Abstract: A biocidal composition suitable for use in marine anti-fouling coatings is a water-insoluble mineral having an internal pore structure, containing, within the pores a biocidal compound effective against marine growth. Preferred minerals are zeolites, particularly synthetic faujasites, and porous silicas; preferred biocidal compounds are organo-tin compounds.The compounds may be incorporated into anti-fouling paints e.g. epoxy, epoxy-coal tar and chlorinated rubber paints or wax coatings.

Abstract: Underwater surfaces are protected against weed and/or shell growth with a wax coating containing one or more biocides effective against weed and/or shell growth when dissolved or dispersed in wax. The biocides are preferably sea-water insoluble and may be fresh water soluble also. They are preferably thermally stable up to 150.degree. C and soluble in wax. Suitable biocides are Cu, Zn, Ni, Co, Mn or Sn salts of carboxylic acids or polyacrylic acids, or organic compounds having an active structure containing S, Cl, N or O.The coating may be 5-500 micrometers thick.

Abstract: Process for making a catalyst precursor by heating an inorganic oxide support with a titanium compound at a temperature in the range 150.degree. to 1200.degree. C and then retreating with titanium one or more times by alternately adding a hydroxyl compound (e.g. water) and titanium compound and heating at 150.degree. to 1200.degree. C. The precursor can be used to make a useful ethylene polymerization catalyst by adding a chromium compound and heat activating at a temperature in the range 100.degree. to 1200.degree. C.