[ 278 ] 



XXXIX. Notices of the Results of the Labours of Continental 



Chemists. By Messrs. W. Francis and H. Croft. 



[Continued from p. 195.] 



New Method of determining Nitrogen. 



JN a letter addressed by Berzelius to Prof. Erdmann, and 

 published in the Journ.f. PraJct. Chem. for June 15th, 184-1, 

 we find the following important notice : — " On preparing the 

 interesting memoir of Dumas on the decomposition of organic 

 substances, by the action of the hydrate of potash, for my 

 Annual Report, it occurred to me that nitrogenous bodies 

 should, when so treated, give off the whole amount of their 

 nitrogen as ammonia, which may be received in muriatic acid 

 just in the same manner as carbonic acid in a solution of pot- 

 ash, and weighed as ammonio-chloride of platinum. I am fol- 

 lowing up this idea with M. Plantamour. To guard against 

 the formation of cyanogen, we have commenced with com- 

 pounds of cyanogen, which give ammonia just as well as sal- 

 ammoniac and lime. If, indeed, all should succeed according 

 to the present appearances, what a valuable and easy control 

 in determinations of nitrogen we shall thus obtain ! We make 

 the experiments in the same way as the usual organic analyses, 

 and pass the vapours over a strongly-heated mixture of the hy- 

 drate of potash and hydrate of lime, to decompose such bodies 

 as, for instance, anil (C 12 H 8 + N H 3 )." 



Nitrurets. 

 On exposing the white precipitate to a gradually increasing 

 heat, a vast quantity of ammonia first passes over without any 

 trace of nitrogen gas, after which perchloride of mercury-am- 

 monia, and ammonia are evolved; and a red body remains in 

 the retort, which decomposes at a temperature above 360° into 

 protochloride of mercury, mercury and nitrogen. This red 

 body is obtained purest when the heating is continued in a me- 

 tallic bath until some protochloride of mercury has formed. It 

 consists of crystalline scales, and has quite the appearance of 

 the crystalline peroxide of mercury. It is insoluble in water, 

 not affected by aqueous alkalies, even at the boiling point of 

 the liquid. The compound may be boiled with dilute and 

 concentrated nitric acid, and with rather concentrated sul- 

 phuric acid, without being decomposed or dissolved, which 

 takes place, however, when it is boiled with concentrated sul- 

 phuric acid, or with hydrochloric acid: no gas is evolved. 

 Heated beyond the boiling point of mercury, nitrogen escapes; 

 mercury and protochloride of mercury are sublimed. Several 

 experiments were made to determine these three bodies ; ac- 



