Oxide of Titanium — Chelidonia and Pirropina. 543 



3rdly. By fusing at a white heat, and out of contact of the air 

 several titaniferous compounds, as, for example, the titaniferous si- 

 licates of lime with iron. These silicates, which are at first colour- 

 less, become more or less blue. 



4thly. By treating the same titaniferous silicates in the same 

 manner with metallic tin. A slight addition of charcoal in powder' 

 appears to favour the formation of blue glass. 



5thly. M. Kersten found that titanic acid might, under certain 

 circumstances, be reduced, by means of hydrogen, to the state of 

 blue oxide of a very fine colour. If into biphosphate of soda, kept 

 in fusion in a porcelain crucible, fine titanic acid be projected, it dis- 

 solves readily at a low temperature, and a white, transparent saline 

 mass is formed. If this mass be put into a bulb of difficultly fusible 

 glass, and hydrogen gas which has been dried by chloride of calcium 

 be passed over it, the saline mass soon becomes of a fine lavender 

 blue at the surface ; if the residue be afterwards dissolved in water, 

 the phosphate dissolves, and oxide of titanium of a fine blue colour 

 remains ; this oxide was left in contact with water during two 

 months, without producing any diminution of its fine colour ; but 

 when heated to redness in contact with the air, it loses its colour, 

 and is converted into titanic acid. This blue compound is not acted 

 upon by hydrochloric acid at common temperatures ; but when 

 heated with this acid it loses its colour, and is converted into titanic 

 acid. Zinc, tin, and iron immersed into this solution, reproduce the 

 blue oxide. 



6thly. If pure zinc be placed at the bottom of a porcelain crucible, 

 and then above it a mixture of titanic acid and biphosphate of soda, 

 or what is still better, if these substances fused together, be strongly 

 heated in a crucible for several hours, a blue saline mass is obtained, 

 sometimes of a violet tint, which dissolves in water, leaving a re- 

 sidue, the blue substance, mixed with a little oxide of zinc, which 

 is not dissolved by the alkaline phosphate. 



7thly. If instead of zinc, tin or iron be employed, the results are 

 similar ; but by the two last methods the blue oxide obtained is, 

 however, not of so fine a colour as when the titanic acid is reduced 

 by hydrogen. 



CHELIDONIA AND PIRROPINA. 



M. Potex has lately discovered two alkalis in the root of the 

 Chelidonium majus ; to the former he has given the name of cheli- 

 donia, and to the latter pirropina. To prepare these, the dried root 

 of the Chelidonium is to be powdered and twice boiled in spirit ; 

 these infusions being distilled, they are poured into a cucurbit, and 

 an equal quantity of distilled water being added, the alcohol is to be 

 separated by another distillation. The residue is to be poured into 

 a capsule ; by perfect cooling a soft resin separates ; the filtered li- 

 quor is to be precipitated by carbonate of soda, which throws down 

 the two alkalis. Filtration is to be performed again, and the pre- 



