256 Scientific Intelligence. 



SCIENTIFIC INTELLIGENCE. 



I. Chemistry and Physics. 



1. Phosphorescent Elements. — Several years ago Sir W. Crookes, 

 from a study of the spectra of the phosphorescent light emitted 

 by various fractions of rare earth sulphates under the influence of 

 cathodic rays, assumed the existence of several new element 

 and " meta-elements" in the gadolinium group, designating them 

 as Gft, Gf, Ga, ionium, and incognitum. G. Urbain has now- 

 made an examination of the spectra produced by fractions of 

 earths between gadolinium and terbium, and has found all the 

 bands described by Crookes, but he fails to agree with the latter 

 investigator in regard to the presence of new elements in the 

 mixtures. There is no indication of them in other kinds of spectra. 

 The terbium plays the role of an active phosphorescent substance 

 in the gadolinium sulphate, and slight changes of composition, 

 such as occur between one fraction and the succeeding one, may 

 cause the complete disappearance of certain bands. It was shown 

 by mixing pure gadolinium sulphate with pure terbium sulphate 

 in varying proportions, that a mixture containing one per cent of 

 the terbium salt gave many bands, while preparations containing 

 less than - 5 per cent or more than 10 per cent of it were very 

 slightly phosphorescent. Variations in the mixture showed dif- 

 ferent effects upon different bands. — Comptes Pendus, cxlv, 1335. 



H. L. W. 



2. Metallic Vacuum Vessels for Liquid Air. — In a lecture 

 delivered at the Royal Institution, Sir James Dewar has de- 

 scribed a metallic vacuum vessel which will be of use in industrial 

 cryogenic operations, and for the storage and safe transit of liquid 

 air. The metallic vessels resemble the ordinary glass silvered 

 vessels and are from 2 to 10 liters capacity. The envelopes may 

 be made of brass, copper, nickel, or tinned iron, with necks made 

 of a bad conducting alloy. The vacuum between the walls of 

 these vessels is maintained by enclosing some charcoal in a small 

 globular space made in the bottom of the inner vessel. The necks 

 may be covered with silvered glass vacuum cylinders which act as 

 stoppers and at the same time utilize the cold of the slowly evapo- 

 rating liquid. The efficiency of the best metallic flasks is equal to 

 that of the chemically silvered glass vacuum flasks now generally 

 used in low temperature investigations. — Chem. News, xlvii, 7. 



H. L. W. 



3. Manganese and the Periodic Law. — The classification of 

 manganese with the halogens in the periodic system of the elements 

 is doubtless somewhat unsatisfactory, so that Reynolds has 

 recently advocated the transference of this element into the eighth 

 group in company with iron, nickel and cobalt. He argues that the 

 present arrangement is based on the facts that unless Mn were 



