The sloping sides of the conical bottom can be freed from the coating of scum which forms upon them every two or three hours by two rotatory scrapers, formed of L-irons, which can be slowly turned by an attendant by means of a central shaft provided with a suitable handle.
Rotating zinc cathodes were used, with scrapers to prevent the accumulation of a layer of insoluble magnesium compounds, which would otherwise increase the electrical resistance beyond reasonable limits.
Scraping ToolsFlint scrapers are found from S.D.
Round scrapers were also made (44).
Flint scrapers were used in dressing down limestone sculpture in the IIIrd Dynasty.
The scrapers seem to have always been of copper.
The hieroglyphs was done partly with copper and partly with flint scrapers (P.M.
In later work we may note that copper scrapers were used for facing the limestone work in the VIth, the XIIth and the XVIIIth Dynasties.
Large thin spear-heads; scrapers with edge not on the side but on the end; flint knives and saws, but all still chipped, not ground or polished; long spear-points, with tang and shoulder on one side only, are also characteristic implements of this epoch.
The stone hatchets are symmetrically shaped and edged by grinding, while the cutting flakes, scrapers, spear and arrow heads are of high finish.
The deposit from this solution even with low currentdensities is pulverulent and non-coherent, and therefore during electrolysis wooden scrapers are automatically and intermittently passed over the surface of the cathode to detach the loose silver, which falls into cloth trays at the bottom of the tanks.
Sometimes the opium is in a fluid state by reason of dew, and in some places it is rendered still more so by the practice adopted by collectors of washing their scrapers, and adding the washings to the morning's collection.