urea salts have been found to have a significant and unexpected property in inhibition of iron in aqueous systems . the urea salts disclosed herein increase the amount of iron that will remain in solution in said aqueous system , thereby preventing iron deposits therein . alternatively , said urea salts can be added directly or in accordance with the concept of the invention disclosed herein to aqueous systems . generally , the concept of this invention is best demonstrated by dissolving a urea salt in deionized water and adding an iron generating substance ( such as ferric chloride from a 1000 mg / l atomic spectral standard ) followed by an equimolar quantity of a phosphate ion ( po 4 . sup .. tbd .) generating substance . this solution is neutralized , volume adjusted with deionized water and allowed to stand for approximately 24 hours , filtered and aliquots taken for iron analysis by atomic absorption . dissolved iron values greater than those obtained when no urea salt was present indicate stabilization . the iron inhibitors ( urea salts ) employed herein are not critical . any water soluble urea salts can be used . representative salts employed herein are nitrates , disodium salts , sulfates , and derivatives thereof . the effective concentration limits of urea salts wherein improvement in iron stabilization is shown in as little as 10 mg / l . a more effective concentration is from 15 - 200 mg / l . the preferred concentration ranges between 40 mg / l and 200 mg / l . the phrase &# 34 ; inhibiting the precipitation &# 34 ; is meant to include threshold inhibition , dispersion , solubilization , particle size reduction , or reaction product change . the phrase &# 34 ; aqueous system &# 34 ; is meant to include any system containing water ; including , but not limited to , cooling water , boiler water , desalination systems , gas scrubbers , blast furnaces , sewage sludge thermal conditioning equipment , reverse osmosis , sugar evaporators , paper processing , mining circuits and the like . some studies which further exemplify the concepts of the invention are described below . in the course of an investigation to find iron phosphate inhibitors , it was noted that certain urea salts have the ability to inhibit the precipitation of iron salts in aqueous systems . since iron fouling can be a problem in industrial cooling water operations , the use of an inexpensive compound to keep iron solubilized would be advantageous . deionized water was added to 600 ml beakers . urea nitrate was then dissolved in the deionized water at the desired concentration . iron , as fecl 3 ( from a 1000 mg / l atomic spectral standard ), was added next , followed by a quantity of na 2 hpo 4 to yield an amount of po 4 . sup .. tbd . equimolar to the iron . the solution was water white at this point with a ph of approximately 2 . the ph was adjusted with dilute sodium hydroxide to 7 , giving the solution a yellow cast , and the volume adjusted to 500 ml with deionized water . the solution was covered and allowed to sit for 24 hours , filtered through 2 . 5 micron paper , and aliquots taken for analysis of iron by atomic absorption . dissolved iron values greater than those obtained when no urea salt was present indicate stabilization . the results are described in tables i and ii below . table i______________________________________ concentrationconcentration ofof fe remainingurea no . sub . 3 initial fe , in solution after ( mg / 1 ) ( mg / 1 ) 24 hours ( mg / 1 ) ______________________________________0 10 0 . 0511 10 1 . 3022 10 1 . 7044 10 2 . 4066 10 5 . 40165 10 7 . 50______________________________________ table ii______________________________________ concentrationconcentration ofof fe remainingurea so . sub . 4 initial fe , in solution after ( mg / 1 ) ( mg / 1 ) 24 hours ( mg / 1 ) ______________________________________0 10 0 . 0522 10 0 . 4044 10 3 . 20110 10 1 . 90______________________________________ the above tables give the amount of dissolved iron found by atomic absorption analysis of filtered samples taken after 24 hours . initial iron was 10 mg / l , which drops to & lt ; 0 . 05 mg / l in the absence of any inhibitor . at higher urea nitrate concentrations , iron is kept soluble much above the control ( untreated ) test . also , urea salts show an inhibitory effect on iron phosphate , as orthophosphate iron ( po 4 . sup .═) and showed an increase in solubility as compared with the control ( untreated ) test shown in table iii below . table iii______________________________________ dissolved phosphate initial remainingurea no . sub . 3 initial fe , po . sub . 4 . sup .= in solution after ( mg / 1 ) ( mg / 1 ) ( mg / 1 ) 24 hours ( mg / 1 ) ______________________________________0 17 17 7 . 0011 17 17 8 . 4844 17 17 10 . 10______________________________________