WATERWORKS LABORATORIES 
505 
for B. coli have been confused. The new Edition of the Stand- 
ard Methods provides a uniform scheme which will doubtless 
be extensively followed. 
Chemical standards based upon the ordinary factors of a 
sanitary analysis often mean very little when applied to a treated 
water in routine examination. This is due to the fact that 
there is usually very little oxidation in passing; through a filter 
and a purified water will still show evidence of its former pol- 
lution and unsafe condition. With a stored water there is 
greater oxidation and therefore the individual determinations 
of the sanitary analysis probably mean more. There are a num- 
ber of papers which have been written upon the amount of use- 
less work which has been done on the routine water samples 
from a single plant. In connection with the operation of the 
plant a very few factors are usually sufficient. Alkalinity is 
probably of the greatest importance because it sets a limit upon 
the amount of alum or iron sulphate which can be added to a 
water. Free carbon dioxide is especially important in iron re- 
moval plants. An iron determination can show at once whether 
the iron is being removed. Where waters are softened the total 
hardness, erythrosine or methyl orange and phenolphthalein al- 
kalinities, magnesium, etc., may be determined advantageously 
every day. Most of us, however, run a few thousand nitrite 
and nitrate determinations on the product of a water, plant be- 
fore we realize that the numerical variation throughout the year 
is too small to give important information from day to day. 
It is understood, of course, that the really important factor 
is the bacterial data which on account of cultural methods must 
of necessity be one or two days behind at all times. In work 
with a treated water the chemical substances present which are 
determined in a sanitary analysis usually are of little im- 
portance. It may be, however, that bog water and the colored 
water of the early spring may contain some toxic substances. 
Occasionally the plumbosolvency of a. water will be important 
in soft water districts. A weekly or monthly sanitary water anal- 
ysis in the complete form ought to satisfy any demands. Quar- 
terly minerals analyses ought to meet industrial conditions as a 
rule. 
Laboratories for the State Board of Health, 
The State LIniversity. 
