Soluble vs. Insoluble Cane Manures. 337 
change that ammonia undergoes, by the experiments 
made at Rothampstead, which resulted in proving that 
nitrates enormously increased in drainage water from 
plots manured by sulphate of ammonia, and thus 
accounted for the loss of nitrogen experienced when 
ammoniacal manures were employed. 
Previous to 1873, it was generally considered that the 
conversion of ammonia into nitric acid was effected by 
the dire6l action of atmospheric oxygen under the influ- 
ence of porous substances, such as finely divided soil 
charcoal, platinum black, brick, &c, which were sup- 
posed to act simply by their well-known power of 
condensing air within their interstices, and so bringing 
the atmospheric oxygen in a more concentrated, and 
presumably more active form, into contact with the 
ammonia. Since then, however, it has been indisputably 
proved that the change is due to the action of a living 
organism. PASTEUR, in 1862, first suggested this possi- 
bility on theoretical grounds, and A. Muller in 1873 
drew conclusions favourable to it from experiments on 
the difference in the behaviour of ammonia present in 
sewage and in pure water respectively ; but it was re- 
served for SCHLOESING and Muntz in 1877 and follow- 
ing years, to firmly establish the fa£t. By a system of 
patient cultivation they succeeded in isolating the parti- 
cular organism from numerous similar ones present in 
soils, and describe them as minute, round or slightly 
elongated corpuscles, existing singlv or joined in couples, 
which apparently multiply by budding, and belong to the 
bacteria family. The temperature most favourable to 
their action is 37 C, or 98. 6° F., and below or above 
that temperature their power rapidly diminishes. The 
