105 



boric acid compounds always lieine,- more or less liydrolized in 

 aqueous solution, the splitting up into optical antipodes will be difficult. 



In general liie negative ion will be particularly easil3' formed: 



1. When the liydroxyl groups of the poly-alcohols have a favour- 

 able situation. 



2. When the organic rests bear an electro-negative character. 



3. When the other atom easily cedes an electron. 



1. The researches on the complex boric acid compounds of the 

 last ten years have proved that the substances with a pronounced 

 acid character from scarcely acid compounds are formed particularly 

 easily, when the hydroxyl groups are situated in one plane with 

 the C-atoms hound to them. It may be assumed that the first phase 

 will be the formation of the derivative of the tri-valent boron. 

 When this complex meets a second molecule of the organic com- 

 pound, the uusaturateness of the boron will collaborate with the 

 favourable constellation of the poly-alcohol to form the very stable 

 derivative of the penta-valent boron. 



2. When this favourable situation of the hydroxy] groups coin- 

 cides with strongly electro-negative properties of the poly-oxy-com- 

 pounds, as of «-hydroxy acids and aromatic ortho-hydroxy-acids, 

 these penta-valent boric acid compounds will be exceedingly easily 

 formed. Mr. Hermans has actually succeeded (cf. following commu- 

 nication) in proving this for l)oro di-citric a(;id, and in ascertaining 

 the constitution of the already known boro di-salicylic acid zinc 

 from this point of view. 



3. It was to be expected that especially the alkali-salts of these 

 complex acids could be isolated, because the complexes are only 

 realizable on adoption of an electron, and this is easily ceded by 

 an alkali-metal. We meet here with the same influence which the 

 metal atom in general exerts on the stability of the acid rest, which 

 renders it possible to obtain salts of which the corres{)onding acid 

 is unstable and even unknown. 



This latter circumstance renders it also desirable to write the 

 metal atom by the side of the atom to which it has ceded the 

 electron, though in reality the whole complex becomes a charge 

 richer, and it therefore seems indifferent to a certain extent where 

 this metal atom is placed, since as an ion it is not bound to a 

 definite place '). 



') That this is not quite immaterial may appear from the different behaviour 

 of AgNOj and KNO^ resp. AgCN and KCN towards alky! iodides, which will 

 be discussed later. 



