224 Mr. Waldie’s investigations connected ; [No. 3» 
water of the hot season shewed more indications of vegetation than 
that of the cold season, though greatly less than that of the rains, 
Ammonia. 
Ammonia, perhaps one of the most characteristic evidences of the 
presence of nitrogenous matter, can be detected in natural waters, and 
even when in such minute proportion as in natural waters, its quantity 
can be estimated. Dr. Miller has given a process for doing so with 
sufficient accuracy, and without the necessity of operating on very large 
quantities of water, which will be found in the paper I have already 
mentioned on the analysis of mineral waters in the Journal of the 
Chemical Society for May 1865. It depends on the great delicacy 
of the test for ammonia possessed by an alkaline solution of the 
Hydrarg-lodide of Potassium, which produces a fine rich yellow 
brown colour with a very small quantity of ammonia, or a precipitate; 
if the quantity be larger. In the weaker solutions, the colour varies 
in depth of shade with the proportion of ammonia present, and by a 
comparison with another solution containing a known quantity of 
ammonia the proportion is estimated. Dr. Miller attributes the plan 
of proceeding to Mr. Hadow, and gives the details of procedure. He 
gives the formula for the preparation of the alkaline solution of 
Hydrarg-Iodide of Potassium, which I have strictly followed and 
adopted. His standard solution for comparison is a weak solution of 
pure muriate of ammonia of such strength that 1 fluid grain of the 
solution contains .0001 (one ten-thousandth of a) grain of ammonia 
or 3.17 grains muriate of ammonia in 10,000 fluid grains. I also 
adopt this solution, but have modified the plan of proceeding, it 
appears to me with advantage. It is thus: 
A convenient quantity, 10,000 fluid grains is very suitable, of the 
water, to which a small quantity of pure hydrochloric acid has been 
added, is concentrated by a gentle heat to about 1,000 fluid grains: 
it must of course be slightly acid. This is put into a flask, some excess 
of pure milk of lime added, and the flask connected by a bent tube 
with a small Liebig’s condenser, to the extremity of which is connected 
a small Woulfe’s bottle, and to this another one furnished at its further 
neck with a tube containing broken glass moistened with water, this 
being to prevent escape of ammonia. About half or 500 fluid grains of 
