tM> MR J. Y. BUCHANAN, F.R.S., ON THE 



Thus, to find the weight of alkalies as chlorides in the 1*4805 grammes of nodules 

 used, we have to subtract from 0*0279 grammes 0*00132 grammes (residue left by 5*5 c.c. 

 ammonium carbonate solution) + 0*00127 (which is the residue in 4*088 grammes of 

 barium hydrate) + 0*0004 (insoluble matter). This leaves 0*02491 grammes (or 1*68 per 

 cent.) of alkalies weighed as chlorides. 



The potassium in the above alkaline salts was estimated by means of platinic chloride. 

 0*01356 grammes of the double chloride of potassium and platinum (2KC1. PtCl 4 ) were 

 found — that is, 0*01356 grammes of potassium chloride in 1*4805 grammes of nodules, or 

 0*91 per cent, of KC1. This is equivalent to 0*45 per cent, of K 2 0, leaving 0*41 per cent, 

 of Na.A). 



The error due to the ratio of potash to soda in the nodules being different from that 

 in the reagents can be but trifling. 



C. Analysis of the Precipitate of Bases obtained in separating the Alkalies. — Dis- 

 solved this precipitate in hydrochloric acid, and made up the solution to 250*85 c.c. 



Estimation of Manganese. — Took 100 c.c. of the above solution (0*5902 grammes 

 nodules). Evaporated to dryness to get rid of excess of acid, took up the residue with 

 water, and, as usual, added barium carbonate to precipitate iron and alumina. In the 

 filtrate precipitated the manganese, as usual, as Mn0 2 by means of bromine, filtered off 

 the Mn0 2 , dissolved it in hydrochloric acid, removed any baryta as BaS0 4 , evaporated 

 solution to dryness, took up with water, and precipitated the manganese with sodium 

 carbonate as MnC0 3 . Filtered, ignited to Mn 3 4 , and weighed. The Mn 3 4 weighed 

 0*19646 grammes (or 33*29 per cent.). This is equivalent to 30*96 per cent, of MnO 

 (including cobalt) in the nodules. 



BaC0 3 Precipitate. — Dried this precipitate, redissolved it in hydrochloric acid, and 

 precipitated the baryta with sulphuric acid. Evaporated the solution over water-bath to 

 get rid of excess of acid. Took up with water, filtered from traces of insoluble matter, 

 diluted, and precipitated with a slight excess of ammonia, boiling till all excess was 

 expelled. The precipitate of Fe 2 3 + Al 2 3 when ignited weighed 0*0266 grammes. 

 Fused it with bisulphate of potash in order to see if silica was present. 0*00194 grammes 

 of the fused mass was insoluble, leaving 0*0246 grammes of Fe 2 3 + Al 2 3 , i.e., 4*17 

 per cent. 



To make the figures obtained for the alkalies and manganese comparable with those 

 obtained in X, we have in both cases used substances extracted with water, and therefore 

 free from soluble matter; but in X the substance was used dried at 100°, while in Y it 

 was exposed to the air after extraction, and was therefore in an air-dry condition. X 

 contained 1*47 per cent, moisture, which was driven off at 162° C. ; Y contained 5*53 

 per cent., the difference being 4*06. Therefore 95*94 parts of Y are equivalent to 100 

 parts of X, and we must multiply the results in Y by 1*042, and we have MnO = 32*23 

 per cent., K 2 = 0*47 per cent., and Na 2 = 0*43 per cent. 



Some of the same air-dried samples of nodules were examined without being extracted 

 with boiling water, or rather the extraction formed part of the analysis. 



