Note 12 — Chapter XVII · BORON, ALUMINIUM, AND THE ANALOGOUS METALS OF THE THIRD GROUP
George Kamensky translation
When fused with potassium carbonate it forms potassium cyanate, BN + K2CO3 = KBO2 + KCNO. All this shows that boron nitride is a nitrile of boric acid, BO(OH) + NH3 - 2H2O = BN. The same is expressed by saying that boron nitride is a compound of the type of the boron compounds BX3, with the substitution of X3 by nitrogen, as the trivalent radicle of ammonia, NH3.