Geology and Mineralogy. 71 
A current of -000,000,001 A. gives a deflection with suitable dis- 
tance of reading telescope of 0-7 of a scale division.—Ann. der 
Physik und Chenrie, No. 11, 1886, p. 491. THD: 
6. Metallic deposits formed by electrical discharges:—Pro- 
fessor Wright of Yale College described in this Journal, vols. xiii 
and xiv, 1877, a method of obtaining very thin deposits of metals 
by electrical discharges in rarefied air. The subject has been 
taken up anew by Hr. Bernard Dessau, who investigates the inter- 
ference phenomena produced by such thin layers. Generally 
these layers are thicker directly opposite the electrode from which 
the metallic particles are thrown off. Hence a cone is formed of 
avery small altitude. The deposits showed in reflected light 
colored interference rings. The dispersion in the metals platinum, 
iron, nickel and silver, the author calls normal, and that with gold 
and copper abnormal. The cross of double refraction was also 
noticed in reflected light.—Ann. der Physik und Chemie, No. 
11, 1886, pp. 353-376. iy an 
7. Electricity arising from the condensation of vapor. — It 
has been maintained by Palmieri and others that the condensation 
of vapor results in the production of an electrical charge. Hr. . 
5. Kalischer has renewed his investigations upon this point and 
believes that he has proved that no electricity results from such 
condensation. Atmospheric vapor was condensed upon a vessel 
coated with tin foil, filled with ice, carefully insulated and con- 
nected with a very sensitive electrometer. No evidence could be 
obtained of electricity. —Ann. der Physik und Chemie, No. 11, 
1886, p. 407. deuce 
II. GroLtocy AND MINERALOGY. 
1. The Charleston Harthquake.—The earthquake which oc- 
curred in the southeastern United States on the evening of Aug. 
31, 1886, and which will doubtless always be known as the 
Charleston Earthquake because of the great destruction caused 
by it in that city, is being made the subject of careful study by 
the seismologists of America, and there is good hope that valuable 
results for the future of seismology may issue from their work. 
Rarely if ever has a better opportunity for study been presented. 
The primary shock was of sufficient intensity to destroy many 
buildings in Charleston and vicinity and was felt over a land area 
of nearly 800,000 square miles, extending from the great lakes to 
the gulf and from beyond the Mississippi to the Atlantic, being 
felt also very slightly in the Bermudas and in Cuba, This large 
area is covered with a network of telegraph lines whose offices 
were ready at once to collect and communicate the news of the 
shock; and the standard time is very generally in use, so that the 
records of time give fair promise of accuracy and are readily 
comparable. Our country is also supplied with active newspapérs 
which put on record with care and in full detail the phenomena 
of the shock. 
To these general means of information are to be added others 
Set in operation for this special occasion. Major Powell, the Di- 
