378 GEOLOGY OF THE DENVER BASIN. 



The analyses given in the following table were derived from Table I: 



Table II. — Analyses of coals of the Denver Basin, arranged according to mining 



districts. ' 



1 The folio-wing data regarding the time of sampling and of making the analyses, the places in which the analyses were 

 conducted, and the lapse of time between the two operations of sampling and analyzing, are here added with a view to 

 affording a complete record of the coals represented ahove, and so presenting an appropriate hasis for their discussion: 



Boulder Valley mine, 1J miles east of Erie 

 March, 1891. 

 II. Erie-Canfield, Mitchell, Baker groups, sampled 

 III. Lafayette, Louisville, Davidson group 



Sampled in Octoher, 1890. Analyzed in "Washington, D. C, in 



September, 1886; analyzed in Denver in January, 1887. 

 pled in September-October, 1890; analyzed in Washington in March, 

 1891. Samples crushed, quartered, and bottled some time between November 1 and December 31, 1890. Lafay- 

 ette field not opened in 1886. 

 IV. Louisville, Davidson groups, sampled in August, 1886; analyzed in Denver in September-October (?), 1886. 

 V. Marshall field, sampled in August, 1886; analyzed in Denver in September-October (?), 1886. 

 VI. Golden group, sampled in October, 1890; analyzed in Washington in March, 1891. Samples crushed, quartered, 

 and bottled some time hetween November 1 and December 31, 1890. 

 VII. Golden group, sampled in February, 1887; analyzed in Denver in February, 1887. 

 VIII. Carbon, Lehigh mines, sampled in February, 1887; analyzed in Denver in February. 1887. 

 IX. Scranton mines, sampled iu January, 1887 ; analyzed in Denver in February, 1887. 



PECULIARITIES PRESENTED IN THE FOREGOING TABLE. 



Table II presents some striking peculiarities wholly unforeseen prior to 

 its compilation. Among these are, first, the relations between volatile-com- 

 bustible matter, water, and specific gravity in the more lately sampled coals, 

 which were analyzed in Washington, and in those sampled in 1886-87, 

 analyzed in Denver; and, second, the relations between the volatile-com- 

 bustible matter and the fixed carbon of the foothill coals as compared with 

 the more normal contents in the prairie coals. 



In regard to the first of these peculiarities, upon reference to column 6 

 (water determinations) the percentage of moisture in the samples from the 

 New Boulder Valley mine, the Lafayette-Louisville region, lately devel- 

 oped, and the newly opened mines of the Golden district, all of which 

 were taken more recently and analyzed in AYashington, is found to be 



