Experimental works on the production of magnesium hydroxide with fast sedimentation velocity and low calcium content have been conducted using saline water and dolomite. Best result was shown to be obtained by using 3 % dolime water and 1.2 times of theoretical amount for saline water. The coagulation constant of 0.42 % magnesium hydroxide in 2.27 % NaCl solution was found to be -1.1∼1.5×10².
The calcium content of Mg（OH）₂ and its sedimentation velocity was found to be inversely related, and addition of chlorides to Mg(OH)₂ solution increased flocculation in the order,
CaCl₂>NaCl>MgCl₂
while addition of hydroxides had deflocculation effect in the order
This shows that chlorides and hydroxides have opposite effect on the sedimentation velocity of Mg（OH）₂, and thus Mg(OH)₂ in basic solution may be concluded to be in an unstable colloidal state of Mg(OH)₂/OH.
Coagulation rate of magnesium hydroxide in 2.27 % NaCl solution was found to increase with the period of agitation, and increase in calcium content was observed with the sedimentation velocity, while in the solution which do not contain NaCl the converse was true.