252 Scientifie Intelligence. : 
1. Guass Prism oF 60°. 
Temp. C. a: E. b, ; 
15° C. 25613 2723°2 * ~=——- 2942°6 2979°4 3140°7 
30° C. 2565°8 2727°8 2948°5 2983°9 31463 
2. QUARTZ PRISM OF 60°. 
Bee ck. ae 313°3 397°5 4143 470°0 
a ah § a eee ee 3117 396°5 411°5 468'1 
14° ©. 1172°4 1436.2 1804:9 T8664 Bette 
16° ©. 1173*1 1437-2 1806°5 1867-7 2150°9 
20° C. 11T4+4 1438°4 1807-3 1868°5 2152°8 
30° C, Ltt 1442°0 1811°0 1872°2 2158°6 
From this it appears that this shifting of the a isle lines by 
cnenee of temperature is considerable enough to be mportant, a 
rise of 25° changing the position of the lines as fulloee: 
: bs: E. b. 
Glass prism of 60°, +750 +767 +9°83 +7750 +9°33 
Quartz prismof 60°, ...- —4°10 —2°27 —6'36 —4°32 
Rutherfurd prism, + 8°28 + 9°06 + 9°53 +9°06 +13°75 
All v feoks lines, then, shift by rise of temperature; in Eee 
Morne ward the _vio let; in quartz prisms toward the fr 
oreover AE j i 
d. F. 
Micrometer cpr ty as 4 ae 9 1801°5 1863°1 2144°8 
ave-length at 656°8 589-7 527-4 51777 486°5 
Wayvye-length at oo 658-9 592-0 §29°0 519°2 488°0 
A change of temperature of about 5° suffices therefore to alter 
the oe of wave-length by an amount equal to the dis 
Deo 188 between the D lines.— Ber. Berl. Chem. Ges., hee 2732, 
ec 
top being 
1) a thermometer 
ee in a Poiesitoat aries a lateral oping th 
having its bulb nr bh with cotton, and (2) a glass tube connecte ed 
sabe to be heated to any requi ired t mperature. The reservoir is 
immersed in a cooling mixture. To make an experiment, the 
