103 



available in the outer shell of one of their atoms, without this giving 

 necessarily rise to ionisation. 



Tims BF, forms stable coniponnds with PH, and with ammonia, 



Fig. 7. 

 Boron fluoride ammonia. 



of which the latter can be distilled nndecomposed. Their consti- 

 tntion may be represented by the above simplified symbol ; the two 

 electrons which the N of the ammonia has in excess have penetra- 

 ted into the shell of the sphere of the boron, thus forming a non- 

 polar bond. Both atoms have eight electrons in this shell, and are 

 mntnally saturated (Fig. 7). 



It is not subject to doubt that when different groups are substi- 

 tuted for the H-atoms at the N, a substance is formed which can 

 be split up into its optical antipodes '). 



As regards the valency of the boron, this may be put, like tiiat 

 of the nitrogen, at four, as there is no reason to assume the bond 

 between the N and the B to be of another nature than between 

 the B and the F (resp. between the N and the H). 



Let us now proceed to the complex boric acid compounds. The 

 very weak, volatile boric acid itself is, at least for the greater part, 

 a derivative of the tri-valent boron, in which all the bonds are non- 

 polar. In aqueous solution a very small part will be a derivative 



J) It may cursorily be pointed out that the constitution of the addition products 

 of AICI, with a number of organic and inorganic compounds can be seen in 

 entirely the same hght. 



