=Spray System.=--The “spray system” has been rejuvenated and is very popular. This system is particularly effective for warm beef and sheep coolers and for hog coolers. It can well be installed at slaughter and shipping points, but its use in hanging rooms where beef is aged and held for sale is questionable, by reason of the probability of shrinkage owing to the rapid air circulation maintained. _Width of Rooms._--There are various opinions as to the width and height required in a bunker room for installation of the spray system. A room from thirty-two feet to forty-eight feet wide can be successfully operated. Increased width beyond that means increased height and this, in turn, means more construction cost. Rooms twenty-five feet wide with twenty feet pans have been built and successfully operated, but at less widths the brine is likely to carry over. The value of the spray system, and the rapidity with which a room and its contents can be cooled by its use, seems to be due to two causes, the direct contact of the air with the finely divided brine spray and the induced air currents created by a mechanical circulation. [Illustration: FIG. 22.--SECTION OF COLD STORAGE HOUSE EQUIPPED WITH SPRAY SYSTEM.] _Types of Construction._--The accompanying diagrams show two types of construction. One wherein the brine pan is made of cast concrete and the rails suspended from wood rail beams hung on rods attached to the ceiling. The other one shows the brine pan made of wood built up from supported rail beams. In the first instance the brine spray is collected on what might be termed a composition roof (without the gravel covering) made from asphalt saturated paper, and asphalt laid over a cork sub-base spread upon and cemented to the concrete pan. In the second instance the pan is made from wood, exhibiting a wood paneled surface on the underside, covered with cork, more wood and then lined with a galvanized iron pan. _Arrangement of Piping._--In both instances the brine spray header was located near the top of the hot air flue partition and the sprays directed to a line below the horizontal, to insure the brine falling well within the pan, to prevent splash through the cold air flue. The brine is collected and returned through a main pipe to the brine tank in which are placed the submerged coils. _Salt Brine--Calcium Brine._--One system is operated on salt brine in which the accumulation is sterilized by boiling, then filtered and used for curing purposes. The other is operated on calcium brine which is concentrated by passing over a concentrator. It is then returned to the brine tank. _Spray Devices._--There are various spray devices purchasable on the market, some approaching atomizers. The owner usually selects something to his taste. A common spigot can be used with a piece of bent tin to distribute the brine at the outlet, but more efficient devices are obtainable.