re and Physics. 467 
atomic weight of boron, is really the atomic weight; further - 
the atomic heat of boron is about 5°5, and t at therefore at a 
heat boron obeys the law of. Dulong ‘and 
Small brilliant steel gray crystals of siliau niclahing 1°123 grams, 
were next employed. From’ these it was shown that silicon does 
not form an xeanthions —— on the ‘law of Dulong and 
Petit; so soon as the peo passes 200° it comes within the 
sphere of this law. The smallest anor plier of silicon (28) 
hitherto found in aba salable of any of the gaseous compoun 
of this en is in reality the atomic weight of — —Prhil. 
Mag., xlix, 16 6. OR 
Action a Electrie Currents on Alloys.—M. E. preniare at the 
cee of M. hac agryl has tested the ee of Gerar- 
din on the electrolytic d ical of alloys. A series of ex- 
hetipscte were made ie which he sctkalnies that the passage of 
action of the current sale be mitt the har von mers me mallea- 
bility of the ead pe tin alloys, nor the fluidity of he potassium 
sodium alloys. It introduces in the nei ighborhood of ihe electrodes 
no change exceeding d the limits of at error in the ana cg — 
Univ cevil, 2 
‘ 768 
that on :iserting ina a beers a sn i pace two elee- 
ee é 
of alumi t 
obt ikea: according to the direction of the current. When boar 
aluminum receives the negative electricity the water is dec 
posed and the current traverses the circuit freely. But on eal 
ing the current the igs om geiaeee ceases and sy any elec- 
and not even heated in the 4 second. " galvanometer gave in one 
case a deflection of 22° and in the other of only 2°. 
e effect is produced instantly; it is constant and durable 
whatever the ego Bs of inversions of the current. If other metals 
are used instead of pins they are deposited on the aluminum 
and interfere with the experiment This stoppage of the current 
is not produced by a plate of gold, silver, pepERny copper, zinc, 
magnesium, tin, lead, ete., replacing the a ‘ i 
effect is produced with iron, but the surface is soon ‘altered, with 
the iivenape aims of a bad odor. As to the aluminum, its su 
appears to be preserved by a slight layer of alumina which is 
f peed immediately, and remains, in spite of the inversion of the 
current. 
Many practical si gga god * this property suggest themselves. 
wo messages may be sent over a telegraph line at the same time 
in opposite ‘directions fs using fom voltameters with the aluminum 
on opposite sides. All trouble from variable resistance is thus 
avoided.—Journ. de Phys., iv, 84. 
