660 



PHYSICS, PROGIU>s OP, IN 1895. 



Uriialion for quart*. Iceland *par. and tourma- 



rnntrataaion curve* of the ordinary 



Mid extraonlmarv ray* were entirely different > 



.,..*, i he difference being especially marked 



with l.-.-land *|ar. 



if lion. Sir John ( 



determined the reft 

 Dperature* between " 

 .tii.l fliuU thnt th.- index increases con- 

 Unuouiy up to the fretting |*'tnt. while thr rate 



>.-a-- alter* at alMiui ; 

 mum dcii-ity. and thnt no formula that 



.... v;.-n . 4 - ;i fun.-ti..n -f till- d.-n-ity 



. .. , , . . \; --.. :.i -. 



PkoiomtJry. Kurlhaiim and Lomtner (Berlin 



*] Society) have made a deterralwwoo of 



th.-'uni; <>f Uffal that is baaed on the luht rmit- 



tcd by white-hot platinum foil. To keep the 



temperature constant for a Ion- period and t.. be 



ble to rvcsteblish it at anv time tin- ratio of the 



total radiant energy from tbt foil to that tran- 



i I iy a medium was measured bolomei ric- 



ally. Th.- medium chosen was a thin layer of 



water in a quartz cell. Tl n< .tinted to 



. ami were due chiefly to air currents 



on the surface of t ho foil. 



Sp*)tro*oopy. Wadsworth ("Astronomy and 

 Astro-physics," December, 1894) has devised a 

 way of rotating the prism of a spectroscope, wh -re 

 movement of the collimator .r of the ..!.<. r\ in- 

 telescope is objectionable, in such way as to re- 

 tain minimum deviation for the central ray in t he 

 n. 1 I. A mirror having an angular mot ion equal 

 . _ .uvular motion of the 

 nuniiniiin-deviatjon rav is introduced somewhere 

 between the slit and the focal plane of the ob- 

 serving lens. In the spectro-bolomet. r it i- in 

 continuation of the back face of the | irism. Lang- 

 i a paper on M Recent Researches in the 

 Infra-red S|ectrum M (British Association, 1894), 

 reviews the work now in impress at the Sin it h- 

 nonian Institution in thi-iirreti..ii.".| M M-ially the 

 combination by composite photography of sev- 

 eral linear representatives of the spectrum to 

 form a single one, on which " we may expect to 

 find only what is permanent and not what is ac- 

 cidental'." He concludes that more than 2.000 

 line* will thus be mapped in the infra-re- i 

 tram. Kdler and Valenta (Vienna Academy of 

 Sciences), in a paper summarized in " The Astro- 

 physicJ Journal," May. have discovered two new 

 of mercury, obtained by passing an elec- 



tric spark through mercury vapor that is 

 at low 



low pressure through a capillary tut 

 number of Ixyden jars are in circuit, tho 

 sharp lines : 



ing at 



a large 



wctrura has a great number "f One, shar 



if not, it becomes a series of bands with 



Umanl the red. The band spectrum 



to * slightly lower temperature than the line 



Jiotiure. <ialr "Annalen," 



Htjptembsr) constdcm t tr theory of the 



>r<oMenin of spectrum lines superior to 



2*poppfc i " principle, on KirchhofTs law, 

 damping inoi. it admits of a deTelopmenl 

 *>o the theory of molecular resonators. 

 brr*d,.ninjr i* A consequence. ar< 

 Aibrtu 



bromine, chlorine, sulphur, selenium, iin.l ar- 



- me all ^lo\v ly external heating, ''lit 1:1 \ 



t inuout sjien ra. h.-n-M- soiliuin vaporaets in tin- 



same way, l>ut on a r.-.lui-tion of <l.-i. 



a discontinuous s|N>etrum. Tin .A;., nm, 



>aii-lie.l that li^ pn-caution> prei-lude.l li 



siliility of jiny -hemical acli.n. ... that th- 



t rum was due t> t ru.- .-xternal heal : 



ungbtrichl 



ile method of olitainiiiL' li^'hi- of di: 1 



Fh*' th^.ry exnlains the unsymrnet- 

 m*l-ninff and the influence of tempera- 



phical 

 -," May) finds that the vapors of iodine, 



in iH.lariii. 

 liu'lit tlirough absorption cell 

 suiting li^nt. though not actually 



.gives a uniform tint in the li. M 



iNilarillieter if the rotation le |e lli;. 



' 



( .. IMTI ha- investigated the p..lari/at i.-n .f tho 

 liu'ht emitt.-d l.y in-anl.-x,- ( -n: l..di.->. and lin<ls 

 that it is a minimum with ray- mil t.-d n 

 loth.- surface and a maximum with a L f 

 emi-- ion. which indicates thai tin- vji 

 in a plane at right_ angles to the emittii 

 face. In the following i^ur he studies the pln- 

 noinena jualitatively and finds a striking 



Iliellt between the IliraMireil aillollli! 



/at ion at dilTerent angles of emergemv an 



calculated from < 



lle< tion on the assumption that the ; 



i- due to the refraction of rays connn_ 



the interior on nnerirciice. 'I'h.- a^reemi-nt is 



es|.ecially good in the ca-e of molten -il\er. 



The fluorescenl light developed at tl.> 



ura'iium glass is polar i/.ed in much 1 1; 



and the fart i explained similarly by the author. 



I'ljanin (Berlin Physical Society. March 



:irated t he polarization that isdue toolili.jiie 

 radiation from silver, platinum, and black 

 and finds that curves arrived at bya^umii 

 the radiation of the substance is'dctcnnii 

 its refraction correspond well with those ol 

 by direct experiment, especially in the case of 

 silver. 



/{'tun/ /'n/arization. Rodger and \\ 

 (London Royal Society, Jun. J(h ha\.- att- 

 to determine in absolute measure th* m 

 rotation of lijui<ls at dilTerent tempi-r. 

 the effect of the chemical nature ..f the li.juid 

 on this pro|>erty. and its correlation will 

 |i|iysj<-;ii properties. They conclude that the 

 u-ual measure of the molecular rotation, which 

 involves the properties of water, is particularly 

 ill suited for the purposes to which il 

 since the behavior in water is except ii 

 its rotation is small. In all of the 10 liquitls 

 that they examined, except water, th- 

 tion between rotation and tern]" 

 and the quotient of the rotation by the d 

 diminishes with increase of temperature. Siert- 

 o'-rua (Amsterdam Acalemy of Sci< 

 current*, of :;.") to 65 amperes, ha- b'--n 

 obtain in oxygen a ma-netic n.tary di-p 

 of 8 to 4. A series of measuremei.- 

 made on atmo-pheric air and values for nil 

 were deduced therefrom. 



-K. Wiedemann and Schmidt 

 fWiedemann's " Annalen," April) dr 

 portant distinction between physical and 

 leal luminescence. When there is a pr< 

 afterglow the phenomenon i- probably ch- 

 Luminescence under cathode rays is always ac- 



