ARTIFICIAL SEA-WATER. 



263 



necessary was to bring together tlie salts in proper 

 proportion, and add pure water till the solution was 

 of tlie proper specific gravity. . . . 



" I took Schweitzer's analysis ; but as I found that 

 there was some slight difference between his and 

 Laui'ent's, I concluded that a very minute accuracy 

 was not indispensable. Schweitzer gives the following 

 analysis of 1^000 grains of sea- water taken off 



999-998 



" The bromide of magnesium and the carbonate of 

 lime I thought I might neglect, from the minuteness 

 of their quantities ; as also because the former was 

 not found at all by M. Laurent in the water of the 

 Mediterranean ; and the latter might be foimd in suf- 

 ficient abundance in the fragments of shell, coral, and 

 calcareous alg^, thrown in to make the bottom of the 

 Aquarium. The sulphate of lime (plaster of Paris) 

 also I ventured to eliminate, on account of its extreme 

 insolubility, and because M. Laurent finds it in 

 excessively minute quantity. The component salts 

 were then reduced to four, which I used in the fol- 

 lowing quantities : — 



