Figure 8-4. Electron-microscope picture of infusorial earth (X 20,000) sold by Central 

 Scientific Company, Chicago. Note that fibers and bundles of fibers are very similar 

 to those in photograph of Attapulgus clay in Figure 8-3. Diatom fragment near center 

 of photograph is about l ! /2 V in length and 1 fi wide. Openings in shell are less 

 than l/ 5 j«. in diameter (0.0002 mm) and would barely be discernible in the light micro- 

 scope. (Courtesy R.C.A. Laboratories and Standard Oil Development Company.) 



Long-Range Correlation 



The foregoing discussion has involved detailed correlations between in- 

 dividual beds. It was pointed out that electron-microscope techniques are not 

 in general use as yet and may not be used except in unusual cases. Long-range 

 correlations, of course, depend upon equivalent criteria being found over long 

 distances. For this reason, long-range correlations with the electron microscope 

 are subject to the same considerations as were the closer, detailed correlations. 



Studies of Crude Oil 



It will be necessary to develop a technique for studying crude oils in the 

 electron microscope. A possible approach to this study may be as follows: 



1. All foreign substances in the oil and in the extracts that are possible to 

 prepare for study in the microscope would be studied. 



2. Bacteria in the oils and in the extracts would be observed and identified. 



3. The nature of coloring material in some of the darker oils would be 

 studied. Is color due chiefly to the presence of foreign materials, or could it be 

 due to molecular combinations ? 



147 



