1 878.] 
Scientific Notes. 
287 
At a meeting of the Physical Society, in February last, Mr. F. J. M. Page 
exhibited the action of the telephone on a capillary electrometer. He first 
explained the construction of Lippmann’s electrometer, as modified by Marey, 
and threw the meniscus of the mercury in the capillary tube on the screen by 
the electric light. The delicacy of the instrument was shown by passing a 
current of i-ioooth of a Daniell, which caused a distinct movement of the 
mercury. Resistances of 500 ohms and i-5oth ohm gave approximately the 
same deflection, so that, in practice, the instrument may be considered to be 
independent of resistance, in addition to which it possesses the great advan- 
tage of portability, and its indications are almost instantaneous, To illus- 
trate the use of the electrometer for physiological investigations, a frog’s heart 
was connected by non-polarisable electrodes with the instrument : each beat 
of the heart caused a considerable movement of the mercury column. A 
telephone was now connected. On pressing in the iron plate the mercury 
moved, and on reversing the wires the movement was seen to be in the oppo- 
site direction. On singing to the telephone each note produced a movement ; 
but the fundamental note of the plate, as well as its octaves and fifths, had 
the greatest effect. On speaking, the mercury oscillated continually : some 
letters of the alphabet had scarcely any effect, and the w was especially 
curious, producing a double movement. Reversing the wires did not alter 
the character or direction of these movements. The same effect was observed 
when the telephone was in the primary and the electrometer in the secondary 
coil of a Du Bois Reymond’s induction coil. In conclusion, Mr. Page showed 
the contractions produced in a frog’s leg. On inserting under the sciatic nerve 
two platinum wires coupled with the binding-screws of a telephone, and 
talking to this instrument, violent contractions ensued. In the course of the 
discussion which followed, Prof. Graham Bell said he had made very many 
attempts to ascertain the strength of the current produced by the human 
voice in vain; he considered, however, that the present method will in all 
probability give some most valuable results. 
On Thursday evening, January 10th, M. Raoul Pictet succeeded in lique- 
fying hydrogen gas in the laboratories of the Society for the Construction of 
Physical Instruments, at Plainpalais, The experiment, which was performed 
in the presence of several people, succeeded perfectly. The process consists 
in decomposing formiate of potash by caustic potash, a reaction which, as 
proved by M. Berthelot, gives hydrogen absolutely pure. The pressure com- 
menced to rise at half-past eight ; gradually and without any stoppage it 
attained, at seven minutes past nine, 650 atmospheres, at which point it re- 
mained steady for a few instants. At this moment the tap was opened, and 
a steel-blue jet escaped from the orifice, producing a hissing sound like a bar 
of red-hot iron plunged into water. The jet suddenly became intermittent, 
and there could be observed a hail of solid particles projected violently to the 
ground, on which their fall produced a crackling noise. The tap was closed, 
and the pressure, which was then at 370 atmospheres, gradually descended to 
320, where it remained for some minutes. It then rose to 325. At this mo- 
ment the tap, on being opened a second time, only allowed a jet to escape 
intermittently, rendering it evident that a crystallisation had taken place in 
the interior of the tube. The proof of this can be established by the escape 
of hydrogen in the liquid state when the temperature begins to rise on 
stopping the pumps. Thus has been experimentally demonstrated the lique- 
faction, and especially the solidification, of this gas, which from its properties 
has always been considered probably to belong to the class of metals. 
M. Cailletet sent a paper on the “ Liquefaction of Nitrogen, Hydrogen, and 
Atmospheric Air ” to the Academie des Sciences, which was read at the 
meeting on the 31st of December, 1877. M. Cailletet showed that pure and 
dry nitrogen compressed to about 200 atmospheres, at a temperature of +13 0 , 
then allowed to expand suddenly, condenses in the most perfect manner : it 
first produces an appearance like that of a pulverised liquid in small drops of 
appreciable volume ; this liquid then gradually disappears from the sides to 
the centre of the tube, at last forming a sort of vertical column following the 
axis of the tube. The duration of these phenomena is about 3 seconds. On 
