240 On the Composition of some Deep-Sea 



Acetate of ammonium was then added, and the mixture boiled 

 and filtered, and the precipitate washed. The precipitate was 

 dissolved in hydrochloric acid, and ferric hydrate precipitated 

 with pure caustic potash in a platinum basin. It was then 

 diluted and filtered, ignited and weighed. To the filtrate 

 ammonium chloride was added, and the solution boiled till 

 ammonia ceased to come off. The precipitate was filtered,, 

 ignited to A1 2 O 3 , and weighed. 



In the Fe 2 O 3 the variations are not great. The minimum,. 

 3-45 per cent., is on the Balearic Bank, and the maximum, 

 6-64, in the deep water near the African shore. In this neigh- 

 bourhood all the muds have large amounts of Fe 2 O 3 and small 

 amounts of A1 2 O 3 , except No. 35, where the amount of Fe 2 O 5 

 is small and that of A1 2 O 3 very large in fact, the maximum 

 (12-3 per cent.). It is remarkable that at No. 41 we find the 

 maximum of Fe 2 O 3 (6-64 per cent.), and the minimum of A1 2 O 3 

 (1-3 per cent.). The deep water between Africa and the 

 Balearic Islands covers muds comparatively rich both in A1 2 O 3 

 and Fe 2 O 3 ; on the Balearic Bank the amounts are small, and 

 in the Gulf of Lyons moderate. 



Table VI. Estimation of FeO and Fe 2 O 3 . A weighed 

 quantity of the substance was placed in a 200 c.c. flask and the 

 flask filled with carbonic acid gas. 20 c.c. of strong hydrochloric 

 acid were also added, and the flask fitted with a cork pierced 

 by a tube with an india-rubber valve. It was then heated on 

 the water-bath for half-an-hour, filled up with boiling distilled 

 water, corked, and allowed to cool. 50 c.c. were taken for 

 analysis, and titrated first with potassium permanganate of 



KMnO 4 



- grammes per litre; and then with stannous chloride. 



The stannous chloride used in the case of samples 31 to 46 

 was of such a strength that i c.c. = 0-0047 grms. Fe 2 O 3 , and 

 in the case of samples 64 to 89, I c.c. = 0-0042 grms. Fe 2 O 3 . 

 From the figures in Table VI it will be seen that the bulk of 

 the iron extracted in this way is in the ferrous state; while 

 from column m the total amount of iron, expressed as Fe 2 O 3> 

 extracted in this way is only from 40 to 50 per cent, of the 

 amount extracted by prolonged digestion. 



