COMPOSITION OF OCEANIC AND LITTOEAL MANGANESE NODULES. 479 



moisture in X is 1 '47 per cent, and in Y 5*53 per cent. ; the difference is 4'06. There- 

 fore, 95*94 parts of Y are equivalent to 100 parts of X, and we must multiply the results 

 in Y by 1*042 to make them comparable with those in X. 



B. Estimation of Alkalies. — 3*7014 grammes were dissolved in hydrochloric acid, 

 and the insoluble part removed as usual. The solution was made up to 250 c.c. ; 100 c.c. 

 of this solution was used for the estimation of the alkalies. In the first place, however, 

 the barium hydrate and ammonium carbonate to be used in the separation were tested 

 for their purity. 5 '5 18 grammes of barium hydrate were dissolved in water, and carbonic 

 acid gas passed through the solution to saturation. The whole was then boiled and 

 filtered. The barium carbonate precipitate was dried and roughly weighed. It weighed 

 from 2*95 to 3 grammes, i.e., about 47*6 per cent, of Ba(OH) 2 in the barium hydrate 

 used, the rest being water. The filtrate from the barium carbonate was evaporated nearly 

 to dryness in a platinum basin, a little barium carbonate which settled out was filtered 

 off, and the filtrate evaporated to dryness. The residue was redissolved in water, 

 refiltered, evaporated to dryness again, and weighed. It weighed 0*0017 grammes, 

 i.e., 0*031 per cent, of alkalies as chloride in the baryta hydrate. N.B. — This hydrate of 

 baryta had previously been recrystallised. 



The ammonium carbonate was then tested. It was a solution of 1 part of salt in 5 of 

 water. 5 c.c. of it were evaporated to dryness in a platinum basin, and the residue 

 ignited, and then moistened with hydrochloric acid and ignited again. It weighed 

 0'0012 grammes, therefore 1 c.c. of the ammonium carbonate solution leaves 0'00024 

 grammes of residue. 



To the above-mentioned 100 c.c. solution (containing 1'4805 grammes of substance) 

 4*088 grammes of barium hydrate were added. It dissolved completely, and the whole 

 was allowed to stand over-night. Next morning carbonic acid gas was passed through 

 the turbid solution to saturation, and the solution boiled to get rid of excess of carbonic 

 acid gas ; it was then filtered. The precipitate was dried and transferred to the original 

 flask in which precipitation took place, and the ignited filter ash added. 



The filtrate was evaporated down to a bulk of from 25 to 50 c.c, and the barium 

 and calcium present precipitated by the addition of 5 "5 c.c. of ammonium carbonate. 

 This precipitate was dried and added, along with its filter ash, to the flask in which were 

 the other bases and excess of barium carbonate. The reason for doing this was, that on 

 evaporation of the filtrate from the bases, a further small quantity of a dark-brown 

 precipitate (Mn0 2 most likely) came down. 



The filtrate from the ammonium carbonate precipitate was evaporated to dryness in a 

 platinum basin, the ammonium salts driven off, and redissolved in water. A good deal 

 of grey powder, probably barium carbonate, remained undissolved. This was added to 

 the precipitate of bases mentioned above. The filtrate was evaporated to dryness and 

 ignited. It weighed 0*0279 grammes. This, then, is the weight of alkalies as chlorides. 

 When dissolved in water it left a mere trace of insoluble matter, coloured with carbon. 

 This was filtered off, ignited, and weighed. It weighed 0*0004 grammes. 



