380 Scientific Intelligence. 



It is of interest to compare the wave lengths obtained above 

 with the wave lengths of the coronal lines 1474 and 1250 db 30, 

 lines which also appear in the spectrum of the solar protuber- 

 ances. The wave length of 1474 is 531-59, that of 1250±30 

 is 556-05±3-44. 



While it may be too much to claim that these measures 

 afford an absolute proof of identity, yet certainly the strong 

 suspicion is not without interest, importance and suggestiveness. 



Although it has no immediate connection with the subject 

 of the present article, it may not be out of place to note 

 the presence of these 18*5 and 19"0 lines in the spectra of y 

 Cassiopeias and /5 Lyras. Concerning these spectra we hope to 

 speak later. 



Observatory of Yale College, Oct. 1, 1885. 



SCIENTIFIC INTELLIGENCE. 



I. Chemistry and Physics. 



1. On the determination of the Specific Density of liquids 

 at high temperatures. — R. Schiff has described a convenient 

 form of apparatus for determining the specific d en sity of liquids 

 at high temperatures, based on the principle of the weight ther- 

 mometer. The pyknometer itself consists of a cylindrical glass 

 vessel of 8 to 10 c. c. capacity, with a conical neck terminating 

 in a fine opening. Upon this conical neck a recurved glass cap 

 or helmet is ground air tight. The instrument is placed in a 

 funnel-shaped vessel, the tube of which passes through the cork 

 of a flask placed beneath it, containing the liquid by means of 

 whose vapor the apparatus is to be heated. At top the funnel 

 has three openings ; through one the excess of vapor passes to an 

 inverted condenser, through the second, a thermometer is in- 

 serted ; and through the third, which is central and larger than 

 the others, passes (1) a wire holder to support the pyknometer, 

 and (2) a glass stem to which the cap or helmet is attached and 

 by means of which this may be made to close the opening in the 

 specific density flask. To make an observation, the flask is filled 

 with the liquid to be examined, a small glass plug being used. 

 to close it during the weighings, and is supported within the 

 funnel. As the temperature rises, the liquid expands and over- 

 flows into the recurved portion of the helmet. When the tem- 

 perature has become uniform, the instrument is removed from the 

 vapor, allowed to cool and weighed. The difference between the 

 first and second weighings gives the overflow. This divided by 

 the weight of the substance remaining gives the expansion of the 

 substance per weight-unit. And, knowing the volume of the 

 flask at 0° and its expansion-coefficient (determined by making 

 two experiments with mercury, one in ether vapor at 34° and the 

 other in steam at 100°), the specific density is readily calculated. 

 — Ber. Berl. Chem. Ges., xviii, 1538, June, 1885. g. f. b. 



