CHEMICAL CHANGES IN THE COMPOSITION OF SEA-WATER. 



487 



column d (the precipitated carbonate of lime) we get the theoretical alkalinity due to 

 these reactions, the result being shown in column e. 



Column /gives the alkalinity of the mud- water above the normal as found by actual 

 determination. 



Column g shows the difference between the theoretical values of alkalinity as 

 calculated (e) and the values found on determination {/). The two values (e and f) 

 are thus seen to be very much alike, and go to prove that the reactions noted above 

 are really those which take place in the mud. They are shortly stated in the 



formula — 



b + c — d = e 



using the same letters as given over each column in the table. 



TABLE A. — Showing the Alkalinity in Grammes per Kilogramme of the Mud-Water as determined, 

 and calculated from the various reactions (1st portion omitted). 



o 



t-, 

 o 



P-, 



a. 



Difference of 



Sulphuric Acid 



(SO s ) from the 



Normal. 



b. 



S0 3 in last 



column changed 



to its equivalent 



of Carbonate of 



Lime. 



c. 



Ammonia 



changed into its 



equivalent of 



Carbonate of 



Lime. 



d. 



Precipitated 



Carbonate of 



Lime, taken 



from decrease of 



lime in Table IV. 



e. 



Theoretical 

 Alkalinity above 

 the Normal. (6 

 and c are added 

 together, and d 



subtracted. ) 



Alkalinity 

 above the 

 Normal found 

 on determina- 

 tion. 



g- 



Difference be- 

 tween the Theo- 

 retical and the 

 Found Value. 



2nd 

 3rd 

 4th 



5th 

 6th 



-1-0849 

 -1-0742 

 -1-0309 

 -1-0238 

 -1-0683 



1-3561 

 1-3427 

 1-2886 

 1-2797 

 1-3354 



0-0965 

 0-0784 

 0-0228 

 00620 

 0-0408 



-00271 

 -0-0696 

 -0-0764 

 -0-1709 

 -0-3752 



1-4255 

 1-3515 

 1-2350 

 1-1708 

 1-0010 



1-3478 

 1-2993 

 1-1954 

 1-1033 

 1-0145 



- 0-0777 

 -0-0522 



- 0-0396 

 -0-0675 

 + 0-0135 



When a portion of the clear water filtered from the harbour muds was boiled for a 

 short time, a precipitate was thrown down in a crystalline form, which on analysis proved 

 to be carbonates of lime and magnesia in the following proportions : — 



CaC0 3 73-30 



MgC0 3 2670 



10000 



Before boiling, the water had an alkalinity of 07760 grms. per litre, while after 

 boiling it showed an alkalinity of only 0*2200 grms., thus proving that the alkalinity 

 was mainly due to the formation and presence of these carbonates rendered soluble by 

 free carbonic acid. 



