478 MR J. Y. BUCHANAN, F.R.S., ON THE 



weighed 0*0433 grammes. The solution was just rendered alkaline with ammonia. This 

 precipitated the trace of alumina. It was filtered and weighed, and found equal to 

 0*00414 grammes. Subtracting this from 0*0433 grammes, we have 0*03919 grammes 

 of CaC0 3 , that is, 6*38 per cent, of CaO. 



The sulphide of ammonium precipitate, together with the small precipitate of alumina, 

 was worked up for any lime that might be present in it as phosphate. It was ignited, 

 dissolved in hydrochloric acid, the solution evaporated. The phosphoric acid, iron, and 

 alumina present were precipitated by adding acetate of soda. In the nitrate from this 

 the manganese was precipitated with ammonium sulphide. In the filtrate from the 

 manganese sulphide a small additional quantity of lime was obtained on addition of 

 ammonium oxalate; *09154 grammes of CaC0 3 were thus obtained. This is 0*45 per 

 cent, of CaO of the nodules. Adding this to the previously found 6*38 per cent., we 

 have altogether 6*83 per cent, of CaO in the nodules. 



The filtrates from the oxalate of lime were evaporated down, and the ammonium salts 

 driven off. The residue was taken up with hydrochloric acid and water, and filtered. 

 Ammonia and phosphate of soda were added. A precipitate was obtained, which was 

 filtered off, ignited, and weighed as Mg 2 P 2 7 . It weighed 0*03366 grammes, representing 

 3*53 per cent, of MgO in the substance. Another estimation gave 4*08 per cent, of MgO. 



G. Estimation of Moisture at 162° C. — 0*6215 grammes of substance were exposed 

 in a small bath to a temperature of 162° for about forty minutes. The water driven off 

 was collected in a calcium chloride tube. It was found after heating that the substance 

 had lost 0*0085 grammes (1*37 per cent.), while the calcium chloride tube had gained 

 0*0098 grammes (1*57 per cent.) ; mean, 1*47. 



H. Estimation of Carbon (by combustion). — 0*6215 grammes were ignited with pure 

 lead chromate and oxide of copper in a stream of air free from C0 2 . The carbonic acid 

 given off was collected in a soda-lime tube, and found to weigh 0*0596 grammes, that is, 

 9*59 per cent. As 8*89 per cent, of carbonic acid as such were found in the substance, 

 this gives us 0*70 per cent, of carbonic acid due to organic carbon, or 0*20 per cent, of 

 organic carbon. 



Y. Estimation ofM.nO and Alkalies. 



5*3893 grammes of the same sample of air-dried Loch Fyne nodules were boiled 

 with water as before, filtered, and the filtrate evaporated. The residue, which crystallised 

 out when dried at 110°, weighed 0*1240 grammes, that is, 2*30 per cent, of the nodules 

 were found soluble in water. The insoluble part was dried at 100°, and separated from 

 the filter-paper. The latter was then ignited, and the ash added to the rest. The 

 whole was then air-dried, and this air-dried mass was used for analysis. 



A. Estimation of Moisture (driven off at 150°-160°). — 0*3609 grammes were heated 

 in a small bath, and the water driven off absorbed by a calcium chloride tube. The 

 heating continued for over half an hour. The substance was found to have lost 0*0194 

 grammes (5*53 per cent.), while the calcium chloride gained 0*0183 grammes. The 



