Abstract: A twist drill comprising a bit containing spirally arranged grooves and lands of substantially equal width, with a shank at one end and a pointed tip at the other, the leading edges of the grooves being inclined to the axis of the bit and constituting cutting edges and the lands rearwardly of the cutting edges being relieved, characterized in that there are auxiliary rectilinearly arranged axially spaced cutting edges parallel to the axis of the bit formed by straight line channels spaced peripherally about the axis of the bit but of lesser depth than the spirally arranged grooves.

Abstract: The invention is for a process and composition for pickling metals, especially iron based metals, prior to metal finishing. A hydrohalide acid pickling solution is used which solution is characterized by the addition of urea. The urea substantially reduces, even completely eliminates, the excessive liberation of noxious and corrosive hydrohalide acid fumes normally associated with such pickling operations. This is an advantage as it greatly reduces the cost of the pickling operation as the consumption of acid is dramatically reduced. Moreover, there is less injury to personnel and equipment contacted with said fumes. Finally, a metal surface treated with the pickling solution of the invention is improved as there is less pitting and the surface is more active to a metal depositing solution.