156 Scientific Intelligence. 



4. On a Simple Quantitative method of separating Selenium 

 and Tellurium. — Divers and SnmosE have proposed a method of 

 separating selenium and tellurium founded on their behavior 

 toward sulphurous oxide in presence of sulphuric acid, no hydro- 

 chloric acid being present. A mixture of the two substances in 

 the free state is heated with concentrated sulphuric acid in a cov- 

 ered beaker until it is entirely oxidized and converted into a 

 colorless solution, with a deposit perhaps, of tellurium sulphate. 

 A moderately strong solution of sulphurous oxide is then grad- 

 ually added until the volume is increased at least five-fold, and 

 the solution is heated on the sand bath for some time. The pre- 

 cipitated selenium soon darkens in color and becomes dense with- 

 out aggregating into masses difficult to wash as it does when 

 heated with hydrochloric acid. After dilution, the solution is fil- 

 tered through a tared filter, and the precipitate washed, dried 

 and weighed. The tellurium is precipitated from the filtrate by 

 heating with hydrochloric acid and adding sulphurous oxide in 

 the usual way. To test the process, 0-3115 gram Te and 0-386 V 

 gram Se were mixed, dissolved and separated. The tellurium 

 weighed 0*3107 and the selenium 0*3865 gram. In a second experi- 

 ment the quantities taken were 0*2515 gram Te and 0-3395 gram 

 Se; the quantities recovered were 0*2513 gram Te and 0-3395 

 gram Se. — J. Chem. Soc, xlvii, 439, June, 1885. G. f. b. 



5. On the Illuminating power of Ethane and Propane. — P. F. 

 Frankxaxd has been engaged for some time in determining the 

 illuminating power of the hydrocarbons supposed to be present 

 in coal gas. He had previously shown that the illuminating 

 power of ethylene calculated for a consumption of five cubic feet 

 per hour from a referee's burner, is 68*5 candles; and that of ben- 

 zene was estimated to be six times as great. He has now experi- 

 mented with ethane and propane, the second and third terms of 

 the paraffin series. The ethane was prepared by the action of 

 the copper-zinc couple upon ethyl iodide in presence of alcohol, 

 and was made to pass slowly, first through bromine and water 

 and then through a solution of sodium hydrate and finally over 

 slaked lime. The product showed on analysis 97*88 per cent of 

 ethane. Burned from a referee's burner and comparison being- 

 made with the Methoen standard and with standard candles, the 

 mean result (corrected for five cu. ft. of gas) was 34*99 candles. 

 The propane was prepared by the action of zinc on isopropyl 

 iodide, being passed first through a scrubber containing zinc- 

 copper, then through alcoholic soda, bromine and water, sodium 

 hydrate and slaked lime. The gas contained 95 per cent of pro- 

 pane, and, burned in the same way as ethane, gave 53*91 candles 

 as its illuminating power. Hence this value appears to be pro- 

 portional to the number of carbon atoms in the molecule. — J. 

 Chem. Soc, xlvii, 235, April, 1885. G. f. b. 



6. On the Illuminating power of Methane. — Weight has 

 made a series of experiments to determine the illuminating power 

 of pure methane. The gas was prepared by Gladstone & Tribe's 



