1890.] On the Question of the Fixation of Free Nitrogen. 91 



Determinations of dry matter, and of nitrogen, in the seeds, gave 

 the following results : — 





Dry 

 matter 



at 

 100° C. 



Nitrogen. 



In fresh. 



In dry matter. 



By soda-lime. 



By 



copper 

 oxide. 



% 

 soda- 

 lime. 

 Mean. 



By 



copper 

 oxide. 



Expt. I. 



Expt. 2. 



Mean. 



Maple peas . . 

 Blue lupins . . 

 Yellow lupins 



Per cent. 



93- 26 



94- 03 

 94 63 



Per cent. 

 3 537 

 5 105 

 6-649 



Per cent. 

 3 621 



5- 098 



6- 569 



Per cent. 

 3-579 



5- 101 



6- 609 



Per cent. 

 3 531 

 5 364 

 6-404 



Per cent. 

 3-837 



5- 425 



6- 984 



Per cent. 

 3-787 



5- 705 



6- 767 



It should be stated, as applicable to the whole of the results as well 

 as to those recorded in the foregoing table, that nitrogen was deter- 

 mined by burning in a vacuum with copper oxide, and collecting and 

 measuring the nitrogen and nitric oxide. In all cases, however, where 

 there was sufficient material, determinations were also made by the 

 soda-lime method, as a check. Nitrogen as nitrates was determined 

 by Schlcesing's method. The copper oxide determinations given in 

 the table, which are those used in the subsequent calculations, 

 were made upon three or four of the average selected seeds, ground 

 up with the copper oxide ; whilst the check soda-lime determinations 

 were made on quantities taken from a bulk of ground seeds. 



The Vegetation Experiments in 1888. 



It was intended to commence the experiments early in the summer, 

 but the pressure of other work and the preparations necessary for the 

 experiments themselves, prevented the sowing of the seed until early 

 in August. Nevertheless, the results obtained in this initiative 

 series were not only of value as affording experience on various 

 points, of which advantage has been taken in the conduct of the more 

 extended series made in 1889, but, as will be seen, they have afforded 

 important evidence on the main point of enquiry itself. 



The broken flints, the sand with ash, and the sand without ash, or the 

 garden soil, as the case may be, were weighed and put into the respective 

 pots at the laboratory, taken to the glass-house on August 4, and 

 watered with ammonia-free distilled water. All the seeds were sown 

 on August 6. Three accurately weighed seeds were put into each pot. 



From the first, the peas germinated and grew well in each of the 



