Show A correction the general filtration company inc requests us to correct an impression which might be gained regarding the properties of the porous mineral medium Fil from a description in the article on the koering cyaniding Cyan iding process which appeared in the january issue of the 1111 mining ning review pevie w in this process a dr drum is used which is lined with Fil Fil is composed principally of silica and is therefore proof against any acid with the exception of hydrofluoric Fil is however attacked by alkaline liquids and unless the solution contains less than 5 per cent free alkali the use of Fil is not recommended ber because ause strong hot caustic will disintegrate this ware rapidly weak alkaline solutions are however successfully handled furthermore Fil will and can get clogged unless a sufficiently dense grade ie a grade with sufficiently small pores is used which will prevent the solid particles from entering the body of the plate |