CONDITIONS ESSENTIAL TO NUTRITION. 43 



crystallised carbonate of lime are formed, might, 

 perhaps, attain maturity under such circumstances ; 

 but these experiments alone are sufficient to prove, 

 that cresses, gourds, and balsamines, cannot be 

 nourished by supercarbonate of lime, in the absence 

 of matter containing nitrogen. We may indeed 

 conclude, that the salt ofc lime acts as a poison, 

 since the development of plants will advance fur- 

 ther in pure water, when lime and carbonic acid 

 are not used. 



Moist flowers of sulphur attract oxygen from the 

 atmosphere and become acid. Is it possible that a 

 plant can grow and flourish in presence of free 

 sulphuric acid, with no other nourishment than 

 carbonic acid ? It is true, the quantity of sulphuric 

 acid formed thus in hours, or in days, may be small, 

 but the property of each particle of the sulphur 

 to absorb oxygen and retain it, is present every 

 moment. 



When it is known that plants require moisture, 

 carbonic acid, and air, should we choose, as the 

 soil for experiments on their growth, sulphate of 

 barytes, which, from its nature and specific gravity, 

 completely prevents the access of air ? 



All these experiments are valueless for the decision 

 of any question. It is absurd to take for them any 

 soil at mere hazard, as long as we are ignorant of 

 the functions performed in plants by those inor- 

 ganic substances which are apparently foreign to 

 them. It is quite impossible to mature a plant of 



