a. Chem. [f. SULPHONE + -IC.] Containing the radical SO2 . OH (called the sulphonic group or radical).

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1873.  Jrnl. Chem. Soc., N.S. XI. 277. Action of Phosphorus Pentachloride on Sulphonic Acids.

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1881.  Athenæum, 12 Nov., 634/3. Sulphonic Acids derived from Isodinaphthyl.

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1902.  Encycl. Brit., XXVI. 728/2. The introduction … of the sulphonic group into the aminic group.

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