3363.     TEICHNER, S., AND PERNOUX, E.  [Ultrasonic Fractionation of a Kieselguhr Carrier of a Fischer Catalyst.]  Compt. rend., vol. 230, 1950, pp. 1063-1064.

        Suspension of an acid-treated kieselguhr (Filter Cel) in distilled H₂O was subjected to an ultrasonic treatment (_v=970,000).  2 fractions were obtained:  One (12% of the initial weight of the kieselguhr) was a stable dispersion; the other remained precipitated on the bottom of the vessel.  The specific surface, determined by absorption of N₂ at 195°, of the dispersed fraction was 40 m.² per gm., that of the initial acid-treated kieselguhr 27 m.² per gm.  Besides, treatment with a 5% H₂O solution of Na₂CO₃ involved losses in weight of 21.6 and 14.5%, respectively.  Examination under the electronic microscope revealed an extensive flocculent appearance for the dispersed fraction and considerably less so for the same fraction treated with carbonate.  The precipitated fraction had a specific surface of 15.2 m.² per gm. and a loss in weight by the carbonate treatment of 9%.  The properties were similar to those of a kieselguhr untreated with acid.  The ultrasonic treatment, thus, furnishes further proof of the formation by the acid treatment of kieselguhr of a silica gel of flocculent appearance with a broad specific surface, and easy reaction with Na₂CO₃.  Such a gel is formed for the most part in the dispersed phase of ultrasonic treatment.