386 Scientific Intelligence. 



marks being drawn on the manometer to correspond to those on 

 the pipette. The gas is first compressed to the lowest mark and 

 the pressure is noted on the manometer. The absorption of one 

 constituent is then proceeded with and the pressure is again noted, 

 the volume being adjusted to the same mark, or if this is not pos- 

 sible to the one above it. Finally the author describes a measuring 

 pipette with reserve spaces. It consists of two parallel vertical 

 branches enclosed in a water jacket. One of these branches is a 

 cylindrical tube holding 20 cc and graduated. The other consists 

 of four bulbs having a mark on the constriction below each bulb ; 

 the volume between each of these marks and the upper graduation 

 on the first tube being accurately known. A connecting tube 

 provided with a tap joins the two tubes at top. At bottom these 

 tubes are connected with a movable reservoir by means of rubber 

 hose and a three-way tap. In making a measurement the liquid 

 is driven up to a convenient mark, the rubber tube is closed by a 

 spring clip, and the reservoir is adjusted so as to bring the level 

 of the liquid in it to the same point as in the graduated branch 

 of the pipette ; the volume of the gas may then be read directly. 

 — Ber. Berl. Ghent. Ges., xxx, 2753-2759, 1897. ' g. f. b. 



2. On the Influence of the Rontgen Radiation on the Velocity 

 and Rate of Recombination of the Ions of Gases. — It is well 

 known that air which has been exposed to Rontgen radiation 

 retains the power of discharging positive and negative electrifica- 

 tion for a short time after the rays have ceased. Rutherford 

 has investigated the duration of this after-conductivity in the 

 case of air and other gases and from the data thus obtained has 

 determined the velocity of the ions through various gases. 

 These are given in the following table, in which T represents the 

 time required for the number of ions to fall to one-half their 

 original value. 



Gas. T in seconds. Conductivity, Air = 1. 



Hydrogen _ 0*65 0*5 



Air 0-3 1 



Hydrogen chloride - 35 11 



Carbon dioxide 0'51 1*2 



Sulphurous oxide 0*45 4 



Chlorine 0*18 18 



Apparently there is no very close relation between the values of 

 T and the conductivities, though in general the value of the 

 former diminishes as the latter increases. For the same gas the 

 value of T was observed to depend largely on the intensity of 

 the radiation. It was also noted that the duration of the after- 

 conductivity was affected by the presence of finely-divided matter 

 either solid "or liquid. The author found that the velocities of the 

 ions were independent of the amount of ionization of the gas used, 

 and were inversely as the densities with the single exception of 

 chlorine. The velocity of the hydrogen ion through hydrogen 

 was observed to be nearly four times as great as that of the oxy- 



