450 



Transactions. — Chemistry. 



The water proved to be not only a hard water in the sense of hemg very 

 calcareous, but highly chlorinated too, — that is, one containing an alkaline 

 chloride in quantity, and this fact viewed in conjunction with that of the 

 imperfect operation of Clarke's process upon it led me to suspect that 

 these chlorides can exercise a very decided solvent effect upon mono- 

 carbonate of lime. That they have this effect was clearly shown by an 

 investigation I carried out, and the result of which I now beg to lay before 

 you as follows. First let me give an analysis of the hard water : — 

 Chloride of sodium . . . . . . . . . . 20'17 



Sulphate of soda 



„ magnesia 



Bi-carbonate of magnesia 

 ,, lime 



Silica . . 



1-67 

 4-30 

 4-01 

 10-82 

 3-65 



44-62 



On behalf of any here who may have forgotten the mode in which 

 Clarke's softenmg process effects what is desired of it, I will shortly describe 

 it, as it is necessary to remember it in order that the bearing of the 

 several statements to be made here may be fully apprehended. 



This process then consists in applying lime-water to the water to be 

 softened, by which all the lime existing therein in the form of bi-carbonate 

 is brought into that of the mono-carbonate, and this compound being far 

 less soluble in water than the original one, is in greater part precipitated. 



The full meaning of the effects I proceed to state will now be readily 

 gathered. 



1. — A saturated aqueous solution of sodic chloride was mixed in equal 

 volume with a strong solution of bi-carbonate of lime, and Clarke's soften- 

 ing fluid was added thereto m varying quantities until quite in excess. The 

 liquid remained quite clear, and no precipitate formed in twenty-four hours. 



2. — The same effects followed when either potassic or calcic chloride, 

 potassic nitrate or sodic carbonate were substituted for the sodic chloride 

 in experiment No. 1. 



3. — The Oamaru hard water was mixed with sodic chloride at the rate 

 of one pound to the gallon ; the filtered solution when treated with hme- 

 water in small or large quantity remained quite clear. 



4. — The same water was charged with a slight excess of lime-water 

 alone (sodic chloride being this time omitted) when an abundant preci- 

 pitate formed. This precipitate, when analyzed and the results computed 

 in grains per gallon upon the water taken, gave as follows : — 



Carbonate of lime . . . . . . . . . . 21-75 



Carbonate of magnesia . , , , , . . . . . -SI 



22-56 



