Rev. A. Irving—Water Supply from Bagshot Sands. 411 
the Bagshot strata, such as I have described. Of course that argu- 
ment is completely met by the fact that throughout the district in 
question the water which is found to be wholesome, and is therefore 
generally used by the inhabitants, is obtained from the uncontaminated 
upper ferruginous sands, while that derived from the deeper sands is 
generally avoided. It may be useful here to give some details of 
the results of two analyses made by a responsible professional 
analyst (Dr. Shea, of Reading), of two samples of water, one from 
the upper ferruginous sands, the other from a deep well supplied 
mainly from the Middle and Lower Bagshot strata :— 
SURFACE SPRING. Derr WELL. 
Waiter clear; no smell on boiling; no deposit after |Turbid ; faint smell on boiling ; 
standing for 24 hours; no débris revealed by | much ‘iron’ deposited in 24 
microscopic examination. hours ; amorphous matter 
present (after settling). 
Grs. per gallon. Grs. per gallon. 
Total solids dissolved o.oo 13°00 15°75 
Volatile om ignition o......sssaseccssesees 5°50 5°50 
IDIOTS” Levee aero ee 1-75 1:75 
JN TARPO GEL: cal amet ae eee ves ere 0-12 0-70 
Oxygen consumed in three hours 0-028 0-056 
Free aMMOnia, .......sescesseeee 0-015 parts in 1,000,000 0:02 in 1,000,000 
MOT ATIAC HO. crenccoasBecrccrsnonsses 0-060 a 53 0°10 * 
The rather marked amount of nitrogen in the well-water seems at 
first sight not easy to explain. Such nitrogen is present however 
only as nitrates. Dr. Shea suggests a distant source in space and 
time. A knowledge of the character of the deeper Bagshot strata 
reveals perhaps its real origin. Ammonia (which undergoes slow 
oxidation into nitrates) has been obtained by Fiirst Salm-Horstmar? 
by dry distillation of peat with potash; and it has been pointed out 
above that the fresh green sands from beneath layers of peat give off 
in some cases water showing an alkaline reaction to test-papers, and 
capable of being recognized as distinctly ammoniacal. On the pre- 
sence of nitrogen as nitrates, it is to be noted further that the great 
distance at which we are removed in this neighbourhood from all 
those sources of surface contamination which exist in towns pre- 
cludes all possibility of these nitrates being accounted for from such 
causes; whiie any possible pollution from a grave-yard or cesspools 
in the adjoining parishes would appear in the water of the upper 
surface springs, and be effectually shut off from percolation down- 
wards to the deeper strata for reasons before explained. As further 
evidence of the derivation of nitrogen from vegetation while under- 
going decay, I may quote the results of analyses given by A. A. 
Julien? of peat at different depths from a peat-bog near Gutes 
Jessbach in Hoistein, as follows :— 
Ash. N. C. ile 0. 
Brown peat from the surface .................6 2°72 0-80 | 57°75 | 5:43 | 36:02 
Nearly black peat. at a depth of 7 feet. | 7°42 2:10 | 62°02 | 5:21 | 30°67 
Black peat at a depth of 14 feet .......... 9°16 405) ) | G2:07 0 0-01) 26:57 
1 Berzelius’ Jahresbericht, 1842. 
2 Proc. Amer. Assos. Sci. 1879, p. 314. 
