142 Scientific Intelligence: 
further, this thickness depends on the ratio which exists between 
the sound proper to the membrane and the given sound, and also 
on the a and dimensions of the membrane. 
is 
the pipe, and within certain limits nearly Teearbeae | to the 
breadth of the solid rim surrounding the pipe; it is, on the con- 
trary, panier starting from a certain breadth, and then propor 
tional to the diameter of the pipe.— Ann. Chem. et ee iy Bac 
11. Electrical Resistance.—M. Brnorr has measured with | reat 
goat the oe resistance of various metals at temperature 
860° mployed both the method of the diferential 
Cave and of the Wheatstone’s ee, and for each metal 
has measured several specimens. The mean of these is given in 
the following table, the open column ee the resistance of 4 
wire one meter long an aving a cross section of one mm. in 
Ohms, and column three the same quantity in eens units. 
Column four gives the resistance compared with silve 
Metal. Ohms. Siemens. 
putide Big Sind bss Geet 0154 161 100 
Cop A ac ere ee 0179 90° 
Silver, A (lyicisc. eee 0198 0201 80 
Ue ne es 0217 "0227 71 
Sateen Ae ee ee 0324 49°7 
Magnesium, : Ho. oot cds 0423 0443 36°4 
fino, Ay, at 860%. Ce 0565 0591 27° 
WiMb Sd 2 Ge i "0594 0621 25°9 
Cadmium, Hoo eee 0685 0716 22°5 
Dress, A (2)o.2 22652 se -*0691 0723 22°3 
Rica Al. ais olGe Se 1099 "1149 14°0 
Wie oe ae 1 "1214 13°3 
Aluminum Bronze, A (3)-.----- 1189 1243 13°0 
Pe ue een cues ek 1216 1272 12°7 
Palladian, Ao. oes ecco: 1384 1447 111 
Platinam, 2A 0.222525 1 7s ‘1575 1647 9°77 
Minm. i 20. oA 1831 1914 8°41 
feed ‘1985 ‘2075 7°76 
bem Silver, A (4) 2.21.5 2654 ‘2775 580 
Mawery. 255.0502 oo ea 9564 1-0000 1°61 
A, annealed; H, hardened; (1) silver “75; (2) copper 64:2, ot 33°1, lead 04 
tin 0-4; (3) copper "90, aluminum 10; (4) copper 50, nickel 25, zine 25. 
These results, which are kay taken at 0°, agree closely with thos 
obtained by other observers. M. Benoit has extended his observ® 
tions to a range of igeabienehatos much greater than those prev’ 
