198 [Proc. B.N.F.C, 



the water as quickly as it was gathered. Great care was taken 

 to have the grains as uniform as possible in size and colour. 

 The sample received for analysis was very uniform in size and 

 colour, and weighed a little over one gramme. It consisted of 

 dark green granules of rather less than one millimetre in 

 diameter, very homogeneous and of a rounded contour, inter- 

 mixed with a few white particles. The grains were soft and 

 readily powdered. The powder was treated with cold dilute 

 hydrochloric acid, well washed, dried at 90°C. in an air bath, 

 and the resulting green powder taken for analysis. 



°*3575 g r ' was decomposed with moderately concentrated 

 sulphuric acid, the silica separated in the ordinary way, and the 

 solution used for the determination of total iron, alumina, lime, 

 magnesia, potash, ana soda by the usual methods; 0*1975 S r - 

 was ignited for combined water and organic water ; 0*2780 gr. 

 was decomposed by heating in a current of C0 2 with moderately 

 concentrated sulphuric acid and titrated with standard perman- 

 ganate of potash for ferrous oxide. The results obtained were: — 



S 2 2 Fe 2 3 A1 2 3 FeO CaO MgO K 2 Na 2 H 2 Total 

 40*00 16*81 13*00 10*17 1*97 1*97 8*2i 2*16 6-19 100-48 



Remembering what has been already said upon the variable 

 composition of Glauconite it is not surprising to find that this 

 example shows some deviations from the figures given for other 

 Glauconites, although in some particulars these are noteworthy. 

 To illustrate this and also to show how other Glauconites vary 

 among themselves two tables of analyses are appended. Table 

 1 contains the analyses by Sipocz of four samples of marine 

 Glauconite from the " Deep Sea Deposit " volume of the " Chal- 

 lenger" Report. These were all taken at a depth of 410 fathoms, 

 and in Lat. 34° T3' S and Long. 1 5 1° 38' E ; yet taken as they 

 were from practically the same spot the variations, especially 

 in the essential constituents — silica, ferric oxide, potash, and 

 water — are most pronounced. Our Woodburn Glauconite 

 shows many great differences from all of these, and we may 

 note among the essentials that the silica is over i3°/ lower 



