538 
POPULAR SCIENCE REVIEW 
apparatus has been given by the inventor, M. S. Marcus : — (1.) The electro- 
motive force of one of the new elements is one twenty-fifth of that of a 
Bunsen’s element, and its resistance is equal to 0'4 of a metre of normal wire. 
(2.) Six such elements can decompose acidulated water. (3.) A battery of 
125 elements disengaged in a minute 25 cubic centimetres of detonating gas. 
The decomposition took place under favourable circumstances, for the 
internal resistance was far greater than that of the interposed voltameter. 
(4.) A platinum wire, half a millimetre in thickness, introduced into the 
circuit of the same wire, is melted. (5.) Thirty elements produce an electro, 
magnet of 150 pounds’ lifting force. (6.) The current is produced by heating 
one of the junctions of the elements, and cooling the second by water of the 
ordinary temperature. The alloys employed by M. Marcus are dififerent 
from those in general use, and have the foUoving composition : — 
( Copper 10 1 
< Zinc....; 6 > parts. 
( Nickel 6 ; 
r Antimony 12 1 
< Zinc 5 > parts. 
( Bismuth 1 ) 
The bars are not soldered together, but bound by means of screws. One of 
the most interesting facts in connection with this battery is the proof it 
affords of the actual conversion of heat into electricity, for the water which is 
used in cooling the second point of contact becomes only slowly warmed, 
while the circuit is closed but very rapidly when it is open. — ^Vide The 
Philosophical Magazine, vol. xxix., No. 197. 
The Action of Sulphur in the Voltaic Pile. — M. Matteucci, in commenting 
upon the sulphur-battery lately invented by M. Blanc, observes, (1.) that 
finely-divided sulphur in contact with the electro-negative metal of a pile 
formed of zinc, copper, and solution of common salt, intensified the power of 
the combination ; (2.) Sulphur, though insoluble and an insulator, enters 
into combination with the sodium set free by the current. — Vide Comptes 
Pendus, April 3rd. 
The positive metal 
The negative metal 
ZOOLOGY AND COMPARATIVE ANATOMY. 
Anatomy of the Loujer Echinoderms. — M. Jourdain has published a memoir 
upon the anatomy of the siponculus, one of the lowest and most annuloid of 
the Echinodermata. Notwithstanding aU that has been done toward the 
investigation of the structure of the members of the star-fish class, there is 
still abundant room for inquiry, and M. Jourdain’s researches, though they 
do not tell us a great deal, are nevertheless acceptable. The more inter- 
esting part of his memoir is that which relates to the general lacunar cavity 
of the body, and to the arrangement of the circulatory and respiratory 
systems. The general lacunar fluid contains a great quantity of corpuscles, 
whose clearly-defined characters appear to resemble those of the blood-cor- 
