88 



Sir J. B. Lawes and Prof. J. H. Gilbert. [Jan. 9, 



The Experiments at Rothamsted in 1888. 



This preliminary series comprised experiments with peas, blue 

 lupins, and yellow lupins. The peas were grown — 



1. In washed sand, with the ashes of the plant added; but no 

 supply of combined nitrogen beyond a small determined amount in 

 the washed sand and that in the seed sown. 



2. In similarly prepared sand, but seeded with 25 c.c. of the turbid 

 watery extract from a rich garden soil. 



3. Duplicate of No. 2. 



4. In the rich garden soil itself. 



Each of the two descriptions of lupin was grown — 



1. In sand prepared as for the peas, bat with lupin-plant-ash 

 instead of pea-plant-ash added. 



2. In the same washed sand, &c, but seeded with 25 c.c. of the 

 turbid watery extract from a sandy soil where lupins had grown 

 luxuriantly. 



3. In the lupin sandy soil itself. 



4. In rich garden soil. 



The twelve pots were arranged in a small greenhouse ; and distilled 

 water, free from ammonia, was used for watering. 



The sand employed was a yellow sand from Flitwick, in Bedford- 

 shire, and was of the same description as is used by gardeners in the 

 neighbourhood for potting. It proved, however, not to be a very 

 pure sand. Thus, after the stones and coarser portions had been 

 removed by sifting, the remainder was several times washed, first 

 with well-water and afterwards with distilled, the turbid wash- 

 ings being poured off ; yet it was found to contain after being dried 

 finally for a short time in a water-bath, and mixed with the plant-ash 

 as mineral food, nitrogen as under : — 



Per cent, 

 nitrogen. 



Determined by soda lime 0*00287 



Determined by copper oxicle 0'00245 



Mean 0*00266 



The sandy soil in which lupins had grown, and from which the 

 watery extract was made for seeding the pots where the lupins were 

 to grow, was still less pure ; and it, of course, was not washed, and 

 was only dried at about 24° C. ; and, excepting that visible organic 

 matter was removed by sifting and picking, it was used in its natural 

 state as received. Duplicate determinations of nitrogen were made 

 by soda-lime, in the lupin sand alone, and as used after mixture with 

 the lupin ash. The following are the mean results, in each case, 

 calculated on the dry sand : — 



