173 
For the Chlorine :-—100 C.C. of the water had a few drops of 
the Yellow Chromate of Potash added to it, and was then 
titrated with a standard solution of Nitrate of Silver, and the 
Chlorine calculated accordingly. 
The Iron was determined gravimetrically as follows ; 1} litre 
of the water was evaporated to a small bulk with Nitric Acid, 
the Iron then thrown down with Ammonia as Ferric oxide, dis- 
solved on the filter with Hydrochloric Acid and again precipitated 
with Ammonia, washed, dried, and ignited ; the residue being 
weighed as Ferric oxide, giving 1-5 parts per million. 
The iron was also estimated volumetrically with standard solu- 
tion of Permanganate of Potash, and gave similar results. I may 
here add that a qualitative analysis showed the absence of Alumina 
and Phosphoric Acid. 
The combined Carbonic Acid :—The water for this purpose 
was collected in a separate bottle in which a certain quantity of 
standard solution of Baryta water and Chloride of Ammonia had 
previously been placed. It was afterwards digested in hot 
water, aud an aliquot portion of the clear liquid titrated with 
the standard nitric acid ; thus the amount of free CO? was found. 
The precipitate left in the bottle was then collected and titrated 
with the standard acid, by which the total amount combined and 
free was calculated. The difference between the two calculations 
showed that due as combined only. 
The Nitric Acid :—This little figure, -35 parts per million, gave 
more trouble than all the rest of the analysis put together. Every- 
thing used in the determination had to be chemically pure and 
the apparatus chemically clean. The process adopted was that 
_ recommended by Wanklyn and Chapman. 100 cubic centimetres 
_ of the water were distilled with pure Caustic Soda to drive off 
_ the free Ammonia. When cool, small pieces of Aluminium were 
added to the solution which was set aside for a few hours in 
order that the Nitrates might become decomposed, when it was 
again distilled, and the Ammonia formed by the decomposition 
