ANALYSES. 



The hydrochloric aciil extract (4) yielded : 



SiO.,* 0545 grains =^ 0. 100 per cent. 



AlA 6(>20 '' =1.324 " 



Fe-A ^^<>1 ** =1.812 " 



CaO. 024 •' =0.048 



K,0 0887 '• =0.177 '' 



Na.,0 0698 " =0.139 " 



1.8051 " = 3.609 



AyALVSES OF MATERIAL MECHANICALLV SEPARATED. 



In order to make more clear the change in physical conditions which 

 the rock had undergone, 400 grams of the pulverulent material, free from 

 roots and otlier recognizable organic debris, were submitted to mechan- 

 ical separation by passing tlirougli sieves of varying degrees of fineness. 

 The 17 grams tabulated below as " silt " were obtained by washing the 43 

 grams of material Avhich passed through fine bolting cloth of 120 meshes 

 to the lineal inch, and represents the impalpable mud which remained 

 for some time in suspension, while the 26 grams of " fine sand " sank in 

 the course of a few moments to the bottom of the beaker. 



The results of this mechanical separation are as follows : 



Silt 17 grams : largest grains 0. 1 millimeters in diameter. 



Fine sand 26 " '* " 0.18 



Sand 45 " " " 0.25 



Sand 15 " '' '' 0.65 



Sand 44 " " " 1.00 



Sand 94 " " *' 1.5 



Coarsesand 118 '* " " 2.00 



Gravel 41 *' *' *' 8.00 



Total 400 



The coarser of the.se particles, like the gravel and the coarse sand, are 

 of a compound nature, being aggregates of quartz and feldspar, with 

 small amounts of mica and other minerals. In the finer material, on 

 the other hand, each particle represents but a single mineral, the process 

 of disaggregation having quite freed it from its associates, excepting, of 

 course, in the case of microscopic inclusions, which could l)e liberated 

 only by a comi)lete disintegration of the host itself These particles as 

 seen under the microscope are all sharply angular and in many cases 

 surprisingly fresh and undecomposed. The mica shows the greatest 

 amount of alteration, the change consisting mainly in an oxidation of 

 its ferruginous constituent, whereby the folia become stained and re- 



•Thls nlIlcR is that taken up in acid solution only. A much larger amount would hnvo i...,.n o».. 

 tained by treatment of the residue with carbonate of soda solution (see p. 326). 



