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 he detected in natural waters, and 

 even when in such minute proportion as in natural waters, its quantity- 

 can he 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-Iodide 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 



