tS4 Intelligence and Miscellaneous Articles. 



To test the accuracy of RifFault's statement, that the phosphate of 

 magnesia is decomposed by ebullition into an insoluble basic and a 

 soluble acid salt, a portion of the precipitate we have described, still 

 moist, was repeatedly boiled with water, the whole was filtered and 

 the residue washed with hot water. The filtrate was acid, contained 

 a considerable quantity of phosphoric acid, but little magnesia, and 

 did not yield any crystalline salt. The phosphate of magnesia is 

 thus decomposed by boiling with water into a basic salt and free 

 acid. The former when dried forms a white powder, and only differs 

 from the bibasic salt in being coloured yellow by salts of silver, after 

 having been heated to redness. r087 grm. of the substance dried 

 in the air lost by exposure to red heat 0'267 ; the residue, after 

 being heated with carbonate of soda and washed, yielded 0*37 mag- 

 nesia; consequently the salt is = 3MgO, PjOs + SHO, and should 

 yield, according to calculation, 34"76 per cent, magnesia, 40"02 

 phosphoric acid, and 25 '22 water. 



Lazulite and Blue spar. 

 The only complete analyses, and these were published twenty-six 

 years ago, are of the lazulite from Radelgraben, near Werfen, and 

 of blue spar from Krieglach in Styria. 



Lazulite according Blue spar according 

 to Fuclis. to Brandes. 



Silica 2-10 6-50 



Phosphoric acid . . 41-81 43'32 



Alumina 35-73 34-50 



Magnesia 9-34 13-56 



Protoxide of iron , . 2-64 0-80 



Lime 0-42 



Water 6-06 050 



97-68 99-60 



The author analysed a dark blue lazulite from the Fischbacher 

 Alp in the province of Gratz, and a bright blue spar from Krieglach 

 in Styria. The specific gravity of the lazulite was 3-106-3-123, 

 Fuchs found 3-057 ; that of the blue spar 3-021, according to Brandes 

 3-001 ; according to Klaproth 3-046. On account of the great diffi- 

 culties presented in the analysis of these substances, the author, even 

 by repeating them several times, could not obtain results which 

 agreed perfectly. The mineral was heated to redness, to estimate the 

 quantity of water it contained : this caused the colour to change 

 from yellow to brown, resulting from the oxidation of the protoxide 

 of iron. The substance in fine powder was fused with carbonate of 

 soda and the mass decomposed by muriatic acid. After separating 

 the silica, the acid solution was digested and boiled with concen- 

 trated solution of potash in a platinum dish, which eff^ected the solu- 

 tion of the greater part of the alumina and phosphoric acid. The 

 f)hosphate of alumina was then thrown down by ammonia, from the 

 iquid acidified with muriatic acid ; its composition was ascertained 

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

 it \>Y sulphuric acid and sulphate of soda. The phosphoric acid re- 



