July 2, 1908.] Agriculttiral Gazette of N.S.W. 539 



A variet}' of Mibstance.s have been used for the purpose, some of which are 

 ■of a composite character; while pumice-stone, charcoal, cork, asbestos, saw- 

 dust, and silicate of cotton or slag-wool is favoured. If charcoal is used it 

 should be well dried and packed as nearly as possible to a consistency of 

 11 lb. 23er cubic foot ; and silicate of cottot), 12 to 13 lb. per cubic foot. 



In constructing cool chambers due attention is reifuisite to a proper system 

 of ventilation ; the opening of doors, from time to time, no doubt, permits 

 the escape of vitiated air, but at the same time there is a loss of cold air wlien 

 the doors are opened, which has to be made good by the refrigerating 

 machinery. In some cases ventilating shafts are provided which can l)e 

 regulated by the engineer. 



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No. 2.— Frick Refrigerating macliine. 

 Capacity, 4 to 10 tons. Joseph Baker and Sons, Kent-street, Sj'dney. 



The construction of the chamber, therefore, requires proper provision for 

 the circulation of air. The cold air will find a lower level than the warm air, 

 and in reference to this matter of air circulation, Wallace Tayler says : — 



Using a liroad single distributing duct near the floor in combination with a false ceiling 

 resulted in a very penetrating and uniform circulation of air, and in practical service it 



has been found to produce superior results I his was accomplished by 



perforating the distributing ducts with small holes, and so proportioning them that a 

 larger part of the flow of air is from the bottom of the ducts. The ducts are also 

 perforated to some extent on sides and top. By piling the goods a few inches from the 

 floor the air from the ducts flows under the goods and out to the centre of the room. 

 This action is alsn assis-ted by having the greater number of the perforations in false 

 ceilings in the middle, third, or (piarter of the room, so as to draw the air out from the 

 sides of the room. 

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