The Collaborative International Dictionary of English v.0.48:

Scobs \Scobs\, n. sing. & pl. [L. scobs, or scobis, fr. scabere
   to scrape.]
   1. Raspings of ivory, hartshorn, metals, or other hard
      substance. --Chambers.
      [1913 Webster]

   2. The dross of metals.
      [1913 Webster]