Chemistry and Physics. 



m 



SCIENTIFIC INTELLIGENCE 



I. Chemistry and Physics. 



Arsenides of Iron, and Manganese. — Hilpert and Dieck- 

 mann have devised a convenient method for the prepai-ation of 

 certain metallic arsenides in the dry way under pressure. They 

 heated finely divided metallic iron with arsenic in sealed tubes of 

 Jena glass to 700° C. for 6 to 8 hours and found that a definite 

 compound, FeAs 2 , corresponding to the mineral lollingite, was 

 formed. By heating this product at ordinary pressure in a 

 stream hydrogen to the same temperature as before, a part of the 

 arsenic was driven off, and a definite compound, FeAs, was pro- 

 duced. By the same method, using pressure, an arsenide of 

 manganese, MnAs, was prepared, which lost arsenic at ordinary 

 pressure in hydrogen, even at 500°, but gave no distinct halting- 

 point in loss of arsenic, and hence no indication of the existence 

 of a compound, such as Mn 2 As, which has been supposed to be 

 formed. The manganese arsenide, MnS, as had been previously 

 observed, has strong magnetic properties, while, remarkably 

 enough, neither of the iron arsenides shows this property. — 

 Bericlite, xliv, 2378. h. l. \v. 



2. The Enrichment of Radio-active Substances by Adsorption. 

 — Ebleb and Fellner propose the use of colloid substances as 

 adsorbents of radio-active bodies in the place of the usually 

 employed processes of fractional crystallization and fractional 

 precipitation. The colloid employed must be one which can be 

 volatilized in some way ; for example, silicic acid, arsenic trisul- 

 phide and sulphur, which can be removed in the forms of silicon 

 fluoride, arsenic trichloride, and the last by simple heating. The 

 authors have carried out a number of experiments by the use of 

 colloidal silicic acid prepared by the action of silicon tetrachlo- 

 ride upon water, and the results obtained are promising, espe- 

 cially for the enrichment of small quantities of material. — 

 Berichte, xliv, 2332. h. l. w. 



3. The Fluorides of Vanadium. — Otto Ruef and Herbert 

 Lickpett have prepared a series of vanadium fluorides and oxy- 

 fluorides, none of which have been previously known in a pure 

 condition. The compounds described are VF 3 , VF 4 , VOF 2 , VOF 3 

 and VF 6 . They correspond to known chlorides, with the excep- 

 tion of the last one, which is particularly interesting from the 

 fact that it is the only known compound of vanadium with five 

 halogen atoms. This is distinguished from the other fluorides in 

 possessing a pure white color. It has a noticeable vapor tension 

 at room temperature and boils at 111°. It is decomposed by 

 moist air and becomes colored. — Berichte, xliv, 2539. h. l. w. 



4. A Constituent of Mineral Coal. — Up to the present time 

 we have had practically no knowledge of the original compounds 



Am. Jour. Sci.— Fourth Series, Vol. XXXII, No. 192.— December, 1911. 

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