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problem of weighing a few milligrams of material with the same pre- 

 cision as might be obtained with samples of the usual size. The Nernst 

 quartz fiber balance, capable of weighing to a few ten-thousandths of a 



Fig. 5 — The micromanipulator finds use when it is necessary to operate on unusually 

 small particles or within areas bounded by the microscopic field. 



milligram, has proved very useful in certain types of work, where the 

 total load does not exceed a few tenths of a gram. Its application to 

 chemical analysis, however, is quite limited because of the difficulty 

 of reducing the load to this extent. The quantitative extension of 



