REPORT OF THE DIRECTOR AND STATE GEOLOGIST 1901 1'95 



unburned sand, burns out at a comparatively low temperature, 

 and is therefore of no service to a molding sand. Clay gives an 

 excellent bond, but, if present in quantity, it tends to reduce the 

 porosity of the sand, as has been noted above. 



Occurrence of molding sands 



In New York State the largest and best known deposits of 

 molding sand are those which occur in Albany county and in 

 the adjoining parts of the Hudson river valley. There, deposits 

 contain sands of various degrees of fineness, and furnish a large 

 part of the molding sand used in the eastern United States. 



The molding sand occurs in thin beds, overlain by soil and 

 underlain by clay. In some places the covering of soil has been 

 removed by the action of streams, leaving the molding sand 

 exposed at the surface of the ground. When thus exposed to 

 the atmosphere, the molding sand can be readily distinguished 

 from common sand. In a strong wind the ordinary sand is 

 blown about readily, while the molding sand, owing to its con- 

 tained clay, remains unmoved. The sides of a road-cut in com- 

 mon sand will fall in till the angle of repose of the sand has 

 been reached, while a cut in molding sand will remain with 

 walls vertical, or nearly so, for some time. 



Occasionally the molding sand is dug and marketed by the 

 owners of the land on which it occurs. Usually, however, it is 

 taken out by dealers, who either pay a certain royalty for each 

 ton of sand excavated, or pay a fixed sum for all the sand that 

 can be obtained in a given area. 



The handling of the material is simple, as the stripping is usu- 

 ally thin, while the molding sand is readily excavated. 



Dr G. P. Merrill has examined samples of Albany county 

 molding sand under the microscope; and states 1 that " the Sel- 

 kirk molding sand is of a yellow brown color, showing under 

 the microscope angular and irregular rounded particles rarely 

 more than .25mm in diameter, interspersed with finely pulver- 

 ulent matter which can only be designated as clay. The yellow 

 brown color of the sand is due to the thin film of iron oxid which 



1 U. S. Nat. Mus. Rep't for 1899, p.476-77. 



