2^ Jtitelligeiice and MisceUaneous Article^. 



wavellite free from water and fluorine ; consequently lazulite and 

 blue-spar are the same mineral, and are only distinguished by the 

 former containing a larger portion of protoxide of iron, which is iso- 

 morphous with the magnesia, hence also its darker colour. But as 

 the protophosphate of iron is colourless, and the double salt only 

 yields a blue colour with basic ])hosphate of iron, it is probable that 

 lazulite also contains some peroxide of iron. 



t'T' Amblygonite. 



This mineral, which was discovered by Breithaupt, and is found 

 only in the granite of Penig(Chursdorf and Arnsdorf) and Zinnwald, 

 is one of the rarest, and from its chemical composition, one of the 

 most remarkable minerals. Berzelius found 11 per cent, of lithia, as 

 well as phosphoric acid and fluorine. According to Plattner it also 

 contains soda, tinging the flame of the blowpipe yellow, so that the 

 reaction of the lithia is barely perceptible. Its specific gravity, ac- 

 cording to Breithaupt, is 3"11. After making many fruitless expe- 

 riments the author adopted the following method of analysis : — The 

 mineral, in fine powder, is heated with sulphuric acid in a platinum 

 vessel until the fluorine is driven ofi^, the solution is diluted with 

 water and precipitated by ammonia ; the alumina and part of the 

 phosphoric acid are thus thrown down, and the precipitate may be 

 decomposed by fusion with either carbonate of soda and silica, or 

 bisulphate of potash. The ammoniacal filtrate, which contains the 

 alkalies and the remainder of the phosphoric acid, is decomposed 

 with chloride of calcium to separate the latter, and the excess of 

 lime is afterwards removed by oxalic acid. The alkaline sulphates 

 remaining after evaporation and heating to redness, are estimated by 

 first precipitating the potash by chloride of platinum ; the weights 

 of the sulphate of lithia and soda are next estimated, and finally the 

 quantity of acid they contain. To ascertain the amount of fluorine, 

 the powder of the mineral was distilled with silica and sulphuric acid, 

 and the fluoride of silicium conducted into water, so that none of it 

 could escape. The fluid was supersaturated in a platinum dish with 

 pure carbonate of soda, boiled, and flnally, after the escape of the 

 carbonic acid, precipitated by ammonia and chloride of calcium. The 

 analysis yielded the following results : — 



I. II. III. IV. V. 



Phosphoric acid . 48-00 47-15 



Alumina 36-26 38-43 36-62 36-89 



Lithia 6-33 7-03 



Soda 5-48 3-29 



Potash 0-43 



Fluorine 8-11 



We cannot regard amblygonite as a compound of fluoride of li- 

 thium and sodium with phosphate of alumina, because the amount 

 of fluorine is not sufficient to saturate the metallic bases of the alka- 

 lies ; consequently it must consist of phosphate of alumina and lithia 

 (soda), and fluoride of aluminium (sodium). Three-fourths of the 



