Chemistry and Physios. 61 



SCIENTIFIC INTELLIGENCE. 



I. Chemistry and Physics. 



1. The Vaporization of Solid Substances at Ordinary Tem- 

 perature. — It has been shown by C. Zenghelis that many solid 

 bodies, even at ordinary temperature, possess a certain vapor 

 pressure. This is exceedingly minute in the case of substances 

 which have a very high melting point, such as metals, 'their 

 oxides, and other metallic compounds, so that it has escaped the 

 attention of chemists. The author's method of detecting such 

 vapors consists in absorbing them by means of thin silver leaf 

 which is placed for a long time above the substance to be tested, 

 in a closed space. In many cases the presence of the volatilized 

 substance was detected analytically in the silver leaf, although 

 its presence was usually readily recognized by the change in 

 color of the silver. Other means were also used to detect vola- 

 tilization, for instance potassium ferrocyanide solution for metal- 

 lic copper and iron. Moisture appeared to facilitate the volatili- 

 zation, while silver appeared to be the only metal capable of 

 detecting the vapors with delicacy. The less readily oxidizable 

 metals showed no volatility in these experiments, but copper, 

 lead, iron, zinc, tin, antimony and arsenic, when used in a finely 

 divided form, showed volatilization. Many oxides, for instance, 

 CuO, PbO, ZnO, Fe„0 3 and Fe s 4 gave a reaction, as did also 

 several hydroxides, Ba(OH) , Cr(OH) 3 , etc., and a very large 

 number of salts. — Zeitschr. physilcal. Chem., lvii, 90. h. l. w. 



2. Investigations -upon the Rare Earths. — Atter von Wels- 

 bach, whose investigations of more than twenty years ago led to 

 the well-known important results in practical illumination, and 

 who separated the old supposed element didymium into neody- 

 mium and praseodymium, has announced that he is again work- 

 ing in the field of the rare elements. Long ago he became con- 

 vinced from his observations that certain of these substances which 

 have been considered as elements are actually compound bodies, 

 and that it is within the range of possibility to separate them 

 into their true elements. In a preliminary article he describes 

 work of fractionation carried out upon half a ton of the yttrium 

 earths obtained from monazite, and states that he has obtained 

 certain indications of the decomposition of ytterbium. — Monat- 

 shefte, xxvii, 935. h. l. w. 



3. He-determination of the Atomic Weight of Potassium. — 

 Theodore W. Richards and Arthur Staehler have deter- 

 mined the ratios KChA^Cl and KC1 : Ag, and assuming the 

 atomic weights Ag=107 - 93 and Cl=35 - 473, they have obtained 

 in each case the result K = 39'114. This determination is lower 

 by '007 than the recent result of Archibald, and consequent^ it 

 varies still more from the previously accepted atomic weight 

 based upon the work of Stas. The details of the work are 



