In the foreground of the illustration is given a miniature of the ribbed tube system, which very clearly illustrates the arrangement of the separate ribs. A ventilator not apparent on the diagram conducts air to the tubes in the cooling chamber, and these present a considerable cooling area, in addition to which, the air-stream taking a parallel direction, resistance to its passage is reduced to a minimum. Another method of cooling[119], that is carried out in France consists in placing the moulds, containing cakes of chocolate, upon a travelling belt running horizontally through the whole length of the cooling chamber. The requisite reduction of temperature is effected by apparatus similar to that described above in Wegelin & Hübner’s arrangement. The liquefied carbonic acid flows through a system of pipes fitted to the roof of the cooling chamber, producing by its vaporisation the necessary cooling and then it passes back to the refrigerating machine. Circulation of the air in the cooling chamber is provided for by a suitable ventilator under the pipes of the cooling system, gutters being fixed to carry away any water condensing upon their surface and prevent it from falling upon the chocolate. The travelling belt passes along so slowly that the moulds, containing chocolate, placed upon it at one end, take from ten to fifteen minutes in passing to the other end where they are taken off and carried to the packing rooms. [Illustration: Fig. 62.] Another cooling arrangement that works very well is constructed by T. & W. Cole of the Park Road Iron Works, London E.; figure 62, represents a plan of this arrangement, which has the great advantage of providing for the exclusion of moisture from the cooling chamber. Refrigeration is effected, by means of Cole’s Arctic-Patent Dry Cold Air machines, by compressing atmospheric air and then allowing it to expand, after being cooled by water and having moisture removed by suitable arrangements. The machine is of very solid construction; it works at a pressure of from 70 to 80 atmospheres and drives the dry cooled air through a system fitted in the cooling chamber where the chocolate is spread out, either on portable trucks or on a travelling belt, so that it remains in the chamber long enough to become perfectly cold. The system of cooling can be changed in various ways. The sudden removal of the cold chocolate into another chamber where the air is moist, would be attended with a deposition of water upon the goods. For that reason the goods are first transferred, for a short time, to a warm chamber (ante-room) where they acquire a temperature at which no deposition of moisture can take place. The chief advantage of this arrangement is that it furnishes dry cold air economically, both in summer and also in a moist climate. Cole guarantees that this machine will effect a refrigeration of 5 ° C.; according to the statement of Messrs. Negretti and Zambra the cooled air contains only 40 % of moisture.