WATER OF THE IRISH SEA. 297 



various fucoid plants. About lOO grms. of the dried re- 

 sidue of the water of the Irish Channel^ evaporated with 

 sodium carbonate,, were digested with absolute alcohol for 

 some days, the solution evaporated to dryness, and the 

 solid matter again treated with absolute alcohol, filtered, 

 and a second time evaporated to dryness. The dried salt 

 was then dissolved in a few drops of water, a small quantity 

 of clear starch paste added, together with two drops of a 

 solution of nitrogen teroxide in sulphuric acid. Not 

 the slightest coloration was perceptible. Assuming, with 

 Stromeyer, that i-^injiyu P^-rt of iodine may be thus 

 detected, and assuming, further, that the delicacy of 

 the reaction is not interfered with by the presence of 

 bromides or chlorides, it follows that the amount of iodine 

 contained in sea- water cannot exceed i part in 100,000,000 

 of water, and is probably much less. 



IX. Determination of the joint amount of Chlorine and 

 Bromine, by precipitation as Silver Salts. 



Water taken. Silver salt Containing CI per 1000 



grms. obtained. AgCl. grms. 



I. ... 25-6110 i"93i9 i'9283 i8*6i82 



II. ... 25*6306 1*93521 1*93^5 186348 



Mean 186265 



X. Estimation of the Ammonia. 



S^37'7 grms. of the sea- water were boiled with a 

 quantity of pure caustic soda (made from metal) in 

 a distilling-apparatus until about two litres had passed 

 over; this was a second time distilled through a good 

 condensing-arrangement. The second distillate, contain- 

 ing all the ammonia, weighed 36578. The greatest care 

 was taken in the operation to prevent the solution absorb- 

 ing ammonia from the atmosphere of the laboratory ; and 

 the vessels employed were perfectly clean and new. The 



