MANUFACTURE AND PROPERTIES OF LIME-SAND BRICKS. 137 



is filled by means of a funnel placed above it. When the drum is 

 charged, the interior mixing-blades are set in motion and the contents 

 are heated by means of the steam-jacket surrounding the drum. A 

 vacuum pump attached to the apparatus removes the steam and air 

 from the drum. When the sand has been properly dried the required 

 quantity of finely pulverized lime is introduced into the drum through 



CROSS SECTION A-B 



FIG. 26. Schwarz drying- and mixing-machine. 



a special aperture and the mixture is again stirred and heated. The 

 necessary quantity of moisture is then introduced into the drum in 

 the form of water or steam by means of a pipe penetrating the interior 

 of the drum. After wetting, the mixture continues to be stirred and 

 heated during a sufficient time to allow a preliminary combination of 

 the lime and sand to take place and produce a mixture with sufficient 

 tenacity to permit of easy molding." 



