French Chalk: Talc Powder Ground and Washed from Soapstone

French chalk is soapstone (steatite, the rock form of talc) ground and washed to an impalpable powder: the slippery white dust once used for cosmetic powders, dusted inside boots, to lift grease spots and, in spinning, to let a spindle turn freely in its bowl. Andrew Ure's Dictionary (1839) describes it as 'powdered and elutriated talc' and gives elutriation: the powder is stirred into water, the coarse grains are left to sink, and the milky water is run off to settle out the finest part. Soapstone can contain asbestos, so this is done only with stone tested free of it, and kept wet.