258 HYDKOGENATED COMPOUNDS OF NITROGEN. 



The analysis of it agreed pretty closely with the formula 

 C 3 H 9 NHC1. 



10 gnns. of this salt were dissolved in 500 grms. of water 

 at 180. 



A slight absorption of heat was produced, answering to 

 -5 Gal., for 



C 3 H 9 NHCL = 95-5 grms. 



According to this result, 

 C 3 H 9 NCgas + HClgas = C 3 H 9 NHC1 solid liberates + 39*8 Gal. 



This value is lower than the heat of formation of solid 

 ammonium chloride starting from its gaseous components, or 

 + 45-5 Gal. 



But the value deduced probably does not represent the actual 

 heat of formation of trimethylamine chloride as it exists in 

 diluted solutions. In fact, this salt attracts the atmospheric 

 moisture with such avidity that it falls almost immediately 

 into a liquid state, which indicates the formation of a definite 

 hydrate in its solutions, whereas ammonium chloride seems to 

 exist in its solutions in an anhydrous state. The heat of 

 formation of anhydrous trimethylamine chloride must there- 

 fore be increased in its solutions by the heat of formation of 

 its hydrate, if we wish to calculate the energy really called 

 into action in the formation of the chloride in solution, i.e. the 

 true energy put forth in the reactions of this substance. 1 



6. THE HEAT OF FOKMATION OF SOME AMIDES. 



1. The amides are derived, in general, from the union of the 

 acids and ammonia, with separation of water, that is, they are 

 ammoniacal salts deprived of the elements of water. This class 

 comprises a number of very important compounds ; it extends 

 even as far as the albumenoid principles which form the basis 

 of animal tissues and organs. Many explosive substances are 

 also included in it. But their thermal study is not as yet far 

 advanced, with the exception of that of the cyanide series, 

 which will be discussed in a subsequent chapter. Besides 

 these, the .author has only, up to the present, examined two 

 amides, viz. oxamide and formamide. 



2. Oxamide. Oxamide is a solid body, almost insoluble, 

 differing from ammonium oxalate by the elements of water 



C 2 H 2 4 (NH 3 ) 2 = C 2 H 4 N 2 2 + 2H 2 0. 

 It may be obtained, either by the decomposition of the salt, 



1 We must also take into account its own state of dissociation as a 

 hydrate and as an anhydrous salt. " Essai de Mecanique Chimique," 

 torn. ii. p. 445. 



