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 30Jun*43 
 
 MDDC - 885 
 
 UNITED STATES 
 
 ATOMIC ENERGY COMMISSION 
 
 OAK RIDGE 
 
 TENNESSEE 
 
 QUARTZ FIBER MICROBALANCE 
 
 Argoime National Laboratories 
 
 Published for use within the Atomic Energy Commission, Inquiries for additional copies 
 and any questions regarding reproduction by recipients of this document may be referred 
 to the Documents Distribution Subsection, Publication Section, Technical Information 
 Branch, Atomic Energy Commission, P. O. Box E, Oak Ridge, Tennessee. 
 
 Inasmuch as a declassified document may differ materially from the original classified 
 document by reason of deletions necessary to accomplish declassification, this copy does 
 not constitute authority for declassification of classified copies of a similar document 
 which may bear the same titie and authors. 
 
 Date of Manuscript: Unknown 
 Document Declassified: January 14, 1947 
 This document consists of 3 pages. 
 
- 1 - MDDC - »85 
 
 QUARTZ FIBER MICROBALANCE 
 
 This microbalance indicates by a calibrated dial and vernier the amount of torsion 
 necessary to bring the known and unknown weights into balance. One division on the ver- 
 nier is 6x10'^ grams. The maximum load per pai^is about 20 milligrams. 
 
 The suspension or torsion fiber, beam, and pan holders are of fused quartz construc- 
 tion. The suspension fiber is about 2.3x10"^ centimeters in diameter. Two small platinum 
 pans hold the materials to be weighed. The unknown is balanced as closely as possible with 
 known weights. In balancing, the oscillation of the beam damps out within 2 to 3 seconds. 
 Then, one end of the suspension fiber is rotated until the balance is perfect. The amount 
 of rotation is indicated on the dial and vernier. 
 
 An optical system is used for observing exact balance. Two lamps with exactly centered 
 filaments throw onto prisms the images of two segments of the index fiber. This index fiber 
 is above the beam and parallel to it. The segments chosen for viewing are near the ends of 
 the beam. Through a system of reflecting and combining prisms, the images of the index 
 fiber are shown on a viewing screen for rough balance and may be viewed through an objec- 
 tive lens for exact balance. When viewing the balance through the objective lens, one sees 
 a magnified image of the vernier in the left upper third of the field. 
 
 The accuracy is limited by temperature changes and by vibrations . Temperature 
 changes are minimized by a set of 3 housings with dead air spaces between them. For ex- 
 treme accuracy, the instrument should be used in a temperature-controlled room. 
 
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