A eas ae Sas ee ae ee 
Chemistry and Physics. 407 
compounds of baryta left in the veins of crystalline rocks are in 
a first stage; and that in spite of all present differences of occur- 
ence pe association, the baryta and strontia minerals may be 
ae d to the same origin in the old crystalline rocks of 7 earth’s 
11. The illumination of gases by Electric discharges. aie fes- 
sor K. WiEDEMANN continues sh _ on the nature - aoe 
Ree 
ing at 
be illuminated by electrical aeiasase y means of a at 
calorimeter, in connection with a peculiarly — exhaustion 
tube, Professor Wiedemann was enabled to arrive at the amount 
of heat communicated to the gas under examination at different 
pressures. The t temperature o f the gas in the beginning was in 
the neighborhood of 20° C. and reached a maximum of from 80° 
90° b ans of the discharges from a Ruhmkorf coil, even at 
this temperature the gas was bri inatiy illuminated; and the 
temperatures of 62°-70° was not found to be the lowest at which 
The illumination of the gas at such low temperatures is produced, 
Professor Wiedemann thinks, by an exaltation of the living force of 
the oscillatory movements of the ether envelopes. The electrical 
discharge calls pe - action spr aeyrey: of the increase of 
molecular moveme ich results from the increase of tempera- 
ture, git Page der "Phys sikund Chemie, No. 2, 1879, p. 298. 3.7. 
A new current interrupter.— Dr. F, Nremouier describes an 
extremely simple and efficacious form of paar ide Speke l'o the mid- 
without the inte of parents means. This 5 sate 
when the fundamental note of the string is in unison with t 
pitch of oe interrupter.— Annalen fi Physik und Chemie, No. 2, 
1879, p. 3 
13. The dimensions of Molecules.—R. R@HLMANN, by means of 
the formula 
action, calculates the sum of the molecular sections. Since 
N if I 
ee np the number of molecules in the unit of 
volume, we 
Le ae | 
~ 4a/Qh 
Am. Jour. 8co1.—Tuirp Series, Vou. XVII, No. 101.—May, 1879. 
28 
