THE NITRIFYING PROCESS AND ITS SPECIFIC FERMENT. 
i09 
Calcium sulphate.lOO'OO 
Sodium sulphate.47'91 
Potassium sulphate. 3578 
Calcium carbonate. 13'32 
Magnesium carbonate , , . . . 12'52 
Pichard’s results as regards the beneficial effect of calcium sulphate are confirmed 
by Warington in a paper “ On the Action of Gypsum in Promoting Nitrification ” 
(‘Chem. Soc. Journ.,’ 1885, p. 758), and again, in a furtlier communication “On the 
Distribution of the Nitrifying Organism in the Soil ” (‘ Chem. Soc. Journ.,’ 1887, 
p. 119), he shows that by adding calcium sulphate to the ammoniacal solutions the 
latter may be made to nitrify by seeding with soil taken from greater depths than 
had hitherto been found capable of causing nitrification. 
Munro, in “ Formation of Nitrites during Nitrification of Ammoniacal Solutions” 
(‘Chemical News,’ vol. 56, pp. 62-64; ‘ Cliem. Soc. Journ.,’Abst., 1888, p. 82), 
contends, in opposition to Gayon and Dupetit, that the nitrite found during nitrifi¬ 
cation is actually the result of the direct oxidation of the ammoniacal nitrogen, and 
not due to a reduction of nitrate first formed. 
In “ Distribution of the Nitric Ferment and its Function in the Disintegration of 
Hocks” (‘Annalen Chem. Phys.,’ [6], vol. 11, pp. 136-144; ‘Chem. Soc. Journ.,’ 
Abst., 1887, p. 1135), Muntz states that the nitrifying ferment is to be found at the 
highest elevations of the Alps, amd ascribes to it the power of causing the disintegra¬ 
tion of rocks. He also observes that organisms vvhicli appear to be identical with the 
nitrifying ones are capable of reducing nitrates when air is excluded. 
It is not a little surprising that after the overwhelming evidence of such numerous 
investigators, the vital nature of the nitrification process should have been again 
disputed. This has been done, however, by Frank (‘Forschungen auf dem Gebiete 
der Agriculturphysik,’ vol. 10, p. 56), whose contention has however, received no 
support, and has been rebutted by Plath (‘ Piedermann’s Centralblatt,’ 1888, 
pp. 6-8; ‘Chem. Soc. Journ.,’ Abst., 1888, p. 521), and by Landolt (‘Bieder- 
mann’s Centralblatt,’ 1888, p. 577). 
The modern methods of bacteriological study were first brought to bear upon the 
subject of nitrification by HeRtEUS (‘ Zeitsch. f. Hygiene,’ 1886, p. 193). This investi¬ 
gator, after inducing nitrification in an ammoniacal solution by means of a small 
quantity of garden soil, endeavoured to isolate the organisms present in the nitrifying 
solution Iry means of the method of gelatine-plate cultivation. In this manner he 
obtained four different organisms in a state of purity, and these he distinguished by the 
signs p, cr, (f) and y respectively. These pure cultures he inoculated into ammoniacal 
solutions of the following comjiosition :— 
