476 



REPORT OF NATIONAL MUSEUM, 1899. 



above. W. Ferguson gives ^ the following analyses of molding sand 

 in actual use in his foundries: 



Constituents 



Silica 



Alumina 



Ferric oxide 



Combined water .. 

 Calcium carbonate 



Magnesia 



Potassium 



Manganese 



Organic matter 



Total 



No. 1, fine sand 

 for snap work. 



81.50 



9.88 



3.14 



3.00 



1.85 



0.65 



No estimate. 



Trace. 



Trace. 



No. 2, medium 

 grade for 



medium class 

 of work. 



84.86 



7.03 



2.18 



2.20 



1.10 



0.98 



No estimate. 



Trace. 



Trace. 



100. 02 



98.35 



No. 3, coarse 

 sand for 

 heavy ma- 

 chine castings 



82.92 



8.21 



2.90 



2.85 



1.10 



None. 



No estimate. 



Trace. 



Trace. 



97.98 



No. 4, for heavy 



machinery 



in dry-sand 



molds. 



79.81 



10.00 



4.44 



2.89 



1.25 



0.88 



No estimate. 



Trace. 



Trace. 



99.27 



Sands containing lime or alkalies, that is those containing free calcite 

 or feklspathic granules, are sometimes liable to fusion in the case of 

 heavy castings. It is customary in such cases to coat the surface of 

 the mold with graphite. 



Sands suitable for ordinary castings are widespread, though the 

 finer grades are often l)rought considerable distances, some of those 

 used in bronze casting in America being imported from Europe. In 

 the United States the beds are alluvial deposits of slight thickness. 

 Large areas occur in New York State, in counties extendiag from the 

 Adirondacks to New Jersey. At date of writing a very considerable 

 proportion of the material used in the eastern United States is dug in 

 Selkirk, Albany County, New York. (Specimen No. 61044, U.S.N.M.) 



Nason states that these sands occur in beds varying from 6 inches to 

 3 feet or even 5 feet in thickness. They immediately underlie the 

 surface soil and overlie coarser, well stratified sand beds more nearly 

 allied to (i[uicksands. 



In gathering the sands for market, a section of land 1 or 2 rods in 

 width is stripped of its overlying soil down to the sand, which is then 

 dug up and carried away. When the area thus exposed is exhausted, 

 a like area, immediately adjoining is stripped, the soil from the second 

 l)eing dumped into the first excavation. By this method the field, 

 when finally stripped of its molding sand, is ready again for cultivation. 



It is estimated that a bed of sand 6 inches in thickness will yield 

 1,000 tons an acre. The royalty paid the farmers from whose land it is 

 taken varies from 5 to 25 cents a ton. Some 60,000 to 80,000 tons are 

 shipped annually from Albany County alone. 



The Selkirk molding sand is of a yellow-brown color, showing under 

 the microscope angular and irregular rounded particles rarely more 



1 Iron Age, LX, December, 1897, p. 16. 



