[ 225 J 
XXIV. 
NOTES ON THE VARTRY WATER IN NOVEMBER, 1893. 
By RICHARD J. MOSS, F.C.S., F.I.C. 
[Read NovemBer 22; Received for Publication DecemBer 20, 1893; 
Published Frsruary 13, 1894.] 
Harty in the month of November, 1893, the Vartry reservoir 
at Roundwood had become almost empty owing to the long con- 
tinued dry weather. It was found necessary to cut off the Vartry 
supply from a large area, and to substitute water from another 
source, but part of the city and some of the townships remained 
dependent upon the residue of the Vartry water, and it became 
a matter of importance to ascertain whether this water continued 
sufficiently pure for drinking purposes. I accordingly commenced 
a series of daily analyses on November 7th. I had no intention 
of publishing my results, but as I find there is no public record 
of the condition of the Dublin water supply of this exceptional 
period, the following notes, incomplete as they are, may be of 
interest :— 
The samples were taken from the main at Ballybrack, about 
ten miles from Dublin, from November 7th to the 18th inclusive. 
I believe the water in the reservoir reached its lowest level on the 
16th. The water was darker in colour than it had formerly been, 
and all the samples were more or less turbid. The greatest tur- 
bidity was observed on the 18th. 
My examination was confined to determinations which could 
be rapidly made with small samples of the water. Ammonia 
and ‘albuminoid ammonia’ were determined by Franklin’s 
method. The solids were dried at the boiling point of water 
until loss of weight ceased. ‘The oxygen absorbed was determined 
by submitting a given volume of the water to the action of an 
excess of potassium permanganate for four hours at a temperature 
of 26° C., and titrating with sodium thiosulphate, the results being 
controlled in each case by an observation upon pure water under 
identical conditions. Nitrites were absent in each case. Nitrates 
were not determined on the days on which the samples were 
drawn ; subsequent determinations showed quantities of nitric acid 
varying from 0°18 to 0°24 grain per gallon. 
R2 
