520 M. Engelhardt on the Detection of Baryta and Strontia. 



To investigate two spectra which are not very complicated, two 

 tnbes containing the respective solutions are brought near one 

 another into the flame of a Bunsen's burner. But if the spectra 

 are very complicated, or if other circumstances prevent their 

 being simultaneously introduced into the flame, the following 

 arrangement is adopted : — Two Bunsen's burners are placed in 

 front of one another before the slit. Over that burner nearest 

 the slit a piece of iron plate is fixed somewhat larger than the 

 flame, and about level with the centre of the flame. In this 

 way the upper half of the second flame sends its light over the 

 other ; and by placing the platinum bundles, of glasses contain- 

 ing two different solutions, one in the lower half of the flame 

 nearest to the slit, and the other in the upper half of the other, 

 two different spectra may be simultaneously produced. 



In a mixture of alkaline earths, where the lime greatly predo- 

 minates, the presence of baryta and strontia in the spectroscope 

 is masked, and cannot be discriminated with certainty when 

 their quantity is less than twos of the lime. According to 

 EDgelhardt*, they may readily be detected by concentrating the 

 baryta and strontia in a quantity of lime. When either carbo- 

 nate of baryta or strontia is mixed with a large quantity of car- 

 bonate of lime, it passes into the caustic state much more easily 

 than if it be pure. When such a product of ignition is boiled 

 out with water, all the baryta and strontia are dissolved, and but 

 little of the lime. A solution of 1000 parts of chloride of cal- 

 cium and 1 part of chloride of barium, precipitated by carbonate 

 of ammonia, the precipitate ignited and treated with water, gave 

 a solution in which all the baryta lines, even the two feeble 

 bluish ones, could be seen. And a similar mixture containing 

 strontia gave the same reactions, only more intense. 



The simplest mode of treatment consists in placing the carbo- 

 nate to be tested in a platinum crucible, and heating it for a few 

 minutes in a Bunsen's blast-lamp. The mass is then treated 

 with boiling water, filtered, and evaporated, hydrochloric acid 

 having been added, and tested in the spectroscope in the usual 

 manner. 



Schonbein has made a contribution f on the formation of 

 nitrite of ammonia from atmospheric air and moisture under the 

 influence of heat. On a previous occasion he had shown that 

 when phosphorus oxidized in the air, nitrite of ammonia was 

 formed, and had thence concluded that under these circumstances 

 the salt must have been formed from water and atmospheric 

 nitrogen. 



* Liebig's Annalen, October 1862. t Ibid. 



