laocl to determine the reactivity of the lanthanum compound with respect to phosphate the following test was conducted a stock solution containing 13 75 g l of anhydrous na 2 hpo 4 and 8 5 g l of hcl was prepared the stock solution was adjusted to ph 3 by the addition of concentrated hcl an amount of 100 ml of the stock solution was placed in a beaker with a stirring bar the lanthanum oxychloride from above was added to the solution to form a suspension the amount of lanthanum oxychloride was such that the amount of la in suspension was 3 times the stoichiometric amount needed to react completely with the phosphate samples of the suspension were taken at time intervals through a filter that separated all solids from the liquid the liquid sample was analyzed for phosphorous fig1 shows the rate of phosphate removed from solution to determine the reactivity of a commercial lanthanum with respect to phosphate the relevant portion of example 1 was repeated under the same conditions except that commercial lanthanum carbonate la 2 co 3 3 h 2 o and la 2 co 3 3 4h 2 o was used instead of the lanthanum oxychloride of the present invention additional curves on fig1 show the rate of removal of phosphate corresponding to commercial lanthanum carbonate la 2 co 3 3 h 2 o and la 2 co 3 4h 2 o fig1 shows that the rate of removal of phosphate with the commercial lanthanum carbonate is faster at.