390 Inlelligetice and Miscellaneous Articles. 



into neutral carbonate, eight volumes of ammoniacal gas are neces- 

 sarily replaced by the same number of volumes of the vapour of 

 water. — Hemman's Repertoire de Chimie, 8;c. 



SEPARATION OF SELENIUM FROM SULPHUR. 

 According to Bcrzelius these substances may be readily separated 

 by the following process. When sulphuret of selenium is fused with 

 carbonate of potash, the alkali not being in excess, the fused mass 

 dissolved in water, leaves selenium undissolved and free from sul- 

 phur. Some of the sulphuret of selenium from Lukavvitz in Bohemia 

 was dissolved in potash, and the solution was converted into hypo- 

 sulphite by exposure to the air at the temperature of 65° Fahr., 1 1-^ 

 hundredths of the sulphuret submitted to experiment were precipitated, 

 and found to be pure selenium. The solution being of a deeper red 

 colour than that of the common sulphuret, a piece of sulphur was put 

 into it, and it was boiled for a moment : a quarter of a grain of sele- 

 nium was precipitated, and perfectly free from sulphur. 



A solution of a neutral seleniate, or of one with excess of base* 

 is soon rendered turbid by having sulphuretted hydrogen gas passed 

 into it. At first pure selenium separates ; afterwards sulphuret of 

 selenium : and lastly, mere sulphur ; — the solution should be con- 

 siderably dilute. When the solution is concentrated, the precipitate 

 formed is of a flame-yellow colour ; but it soon becomes of a brown- 

 ish-black colour J and sulphur is deposited, and sometimes crystall- 

 ized at the surface of the deposit.— /ijd. 



STEARIC ACID FROM WAX. 



M. Frommherz, apothecary of Fribourg, observed that some oil 

 obtained by the distillation of wax which had been kept in a cold 

 place, deposited small brilliant pearly laminae ; they were repeatedly 

 washed with alcohol to separate the oil, and were found to be stearic 

 acid. 



Supposing that the substance called butter of wax might also be 

 stearic acid, some was prepared by distilling white wax. A white 

 matter was collected in the neck of the retort, which was repeatedly 

 washed vvith boiling water, and then dissolved in alcohol. By cool- 

 ing, small shining slender acicular crystals were obtained, which 

 were lighter than water, fusible at 130° of Fahr., inodorous, and acid. 



The alcohol in which these crystals were deposited did not contain 

 any oleic acid ; and it is to be observed, that if the heat do not exceed 

 that required for the distillation of the wax, no sebacic acid is farmed ; 

 and the product contains only stearic acid mixed with empyreuma- 

 tic oil. Sebacic acid is formed at a higher temperature. 



The absence of oleic acid in the products of the distillation of wax 

 would appear to be a distinctive character of it ; and it will occur in 

 fatty bodies, in the inverse proportion of their consistence. — Ibid. 



EXTRICATION OF HEAT BY COMPRESSION OF GASES. 

 Mons. D. ("olladon finds that to ignite amadou, atmospheric air 

 must be reduced to one-thirteenth of its volume 3 and to inflame sul- 

 phur. 



