310 Professor William J. Pope [May 1, 



residue, two salts are obtained, each of which contains an optically 

 active basic part and an optically active acidic part ; these are salts 

 of the kinds, d-B, d-A, and 1-B, d-A, and can be separated by 

 crystallisation from a convenient solvent, and after separation has 

 been effected, each salt may bo reconverted into the iodide. These 

 regenerated iodides are found to be optically active in solution, and 

 the conclusion is consequently drawn that optical activity is an 

 attribute of the asymmetric pentavalent nitrogen atom as well as of 

 the asymmetric tetravalent carbon atom. The optical activity of this 

 substituted ammonium compound indicates that its molecule has an 

 euantiomorphous configuration and is extended in three-dimensional 

 space ; the exact nature of this configuration is not yet known, 

 inasmuch as a space arrangement of five groups is concerned, but the 

 environment of the nitrogen atom in ammonium salts is clearly not 

 a simple tetrahedral one. Just as enantiomorphism has been proved 

 to be an attribute of the asymmetric nitrogen atom, we have also 

 demonstrated that asymmetric tetravalent atoms of sulphur, selenium 

 and tin give rise to optical activity ; optically active substances 

 having the constitutions shown below have been prepared, and we are 

 thus well on the way towards obtaining a complete stereochemical 

 scheme embracing all the elements. 



CH3 C2H5 ^6^5 tHg CH3 tJjHj 



\ / \ / \ / 



S Se Sn 



/ \ / \ / \" 



CI CH,COOH CI CH.COOH I C3H, 



It has been mentioned that optically active substances occur as 

 such, rather than in the compensated form, in many animal and 

 vegetable products, and also that when a substance containing an 

 asymmetric carbon atom is prepared synthetically in the laboratory it 

 is of necessity obtained in the compensated form or as a mixture in 

 equal proportion of the dextro- and the laBvo-isomerides. Taken 

 together, these two facts have a very interesting bearing upon our 

 speculations as to the origin of animal and vegetable life. (Jptically 

 active substances have been isolated as products of the vital activity 

 of all forms _^of animal or vegetable life which have been properly 

 examined, but in spite of this, they are never obtained directly as 

 laboratory products; some enantiomorphous influence has always to 

 be exerted in their synthetic preparation, just as Pasteur applied 

 enantiomorphism, either of method or of material, to the resolution 

 of compensated substances. It was very strenuously argued by 

 Professor Japp in liis Presidential Address to the Chemical Section 

 of the British Association in 1898, that no matter how successful we 

 may be in reducing the problems relating to vital processes to mere 

 questions of physics and chemistry, a residuum will always evade 

 explanation by such means ; this residuum will involve the discussion 

 of the way in which the first enantiomorphous substance was resolved 



