Practically all of the rapid-process machines are provided with especially constructed cooling devices. In some of them, as in the Miller and Farrington, the cooling is effected by passing the milk through two separate coolers that are constructed in the same general way as the heater. With the first cooler, cold running water is employed, the temperature often being lowered in this way to 58 deg. or 60 deg. F. Further lessening of the temperature is secured by an additional ice water or brine cooler which brings the temperature down to 40 deg.-50 deg. F. In the economical use of ice the ice itself should be applied as closely as possibly to the milk to be cooled, for the larger part of the chilling value of ice comes from the melting of the same. To convert a pound of ice at 32 deg. F. into a pound of water at the same temperature, if we disregard radiation, would require as much heat as would suffice to raise 142 pounds of water one degree F., or one pound of water 142 deg. F. The absorptive capacity of milk for heat (specific heat) is not quite the same as it is with water, being .847 for milk in comparison with 1.0 for water.[151] Hot milk would therefore require somewhat less ice to cool it than would be required by any equal volume of water at the same temperature. ~Bottling the product.~ If the milk has been properly pasteurized, it should, of course, be dispensed in sterilized bottles. Glass bottles with plain pulp caps are best, and these should be thoroughly sterilized in steam before using. The bottling can best be done in a commercial bottling machine. Care must be taken to thoroughly clean this apparatus after use each day. Rubber valves in these machines suffer deterioration rapidly. [Illustration: FIG. 29. Relative consistency of pasteurized cream before (A) and after (B) treatment with viscogen as shown by rate of flow down inclined glass plate.] ~Restoration of "body" of pasteurized cream.~ The action of heat causes the tiny groupings of fat globules in normal milk (Fig. 22) to break up, and with this change, which occurs in the neighborhood of 140 deg. F., where the milk is heated for about 15 minutes and at about 160-165 deg. F. where rapidly heated in a continuous stream, the consistency of the liquid is diminished, notwithstanding the fact that the fat-content remains unchanged. Babcock and the writer[152] devised the following "cure" for this apparent defect. If a strong solution of cane sugar is added to freshly slacked lime and the mixture allowed to stand, a clear fluid can be decanted off. The addition of this alkaline liquid, which is called "viscogen," to pasteurized cream in proportions of about one part of sugar-lime solution to 100 to 150 of cream, restores the consistency of the cream, as it causes the fat globules to cluster together in small groups. The relative viscosity of creams can easily be determined by the following method (Fig. 29):