fig1 b shows that the compositions of the present invention have substantially more uniform coatings on the surfaces of the individual particles and among particles in the composition 10 mg of tio 2 powder is placed in a test tube containing a magnetic stir bar 2 ml of an 0 40m solution of 2 propanol in pentane containing 0 01m cis trans decalin as an internal standard is added the test tube is sealed by attaching a stopcock and a vacuum adapter using a viton u00ae 34 o ring 34 and a pinch clamp the solution is irradiated with continuous stirring for 2 hours at a fixed distance from a medium pressure hg lamp contained inside a pyrex immersion well standard samples are irradiated simultaneously and identically to assure run to run reproducibility conversion of 2 propanol to acetone is determined by gas chromatography see generally p r harvey r rudham and s ward j chem soc faraday trans 1 1983 79 pp 1381 1390 results are reported in table 1 for comparison purposes the photoactivity of uncoated tio 2 pigment r902 grade 34 durable 34 pigment available from dupont and tio 2 pigment coated at the same weight percent silica by the sodium silicate solution method are also reported table 1______________________________________sample identification photoactivity______________________________________uncoated tio2 14 3 coated tio sub 2 sodium silicate method 7 10 dupont r902 durable pigment 1 0 coated tio sub 2 inventive method 1.