Physics and Chemistry. 415 
on drying, detonates violently when heated or struck. This substance is 
identical with the red compound which acetylene forms with 
¢ 
C,H, Br,-+K0O, HO=C,H,Br-++-KBr+2HO 
C,H,Br+-KO, HO=C,H,+KBr+2HO 
When monobromid of ethylene is heated with amylate of sodium, bromid 
of sodium, amylic alcohol, and acetylene are produced. The equation is 
C,H, Br Croll t Oy = Cros 1 Oy-+NaBr+-C,H, 
1 
a 
nO { 
Oxyd. Titanic acid forms brilliant crystals of a bluish tint like anatase. 
Vanadium in many rutiles; that of St. Yrieux is one of the richest ores 
‘of this metal. The author has prepared by the chlorhydric acid process 
fgg in colorless or greenish octahedra; haussmanite in square octa- 
ra; protoxyd of manganese in beautiful emerald green octahedra or 
: bo-octahedra ; specular iron in beautiful crystals like the Elba ore. In 
the last case the current of gas must be slow and regular otherwise the 
