted.

Sound Propagation in Gas Mixtures

An earlier treatment of the propagation of sound in mixtures of two gases is generalized and simplified somewhat. The essential point of the theory is the consideration of the internal energy variations by the assignment of fictitious internal state temperatures which, in the simplest case assumed here, are taken to be constant for each of the component gases. The long wave-length velocity expression is directly interpretable as a Laplace formula for a gas of mean reciprocal mass and averaged specific heat. From a more general point of view the velocity of propagation of infinitesimal waves is always given by the Laplace result provided a frequency variation of specific heats be recognized. Explicit mention is made of the detailed effect of viscosity and the two conductivities. Experimental data support theory.

Experimental Study of the "Soaring" of Albatrosses

A SERIES of experiments was made by me in Africa in 1920 in order to study the flight of the vulture. Kites were brought into the immediate vicinity of the soaring birds, and carried with them sensitive apparatus, making it possible to find, by means of electrical connexions with registering apparatus on the ground, the variations of internal energy of the air (temperature within 0.02° C., pressure within 0.1 millimetre; speed, direction, and horizontality of wind variations).