276 Royal Society : — 



In the former case it would range in the same class with tungstic 

 acid, with which it has some similarity ; in the latter case, in the 

 same class as antimonic acid. But he holds, that on the whole 

 there is a balance of probability in favour of its being considered 

 as TaO^, and hence like stannic and titanic acids. On this 

 view its atomic weight would be 68'82*. 



The bromide of tantalum is obtained like the chloride. It is 

 yellowish in colour when free from excess of bromine, in which 

 state, however, it is obtained with extreme difficulty. Iodide 

 of tantalum could not be prepared. 



Fluoride of tantalum is obtained by dissolving hydrated tan- 

 talic acid in hydrofluoric acid. On heating, the fluoride of tan- 

 talum volatilizes. Tantalic acid which has been heated does not 

 dissolve in hydrofluoric acid. Fluoride of tantalum has a great 

 tendency to unite with metallic fluorides to form double salts : 

 with fluoride of potassium it combines in several proportions. 



Rose obtained a nitruret of tantalum by exposing chloride of 

 tantalum to the action of ammoniacal gas. This is absorbed at 

 the ordinary temperature, and a solid crust is formed, from 

 which, when heated in ammoniacal gas, tantalum is reduced 

 combined with nitrogen. A black powder is thus obtained, 

 which, when rubbed in the mortar, assumes a metallic lustre. 

 It conducts electricity very well : it burns in the air with incandes- 

 cence to white tantalic acid. It is only dissolved by nitrohydro- 

 fluoric acid; fused with hydrate of potash it gives ofi" ammonia. 

 It has very probably the formula N^ Ta^. 



XLII. Proceedings of Learned Societies. 



ROYAL SOCIETY. 



[Continued from p. 208.] 



June 12, 1856. — The Lord Wrottesley, President, in the Chair. 

 '"I^IIE following communication was read : — 



J- " Researches on the Action of Sulphuric Acid upon the Amides 

 and Nitriles, with Remarks on the Conjugate Sulpho-aeids." By 

 George B. Buckton, Esq., F.L.S., F.C.S., and A. W. Hofmann, 

 Ph.D., F.R.S. 



Since we had the honour of addressing the Royal Society upon 

 the subject of the behaviour of acetamide and acetonitrile towards 

 sulphuric acid, we have completed our experiments upon the amides 

 and nitriles, and extended our researches to other groups of bodies. 

 The results of these additional inquiries we now beg to present in the 



* In fixing the equivalent of tantalum, it deserves to be mentioned that 

 if we take it at (if), it will be the arithmetical mean between the equivalents 

 of molybdenum and of tungsten, which are respectively (in round numbers) 



46and92: thusi5i:t^=69. 



