3 18 Intelligence and Miscellaneous Articles, 



it was terminated, there was not the slightest indication of the pre- 

 sence of ammonia in the solution. The result was equally negative 

 with sulphuret of iron and dilute sulphuric acid. 



2nd. A certain weight of copper recently reduced by hydrogen 

 was placed in an organic analysis glass tube, and subjected for about 

 half an hour to the action of a red heat and a current of washed 

 nitrogen, which had been afterwards dried by pumice-stone and 

 sulphuric acid, taking the precaution of not heating the tube till 

 after all the atmospheric air had been driven out by the disengage- 

 ment of the gas. The experiment was repeated several times, and 

 no alteration was observable in the exterior appearance of the copper, 

 nor had it increased in weight. — Ann. de Ch. et dePh., Juillet 1849. 



ON THE QUANTITY OF AMMONIA CONTAINED IN ATMOSPHERIC 

 AIR. BY M. R. FRESENIUS. 



In the following table the author has arranged the results of his 



own experiments and those of MM. Grager and Kemp ; 1,000,000 



parts of air contain — 



Oxide of Carbonate of 



Ammonia. ammonium, ammonia. 



Grager 0-333 0'508 0-938 



Kemp 3-880 5-610 10-370 



^ . /day 0-098 0-153 0-283 



rresenms ^^jgj^j. ^.^g^ q.^^^ ^.^^^ 



Fresenius' mean 0133 0205 0-379 



The proportional quantities of ammonia found by these chemists 

 are — 



Fresenius 1 day 



Fresenius 1*7 night 



Grager , 3-4 



Kemp 37-5 



M. Fresenius observes that he is far from setting a high value 

 upon his experiments, though he took great care in all his operations ; 

 he is, however, of opinion that he may draw the following conclu- 

 sions from them : — 



1st. The determinations hitherto arrived at respecting the quan- 

 tity of ammonia contained in the air have given too large results ; 

 for the differences between the analyses are so great, that it is im- 

 possible to attribute them to a change in the composition of the 

 air, unless the change has been accidentally produced and purely 

 local. 



2nd. To determine with exactitude the quantity of ammonia con- 

 tained in the atmosphere, much larger quantities than have hitherto 

 been acted upon must be submitted to experiment. It would be 



