396 Scientific Intelligence. 



The analysis is as follows : 



Fe 88-05 



Ni 10-37 



Co -68 



Cu -04 



p : -2i 



S _ -08 



Si __ -02 



99-45 



Laboratory IT. S. Geological Survey, March, 1890. 



SCIENTIFIC INTELLIGENCE. 



I. Chemistry and Physics. 



1. On the Determination of Gas volumes by Direct Reading. — 

 A very simple apparatus has been contrived by Lunge which 

 he calls a "gas-volumeter," by means of which the volume at 

 normal pressure and temperature of the gas set free in any reac- 

 tion can be read directly without requiring reduction. In its 

 complete form, the apparatus consists of three tubes called 

 respectively the measuring tube, the reduction tube, and the 

 pressure tube. The measuring tube is graduated, and is closed 

 at top by a two-way tap, one opening being to the air and tb^ 

 other into a lateral tube connected with the gas evolution appa- 

 ratus. The reduction tube is enlarged at the upper end and is 

 closed by a well fitting tap. The pressure tube is open above. 

 All these tubes are drawn out below, so that strong rubber tubes 

 can be slipped over them. By means of a Y-tube of glass the 

 pressure tube is connected with the other tubes. The two taps 

 being open, mercury is poured into the pressure tube, previously 

 moistened, which of course rises in the other tubes. The barom- 

 eter and thermometer are then noted, the height of the barometer 

 corrected for the temperature and the pressure of aqueous vapor, 

 and the volume which 100 c. c. of air would occupy at the result- 

 ing pressure and temperature is calculated. The pressure tube is 

 then so adjusted in height that the mercury in the reduction tube 

 (graduated for this purpose from 110 to 130 c, c.) stands at the 

 division which represents the volume of 100 c. c. at the actually 

 corrected pressure and temperature, when the tap on the reduc- 

 tion tube is closed. This tube is thus made to enclose once for 

 all a quantity of air such that when the temperature is 0° and 

 the pressure 760 mm , the air being dry, it shall occupy 100 c. c. 

 By raising the pressure tube the measuring tube is filled with 

 mercury and the evolution of gas into it is proceeded with as usual. 

 To measure it, after the apparatus has acquired the temperature of 

 the room, the division 100 on the reduction tube is made some- 



