80 Intelligence and Miscellaneous Articles. 



so, against the side of the glass. In virtue of the slight difference 

 in density, this liquid assumes the spheroidal form, and does not 

 adhere to the glass. I have seen glohules 8 millions, in diameter 

 retain the liquid state to 55°. 



It is prohable that other bodies, if placed in suitable conditions, 

 would also present the phenomenon which the preceding bodies mani- 

 fest in such a pronounced degree. Unfortunately it is difficult with 

 a large number to realize the essential condition, which is to pass 

 the ordinary temperature of change of state while the body floats in 

 equilibrium in a liquid of the same density. The liquid selected 

 must, in point of fact, fulfil the four following conditions : it must 

 have the same density as the body under experiment, retain the fluid 

 state above and below its melting-point, and not exert any chemical 

 action. Spite of these requirements, I do not doubt that chemistry 

 will furnish the means of successfully applying to other substances 

 the method by which the retardation of the solidification of water, 

 sulphur, and phosphorus is so easily and certainly effected. — 

 Comptes Rendus, April 29, 1861. 



ON THE CHANGES PRODUCED IN THE POSITION OF THE FIXED 

 LINES IN THE SPECTRUM OF HYPONITRIC ACID BY CHANGES 

 IN DENSITY. BY M. WEISS. 



Weiss has found by actual measurement that the distance between 

 the dark lines in the spectrum of hyponitric acid diminishes as the 

 density of the gas increases. The measurements were made with an 

 Oertling's circle reading directly to two seconds of arc, and, by a 

 filar micrometer in the ocular, to a single second. The same pheno- 

 menon occurs with the spectrum of chlorophyll. The stronger the 

 extract in ether, the less is the distance of the absorption-bands. 

 Thus the absorption-band in the red, in the case of a strong extract, 

 corresponds quite well with Fraunhofer's line C ; in the case of a 

 weak extract it stands at some distance from it. The other absorp- 

 tion-bands in this spectrum undergo similar dislocations. 



These changes in the distances of the dark lines are very sensible, 

 even in the spectrum of hyponitric acid, when the changes in the 

 density of the gas are considerable ; they are not, however, equal for 

 all the dark lines. 



The cause of these dislocations is to be sought, according to Weiss, 

 in a one-sided absorption which each line undergoes toward the 

 violet end of the spectrum when the density of the body is increased. 

 This is shown by direct observations and comparisons with the solar 

 spectrum as well as by numerous measurements. There is no spe- 

 cific absorption upon both sides of each line, but only an absorption 

 upon the side of the line which lies toward the violet end of the 

 spectrum. In this manner the bands become broader, and the di- 

 stance between them less. The author has observed similar changes 

 in the breadth of Fraunhofer's lines at sunset. In this case also the 

 absorption was only upon one side. From this it appears that the 

 lines of hyponitric acid cannot be used as standards in determinations 

 of indices, &c. — Poggendorff 's Annalen, vol. cxii. p. 153, Jan. 1861 ; 

 and Silliman's Journal for May. 





