426 J. P. Kimball—Geological Relations and Genesis 
proximate analyses from commercial samplings, exclusive of 
own, moisture, in part hygroscopic, is constantly present 
in percentages of 0°24 to 0°81; silica and insoluble 5 to 103; 
phosphorus 0009 to 0°065; sulphur 0-045 to 0°248; and iron 
of peroxidation from ferrous carbonate and from ferrous sul- 
* phate, and its concentration under favorable conditions by segre- 
gation or as a sediment as the case may be, are common and 
mediation of basins. (3) The basic character of their siliceous 
impurities, occurring as residuums, characterizes them still 
ese in point of sizable development and, cursorily 
