IRON AND IRON MOLDING 



379 



casting should be taken into consideration. Mold sand is a 

 mixture of sand, clay, and molasses, or other binding material 

 that aids the sand in retaining its shape under pressure. 



FIG. 193. Refining of Sand. Showing foundry derrick for lifting 

 heavy loads of sand, etc., and sieves to separate the fine from the 

 coarse sand. 



Sand is said to be sharp when its grains are angular, and 

 dull when they are round. It is termed strong when a body 

 of it manifests a disposition to retain any shape that may be 

 given it, and weak when it tends to fall apart. For light 



