142 Composition of Waters of Land-Drainage and of Rain. 



In France especially a great deal of attention has lately been 

 paid to the subject, and names of the highest note in chemical 

 science are associated with its investigation and discussion. In 

 a very able paper, M. Barral recorded experiments which for the 

 first time had been made by him for the estimation of ammonia 

 and nitric acid in the rain-water of Paris. M. Boussingault re- 

 peated M. Barral's experiments (so far only as ammonia was con- 

 cerned), and found them perfectly correct for Paris, but totally 

 inapplicable to rain falling in the country, which latter contained 

 very much less ammonia.* 



Messrs. Lawes and Gilbert entered into the subject in Eng- 

 land with their usual spirit ; and having made special arrange- 

 ments for the collection of rain-water falling at Rothamsted, they 

 carefully examined the different methods of determining am- 

 monia in water, as practised at the time, and obtained a series 

 of results, which were reported to the British Association in the 

 year 1854. But, finding that the methods which were available 

 for the determination of nitric acid were anything but trust- 

 worthy, and that the results which they obtained were conflicting 

 and unsatisfactory, they very wisely forbore from publishing 

 them. 



The possession of an accurate process for the determination 

 of minute quantities of nitric acid gave me, however, in the 

 spring of the present year, the opportunity of approaching this 

 question with some prospect of success ; and Mr. Lawes, with a 

 liberality which cannot be too much admired, placed at my dis- 

 posal a complete series of the rain-waters of each month of the 

 year 1855. Through his kindness, therefore, I am now in the 

 position of placing before the agricultural public for the first 

 time a reliable statement of the composition of the rain of a 

 whole year, so far as regards the ammonia and nitric which it 

 contains, as collected in the open country. However interesting 

 the drainage results may be found, I attach to this part of my 



* I have examined samples of rain-water, falling at the back of my house in 

 London. The water was collected in a large painted sponging-bath. After 

 filtration, so as to remove the sooty matter, it was examined for nitric acid and 

 ammonia. 



The first sample, collected on tlie 11 th of April, in the present year, during a 

 short shower, gave me 0*09 of nitric acid per gallon, or about the same as was 

 found in the water of June collected at Rothamsted, as will be seen further on. 

 The second sample, collected May 1st, gave me 0'12 nitric acid, or rather more 

 than the first, but it was found to contain 1"077 grains of ammonia per gallon, — a 

 quantity more than ten times as great as that found in the rain-water of the 

 country. So far, therefore, njy results on London rain do not bear out M. Barral's 

 experiments on that of Paris : and unless there be some cause connected with the 

 difference of fuel employed in the two capitals (one being coal and the other 

 wood), I should be inclined to think that M. Barral's determinations of nitric acid 

 were in error from the faultiness of the method to which he was compelled to have 

 recourse. 



