Intelligence and Miscellaneous Articles. 235 



maining in the liquid was precipitated by chloride of calcium. The 

 portion undissolved by the potash, which contained the oxide of iron, 

 lime and magnesia, with some alumina and phosphoric acid, was dis- 

 solved in muriatic acid and precipitated by ammonia. 



This threw down everything except the greater part of the lime 

 and magnesia, which was separated from the filtered solution in the 

 ordinary way. The precipitate was heated to redness with carbonate 

 of soda, a little caustic potash being added, then exhausted with 

 water, and the solution treated in the same manner as the potash 

 solution obtained at first, to which it was added, whilst the residue, 

 dissolved in muriatic acid, yielded the amount of iron, lime, and mag- 

 nesia. The following are the results of five aaalyses of lazulite and 

 three analyses of blue spar : — 



Lazulite. 



I. II. in. IV. V. 



Silica 0-53 4-44 4-44 176 8-04 



Phosphoric acid 42-19 4158 44-91 40-60(46-10*) 43-26(49-8) 



Alumina 29-42 31-63 26-39 3210 24-76 



Magnesia 1061 8-60 10-69 937 9-81 



Protoxide of iron ... 10-55 6-69 6-18 Q-^l 721 



Lime Ill 138 203 0-77 Ml 



Water 5-59 5-68 5-36 6-03 5-81 



100- 100- 100- 100- 100- 



Blue spar. 



I. II. III. 



SUica 6-64 6-64 12-56 



Phosphoric acid. .. . 38-05 (43-05) 44'21 40-12(42-77) 



Alumina 33-93 28-05 24-12 



Magnesia 12-04 11-39 10-67 



Protoxide of iron . . 1-54 ]-77 2-56 



Lime 1-32 1*54 4-67 



Water 6-48 6-40 5-30 



100- 100- 100- 



These analj'ses differ principally in the quantity of phosphoric 

 acid and alumina they contain, and the amount of the latter is much 

 too small, which is dependent on the method used in its separation. 

 The silica exists accidentally in the mineral in the form of quartz, 

 its amount must therefore be deducted. Now if we calculate the 

 oxygen in the quantities ascertained, it is found that in most of the 

 experiments the amount of oxygen in the alumina is twice as great 

 as that in the bases (RO). That of the phosphoric acid is apparently 

 twice as great as that of the alumina, and that of the water is equal 

 to that of the bases (RO). The quantities of oxygen in RO : Al^Oj 

 : Pa Oj : HO are in the proportion of 3:6:12-5:3. The most pro- 

 bable expression of lazulite and blue spar then is, 2R3 O^ Pg O5 

 -f4AL2 03, 3P2O5 + 6HO ; a formula the first member of which cor- 

 responds with the ordinary degree of saturation, the second with a 



* The figures within the brackets indicate the quantities of phosphoric 

 acid found, those in the diagram itself are calculated. 



