( 140 ) 



the second that of the double salt Li 2 S0 4 . (NH 4 ) 3 S0 4 , the last that 

 of (NH 4 ) 3 S0 4 . As the line W D Li intersects (he saturation line of the 

 double salt it is soluble in water without decomposition. 



As regards the branch be I stated that this indicates solutions 

 which are in equilibrium with Li 3 S0 4 . H 3 ; this is not quite correct 

 for lithium sulphate, although only to the extent of a few %, gives 

 mixed crystals with ammonium sulphate. 



3. Lithium sulphate — copper sulphate — water. Whereas in the two 

 previous ternary systems a double salt occurs, this is not the case 

 in this system at 30'; the isotherm therefore only consists of two 

 branches; ad is the saturation line of Cu S0 4 5 H 3 and bil that of 

 Li, S0 4 . H 3 0. 



These two branches have been determined by Mr. Koopal. 



The quaternary equilibria at 30° are represented by surfaces, lines 

 and points. 



The surface ahkd is the saturation surface of Cu S0 4 , 5 H,0 ; it there- 

 fore indicates the quaternary solutions which are saturated with 

 CuS0 4 .5H 2 0. 



The surface dkleb is the saturation surface of Li 3 S0 4 . H 3 0. 



The surface c/mg is the saturation surface of (NH 4 ) 8 S0 4 . 



The three surfaces observed are the saturation surfaces of the com- 

 ponents or of their hydrates; in addition we also have the saturation 

 surfaces of the double salts; that of Li, S0 4 . (NH 4 ) 2 S0 4 is represented 

 by elmfq; that of Cu S0 4 . (NH 4 ) 3 SO, . 6 H,0 by hklnïgph. 



The saturation lines are formed by the intersection of the saturation 

 surfaces taken two by two; they consequently represent solutions 

 saturated with two solid substances. 



We now see at once that solutions represented by the points of 

 the lines : 



hk are saturated with Cu S0 4 . 5 H 3 and Dc u 

 dk „ „ „ Cu S0 4 . 5 H 3 and Li, S0 4 . H s O 



M „ „ „ Li, S0 4 . H,0 and D Cu 



le „ „ „ Li, S0 4 . H,0 and D Li 



l™ » >, „ D Li and D c „ 



mf „ „ „ D Li and (NH 4 ) 3 S0 4 



mg » » „ Dou and (NH 4 ), S0 4 



The quaternary saturation lines may be distinguished into external 

 lines and middle lines; the external lines such as kh, kd, le, mf and 

 mg each terminate in a point of a side plane, therefore in a ternary 

 solution; the middle lines such as Jd and lm are situated quite within 

 the tetrahedron. 



