20 0 7 3______________________________________ sup a oildri u00ae 134 115a an experimental attapulgite gelling and suspending clay particle size is gt 70 percent 325 mesh oildri corporation of america chicago illinois sup b minu gel u00ae 400 clay is an attapulgite gelling and suspending clay particle size gt 95 percent 400 mesh floridin company quincy florida referring now more specifically to fig2 supra and using the data in table ii supra a comparison of urea containing formaldehyde with urea containing channelized 2 1 clay minerals is graphically illustrated it may be appreciated by those skilled in this art that the depictions in fig2 clearly illustrate that sulfur coated urea containing channelized 2 1 clay minerals require less total coating weight to achieve the same 7 day dissolution rate than does urea conditioned with formaldehyde by way of explanation the curves in fig2 were developed by computer analysis of the data in table ii supra and are based on equations which best fit the data these equations are equ1 in each equation x is the total weight of sulfur sealant and conditioner dust expressed as percent by weight of the product in each equation y is the 7 day dissolution rate expressed as percent of the urea substrate after sifting and winnowing through the data supra as well as other results and operations of our new novel and improved technique including methods and means of the effecting thereof the operating variables including the acceptable and preferred conditions for carrying out our invention are summarized below ______________________________________ most operating preferred preferred limits limits limits______________________________________type of hardening agent 0 03 4 0 0 05 1 0 0 08 0 3channelized 2 1 clay mineralsweight percent addedsulfur of coated product 5 30 5 20 10 16sealant of coated product 1 5.