By Edward Solly, Esq. 



39 



had received : that to which 16 oz. had been applied being decidedly 

 the best in the row. Beyond one pound no benefit appeared to be 

 produced by increased doses of the Nitrate, and a plant which re- 

 ceived 2 lbs. was evidently injured ; it soon began to look unhealthy ; 

 the leaves became yellow and sickly, being covered with yellow 

 and brown spots. The best plant, that which had received 1 lb. 

 of the Nitrate, was then compared with another which had grown 

 under precisely the same circumstances but had received no ma- 

 nure at all ; their relative composition was 



The proportion of azotised matter in the two plants was for each 

 10000 parts 



In the examination of these plants a very remarkable fact was 

 observed, which at first was supposed to be an error of observation, 

 until it was confirmed by repetitions, and subsequent experiments. 

 The plants of Tobacco which had received no manure contained a 

 considerable quantity of Nitric acid ; those which had been ma- 

 nured with Nitrate of Soda, however, contained no appreciable 

 quantity. 



A corresponding experiment was made with Lettuces, another 

 plant commonly found to contain Nitrates ; but the results obtained 

 in this case were less marked, because the plants had all been pre- 

 viously manured with rotten dung in the usual manner. Some of 

 the plants were manured with the Nitrate, and others with the 

 Carbonate of Soda ; the latter were very nearly as healthy in ap- 

 pearance, as those which had merely received dung ; in fact there 

 was very little visible effect produced by either salt. On examina- 

 tion they were found to contain 



Carbonate of Soda was employed, in order to compare the effect 



