TKANSACTIONS OF SECTION B. 583 



mo nitrification was obtained. The considerable diflerence between the earlier and 

 later results is to be attributed to the employment of gypsum in the later solutions. 

 The nitrifying organism in the subsoil is indeed less abundant, and probably much 

 more feeble than in the surface soil, and is apparently imable to start nitrification 

 in the decidedly alkaline solution which urine produces in the absence of gypsum. 



Although it appears that the nitrifying organism may exist at considerable 

 depths, nitrification is practically confined to the surface soil. The quantity of 

 nitrogen as nitric acid annually obtained in the dram age water from soils of 

 diflei-ent depths in the drain gauges at Rothamsted is on an average of nine years : — 



Soil 20 inches deep .... 40.2 lbs. per acre 



Soil 40 „ „ .... 350 „ 



Soil 60 „ „ .... 38-8 „ 



There is no evidence here of a greater production of nitrates when the subsoil 

 is included in the experiment. 



Nitrates are always found most abundantly in the surface soil unless heavy 

 Tain has occurred to wash them downwards. Two fallow soils at Rothamsted 

 ■were found to contain the following quantities of nitrogen as nitrates in lbs. per 



acre : — 



1st 9 inches 28-5 40-1 



2nd , 5-2 14-3 



3rd „ j::;_ ^ 



Total . 33-7 599 



3. On the Action of Drinking-water on Lead. By Dr. C. Metmott Tidt. 



4. Micro- Organisms in Vrinking-tuater. By Professor Odling, F.B.S. 



MONDAY, SEPTEMBER 6. 

 The following Report and Papers were read : — 



1. Beport of the Committee appointed to investigate the Influence of the 

 Silent Discharge of Electricity on Oxygen and other Gases. — See 

 Reports, p. 213. 



2. On the Breservation of Oases over Mercury.^ 



By Harold B. Dixon, M.A., F.B.S. 



The author has found that different gases (hydrogen, electrolytic gas, cyanogen, 

 and sulphurous acid) could be preserved over dry mercm-y for several years with- 

 out any sensible alteration. This result is contrary to the conclusion arrived at by 

 Faraday, that it was impossible to preserve gases over dry mercury, but agrees 

 with the expeiiments of Sir Himiphry Davy, recorded in the Laboratory Notebook 

 of the Royal Institution. The author collected the gases in hot tubes over pure 

 Jiot mercury. 



3. On the Methods of Chemical Fractionation.'^ 

 By William Crookes, F.B.S., V.F.C.S. 



Broadly speaking, the operation of chemical fractionation consists in fixing 



' Printed in. extenso in the Chem. News, 54, p. 227. 



2 The original paper was published in extenso in the Chemical News for September 

 10, 1886. 



