34 BUILDING AND EQUIPMENT 



of gravel. The sand should be sharp building sand and the gravel 

 should be washed pebbles, ranging 1 in size from one-half to one 

 inch. The top dressing should be not less than one inch thick, 

 consisting of one part of cement and one and one-half parts of 

 sharp building sand. It should be carried up on the walls and 

 partitions at least two inches, forming a sanitary cove. After 

 finishing, the floors should be allowed to harden for at least 

 two weeks. .This will greatly prolong their life. It is advisable 

 to use cement hardener such as Master Builders' cement, or 

 Lapidolith, etc., which will help to make these floors more nearly 

 wear-, water-, dust- and crack-proof. It is difficult to keep the 

 condensery in sanitary condition and to protect the product 

 against contamination, unless the floors of the factory are and 

 stay free from cracks and holes. 



Ventilation. A. proper and effective system of ventilation 

 is another very important and too often entirely neglected factor 

 in the planning of the condensed milk factory. This applies to 

 all parts of the plant where work is being done, but it is espe- 

 cially essential in rooms where free steam escapes. The ventilat- 

 ing system should be adequate to afford ready and quick escape 

 of steam, to- remove foul air and to facilitate the regulation of 

 temperature. Unless free steam does promptly find an exit from 

 the factory rooms, it condenses on the walls and ceilings, mak- 

 ing them sweat profusely, causing corrosion of the walls and 

 ceiling, deterioration of motors and other similar equipment, 

 and molding of supplies ; this is especially the case during the 

 winter months. The removal of foul air and the control of the 

 temperature of the air are essential for the comfort, health and 

 efficiency of the employes. 



The system of ventilation that will accomplish efficient ven- 

 tilation will of necessity vary with the type of plant and arrange- 

 ment of equipment. Gravity ventilation is, under average con- 

 ditions, inadequate to produce satisfactory results in factories, 

 like milk co<ndenseries, where there is bound to be much escape 

 of free steam. The exchange of air is not rapid enough to remove 

 the steam before it condenses on the walls and ceilings, espe- 

 cially in cold weather. It is, therefore, advisable to provide for 

 some form of forced ventilation. Under certain conditions of 

 construction an air flue connecting with the smoke stack may 



