CXXl 
EXPLANATORY NOTES TO TABLE OF ANALYSES, 
Nitrogen is present in considerable quantity throughout the bodies of 
animals, and in smaller quantity in plants, chiefly in the fruits and 
seeds ; consequently the estimation of nitrogen, found in the three forms 
of free ammonia, nitrogenous, or albuminous organic matter, and nitrous 
and nitric acids, forms the most important part of the analysis of drinking 
water. ' 
Free ammonia, present in larger proportion than 0°08 part per million 
of water, is usually due to the decomposition of urea, showing that 
admixture with urine has occurred. The average amount of free am- 
monia in river waters is0‘01 part per million, but this is subject to some 
variation. Albuminoid ammonia is formed in the process of analysis 
employed, and represents approximately ten times as much living or 
dead nitrogenous organic matter. A water yielding more than 0°15 
part of albuminoid ammonia is considered to be unfit for drinking pur- 
poses. Imperfectly filtered water yielding 0°10 - 0°29 part per million 
is stated to frequently produce diarrhea. Nitrous and nitric acids 
are formed by the oxidation of nitrogenous matter, and have 
been described as the ‘“‘ Skeleton of Sewage,” and as representing ‘‘ pre- 
vious sewage contamination ;’ but the term ‘‘old organic matter” 
seems more appropriate, the nitrogen not being of necessity originally 
derived from sewage, but possibly from other contaminating matter. 
The admixture of sewage, etc., may, however, have been quite recent. 
A good water will contain no nitrous acid. In ordinary cases the total 
solids consist chiefly of dissolved mineral matter, which in small 
proportion is unobjectionable ; but in some spring and well waters are 
found excessive quantities of lime, magnesia, and soda salts (chlorides 
and sulphates), which render them wholly unfit for every-day use. 
Waiter containing more than eight grains per gailon of lime and magnesia 
saltsis stated to be injurious to many persons, but in limestone dis- 
tricts a much greater proportion is always present. 
The proportion of chlorine in natural waters varies greatly, but as it 
is always found in some quantity in urine and sewage, the knowledge 
of the amount, considered withthe other results of analysis, may be of 
some assistanc in forming an opinion as to purity. 
NOTES ON SAMPLES EXAMINED, 
Cressy. 
Samples 1 and 2, taken from creek supplying Cressy. Colour. 
brownish, from finely divided matter in suspension; living organisms 
present. 
Sample 3, taken from marsh draining into creek about 100 yards above 
spoc where Nos. 1 and 2 were taken, Milky, from the presence of much 
suspended matter, the quantity being sufficient to render the water 
Opaque when seen in a layer of about Yin. in depth. A farm-yard and 
peiy drained into the creek near the point where the marsh joins the 
creek. ° 
Sample 4, taken from tank of house where typhoid fever had occurred. 
Water orignally taken from creek. Colour, brownish yellow, sediment 
amounting to 63 grains per gallon, about 52 grains being mineral, 
and the rest organic filth, swarming with life, inuluding worms. 
Sample 5, from tank or barrel next door to house where sample 4 was 
taken. Water originally from creek. Colour brownish yellow, slight 
turbidity, offensive smell, contained portions of insects, much organic 
matter, sporules, etc. 
Sample 6, from tank or barrel in neighbourhood, filled from creek. 
Colour faintly yellow, slight sediment, and living organisms, including 
worms. 
In the case of Nos. 4.and 5, and to a less marked extent in No. 6, 
