Revie ius
1.51
chlorine set free ; in the slow decomposition of barium chlorate, the arnoant of free chlorine is less than one-tliousandtli of tlie chlorine in the salt. With lead chlorate the decomposition-products are lead chloride, lead peroxide, oxygetl and chlorine ; about eighty-seven percent of the chlorine is set free. 1V. D.B.
The persulphuric acids. T. X . L o w ) y n n d j . 1% ll'cst. JOUT-. Chem. soc. authors have determined the amount of persulphuric acid fornied when hydrogen peroxide is added to sulphuric acids of varying concentrations. If we assume that the mass law applies, without corrections for electrolytic dissociation, the results poiiit to the existence of pertetrasulphuric acid, EI,S,O,,. 1v.D. B. 7 7 , 950 (1900).-The
The reducing action of calcium carbide. Geelmuyden. Comftes rendus, (1900).- At the temperature of the electric furnace, calcium carbide reduces iron pyrites, galena, magnesium sulphide, and antitrioiiy sulphide to the metal ; aluminum sulphide is not reduced ; boric anhydride is converted 1v.D. 0. into calcium boride. 130,1026
Preparation of the phosphides of iron, nickel, cobalt, and chromium. 1. iVaronnenx. Comfii'es il-endus, 130, 657 (zpoo). -The phosphides of iron, nickel, cobalt, and clironiiuni have been prepared by heating the metal in question in the electric fiirnace together with the phosphide of copper. W. D.B. The separation of the rare earths. R.Chavustelon. Coiuptes rendus, 130, 781 (IF). - The author precipitates everything except tlioriurn by means of an alkaline sulphite, or else he gets the thorium and cerium alone in solution by 1V. D. B. the action of bicarbonates on the mixed oxides. A new method of fractioning some of the rare earths. E. Demarqay. Covififesrendus, 130, zor9 (z9oo).-The method consists in the fractional crgstallization of the double magnesium nitrates in nitric acid. 1 . . D. B.
Velocities
On the velocity of solidiiication and viscosity of supercooled liquids. H.A. Wilson. Phil. Mag. [ 51 5 0 , 238 11900). -Considering the expression which the author previonsly obtained to represent the velocity of solidification (3,423), if F, the latent heat of fusion of one gram of the solid, R , the thickness of tlie surface of separation of liquid and solid, and A, the force required to give unit velocity to one gram of the liquid diffusing through itself, be all regarded as constant, then v = c - ,S
v
where C is a coiistant, S is the actual supercooling, and V is the viscosity of the liquid. The present paper contains experimental data taken to test this formula. The substances chosen were salol, benzoic anhydride, benmphenone, and azobenzene. The results show that the velocity of solidification of a pure substance varies directly as the actual supercooling at which solidification occurs, and inversely as the viscosity of the liquid. H. T. B.
