114 THOMPSON YATES LABORATORIES REPORT 
bacterial flora which is being gradually formed is of use for reference. The classification which 
we adopt is an artificial one, and based upon the action of bacteria upon various media. 
Comparison of Results with those of other Towns 
As far as we are aware, the routine bacteriological examination of the water as carried out 
in Liverpool is practised in no other large city in Great Britain. On the continent daily 
examinations are common. At first it was the practice in some places abroad to examine the 
water from each filter bed, in order to ascertain whether each bed was working satisfactorily. 
Now, however, it is usual to simply examine the water as it is supplied to the town. 
The following is a comparison of the number of bacteria per c.c. present in the water 
supplied to a drinking fountain in the city of Liverpool and that supplied to certain other large 
cities in Europe : — 
Liverpool 
Hamburg 
Berlin ... ... ... ... under 
Paris 
Buda Pcsth ... ... ... under 
Munich 
From these figures it will be seen that the water of Liverpool is exceptionally good, that 
of Munich alone being better. Further, that as neither the B. coli nor the B. enteriditis 
sporogenes have been found in the filtered water the purity is still further accentuated. 
METHODS EMPLOYED 
The following methods are used for both classes of investigation. 
Collection of Samples 
Small (i-ounce capacity) sterilized bottles are used for collecting the water from the mains. 
For collecting water at considerable depths vacuum tubes which can be broken under water are 
employed. Each bottle has a distinctive number ground on it, and the particulars of the samples 
are entered in a note-book at the time of collecting. 
Time of Making the Analysis 
The bacteriological investigations are made as soon after collecting as possible. Li the 
case of the daily examinations the average time of analysis after collection is one half-hour. In 
the case of the fortnightly and monthly samples a delay of two to three hours occurs ; but as the 
sample-bottles are kept enclosed in a special ice-box during the delay of two or three hours there 
is very little chance of bacteriological multiplication. If in special cases there is a greater delay, 
the special box containing the samples is placed in the refrigerator chamber. 
Media 
Gelatine. — The composition of the gelatine is constant, and the reaction is standardized. 
Agar. — Carbolized agar, in the proportion of i in i,000, is always used. 
Milk. - Fresh sterilized litmus milk tubes are used. 
24 bacteria per c.c. 
70 
50 
1,125 
100 „ „ 
4 „ „ 
