292 MESSRS. THORPE AND MORTON ON THE 



mixed magnesium oxalate. The precipitate was collected, 

 dried; ignited, and weighed as caustic lime. 







Amount in 



Water taken. 



CaO obtained. 



1000 grms. 



I. ... 153138 



0-0878 



0-57466 



II. ... 153*328 



0-0883 



0-57589 



III. ... 153266 



o-o88i 



0-57482 



Mean 0-57512 



The amount of lime contained in the water of the Irish 

 Channel is somewhat less than that usually found in the 

 Atlantic Ocean, — according to Forchhammer 0*0597 P^^ 

 cent. 



IV. Estimation of the Magnesia, determined in the filtrates 

 obtained in the foregoing estimations. 





Water taken. 



P. 



MgO in 



1000 grms, 



I. 



... 153-328 



0-8649 



2-03275 



I. 



... 153*266 



0-8642 



2-03192 



Mean 2*03233 



According to the authority already quoted, the amount 

 of magnesia -contained in the water of the ocean far distant 

 from land varies about 0*0093 per cent. ; max. 0*2209 per 

 cent., min. o*2ii6 per cent. 



V. Estimation of the Calcium Carbonate. 



The lime contained in sea- water exists as sulphate and 

 as carbonate, the latter salt being dissolved in an excess 

 of free carbonic acid. On boiling the water the gas escapes, 

 when the calcium carbonate separates out. Its amount 

 was determined by boiling a weighed quantity of water for 

 about an hour, taking care to add distilled water from time 

 to time in order to prevent the precipitation of the cal- 

 cium sulphate. The water on cooling was again weighed, 

 divided into two portions, and filtered through dry filters ; 



