mesh glass powder which had been dried at 450 u00b0 c for 20 minutes and then cooled in a desiccator before blending into the partially polymerized cr 39 resin those lenses transmitted an average of about 64 of the incident light at room temperature the third set of lenses was produced from the glass particle fraction 140 400 mesh which had also been dried at 450 u00b0 c for 20 minutes and cooled in a desiccator before mixing in the resin those lenses transmitted an average of about 87 of the incident light the second and third sets of lenses were heated to 95 u00b0 c and then cooled to room temperature u03b4t rt 95 u00b0 c the average transmittance of incident light of the second set of lenses was only about 28 a loss of 36 whereas the average transmittance of the incident light of the third set was about 81 a loss of only 6 table i______________________________________sample particle size dried t sub o u03b4t rt 95 u00b0 c ______________________________________a 400 mesh no 2 4 b 400 mesh yes 65 36 c 140 400 mesh yes 87 6 ______________________________________ an examination of the above data indicates that transparency can be achieved through a combination of particle size and removal of adsorbed surface water from the particles as a matter of convenience samples a b and c were prepared from a potentially photochromic glass composition of the type described in u s pat no 4 076 544 thus levels of haze can be more accurately determined on glasses in the undarkened state the glasses of u s pat no 4 076 544 are especially.