frigerating capacity, because of the many unavoidable losses due to exposure of the freezing tank, loss of ice in thawing off and in handling.

Ice cans. The ice is frozen in metal cans which are placed in a tank of strong brine. The brine is kept cold by expansion coils connected with the ammonia compressor.

The time required for freezing ice will depend upon the size of the ice cans and the temperature of the brine. The following table shows the approximate time required for freezing various sizes of ice cakes at different tempera

It will be noticed that there is an appreciable difference in the time required for freezing with the brine at 8° F. instead of 16° F., but it is more economical to freeze at the higher temperature because of the greater refrigerating capacity of a machine when operated at the higher suction temperature and pressure.

The brine solution may be made from sodium chloride (NaCl) or from calcium chloride (CaCl). The latter is to be preferred, especially where very low temperatures are

to be maintained. The freezing point of brine at different degrees of concentration is shown in the following table:1

For the manufacture of germ-free ice or for the manufacture of very clear ice the water to be frozen is first distilled and filtered, to remove all impurities. The time for freezing is somewhat prolonged, as this gives a clearer ice than rapid freezing. In the manufacture of ice in ice cream factories, however, these precautions are not observed, for the reason that the ice is used only for packing purposes so that its appearance and germ content are of secondary importance. Water that is pure enough for drinking purposes will do for the manufacture of ice of the quality required for packing ice cream.

The equipment. The most important part of the additional equipment needed for the manufacture of ice in the ice cream factory consists of a properly insulated brine tank which is divided into compartments for the freezing cans, heavy sheet metal cans in which the ice is frozen, and an 1" Modern Refrigerating Machinery."

agitator to keep the brine in constant circulation. In addition to these there must, of course, be a certain amount of other apparatus, such as an ice hoist, thawing apparatus, can filler, etc.

The brine tank is provided with necessary expansion coils of ample area. It will require approximately 100 to 125 square feet of pipe surface to each ton of ice capacity. The agitator. The brine in the tank must be kept in constant circulation by an agitator of some sort. In small tanks a propeller-like agitator of 12 or 18 inches diameter running at about 200 revolutions a minute, or a small centrifugal pump, will insure a sufficient circulation of the cold brine around the freezing cans.

The freezing cans are made a little smaller at the bottom than at the top and hold from 50 to 400 pounds of ice, the size and dimensions of the can being varied to suit conditions. The cans are usually made of about No. 16 gauge material. The following table 2 shows the dimensions of different sizes of ice cans and the weight of the cakes of ice from each.

2 Haven and Dennis, American Practice in Refrigeration."

NOTE: The brief discussion given in this chapter is intended to give the beginner a general idea of the subject. Those who desire more detailed information on mechanical refrigeration should consult some standard work. Siebel's "Compend of Mechanical Refrigeration and Engineering," published by Nickerson & Collins Co., Chicago, and "Modern Refrigeration Machinery," published by Wiley & Sons, are suggested as suitable references for students. Steven's "Mechanical Catechism," published by Laird & Lee, Chicago, and Levey's "Refrigeration Memoranda," published by Nickerson & Collins Co., Chicago, are suggested as helpful references for those who are particularly interested in engine room practice.

CHAPTER XVI

SCORING ICE CREAMS AND ICES

The problem of scoring ice creams and ices is a new one and presents some difficulties which are not encountered in scoring other dairy products. In the first place, the ideal flavor for ice cream is far more variable than the ideal flavor of other dairy products and depends upon the kind and amount of flavoring used and the presence or absence of other substances which blend with and modify the added flavoring material. Such a blend or combination, even if it be unintentional, is not always displeasing. Our ideal or our standard for comparison will have to be varied somewhat to make it apply in individual cases. For example, if we are scoring vanilla ice cream, its flavor must be judged according to the quality of the vanilla flavor which has been imparted to the ice cream.

The flavor of ice cream is so variable that it will be necessary to discuss it under several heads in order to view the subject from every angle. We shall first consider the flavors imparted by the extracts or other added flavoring material.

The qualities of flavor imparted by the flavoring material may be designated as high, low, mild, harsh or sharp, and foreign. The flavoring material itself may be of excellent quality, but if used in insufficient amounts or in too large amounts, the results will be far from satisfactory.

High flavor is characterized by the presence of large