240 NEW YORK STATE MUSEUM 



Such sands only result from attrition accompanying the transport 

 of rock debris by moving ice. This angularity has its practical 

 significance in the greater pore space of the sands as compared with 

 those made up of well rounded particles, for in casting metals the 

 gases given off must have opportunity of escape through the mold. 



The molding sands proper represent the uppermost layer which 

 is never more than a few feet thick and seldom exceeds 2 or 3 feet. 

 Thus their removal consists in skimming off a thin horizontal seam, 

 rather than working a bank as in the usual building sand operations. 

 The land under exploitation is divided off into sections according 

 to the various qualities of sand present, and then the sod is stripped 

 off down to the layer. This operation is usually performed in 

 successive trenches, each about 3 feet wide, so that the sod and 

 soil of one bench is placed in the trench left by the removal of the 

 sand from the preceding one. The width is determined by the 

 convenience of the workers who carry out the whole operation with 

 hand shovels. After a plot has been worked in this way the land 

 may be returned to agriculture without much deterioration of value. 

 The right of digging the land is usually sold under a contract, the 

 shipper paying a lump sum or a certain amount for each ton removed. 

 The yield obtainable is figured roundly at 1000 tons to the acre 

 for each 6 inches of thickness; an 18-inch seam which is not far 

 from the average size thus will yield 3000 tons for every acre of 

 surface. 



The grading of the sand is performed by mere rule-of-thumb 

 tests dependent for their value upon the skill and experience of 

 the operator. The lack of positive standards for sizing and indicating 

 the particular uses of different sands in the field is a feature of present 

 practice that seems to offer opportunity for improvement, since 

 anything like uniformity in grading between different producers 

 is out of the question. To the foundrymen it is a matter of most 

 importance that there should be a fair degree of uniformity in the 

 sands with regard both to the size of the particles and the bonding 

 qualities. 



The grades of sand shipped from the Hudson valley run from 

 No. o, the finest, to No. 4, which is the coarsest size that is commonly 

 produced in the district. No. o is the size used in stove-plate and 

 fine castings and consists of sand of which 95 to 98 per cent will 

 pass the loo-mesh screen or of which the average grain diameter 

 is smaller than .147 mm (.0058 inch). No. o and No. i are the 

 sizes for which the chief demand exists since they are not common 

 in the molding sand districts elsewhere. 



