372 lExperiments on Ammonia. 



measures (each = 10 grains of mercury) became 1 15. Tlie 

 following table shows the expansion of various quantities 

 of ammonia. 



Exp. 



1 . 60 measures of ammonia gave permanent gas 1 12 



2. CO - - - - 120 



3. 59 (potash being left in the tube) - 115 



4. 55 - - - - 115 

 3. 75 (under the pressure of half an atmosphere) 150 



6. 65 - - - - ISO 



7. 65 - - - - 130 



8. 53 (one of the conductors being of steel wire) 106 



492 . 9" 8 



and -192 : 978 : : 100 : 19B-78. These proportions, you 

 will find, correspond very nearly with those long ago stated 

 by Bcrthollel*, who converted 17 measures of ammonia 

 by electrization into 33 measures of permanent gas, which 

 is at the rale of 194 from 100. Having lately, however, 

 carried on the process with the observance of additional 

 precaution, (the mercury being first boiled in the tube, be- 

 fore admitting the ammonia, and still remaining hot when 

 the gas was passed up,) I have obtained from the alkali less 

 than double its volume of j)ermanent gas, viz. 280 measures 

 from 155, or at the rale of 180-6 from 100. The varia- 

 bleness of the first set of results arises, I believe, from the 

 uncertainty of the quantity of ammonia decomposed. For 

 if the smallest portion of moisture remain in the tube, a 

 little ammoniacal gas will be absorbed, and will be slowly 

 given out again as the electrization goes on, thus rendering 

 the actual quantity submitted to experiment greater than 

 appears. It is probable also, from a fact which I shall af- 

 terwards state, that mercury itself, unless when heated, may 

 absorb a small portion of alkaline gas. 



The proportion of the hydrogen and nitrogen gases to 

 each other in the products of ammonia decomposed by 

 electricity, I am satisfied by recent experiments (June 1809) 

 is as nearly as possible what you have determined, viz. 

 74 measures of hydrogen gas to 26 of nitrogen. The 

 .nearest ap,)roximation I have made to these numbers is 

 73*75 to 2623. Our only method of analysing mixtures 

 of these two gases (viz. by combustion with a redundancy 

 of oxygen) is not, 1 believe, gufficienlly perfect to afford a 

 nearer coincidence. 

 ■ The extreme labour and tediotisness of the decomposi- 



* Journal de Physi(jue, 1786, ii. 1-76. 



ttoa 



