Examination of the hexamethylenetetramine procedure for separation of thorium from rare earths and for determination of thorium.
An examination has been made of the efficiency of the gravimetric reagent hexamethylenetetramine in the separation of thorium from rare earths and in the determination of thorium. Losses to the filtrate, beaker and filter paper are evaluated as well as the extent of rare earth and other contamination of the thorium hydroxide precipitate. When hydroxylamine is used as the reducing agent to keep cerium in the tervalent state, excellent separations are obtained. The efficacy of the reagent is offset by the loss of small amounts of thorium to the precipitation vessel, the scavenging properties of the precipitate for silica and the difficulty in evaluating a true reagent blank.
Development and publication of new gravimetric methods of analysis.
A review is made of the factors affecting the accuracy of gravimetric methods, and which need to be investigated in the development of new methods. Recommendations are made for writing up such investigations for publication.
Beiträge zur Keramik hochfeuerfester Stoffe. l. Die Formen des Zirkondioxyds
1. Bezuglich der verschiedenen Formen des ZrO2 wird durch Verwendung von Spezialrontgenkameras festgestellt, das das handelsubliche, bei 1200° C vorgegluhte Oxyd bei etwa 1000° C einen reversiblen Modifikationswechsel von monokliner Symmetrie in tetragonale durchmacht.