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nium sulphate. The side AW being invisible has been left out, also 

 the side Li Am. 



Li 3 S0 4 . H 2 and the double salt LiNH 4 S0 4 may also occur as 

 solid phases besides Li 2 S0 4 and (NH 4 ) 2 S0 4 . The first is represented 

 by a point Z on the side LiW, the second by a point D, not 

 indicated, on the side Li Am. 



The equilibria occurring at 6°5 are represented schematically 

 by Fig. 1. The solubilities of the (NH 4 ) 3 S0 4 and of the Li 3 S0 4 . H 3 

 in water are indicated by the points a and e; point c indicates 

 the solubility in water of the double salt and must, therefore, be 

 situated on the line WD (the point I) is on the side Li Am). As 

 Li 2 S0 4 , (NH 4 ) 3 S0 4 and LiNH 4 S0 4 are practically insoluble in alcohol, 

 their solubility may be represented practically by the point A. 



The curve aA is the saturation line of the (NH 4 ) 3 S0 4 ; it indicates 

 the aqueous-alcoholic solutions which are saturated with solid 

 (NH 4 ) 2 S0 4 . 



The aqueous-alcoholic solutions saturated with Li 3 S0 4 and Li a SO.H 3 1 

 are represented by the curve eA which, however, must show a 

 discontinuity in the immediate vicinity of the point .4, for the curve 

 consists of two branches, of which the one to the right indicates the 

 solutions saturated with Li„S0 4 . H s O and the one to the left those 

 saturated with anhydrous Li 3 S0 4 . 



The equilibria in the ternary system : water, lithium sulphate and 

 ammonium sulphate are represented by the curves ab, lied and de, 

 which are situated in the side plane of the tetrahedron, ab is the 

 saturation line of the ammonium sulphate, bed that of the double 

 salt LiNH 4 S0 4 , de that of Li 2 S0 4 . H 3 0. In my opinion, however, 

 this latter is not quite correct, for, according to several analyses, 

 Lithium sulphate seems to mix with the ammonium sulphate, 

 although only to the extent of a few per cent, so that branch de 

 indicates solutions saturated with mixed crystals. As, however, I have 

 not accurately investigated this mixing, I will continue to speak in 

 future of lithium sulphate monohydrate Li 2 S0 4 . H 3 0. 



Let us now look at the equilibria in the quaternary system. The 

 surface Am or Aabb.JcJy^A represents solutions saturated with solid 

 ammonium sulphate ; surface D or AbJcJ)J)cdA represents the solutions 

 saturated with LiXH 4 S0 4 ; the curve Ac of this surface has as pecial 

 significance, because it indicates the solubility of LiNH 4 S0 4 in aqueous- 

 alcoholic mixtures. The points of the surface D facing the curve Ac 

 represent solutions which, in relation to the double salt, contain an 

 excess of (NH 4 ) 2 S0 4 ; the points behind this line show solutions 

 containing an excess of Li 2 S0 4 . 



