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 LVIII. Intelligence and Miscellaneous Articles. 



ON PHOTOGRAPHS OF RAPIDLY MOVING OBJECTS. 



To the Editors of the Philosophical Magazine and Journal. 

 G-ENTLEMEK, St. Petersburg, October 24, 1890. 



1\/FB. C. V. BOYS has published in the September number of the 

 ItX Philosophical Magazine a paper (" Notes on Photographs of 

 Rapidly Moving Objects, and on the Oscillating Electric Spark") 

 containing the description of a direct method for photographing a 

 liquid jet. 



I myself have already successfully used the same method in 



1889, and I communicated the results of my researches to the 

 Russian Physico-Chemical Society at the meeting on February 11, 



1890. By the aid of this method I have now investigated the 

 constitution of the jet of a pulverulent body issuing through the 

 orifice of an ordinary glass funnel, C millim. in the clear, either 

 under the influence of its own weight or aided by the pressure of 

 compressed air ; and I have the honour of sending you the results 

 in the form of the four photographs enclosed, which may interest 

 you. A plate or a sheet of paper sensitized with gelatino-bromide 

 of silver was placed vertically behind the jet, which was illuminated 

 in front by the spark of a Voss's machine. The enclosed photo- 

 graphs show clearly that jets of pulverulent bodies are made up 

 of nodes and loops, and of detached drops like those of liquids. 

 The powders used were lycopodium, emery, and sand. 



I am continuing my researches with the object of determining 

 whether the constitution of jets of pulverulent bodies may be 

 attributed to a kind of surface-tension, or to some other cause ; 

 and, further, to examine the influence of heat on the phenomenon, 

 and so forth, 



I have the honour to be, 



N. Khamontoff, 

 Assistant in the Physical Laboratory of the 

 University of St. Petersburg. 



ON DROPPING-MERCURY ELECTRODES. BY W. OSTWALD. 



I am glad to find a perfect agreement between Mr. Brown's 

 observations on dropping-currents and mine. For I have asserted 

 that the current between a dropping electrode and an electrode of 

 stationary mercury is constant if the latter receives the drops, but 

 is much weaker, and decreasing, if not. Mr. Brown likewise 

 asserts that at the first moment both currents are of the same 

 strength. I have not the least doubt that this is so, for at the first 



