REPORT OX THE COMPOSITION OF OCEAN-WATER. 
131 
Found for 
Alkalinity per litre, ...... 364-4 mgrms. 
Original alkalinity, . . . . . 50 - 2 „ 
Additional alkalinity due to the added lime, . . . 314-2 „ 
The experiment was then repeated with the water in its original condition, which for 
the present purpose is sufficiently defined by stating that the water in its natural state, 
according to a direct determination of the total carbonic acid, contained — 
Carbonic acid as R 2 C0 3 , from alkalinity, . . .50-2 mgrms. 
Additional carbonic acid, . . . . 47 -5 „ 
showing that the free base was very nearly in the condition of bicarbonate RHC0 3 . 
260 c.c. when digested with two grms. of carbonate of lime for forty-eight hours and 
filtered, gave a filtrate exhibiting an alkalinity of 46 ’96 mgrms. per litre, which is 
3 ’2 mgrms. less than that of the original water. A very irregular result, which I 
regret it was forgotten to verify by a repetition of the experiment. 
Experiment II. — Alkali-free carbonate of magnesia was prepared by passing carbonic 
acid into a mixture of magnesia alba and water, filtering, boiling down the filtrate, and 
collecting the thus re-precipitated carbonate of magnesia. Two grms. of this preparation 
were digested for forty-eight hours with 260 c.c. of Ailsa Craig water previously saturated 
wfith carbonic acid, the mixture then filtered, and the alkalinity of the filtrate determined. 
The experiment was then repeated with the natural water. The results were as follows : — 
Additional alkalinity, due to the added carbonate of magnesia, per litre : — 
In the case of the water saturated with carbonic acid, . . 1234-0 mgrms. 
In the case of the natural water, .... 10-64 ,, 
From these experiments we see that carbonate of magnesia is far more freely soluble 
in sea-water than carbonate of lime is. 
