HEAT LOSS FROM DEWAR FLASKS
Sigmund Kenneth, Robert H. Cole · Review of Scientific Instruments · 1932
Dewar flasks obey Newton's law of cooling when the contents are adequately stirred. From cooling curves the water equivalent has been determined and the heat loss coefficient in calories per hour degree C difference has been found to be independent of the volume of contents between 50 percent and 90 percent capacity. For twin calorimetric purposes, flasks may be equalized by variation of the volume of contents as suggested by Hill, but it has been found that the best flasks are quite uniform and require but little compensation. The half-pint flasks used have a heat loss of about 12 calories/hour degree C difference and water equivalent of about 36 cc.