314 Browning — Separation of Barium from, Calcium. 



cent of the total heat of combustion ; as compared with 15 

 per cent to 20 per cent in the case of illuminating gas. 



5. The thermal equivalent of one candle-power-minute of 

 magnesium light is about 24 lesser calories, as against 3*5 to 

 ■±•0 for other artificial illuminants. 



6. The total efficiency of the magnesium light is about 10 

 per cent ; as compared with "25 per cent [a quarter of one per 

 cent], for illuminating gas. 



7. Taking into consideration the greater average luminosity 

 of the rays of the visible spectrum of the magnesium flame, it 

 is certain that per unit of energy expended, the light-giving 

 power of burning magnesium is from fifty to sixty times 

 greater than that of gas. 



Physical Laboratory of Cornell University, June, 1891. 



Aet. XXXYII. — A method for the quantitative separation of 

 Barium from Calcium by the action of Amy I Alcohol on 

 the Nitrates ; by P. E. Browning. 



[Contributions from the Kent Chemical Laboratory of Tale College — XIL] 



The fact that strontium can be separated quantitatively from 

 calcium by boiling the nitrates with amyl alcohol, as I have 

 recently shown,* naturally suggested a similar separation of 

 barium from calcium by the same general treatment. Solu- 

 tions of specially purified barium and calcium nitrates were 

 prepared and standardized, either by the evaporation or filtra- 

 tion of definite portions after treatment with sulphuric acid. 

 The mean of several closely agreeing results, both by evapora- 

 tion and filtration, was taken as the standard. The method 

 followed was essentially the same as described in the method 

 for the quantitative separation of strontium from calcium 

 referred to above. The first series of experiments was directed 

 toward an investigation of the action of amyl alcohol upon 

 barium nitrate alone. Accordingly definite amounts of the 

 barium salt were measured into Bohemian beakers of about 

 100cm 3 capacity and weighed. The water was then evapora- 

 ted over a water bath, and the dry salts dissolved in a few 

 drops of water and boiled with 30cm 3 of amyl alcohol, that 

 amount being determined upon as convenient, until the normal 

 boiling point of the alcohol was reached — 128° to 130° C. 

 During the boiling the beaker was placed upon a piece of 

 asbestos board about 15 cm square to keep the inflammable 

 fumes of the alcohol from the flame. When the temperature 



* This Journal, vol. xliii, p. 50. 



