J_{1} |{ MgCl_{2},6H_{2}O; }| 116.67° | 161.8 MgCl_{2} |{ MgCl_{2},4H_{2}O }| | | | | J |{ MgCl_{2},6H_{2}O; }| 115.7° | 162 MgCl_{2}; 4 KCl |{ MgCl_{2},4H_{2}O; }| | |{ carnallite }| | | | | K |{ MgCl_{2},4H_{2}O; KCl; }| 152.5° | 200 MgCl_{2}; 24 KCl |{ carnallite }| | | | | L_{1} |{ MgCl_{2},4H_{2}O; }| 181° | 238.1 MgCl_{2} |{ MgCl_{2},2H_{2}O }| | | | | L |{ MgCl_{2},4H_{2}O; }| 176° | 240 MgCl_{2}; 41 KCl |{ MgCl_{2},2H_{2}O; KCl }| | | | | M | Carnallite; KCl | 167.5° | 166.7 MgCl_{2}; 41.7 KCl | | | [N_{1} | MgCl_{2},2H_{2}O | 186° | ca. 241 MgCl_{2}] | | | N | MgCl_{2},2H_{2}O; KCl | 186° | 240 MgCl_{2}; 63 KCl | | | [O | KCl | 186° | 195.6 KCl] ------------------------------------------------------------------------- With the help of the data in the preceding table and of the solid model it will be possible to state in any given case what will be the behaviour of a system composed of magnesium chloride, potassium chloride and water. One or two different cases will be very briefly described; and the reader should have no difficulty in working out the behaviour under other conditions with the help of the model and the numerical data just given. {289} In the first place it may be again noted that at a temperature above 167.5° (point M) carnallite cannot exist. If, therefore, a solution of magnesium and potassium chlorides is evaporated at a temperature above this point, the result will be a mixture of potassium chloride and either magnesium chloride tetrahydrate or magnesium chloride dihydrate, according as the temperature is below or above 176°. The isothermal curve here consists of only two branches. Further, reference has already been made to the fact that all points of the carnallite area correspond to solutions in equilibrium with carnallite, but in which the ratio of MgCl_{2} to KCl is greater than in the double salt. A solution which is saturated with respect to double salt alone will be supersaturated with respect to potassium chloride. At all temperatures, therefore, carnallite is decomposed by water with separation of potassium chloride; hence all solutions obtained by adding excess of carnallite to water will lie on the curve EM. _A pure saturated solution of carnallite cannot be obtained._