600 SCIENTIFIC RECORD FOR 1883. 



one for controlling perpendicular surfaces. Most of these devices may- 

 be used during the working of the surfaces. ( C. B., xcvi, 1035 ; J. Phys.j 

 September, 1883, II, n, 411.) 



Soret has modified the total reflection refractometer of Kohlrausch 

 so that it may be used with white light. The new apparatus is illu- 

 minated with a strictly parallel beam of solar light, which, after reflec- 

 tion at the contact-surface of the given substance and carbon disul- 

 phide, is received on the slit of a spectroscope. For any convenient 

 incident angle a dark well-defined shadow moves from the red to the 

 violet with an increasing incidence, limiting the totally reflected rays. 

 The index of the given substance for the part of the spectrum with 

 which the edge of the shadow coincides is obtained by multiplying the 

 index of carbon disulphide by the sine of the incident angle. (J. Pliys., 

 March, 1883, II, n, 138.) 



Wiedemann has determined the density and refractive index at 19° 

 for the three lines of lithium, sodium, and thallium of ethyl-carbonic 

 ether and the five corresponding ethyl sulphocarbonates. From these 

 values he calculates, by Lorenz's formula, the atomic refraction of sul- 

 phur, and finds it to be 7.94 in the case where only one atom of sulphur 

 is united to the same atom of carbon, and 9.28 where two atoms are 

 thus united. ( Wied. Ann., xvii, 577; J. Phys., March, 1883, II, n, 139.) 



Dufet has investigated the influence of temperature on the index of 

 refraction of water and quartz. When a parallel beam passes through 

 a rectangular trough filled with water and containing a quartz plate 

 with parallel sides, one-half of the beam passing above this plate, Tal- 

 bot's bands are perceived on passing the light through a prism. By the 

 displacement of these bands the temperature may be determined to 

 within 0°.02. The variation of the ordinary index of quartz for D and 

 one degree is —0.0000050. (G. B., xcvi, 1221, April, 1883.) 



Quincke has studied the changes which the volume and the refractive 

 index of liquids undergo under hydrostatic pressure. The compressi- 

 bility was measured in glass vessels provided with capillary tubes, 

 while the indices were measured by observing with an interferential re- 

 fractometer the number of bands in homogeneous light. The ratio of 

 these changes exhibits a definite relation, and the results go to confirm 

 Dale and Gladstone's formula for the constant of refraction, i. e., the 

 index, less unity, divided by the density. Or, in other words, the ex- 

 cess of the index above one increases proportionally to the density. 

 (Ber. A7c. Berl, April, 1883 ; Nature, xxvni, 308 ; J. Phys., June, 1883, 

 II, II, 279.) 



Ohappuis and Eiviere have measured the refractive indices of gases 

 at high pressures, employing the interference method of Jamin. The 

 gas was compressed in a prismatic cavity in a block of steel 20 centim- 

 eters long, closed at the ends by glass plates a centimeter thick. One 

 of the interfering rays traverses this cavity, the other passes outside of 

 it and one centimeter distant. They are united by the second mirror, 



