On Felspar ', Albite, Labradore, 8tc. 107 



The second species, Albite, is more rare. It is denoted by 

 NS 3 + 3 AS 3 . Egberts first found it in an uncrystallized fibrous 

 and granular form at Finnbo and Broddbo, near Fahlun, and 

 thereafter Haussmann and Stromeyer in a mineral from Chester- 

 field, in North America, to which the former gave the name of 

 Kiefelspath. Nordenskiold found it in a granite at Kimite, near 

 Pargas, in Finland ; and Ficinus in a granite from Penig, in 

 Saxony. All these are uncrystallized varieties. To the crystal- 

 lized, which I have had occasion to see, belong the white schorl, 

 first described by Rome de ITsle ; the felspar crystals of Dau- 

 phiny of Hauy; the small crystals from Saltzburg and the Tyrol, 

 known a few years ago under the name of Adularia. 



The third species forms the Labradore spar, which Klaproth 

 analyzed and distinguished from felspar, though mineralogists did 

 not consider it as a distinct species. Berzelius has assigned to it 

 the formula NS 3 + 3 CS 3 + 12 AS from Klaproth's analysis. 



The fourth species is the rarest of the whole. Mr. Rose has 

 recognised it only in the druses of limestone blocks, which are 

 found at Mount Somma, near Vesuvius, where it occurs in small 

 shining perfect crystals. He has determined its formula to be 

 MS + 2 CS + 8 AS ; and has called it Anorthite. 



Albite is readily distinguishable by the twin grouping of its 

 crystals. Its primitive form is an irregular parallelopiped. In its 

 massive state, it differs from felspar, in not being straight foliated, 

 but always radiated. Labradore spar is completely decomposed 

 by concentrated muriatic acid, while felspar and albite are not 

 affected by it. Anorthite yields to muriatic acid as Labradore- 

 spar does. The name is derived from avofto*;, not rectangled ; as 

 the want of a right-angled cleavage, in both directions of its 

 laminae, peculiarly distinguishes it from felspar. We must refer to 

 the paper itself for the details of the Crystallization-system of the 

 above minerals. — Gilbert's Annalen, No. lxxiii. p. 173. 



8. On the influence of Tartaric Acid in certain cases of Analysis. 



By Mr. Henry Rose, of Berlin. 

 In the first part of Mr. Rose's Memoir on Titanic Acid, (or 

 Oxide,) we find the following method prescribed as the most con- 

 venient for obtaining it pure ; to which a note is appended rela- 

 tive to the influence of tartaric acid in analysis. 



The rutile of St. Yrieux, in the department of Upper Vienne, in 

 France, was the titanium-ore employed. He fused the rutile with 

 thrice its weight of carbonate of potash, washed the fused mass 

 with water, dissolved the residuary combination of titanium oxide 

 and alkali in muriatic acid, and threw down the oxide from this 

 solution by ammonia. The flocculent precipitate contained as 

 much iron as the rutile itself, and this iron is chemically united 

 with the oxide of titanium, for muriatic acid does not abstract it. 



