44 Mr. Davy’s Experiments on 
found to hold in solution, small quantities of ammonia ; when 
the operation was repeated upon the same mixture, ignited a 
second time, the proportion diminished ; in a third operation 
it was sensible, but in the fourth barely perceptible. The 
same mixture, however, by the addition of a new quantity of 
potash, again gained the power of producing ammonia in two 
or three successive operations ; and when any mixture had 
ceased to give ammonia, the power was not restored by cool- 
ing it in contact with air. 
Ammonia was produced in a case in which more than 200 
cubical inches of gas had passed over from the action of 
water upon a mixture, and when the last portions only were 
preserved in contact with it during the cooling. In a compa- 
rative trial it was however found, that considerably more 
ammonia was produced, when a mixture was cooled in con- 
tact with the atmosphere, than when it was cooled in contact 
with the gas developed in the operation. 
I shall not attempt to draw any conclusions from these 
processes. It would appear from some experiments of M. 
Berthollet, that nitrogen e adheres very strongly to char- 
coal.* The circumstances that the ammonia ceases to be 
produced after a certain number of operations, and that the 
quantity is much greater when free nitrogene is present, are 
perhaps against the idea that nitrogene is composed in the 
prodess. But till the weights of the substances concerned 
and produced in these operations are compared, no correct 
decision on the question can be made. 
The experiments of Dr. Priestley upon the production of 
nitrogene, during the freezing of water, induced that philo- 
* Mem. d’Arcueil, Torn. II. page 485. 
