Chemistry and Physics. 85 



another sample of chromium which showed fluctuations while 

 dissolving, but in this case the periodic action took place only 

 with particular acid solutions, while with other samples of acid of 

 the same concentration a slow, uniform action Occurred. It was 

 finally discovered that the acid solutions which induced periodic 

 action contained a trace of dextrin, derived from cloth bags that 

 had been put into the liquids, and upon adding dextrin to other 

 acids they also gave regular fluctuations. An examination of 

 other carbohydrates and similar substances showed that their 

 action is the more pronounced the higher their molecular weight 

 is. The presence of '001 per cent of glycogen, '01 per cent of 

 lichenin, "1 per cent of inulin, or 1 per cent of raffinose sufficed to 

 produce the effect, while more concentrated solutions of cane 

 sugar, milk sugar and dextrose gave a similar result. Certain 

 kinds of chromium are " self-fluctuating," and an addition of dex- 

 trin to these produces irregularity in the hydrogen curve, which 

 is more marked the greater the addition that is made. — Zeitschr. 

 physikal. Chem., xxv, 83 ; 204. h. l. w. 



2. On Krypton. — This rare constituent of the atmosphere, 

 which was discovered by Ramsay and Travers, has been further 

 studied by Ladenburg and Kruegel. They used for the pur- 

 pose about three liters of residue left by the evaporation of the 

 greater part of 850 liters of liquid air. Upon conversion into 

 gas this residue occupied 2300 liters, and after oxygen and nitro- 

 gen had been removed in the usual manner about 3*5 liters of 

 inactive gas were obtained. The latter was condensed by cool- 

 ing with liquid air, when it formed a colorless liquid in which 

 floated a small quantity of colorless crystals. The liquid was 

 now raised to the boiling-point and fractions of gas were collected 

 according to the boiling temperature, which rose quickly from 

 — 189° to — 181-2, where it became nearly constant while about 

 2*5 liters of gas consisting chiefly of argon were given off; then 

 the temperature rose rapidly to — 153° where the last portions of 

 the liquid evaporated. At last there remained a crystalline 

 residue which melted at about — 147°, then quickly evaporated 

 and was separately collected. This last fraction showed a strong- 

 krypton spectrum in which the lines D 4 , 589*9 //,//,, and 558*1 fxfx 

 were very brilliant, while many argon lines, including the whole 

 of the violet end of the argon spectrum, were wholly wanting. 

 It was therefore evident that the product contained very little 

 argon, or only a constituent part of that gas. Compared with 

 oxygen as 32, the density was found to be 58*81 and 58*67. 

 These numbers correspond to the atomic weight if the gas is 

 monatomic. Some of this gas was afterwards condensed by use 

 of liquid air, when the tube containing it became covered with a 

 crystalline layer, but no liquid was formed. A fraction of gas 

 which evaporated last from the crystalline deposit gave a density 

 of 59'01. Ramsay expected that the atomic weight of krypton 

 would be about 80, although his density determination with gas 

 which certainly contained much argon gave an atomic weight of 



