REVIEWS 
Chemical Analyses of Igneous Rocks. Published from 1884 to 1913 
Inclusive. By HENRY STEPHENS WASHINGTON. U. S. Geol. 
Survey, Prof. Paper 99. Washington: 1917. 
Students of petrology are still further indebted to Dr. Washington 
for a great store of chemical data in the form of 8,602 rock analyses, 
gathered together from all manner of geological and petrographical 
publications and from personal contributions of analyses which were 
awaiting publication. The value of such a carefully prepared and vast 
accumulation of rock analyses is obvious to all who desire to know the 
chemical composition of igneous rocks and wish to compare the rocks of 
different regions. The labor involved in collecting and arranging the 
analyses and in calculating the mineral norms is indicated by the state- 
ment of the author that “on an average the 4,980 analyses in Part I took 
45 minutes apiece and those in Parts II, III, and IV (3,622) took about 
30 minutes or more apiece,” in all more than 5,546 working hours. 
The analyses have been arranged according to their quality in four 
groups: (I) superior analyses of fresh rocks, designated as “excellent,” 
“good,” and “‘fair,”’ except those which could not be classified properly 
in the quantitative system of rock classification; (II) superior analyses, 
generally good or fair, not properly classifiable in the quantitative system; 
(III) superior analyses of tuffs and of weathered or altered rocks; 
(IV) analyses deemed poor or bad. Nearly 5,000 analyses have been 
classified and arranged according to the quantitative system of classifica- 
tion of igneous rocks, and form the major portion of the collection, which 
includes those in the first collection by Dr. Washington, published as 
Professional Paper 14, in 1903. ‘The new publication is a revision and 
expansion of the former, in which Part I contained 1,711 superior 
analyses. The amount of expansion is shown by a comparison of the 
number of analyses published in each paper. In No. 14 the total was 
2,881, of which 1,711, or 59 per cent, were placed in Part I. In No. 99 
the total is 8,602, of which 4,980, or 58 per cent, are put in Part I. 
There are 5,721 more in the new collection, or nearly three times as 
many as in the former one. This shows an increased production in 
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