TABLE V-SPECIFIC HEATS OF MILK AND MILK DERIVATIVES. Including heat required to melt fat if this factor enters. Values obtained from Curves, Plate V. Temperatures in Centigrade. Values in parenthesis were obtained by extrapolation, under assumption that the speciifc heat is about the same in the solid and liquid states. entirely melted and equilibrium is established. Fleischmann obtained results as high as 1.58 for a 26% cream. These values were probably obtained because of the method employed, which consisted of dropping into the sample a copper cylinder heated to 100° C. All of the readily meltable substances next to the cylinder would be quickly changed to the liquid state, possibly even decomposed to some extent, and, especially if the stirring was not very rapid, an abnormal result would be expected. The third portion of the curves, A to B, is particularly interesting because of the marked drop in the specific heat. The values near the freezing point of water are of importance in their bearing on the question of the relation of the specific heats of ice cream mixes to the effect on the palate. An ice cream very rich in fat would not only have a low specific heat at low tem peratures, but as is apparent from the very great slopes of the specific heat curves and the high maximum reached, it would absorb heat rapidly with an increase in temperature. From the data obtained and disregarding other factors it appears that an ice cream carrying considerable fat, when first coming in contact with the warm palate and tongue would give a sensation that was not disagreeably cold. Then as the temperature increased, because of the absorption of heat by the fusion of the fats, the mass would be automatically maintained cold longer than it otherwise would remain. In short there is no sensation of extreme coldness but still the mass remains cold for a longer time than if smaller amounts of fat were present. On the other hand, with low fat ice creams and sherbets, there is a sensation of extreme coldness when the material is first taken into the mouth, but the mass soon warms up. As before stated table V gives the results obtained in this study. Values are given for the various materials at 0°, at 15°, at 40°, and at 60° C. and over the ranges from 0° to 15°, from 0° to 40°, from 0° to 60°, from 15° to 40°, from 40° to 60°, and from 15° to 60° C. |