36 



On the Inorganic Constituents of Plants, 



on the absorption of inorganic, and the formation of organic, matter. 

 The first results obtained were wholly negative, principally from 

 the fact that too small a quantity of the various manures employed, 

 was taken ; great inconvenience was also experienced in conse- 

 quence of the very unequal nature of the soil of the gardens, which 

 led to irregular and unexpected results. 



Before describing any experiments, it will be proper to say a 

 few words respecting the nature of the soil on which they were 

 made. The soil of the Horticultural Gardens varies a good deal 

 both in mechanical texture, and in chemical composition. The 

 greater part of it may be termed loamy ; but its exact nature of 

 course differs considerably according to the treatment it has 

 received, the mode in which it has been worked, and the nature 

 and quantity of manure which has been applied to it. Generally 

 speaking, it is rich in organic matter, both animal and vegetable, 

 and consequently like all soils of that description, contains a nota- 

 ble quantity of Salts of Ammonia. From its uncertain nature it is 

 far more difficult to define its chemical composition, than is the case 

 with ordinary land ; the following are average results, and may be 

 taken as expressing pretty nearly the composition of the soil of the 

 Gardens. A fair sample, freed from stones and well dried, being 

 subjected to mechanical analysis, was found to consist of 



The sand and small stones were chiefly of a siliceous nature ; 

 the chemical composition of the dry soil was 



In expressing these results, as well as in all the following 

 analyses, 1 have carefully avoided the use of fractions of any 

 kind ; in all the experiments described, the numbers given are 



