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 UNITED STATES ATOMIC ENERGY COMMISSION 
 
 NOTE ON THE USE OF SILICA-FREE GLASSES 
 FOR HANDLING ANHYDROUS HYDROGEN FLUORIDE AND URANIUM HEXAFLUORIDE 
 
 by 
 Aristid V. Grosse 
 
 Columbia University 
 
 This document consists of 3 pages 
 Date of Manuscript: September 1945 
 Date Declassified: .Tune 13,1947 
 
 This document is issued for official use. 
 
 Its issuance does not constitute authority 
 
 to declassify copies or versions of the 
 
 same or similar content and title 
 
 and by the same author (s) . 
 
 Technical Information Division, Oak Ridge Directed Operations 
 Oak Ridge, Tennessee 
 
NOTE ON THE USE OF SILICA -FREE GLASSES 
 FOR HANDLING ANHYDROUS HYDROGEN FLUORIDE AND URANIUM HEXAFLUORIDE 
 
 By Aristid V. Grosse 
 
 In trying to locate silica-free glasses, we came across the silica-free aluminum phosphate 
 glasses, invented by Mr. A. Pincus of the American Optical Company, in Southbridge, Massachusetts. 
 
 A perfectly clear colorless cylinder of this glass, 43.4 mm in diameter and 7.9 mm thick, weigh- 
 ing 30.8721 grams (D= 2.64 g./cm^) was immersed for 2.5 hours in boiling pure anhydrous hydrogen 
 fluoride (from the Harshaw Chemical Company), contained in a copper beaker. After this treatment 
 the loss in weight was only 8.3 mg or the 
 
 8 Q 
 
 rate of solubility = „ ^ - " _ ^ = 0.1 mg/cm' of surface and hour 
 o4.D • 2.D 
 
 The glass remained perfectly clear and transparent. Under the same conditions, ordinary glass is 
 completely corroded and becomes opaque. 
 
 Further experiments on subjecting such glass to the continuous and simultaneous action of both 
 gaseous and liquid hydrogen fluoride, at room temperatures, showed their remarkable corrosion 
 resisting properties. Thus the dream of every fluorine chemist to have a transparent and practically 
 usable material for work with hydrogen fluoride is now realized. 
 
 A similar experiment was performed with uranium hexafluoride. A flat cylinder of the silica- 
 free glass was sealed, without precautions (that is, HF and SiF^ present!) with excess of UF, in a 
 Pyrex tube. This tube was heated for 5 1/4 hours to 97-100°C, in a boiling water bath. Liquid UF^ 
 covered part of the test piece. On opening the glass tube, which was badly corroded, it was found 
 that the silica-free glass remained unchanged and stayed perfectly clear. 
 
 REACTION VESSEL WITH SILICA-FREE GLASS 
 
 While efforts were being made to produce glass tubing and other glassware from this new glass, 
 we built a cylindrical reaction vessel using silica-free glass as one side of the vessel. 
 
 It was made by drilling out a hole in a copper block; another hole was drilled to permit cooling 
 this block with either ice or dry ice. A condenser, two valve openings, at top and bottom, and a 
 thermometer well were provided. Additional details can be gathered from Figure 1, showing the top, 
 side, and front views respectively, of this vessel. 
 
 The silica-free glass plate was arranged as shown in Figure 2. The rim of the plate was lying 
 flat on the polished clean metal surface of the ledge. The narrow space between the plate and the 
 copper walls was filled with dry precipitated and powdered calcium fluoride. This fluoride has the 
 property of swelling somewhat in the presence of HF. The annular space was then filled with two 
 carefully cut-to -fit rings of butyl rubber. These were pressed down evenly by a wedge ring, which 
 in turn was pressed down by metal ring A, by means of six hexagon bolts. 
 
 For experiments with hydrogen fluoride, the copper block was first insulated, the cooling hole 
 filled with ordinary ice, and the condenser cooled by surrounding a section with a belt of dry ice 
 chips. Gaseous anhydrous HF was then admitted through a copper tube into the condenser until the 
 
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 CONDENSER 
 
 TUBE 
 
 — COOlING 
 HOLt 
 
 r 
 
 rT.C.WELL 
 
 \ 
 \ 
 
 --^rn Trn ^ 
 
 COOLING 
 OLE 
 
 'I , 
 
 5LICA- 
 
 rKtLGLASi; 
 
 T. ..W£l 
 
 TOP VIEW 
 
 tf 
 
 \\ -1 
 
 I V»' DRAIN 
 
 H^CONDENSER 
 TUBE 
 
 SIDE VIEW 
 
 FRONT CROSS SECTION 
 AT A-A 
 
 HI 
 
 ■I I 
 
 
 ^^./ 
 
 / / 
 
 Figure 1. Silica-free glass reaction vessel. 
 
 
 
 
 
 
 1 ' 
 
 1 1 
 
 
 — 
 
 p^ t-f^[ 
 
 
 BUTYL RINGS-^ •- 
 CAF2 • --K 
 
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 / 
 
 
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 SILICA-FREE GLASS 
 
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 COPPER blc:k 
 
 Figure 2. Details of plate arrangement 
 
""^^ MDDC - 1040 f 3 
 
 desired amount collected. Various chemicals could then be added and their reactions in or with HF 
 readily observed through the clear glass. 
 
 Thus a conclusion reached tediously, previously, namely that uranium hexafluoride has a very 
 small solubility in anhydrous hydrogen fluoride, could be checked in a matter of seconds by observing 
 a crystal of UFg sink in an excess of boiling HF and dissolve to only a small extent. 
 
 ACKNOWLEDGMENTS 
 
 This work was carried out in January 1941 at the Department of Physics of Columbia University. 
 It was not submitted for publication earlier in view of National Security considerations. 
 
 Acknowledgments are due to Mr. A. Pincus of the American Optical Company for samples of 
 silica-free glass, to Dr. H. C. Urey for his continuous interest and to Mr. Sam Cooie, senior machin- 
 ist of the Department of Physics, for the construction of the reaction vessel. 
 
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