468 KECORD OF SCIENCE FOR 1887 AND 1888. 



yellow; it is trauslucent aud resembles chalcedony. It is optically, 

 imiaxial and negative. The hardness is about 5 and the specific gravity 

 3.053. An analysis yielded the following results: 



r.,05 CO, CaO FeO Na-iO KjO HjO 

 38.44 6.29 53.00 0.79 0.89 0.11 1.37 = 100.89. 



This leads to the formula 4 Ca^ P.On + 2 Ca CO, + H.O. The locality 

 where it has been found, though only very sparingly, is the apatite re- 

 gion in the parish of Bamle, ISTorway. Named after by W. C. 



Brogger and Backstrom in the CEfversigt Vet.-Akad. Forhandliugar, 

 Stockholm, 1887, p. 493. 



Bihydro-thenardite, — A sodium sulphate, allied to thenardite, but, as 

 tbe name suggests, containing two molecules of water. It crystallizes 

 in the monoclinic system. It forms a thin bed on the shores of Lake 

 Gori, Tiflis, Eussia. (Described by Markovnikoff in Journ. Kuss. Phys. 

 Chem., aud an abstract in the Berichte deutsch. Chem. Ges. Berlin, 

 1887, p. 54G). 



Edisonite. — A rare mineral consisting of titanium dioxide and (if dis- 

 tinct from rutile) the fourth torm in which this oxide is kuown to occur in 

 nature. The original specimen was found in 1879 by W. E. Hidden at 

 the Whistnant gold mine, Polk County, North Carolina, in the concen- 

 trations of placer washings. It was associated with zircon, xenotime, 

 rutile, monazite, and a number of other species. It has a bronze-yellow 

 or golden-brown color, a resinous to adamantine luster and a yellowish 

 white streak. The hardness is about 6 and the specific gravity 4.26 to 

 4.28. The symmetry of the form is that of an orthorhombic crystal and 

 the crystallographic study by Des Cloizeaux (Bull. Soc. Min., 1880, 

 vol. IX) shows that it does not vary very widely from the tetragonal type, 

 and in angle bears a certain relation to rutile; he calls it, in fact, a 

 dimorphous form of rutile. A qualitative examination by Damour 

 showed it to be essentially TiOa in composition antl a more thorough 

 analysis by Penfield, undertaken later, has confirmed this and proved 

 tbe absence of all other substances except a trace of iron. Named after 

 Mr. Thomas A. Edison, by W. E. Hidden, in Amer. Jouru. Sci., Oc- 

 tober, 1888, vol. XXXVI, p. 272. 



JEudidymife. — A new silicate of sodium and beryllium from the island 

 Obere Aro in the Laugesundtjord, Norway. In his preliminary account 

 Brogger describes it as occurring in tabular monoclinic crystals having 

 the axial ratio a:b: c= 1.7107: 1: 1.1071, /5=86o 14.y. The crystals are 

 twins with the basal planes as twinning plane, which is also the direc- 

 tion of cleavage. The color is white and the luster vitreous or pearly. 

 The hardness i^ 6 and the specific gravity 2.553. The optic axes lie in 

 the plane of symmetry and the acute positive bisectrix makes an angle 

 of 58^30' with the vertical axis in the acute angle of /?. The first an- 

 alysis by Flink made the mineral contain aluminium instead of beryllium. 

 This was corrected by Nordenskiold, whose analysis gave 



Si02 BeO Na^O H2O 



73.11 10.62 12.24 3.79=99.76. 



