328 NATtJRE AND DECOMPOSITION OP THE FIXED ALKALIS. 



iron and the mercury, which might again have been given 

 out in the progress of the operation. 



I now used recently distilled mercury, which did not leave 

 the slightest film on the glass tube, and wires of platina. The 

 ammonia had been exposed to dry caustic potash, and proved 

 to be equally pure with that mentioned in page 326. 60 mea- 

 sures of it, each equal to a grain of water, were electrized 

 till no farther expansion could be produced, the gas filled a 

 space equal to that occupied by 108 grains of water. The 

 thermometer in this experiment was at 56°, and the barom- 

 eter at 30*1 inches. The wire of platina transmitting the 

 spark was slightly tarnished*. The 108 measures of gas, 

 carefully analyzed, Avere found to consist of 80 measures 

 in volume of hidrogen, and 28 measures of nitrogen. 

 Specific gravity The results of an experiment. that I made in 1799 + give 

 of ammonia. ^^^ weight of 100 cubic inches of ammonia as 18-18 grains 

 at the mean temperature and pressure. I had reasons however 

 for suspecting, that this estimation might be somewhat too 

 low, and on mentioning the circumstance to Messrs. Allen 

 and Pepys, they kindly undertook the examination of the 

 subject, and Mr. Allen soon furnished me with the following 

 data. '^ In the first, experimental cubic inches of ammonia 

 weighed 4*05 grains; in a second experiment the same quan- 

 tity weighed 4'06 grains, barometer 30*65, thermometer 

 64'^ Fahrenheit." 



Now if tlie correctness for temperature and pressure be 

 made for these estimations, and a mean taken, 100 cubic 

 inches of ammonia will weigh 18*67 grains, barometer being 

 at 30, and thermometer at 60° Fahrenheit: and if the 

 quantity used in the experiment of decomposition be calcu- 

 lated upon as cubic inches, 60 will weigh 11*2 grains. But 

 the hidrogen gas evolved equal to 80 will weigh 1*93 :|: 

 grains, and the nitrogen equal to 28 §, 8*3. And 1*94- 



8-3 



* This most probably was owing to oxidation. When platina is 

 made positive in the Voltaic circuit in contact with solution of am- 

 monia, it is rapidly corroded. This is an aaalogous instance. 



t Researches Chem. and Phil. p. 62. 



X Lavoisier's Elements, p. 569. A "cubical inch of hidrogen is 

 considered as weighing '0239. 



§ R «?^ia*jt^'*^tChem. and Phil, page 9. From my experiments 



100 



