342 J. Trowbridge—Electro-motive action of Liquids. 
gas-pipe, fifteen inches long and three quarters of an inch in 
diameter, gave, when set for a continuous sound, quite a low 
and mellow tone. If the jet be moved slightly aside, so that 
the flame just grazes the side of the tube, a note somewhat 
lower than the fundamental one of the tube is produced. This 
sound is stopped by external noises, but it goes on again when 
left undisturbed. All these experiments can be made under 
the ordinary pressure of street gas, three-fourths of an inch of 
water being sufficient. 
Hoboken, March 18, 1872. 
Art. XLV.— Contributions from the Physical Laboratory of 
Harvard College.—I. On the Electro-motive action of Liquids 
separated by Membranes; by JOHN TROWBRIDGE. 
Tr is well known that two liquids, of a dissimilar chemical 
composition, separated by a porous partition, give rise to a gal- 
vanic current. This fact has an important bearing upon the 
subject of animal electricity. Desiring to prove certain theories 
in regard to muscular currents, I undertook the following line 
of investigation. 
: th ings pro 
by porous partitions, and filled with the following “ 
undietilled water; weak solution of salt in distilled pone 
solution of various salts of iron; blood; acidulated watt, 
n; : 
Having carefully placed the artificial muscle in position 
