Chemistry and Physics. 259 
For tubes filled respectively with air, carbonic acid, illuminating gas 
and hydrogen, Mr. Kundt obtained ree aes 32, 40, 20, and 9 heaps, 
from which the velocity of sound (air = 1) is for carbonic acid 232 =°8, 
ee gas 32 = 1-6, hydrogen 32 = 3°56. ssp found, ‘bya 
y difficult method, for carbonic acid *79, for hydrogen 
tT obtain still greater accuracy, and also determine rie velocity of 
sound in different solids, Kundt closes one end of the glass tube 
ta a an rod 9415 mm. long and 5 mm. diameter, Mr. Kundt ob- 
— in three —— Ses Balan in each making numerous measure- 
s of the distances, the velocities 10°87, 10°87, 10°86. Another 
ra rod gave 10°94 2a 10°90. Similarly for steel, 15: hes - 334 and 
| 2 15°343 ; for glass, 15°24, 15°25 and 15°24; for copper, 
% Wertheim found for cast-steel, 14°961; for steel a5 7 108; for 
q copper, 11°167. 
: e above leaves no doubt that Mr. Kundt has enriched science with 
a a new method for the aang of the velocity of sound in solids, 
4 gases and vapors, alike excellent for a high degree of accuracy in i 
numerical Jebciin gies ease of execution, elegance and simplicity, 
making it exceedingly convenient for lecture experimen 
We are engaged in experiments to try the application of this method 
to liquids.— Poggendorf’’s Annalen, 1866, exxvii, 497-523 ; pion”, 
1866, p. nee Cosmos, 1866, ili, 98-100. 
ee now s 
an apparatus which affords positive proof of og presence or absence 
condensed vapor, “ fog.” He has found that the radiation (which js pro- 
portional to the absorption) of the following gases and vapors gave the 
following deflections — his very delicate thermo-multiplier, all the gases 
being heated about to 230° C.: dry at mospheric air 3 mm.; air having 
through water % 2 5; dry carbonic — gas 100 to 120; com- ae 
mon illuminating gas, about the same; air having passed thro’ ugh bil- 
ing water, irregular, but maximum deflection only 20, and only eradhally > 
