SCIENTIFIC SUMMARY. 
175 
retted hydrogen and nitrogen he mixed and exposed to electricity ; a mixture 
is obtained which, besides containing nitrogen and hydrogen, also indicates 
the presence of, but little it is true, some one per cent of ammonia. The 
solid body on the other hand, which is formed, also fixes nitrogen, which, 
when it is fused with potash or soda, is expelled in the form of ammonia. 
Precisely similar results are obtained with methane. By heat alone the 
siliciuretted hydrogen is likewise decomposed, though only at 400° ; and the 
decomposition is complete, into silicium and hydrogen. Arseniuretted hydrogen 
is also decomposed by the electric effluvium and As 2 H, analogous to P 2 H, is 
formed. ( Compt . Rend. lxxxix. 1068.) 
The Acid Reaction of Cryolite. — On account of the composition of cryolite 
6 Na F, Al 2 F 6 , and its slight but perceptible solubility in water, Stolba was 
led to expect that this mineral would exhibit an acid reaction. This view 
was found to be a correct one ; when very small quantities of powdered cryolite 
were placed on moistened litmus paper it became gradually red. The author 
recommends this reaction as a test for mineralogical purposes. An attempt 
was made to determine the fluorine of the aluminium fluoride, which alone 
contributes to this reaction, by an acidimetric method, but without success. 
Action of Potassium Permanganate on Potassium Cyanide. — This subject, 
already investigated by Pean de St. Gilles, and Cloez, and Guignet, has been 
studied afresh by E. Baudrimont. By allowing a titrated solution of potas- 
sium permanganate to act on a titrated solution of potassium cyanide, it was 
found, 1. That the decoloration of the first-mentioned salt has a limit ; 2. 
That the decoloration of the salt goes more easily with a rise of temperature 
and concentration of solution ; 3. That the limit appears to be reached when 
two equivalents of potassium cyanide and five equivalents of permanganate 
are mixed ; 4. That the decoloration takes place less rapidly when the 
solutions are more or less acidulated with sulphuric acid ; 5. That the 
products of the reaction vary, if not as regards their nature, as regards 
their quantity. The formation of the following bodies was noticed : urea, 
carbonic acid, nitric acid, nitrous acid, oxalic acid, formic acid, and ammonia, 
due to the decomposition of the urea. The formation of these substances is 
in accordance with the subjoined formulae : 
2 C 2 NK+ Mn 2 0 7 , KO + 6 HO = C 2 H 4 N 2 0 2 + C 2 0 4 , (KO) 2 
+ KO, HO + Mn 2 0 3 HO 
C 2 N K + 2 (Mn 2 0 7 , KO) + 2 HO = N0 3 , KO + C 2 0 4 , (KO) 2 
+ 2 (Jtfn 2 0 3 , HO) 
2 C 2 N K + 5 (Mn, 0 7 , KO) + 6 HO = 2 (NO s , KO) + 2 (C 2 0 4 , KO)., 
-f KO HO + oCMn^HO) 
Formic and oxalic acids may be regarded as derivatives of hydrocyanic 
acid and cyanogen which are the nitril of formate and oxalate of ammonia 
respectively ; their formation is simply explained by the action of water on 
the cyanogen molecule. As regards the ammonia, it appears to be formed by 
a secondary action of free potash on urea after the complete decomposition 
of the permanganate. {Comp. Rend, lxxxix. 115.) 
