Chemistry and Physics. 255 
The coéfficient of expansion for a volume of mercury he finds from 
five series of determinations (per degree C.) 
0°0001812 
Regnault found 0°0001815. 
—Poggendorff’s Annalen, 1866, exxviii, 512-540. G. He 
17. On the expansion of crystals—Fizzau has invented a method for 
the exact determination of the coéfficient of expansion of small solids 
—=« cos? J+-2’ cos? J’-a" cos? 3”, 
and the cubical expansion is 
cma aa a! oa ot; 
which is the same as D for d= 0d’ =0"= 54° 41’, or in a direction at 
ght angles to the surface of a regular octahedron whose axes coincide 
with the directions of a, a’, a”, 
Fizeau determines @ for three temperatures (viz., 20°, 40° and 60° C.) 
from which he deduces the value for « at any temperature #, and also 
a beak 
the variation of « for each degree, that is re which is a constant 
quantity. 
Slon cma+2e’, A the variation for each degree; ¢ is the temperature at 
which the body has a mazimum of density. The unit of a, «,c and A 
18 000000001, or one hundred millionth of the unit of length or volume. 
ee gi a A a! A c A are) 
Platinum with 0°] iridium, 883647 |0-7668}....|..-. | ...-| 0. [rcseee 
Mirror-glass, ............ ee Eiise | acist. 2801| PRT 
Diiiiead: 22) See Soe PEs Per 8 3 32 | -42°3 
Cuprite,. 22... f Seaid sg 3 ee 279} 63 4 
Beryl,...., 06 8614 4 33 | 380] 3:30 |- 42 
cen ch ee ae ae 781 177 [1419 | 2°38 | 3619|-653 |....-6 
me eas 919 2-25 "14 | 1:10] 2374] 445 f....-- 
Paes ae 92 119 | 321 | 076 | 1034} 272 J.ci... 
Periclase (artificial), ‘seed * woes vais 3129 80 oneeee 
Spartalite (ZnO),.....-... 3ie «=| 186 «|: «539 | 1:23] 1994] 482 J....-s 
um,. aks eee 19 2°05 2°25 1705 6 . 
eee ee tecsees OSD 119 8 2-62 640 1.....: 
