Show i t t i 1 For Hardening Drill t l Hardening an ordinary drill In auV frith phone ncld states the Kngllsh Mechanic Me-chanic stakes an edge that will cut Y tempered steel or facilitate cutting Y I hard rock Tho acid should bo poured Into a flatbottomed vessel to a depth of about oncelshth of an Inch The point ot lho drill Is heated to a dull cherry red and dipped In tho acid to that depth This makes the point extremely hard while the remaInder i remains soft If tho point breaks re t il harden but with a little less acid In tho vessel |