406 Scientific Intelligence. 
previous elongation. If we assume that the volume added to the 
wire is represented by both the elongation and contraction the 
mobility of the palladium particles ees determined by the first 
entrance of the hydrogen, the volume of the hydrogen in the alloy 
will rise from 4°68 per cent to 9°36 per cent and the density of hy- 
drogenium will fall from 1°708 to ? le Se a ene to - new _ 
Density of yogi 
When united with palladium —< a ait bak gril 0°854 to 0°872 
nd platinum, 0" 7401 [ 0°7545 
. “ weld es coo 0-711 to 0-715 
. ©. SVG aaeok 0°727 to 0°742 
The mean of these numbers is 0°733 which may be accepted 
> gyagepae! as the approximate ere of hydrogenium.—/roe. 
oyal Society, vol. xvii, p. 51 w. 
9. ‘On the properties of fluoh sl acid pti xtract t from an 
Mr. G. 
as 1; it boils at 19°4° C. and remains fluid 
is a most dangerous substance to handle, requiring the utmost care. 
Dry gaseous fluohydric acid does not attack glass so pe as moist- 
ure is completely excluded.— Proc. Royal Society xvii, p. 256 
10. On a new mode of formation oft the nitro-prussids, When 
potassic cyanid is added to a solution of a ferrous salt an orange 
colored precipitate, as is well known, is formed. Stadeler finds that 
this precipitate has the formula Fe. 2CYys K, and that with potassic 
nitrite it yields, on boiling, potassic nitro-prusside, ammonia and 
¢oxyd. The equation representing the reaction is here— 4 
Fe,Cy, K+N0, aeear HET kee 
ges ivi phi ia areata hes 
LE ee oy ae 
d upon 
be regarded as a Ad ai uct. After a careful discussion ite a 
the whole subject Stideler arrives at the conclusion that t Gerhardt’s 
formula for sodic nitro-prusside is correct ; and’ it therefore contains 
oe yl (NO) and not rNe,) as oth ee ‘and in partic cular range 
had maintained. Stideler agrees with Playfair in deriving the 
fico pracai des from a hitherto unknown ferrocyanhydric acid 
FeCy6H, which may be termed i ld ewe koae Ke acid. Th 
peteenic salt of this acid appears to be formed b + the action of 
a 
