318 Scientific Intelligence. 



6, Potassium and Sodium Carbonyls. — For some years Joax- 

 nis has been investigating the peculiar compounds potassammoni- 

 um and sodammonium formed by potassium and sodium respec- 

 tively with ammonia. He has now studied the reaction which 

 takes place between these substances and carbon monoxide. 

 When dry carbon monoxide is caused to bubble through a solu- 

 tion of potassammonium in liquefied ammonia, the containing vessel 

 being cooled to —50°, the deep blue color gradually decreases in 

 intensity and is eventually replaced by a pale pink tint, indicating 

 the end of the reaction. On removing the liquid from the cooling 

 mixture, the ammonia gradually evaporates, leaving a rose-col- 

 ored powder which analysis shows to be pure potassium carbonyl 

 KCO. It darkens when left undisturbed for some time in a sealed 

 tube. It cannot be heated to the temperature of boiling water, 

 explosion taking place below this point. It likewise detonates if 

 the merest trace of air is admitted, and also when touched with a 

 drop of water. If, however, a drop of water be admitted into an 

 exhausted tube so as not to come in direct contact with the 

 potassium carbonyl, the vapor acts upon it and produces a yellow 

 viscous liquid. If sodammonium be similarly treated, sodium 

 carbonyl NaCO is formed. It is a pale lilac colored substance 

 and is also powerfully explosive, even by small quantities of air 

 or water. When exploded by percussion the reaction was found 

 to be (NaCO) 4 = Na 2 CO s + Nn o _0 + C 3 . Ab90° the explosion is 

 so violent that no glass can withstand it. — C. M. cxvi, 1518, 1893. 



G. F. B. 



II. Geology and Mineralogy. 



1. International Congress of Geologists. — The sessions of the 

 6th International Congress of Geologists will be held at Zurich, 

 Switzerland, from the 29th of August to the 2nd of September. 

 As many geologists may not have received the descriptive circu- 

 lars, the following brief summary of the announcement is made 

 for their benefit. 



Besides the general meeting there will be meetings of sections, 

 at the same time, for the following general subjects: 



Section 1. General and Structural Geology. 

 " 2. Stratigraphy and Paleontology. 

 " 3. Mineralogy and Petrography. 



Any person may become a member of the Congress by sending, 

 by postal order, a fee of 25 francs = 15.00 to the Treasurer, M. 

 Casp. Escher-Hess, Bahnhofstrasse, Zurich. 



A large number of excursions have been planned for the weeks 

 immediately preceding and following the Zurich meetings. The 

 latter are so arranged as to concentrate at Lugano for the closing 

 session of the Congress on the 16th of September. They are of 

 two kinds. Pedestrian excursions for geologists alone, and Round 

 trips by rail, steamer and carriage, in which ladies may take part 



