COAL DEPOSITS IN RHODE ISLAND ?83 



RHODE ISLAND GOAL^^ 

 BY CHARLES W. BROWN 



{Abstract) 



Coal deposits in Rhode Island have been mined intermittently for the past 

 100 years and at various places — in regions about Providence, along the west- 

 ern edge of the Narragansett Basin, and at Portsmouth, in the central southern 

 portion. The recent development of the Portsmouth coal mine has led to a 

 careful study of the geology, extent, and testing of the fuel values and chem- 

 ical condition of this coal. The coal beds are found in the lower members of 

 the Carboniferous in Rhode Island. Former mining covered an extent of 4,000 

 feet along the strike and 1,200 feet or more down the dip. 



The coal is extremely hard anthracite, having a grayish black color and 

 bright luster, with some bone and more or less impurities of quartz and pyrite, 

 becoming only graphitic along shear planes. It is found in beds averaging 

 2 or 3 feet, and occasionally in large "rolls" from 60 to 72 feet in diameter 

 and 75 feet wide. The best coal is found in the rolls, the *'vein" matter in- 

 creasing as the bed becomes thinner. 



Official tests show that the coal will burn and has a certain fuel value. By 

 the proposed "chemical treatment" this value is supposed to be enhanced. 

 The practical value of this treatment has not been officially determined. The 

 variation in the thickness of the beds, together with unknown extent of the 

 basin and possible increase or decrease of impurities, make final statement aa 

 to amount and value of coal beds impossible. 



GEOLOGIC THERMOMETRY 

 BY FRED E. WRIGHT 



(Abstract) 



In ordinary thermometry, temperature is defined by the expansion of a per- 

 fect gas, and is expressed in terms of fixed units, determined by the freezing 

 and boiling points of water under standard conditions. Temperatures are 

 ascertained practically by means of thermometers which, although they differ 

 greatly in type, are all based on some property which varies in a definite way 

 with the temperature. In geology temperatures are of fundamental impor- 

 tance, particularly the temperature to which rocks were heated in past 

 geologic ages and under inaccessible conditions. Points on the geologic ther- 

 mometer scale must, therefore, be historical points, to be determined primarily 

 by the permanent effects which such temperatures have produced on the rocks 

 and rock components, and which are clearly marked even at lower tempera- 

 tures. The factors which may serve to furnish points of this nature are, 

 especially, melting temperatures of stable minerals and of eutectics, inversion 

 temperatures of minerals, temperate limits beyond which monotropic forms 

 can not exist under different conditions of pressure ; stability ranges of enantio- 

 tropic forms and of minerals which dissociate or decompose at higher temper- 

 atures, and temperatures beyond which certain optical or physical properties 



i« Read by title, In the absence of the author. 



