Vauquelin on a new Crystalline Matter. 303 



What is then the composition of these crystals ? This question 

 is not easily answered, especially when one has at his disposal 

 only a very small quantity of material. 



However, if we bear in mind that cyanogen formed of carbon 

 and azote, when decomposed in water, gives birth to hydrocyanic 

 acid, ammonia, carbonic acid, and charcoal, which precipitates ; 

 and that in the case under consideration, the same effects take 

 place, with the exception of the precipitation of carbon, it will 

 appear undoubtedly probable, that this carbon is united with a 

 portion of the undecomposed cyanogen, and that it is thereby 

 rendered insoluble; but in falling down slowly it has had time 

 to combine with a small quantity of water, and to assume the 

 crystalline form ; effects due to the low temperature in which 

 the cyanogen was exposed during the winter. If this be the 

 case, we might call this substance sub'Cyanoyen or proto- 

 cyanogen. 



We consider this nomenclature highly objectionable, ad- 

 mitting the composition to be clearly made out, which it is not. 

 Cyanogen and sub-cyanogen should, strictly speaking, be called 

 deuto-carburet and trito-carburet of azote; from which name 

 their composition would immediately be seen. — Ann. de Chim. 

 et de Phys. xxii. 132. 



5. Effects of Boracic Acid on the Acid Fluate of Potash. 



M. Zeise has made the observation that fluate of potash, in 

 which the acid was in excess, might be rendered alkaline, by a 

 suitable addition of boracic acid. The first portion of acid 

 added diminishes the acidity, the following additions make it 

 disappear entirely, for litmus paper is no longer changed by it; 

 and lastly, the saline solution took an alkaline character, and 

 restored to the blue colour, litmus paper which had been red- 

 dened by the acid fluate of potash. 



A solution of litmus reddened by the boracic acid, was mixed 

 with another solution of litmus reddened by the acid fluate, and 

 instantly a blue colour was developed ; the same effects take 

 place by substituting soda or ammonia for potash ; and it is the 

 same whether we employ water or alcohol to dissolve them. 



Syiup of violets, reddened by the acid fluate of potash, became 

 blue by the addition of boracic acid, and a new quantity of acid 

 rendered it green. Papers, stained with curcuma (turmeric) and 

 Brazil wood, experienced analogous changes of colour; so that 

 all the re-agents seem to indicate that alkali is separated from 

 the acid fluate of potash by the addition of boracic acid ; or 

 otherwise, that the fluoboric acid, which may be formed by 

 means of the fluoric and boracic acids, saturates less alkali, 

 than each of its components would neutralize alone. — Ann. de 

 Chim. et de Phys. xxi. 22. 



Vol. XV. X 



