Über den Hedvall‐Effekt. I. Die Reaktion von Bariumoxid mit Silberjodid

Abstract

Die Reaktion von BaO mit AgJ, die häufig als Beispiel für den HEDVALL‐Effekt angeführt wird, läßt sich bei sorgfältigem Ausschluß von Feuchtigkeit und CO2 der Luft nicht nachweisen.

Thermal analysis

“…The second edition of Songina's monograph ( 236) is a welcome contribution to the literature of amperometric titrations. Several accounts of electroanalytical methods include such titrations (1,13,29,51,109,110,229,257).…”

“…TGA has been applied to the reaction of BaO and Agí and it was shown that the Hedvall effect was not observed if contamination by atmospheric H20 and C02 was prevented (109). Among the oxides studied by TGA have been U3Os (170), Pb02 (267), and NiO, CoO, Fe203, and Cr203 with H2 and CO (281).…”

Investigation of exchange reactions between alkaline earth metal oxides and some transition metal halides

“…Since the alkaline earth metal oxides are strongly hygroscopic, this constancy of the temperature at which interaction starts led some investigators to suggest that Hedvall and Tamman had used hydroxide-contaminated oxides whose melting points were rather low, and the interaction had been brought about by the presence of a liquid phase [4,5]. A number of attempts were made [6][7][8] to reproduce the Hedvall effect. Some of these ended in failure, as was the case with calcium and magnesium oxides for instance [8].…”