acid and calcium nitrate are also used the slurry for the modifiers is approximately 8 18 solids the total solution is between 20 40 solids other modifiers may be added in quantities from about 1 10 these other modifiers may include pb mgo al 2 o 3 bao li 2 o ge and s a preferred method of making the pre glass agglomeration of example 1 comprises the following steps the constituents are mixed together in two separate factions comprising the silicate part and the modifier part the modifier part is boric and calcium in an aqueous slurry the modifier solution is either poured into the silicate solution with vigorous mixing or the two are mixed together using an impeller pump with a recirculation loop vigorous mixing and slow addition of the boric calcium solution are essential the solution once mixed together has a ph of 10 12 mixing temperatures approach 60 u00b0 c this solution is fed to a two fluid nozzle for atomization via a diaphragm pump at 25 200 psi alternatively a centrifugal atomizer may be utilized at 10 000 25 000 rpm while air atomizing air pressure varies between 80 1000 psi the drying step occurs at about 100 u00b0 c to about 300 u00b0 c the outlet temperature is 300.