121 



to the lining, since between the lining and the case there is provided an in- 

 sulation space, which in some refrigerators is filled with materials like 

 sawdust, cork, and charcoal, and in other refrigerators the space is left 

 unfilled, the dead air being regarded the most effective insulation. Lum- 

 ber for refrigerators must be well dried as otherwise the extreme variations 

 of temperature are apt to cause it to buckle and check. The large refrigera- 

 tors or cooling rooms are built to order in the place in which they are 

 used. Though hardwoods are called on for the exterior or case work of the 

 higher priced work, softwoods answer to a considerable extent both for the 

 linings and cases. The materials for both of these parts are usually rather 

 thick and are preferred to guard more effectively against the penetration 

 of heat. It is possible, so the Pennsylvania manufacturers claim, to secure 

 a temperature of 38 degrees from ice alone in these large refrigerators. 



Table 76. Wood for Refrigerators and Kitchen Cabinets, year ending June, 



1912. 



EXCELSIOR. 



Formerly excelsior was called wood fiber but later it received its present 

 name given it by an upholstery firm in its advertisement. In 1860 this 

 commodity was first placed on the market by a Maine manufacturer, but 

 it was not called on to meet much of a demand for a decade; then with 

 the improved machinery invented by Europeans the manufacture of excelsior 

 was greatly facilitated. Since that time it has become a staple product. 

 According to a recent report by the Forest Service and the Bureau of the 

 Census, it was ascertained that 85,000,000 feet of forest material is yearly 

 demanded for its manufacture. Pennsylvania is not so important an excelsior 

 state as either Virginia or New York, the former being second and the 

 latter third. Pennsylvania is the tenth, consuming each year over one and 

 a half million feet of wood all cut within the State. In the New England 



