H4 MOLECULAR STRUCTURE 



tively to racemate without excess of either active tartrate, 

 and to the tartrate mixture. To complete the figure in 

 the plane of the dextro-tartrate, the line RR' is drawn for 

 the solubility of the dextro-tartrate alone, from the data 



25 ioo H 2 10.9 Rb. 2 C,0 6 H 4 



52-5 ij n-79 



We may now, on account of the solubility of the two 

 antipodes, draw on the same figure S"B and ss' as ex- 

 pressing saturation with racemate and laevo-tartrate, or 

 with the latter alone, and joining these various lines by 

 surfaces we have 



area RR'CBR" saturation for dextro-tartrate ; 

 SS'CBS" laevo-tartrate; 



R"BS" racemate. 



The bounding lines refer to saturation for two salts ; the 

 point B, in which they meet, to saturation for all three. 



According to what precedes, inactive bodies containing 

 asymmetric carbon may be divided into three classes : 



1. Those, the most, that appear in racemic form, like 

 racemic acid, and whose transition point is so far removed 

 from ordinary temperatures that they appear from the 

 inactive solution practically only as racemoids ; the race- 

 moid here has a much smaller solubility than the inactive 

 mixture. 



2. Others, rarer, that appear split up, like gulonic lactone ; 

 here the racemoid has a much greater solubility than the 

 inactive mixture. 



3. The third category includes the rarest cases, so far 

 observed only in sodium-ammonium racemate, ammonium- 

 bimalate, rubidium, and potassium racemates and methyl- 

 mannosid, in which, according to the temperature, cases 

 i and 2 meet, so that a transition point separates the 

 regions of the two phenomena. 



(/3) Separation by forming salts with active acids and 

 bases. A method very suitable for separation, when dealing 

 with bases or acids, is to combine with suitable active 



