64 Scientific ^Intelligence. 



his examination of the spectrum of compressed oxygen gas that 

 A, B, and probably a, are due to oxygen. To these Janssen 

 added some other bands, seen by him in the spectrum of com- 

 pressed oxygen. As to the lines A and B, Olszewsky has not 

 been able to make sufficiently exact observations in that part of 

 the spectrum of liquid oxygen in which they occur, to enable 

 him to establish definitely their existence in that spectrum. — 

 Wien Monatsch. f. Chem., viii, 73, Nature, xxxvi, 42, May, 1887. 



G. F. B. 



3-. On the action of Platinum on a mixture of Oxygen and 

 Ammonia gases. — Kraut has modified the form of apparatus 

 which he at first devised to show the action of oxygen upon am- 

 monia in presence of platinum. He now takes a strip of plati- 

 num or palladium foil 5 or 6 cm long, l cm broad and 0*2 mm thick, 

 and hangs it in a flask of 800 or 900 cc capacity by means of a 

 platinum wire. Through the stopper of the flask two glass tubes 

 pass each about 4 mm in diameter and bent at right angles. One 

 of these tubes terminates just below the stopper, the other two- 

 thirds the way down. The flask is now filled to one-quarter or 

 one-third its volume with a 20 per cent solution of ammonia, the 

 ignited foil is hung within it, of course so as not to touch the 

 liquid, and a rapid current of oxygen is admitted through the 

 longer tube. On shutting off the gas, the foil rises to a dark red 

 heat and white clouds of ammonium nitrate are formed. If the 

 oxygen be admitted for a second time for a few seconds, the foil 

 glows still brighter and brighter, and yellow vapors of nitrogen 

 tetroxide appear. By a third or fourth admission of oxygen the 

 color of the gas in the flask may be made dark enough to be visi- 

 ble at a distance, and this without danger of explosion and with- 

 out igniting the oxygen. — Ber. Berl. Chem. Ges., xx, 113, April, 

 1887. G. F. B. 



4. On two new Hydrates of Potassium hydroxide. — The only 

 definite hydrate of potassium hydroxide thus far known has the 

 formula KOH . (H 2 0)„ and crystallizes from a hot concentrated, 

 aqueous solution in rhombic octahedrons. Gottig has now de- 

 scribed two more hydrates, obtained not from aqueous but from 

 alcoholic solutions. To produce the first of these, pulverized 

 potassium hydroxide is rubbed in a mortar with 96*8 per cent 

 alcohol so as to obtain a solution of sp. gr. 1*050 to 1*058, and the 

 mass is filtered. Even during filtration, large prismatic crystals 

 separate, and on cooling, the filtrate becomes a mass of such 

 crystals. On analysis these crystals gave the formula (KOH) 2 

 (H„0) 9 . They fuse below 40°, and give up 41*5 per cent (about 

 3 molecules) of their crystal water on standing 144 hours over 

 sulphuric acid. The second hydrate is obtained from solutions of 

 potassium hydroxide in 96 *8 per cent alcohol, but which have a 

 specific gravity of only 0*980 to 0*985. Such a solution is boiled 

 down to one-half its bulk, the boiling point rising from 95° to 

 116°. On cooling, exceedingly long, delicate needles separate, 

 and at 35° the mass is nearly solid. During drying these needle 



