WATER OF THE IRISH SEA. 289 



Schweitzer to be 1-0271 ; on nearing the land the specific 

 gravity fell to 1-0268. 



The following substances are stated by Forchhammer to 

 exist in sea-water"^ : — 



Acids, or elements replacing them : Sulphuric, carbonic, 

 phosphoric, silicic, boracic, nitric, arsenic, bromine, chlo- 

 rine, iodine, fluorine. 



Bases: Sodium, potassium, magnesium, lithium, caesium, 

 rubidium, ammonia, strontium, barium, iron, manganese, 

 aluminium, zinc, cobalt, nickel, lead, copper, and silver. 



In addition to these are variable quantities of organic 

 matter, concerning the true nature of which we know as 

 yet absolutely nothing. Dr. Angus Smith and Mr. Hunter, 

 however, have already applied the permanganate reac- 

 tion to determine the amount of this organic matter. None 

 of the peculiar organic substances, such as crenic and apo- 

 crenic acids, butyric, acetic, propionic, and formic acids, 

 discovered in several mineral waters on the Continent, have 

 been detected in sea-water. Of the thirty-one elements 

 occurring in sea-water, the quantitative determination of 

 nine or ten is alone possible. These are sodium, magne- 

 sium, potassium, calcium, iron, chlorine, bromine, and sul- 

 phuric and carbonic acids. We have further attempted 

 to estimate the amount of nitric acid and ammonia. The 

 remaining constituents have either been detected in the 

 ashes of sea-plants and animals, whence their existence in 

 sea-water has been inferred, or, as in the case of phosphoric 

 acid and fluorine, they have been found in the boiler-de- 

 posits of sea-going steamers. 



I. Estimation of the Total Solid Contents. 



The weighed quantity of water was evaporated to dry- 

 ness in a platinum crucible, and the dried mass exposed to 



* Proc. Royal Soc. lii. p. 130, 1862. 

 SER. III. VOL. IV. U 



