CHEMICAL SCIENCE. 279 



ON THE AMOUNTS OF AMMONIA AND NITRIC ACID IN_RAIN WATER. 



At the British Association, Dr. Gilbert and Mr. Lawes communicated 

 the results of their investigations on the amounts of ammonia and nitric 

 acid in rain water. Their results during many months of the last two 

 years were tabulated and compared with those of Boussingault ; the great 

 result being, that rain water contains not quite one part of nitrogen to the 

 million in the form of ammonia, and about five parts to the million in 

 that of nitric acid. The ammonia is found in largest quantity in mists 

 and dews, as might naturally be expected from its being evolved at the 

 surface of the earth, and being absorbed by any moisture. In answer to 

 questions put to him afterwards, Dr. Gilbert stated that the nitric acid 

 was found most abundantly after storms, and varied very greatly at differ- 

 ent periods of the year. The amount of ammonia which descended in a 

 month's rain was more constant. The doctor expressed his opinion, but 

 with hesitation, that nitric acid and ammonia were about equally efficient 

 in supplying nitrogen for plants ; and therefore, as nitric acid is the more 

 abundant in the atmosphere, he conceived that it afforded actually the 

 larger quantity of azote to the vegetable world. 



Boussingault has recently published some additional researches on the 

 above subject, from which it appears that the rain of the country contains 

 less ammonia than that of the city, and that the ammonia is more abun- 

 dant at the beginning than at the end of a shower. He has also exam- 

 ined the dew, and always found it to contain ammonia. The proportions 

 by several trials were six milligrammes to the litre ; but the amount is 

 reduced to 1.02 after a rainy day. On the 1-ith to the 16th of November 

 a thick mist preA^ailed, so rich in ammonia that the water had an alkaline 

 reaction ; a litre of the water 'contained about two decigrammes of car- 

 bonate of ammonia. Seventy-five rains, including the dew and mist, 

 examined, contained as a mean half a milligramme of ammonia. The 

 great quantity of ammonia contained in the mist appears interesting in its 

 bearing on vegetable pathology ; in fact, although ammonia in small quan- 

 tity is favorable to vegetation, a large proportion would be injurious, and 

 would show its effects, especially on the leaves of flowers. Moreover, such 

 a storm might have a deleterious influence upon respiration, and especially 

 on the lungs of persons with pulmonary affections. 



ON THE ABSORPTION OF NITROGEN. 



A debate of great interest has been entered into in the French Academy, 

 between M. Boussingault and M. Ville, respecting the absorption of nitro- 

 gen by plants, which has been conducted with unusual interest, and seme 

 acrimony. 



The question discussed by these gentlemen was this : May we ascer- 

 tain whether or not vegetables possess the faculty of directly absorbing, to 



