1890.] Mineralogy and Petrography. 1077 
azurite and gerhardite by allowing a solution of nitrate of copper to 
act on particles of calcite several years under the ordinary pressure, 
Nepheline, leucite and orthoclase have been obtained by Messrs. 
C. and G. Friedel® upon treating finely-powdered muscovite with 
alkalies and alkaline silicates in various proportions. With potash 
containing about two per cent. of soda a portion of the muscovite is 
dissolved, and prismatic hexagonal crystals of nepheline are yielded. 
The composition of these shows them to consist of a mixtnre of one 
part of potash nepheline to two parts of the corresponding sodium 
compound. When soda is substituted for potash the nepheline crystals 
produced measure 5—8 mm, in length, and consist of one part potash 
nepheline to three parts of the sodium compound, When treated with 
silicate of potash and heated, beautiful crystals of orthoclase are pro- 
duced. . Leucite, together with orthoclase and nepheline, are yielded 
by a mixture of mica with half its weight of calcined silica and seven- 
tenths of its weight of potash, The same experimenters 5* produced 
anorthite by treating mica at 500° with lime in the presence of water. 
Having obtained sodalite * by the action of soda and sodium chloride 
in mica, they next attempted to make nosean by substituting the sul- 
phate for the chloride in the last experiment, but succeeded * only in 
the production of prismatic negatively uniaxial crystals differing from 
nosean in containing two molecules of water. ——Nitrate of copper 
heated to 130° in sealed tubes with urea yields% a basic nitrate identi- 
cal with gerhardite.9 
3? Ib., p. 129. 
s Ib., XIII. p. 233. 
94 Ib., XIII., p. 183. 
35 Ib., XIII., p. 238. 
86 Mallard. Ib. p. 67. Cf. Ref. to Michel's Syntheses above. 
37 Wells and Penfield. Amer. Jour. Sci., 1885, XXX., p. 50. 
