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XIX. An Experimental Inquiry into the influence of Nitrogen on the growth of 

 Plants. By Robert Rigg. Communicated hy the Rev. J. B. Reade, M.A. F.R.S. 



Received May 10, — Read May 31, 1838. 



About two years ago I had the honour of laying before the Royal Society an ex- 

 perimental inquiry into some of the chemical changes which occur during the germi- 

 nation of seeds and the decomposition of vegetable matter. On the present occasion 

 I purpose to confine myself to an extensive series of experiments which have reference 

 to the presence of nitrogen, earths, and salts in vegetable compounds, with a view of 

 directing attention to the influence of nitrogen in the growth of vegetables. 



As my inquiry is purely experimental, I may premise that I have had recourse to 

 the well-known method of ultimate analysis, and the equivalent numbers which I 

 employ are, carbon 6-12, hydrogen 1*0, oxygen 8*0, and nitrogen 14"0. That we may 

 the more readily apply the proportionate quantity of nitrogen to our immediate pur- 

 pose, I shall make one column in each analysis, which will represent by weight the 

 quantity of nitrogen when compared with 1 000 parts of carbon in the same compound. 

 I also designate by the term residual those earthy and saline ingredients which are 

 not decomposed during the analysis. In some of the experiments this residual may 

 contain a little foreign matter, for in preparing the different compounds for analysis I 

 seldom had recourse to any process of ablution, rather choosing to have a little foreign 

 matter present, than to remove any part of that which was more particularly the ob- 

 ject of research. That I might also examine the compounds as nearly as possible in 

 their natural state, I very rarely exposed them to a higher temperature than 100° Fahr., 

 inclosing them in very thin paper, and afterwards allowing them to acquire the hy- 

 grometric state of the atmosphere. 



The first series of experiments to which I shall refer tends to show, that in that 

 part of the seed where germination takes place nitrogen preponderates, when com- 

 pared with its quantity in the other part of the seed. This result is derived from the 

 analysis of the germ and cotyledons of beans, peas, barley, wheat, &c., a large excess 

 of nitrogen being invariably indicated in the germ. 



Table I. 



3 E 2 



