﻿474 Intelligence and Miscellaneous Articles. 



of the precipitate, removing the excess of sulphuretted hydrogen by 

 carbonate of silver, distilling the filtered liquid in a leaden retort 

 with a condensing-tube of platinum, and, finally, rectifying. 



The effect of cold upon the aqueous acid was briefly examined, the 

 result being that a comparatively small amount of hydrofluoric acid 

 lowers the freezing-point of water very considerably. 



The chemico-electric series of metals &c. in acid of 10 per cent, 

 and in that of 30 per cent, were determined. In the latter case it 

 was as follows : — zinc, magnesium, aluminium, thallium, indium, 

 cadmium, tin, lead, silicon, iron, nickel, cobalt, antimony, bismuth, 

 mercury, silver, copper, arsenic, osmium, ruthenium, gas-carbon, 

 platinum, rhodium, palladium, tellurium, osmi-iridium, gold, iridium. 

 Magnesium was remarkably unacted upon in the aqueous acid. The 

 chemico-electric relation of the aqueous acid to other acids with pla- 

 tinum was also determined. 



Various experiments of electrolysis of the aqueous acid of various 

 degrees of strength were made with anodes of platinum. Ozone 

 was evolved, and, with the stronger acid only, the anode was cor- 

 roded at the same time. Mixtures of the aqueous acid with nitric, 

 hydrochloric, sulphuric, selenious, and phosphoric acids were also 

 electrolyzed with a platinum anode, and the results are described. 



LXVI. Intelligence and Miscellaneous Articles. 



ON THE VOLTAIC DEPORTMENT OF PALLADIUM. 

 BY J. C. POGGENDORFF. 



TIN" his remarkable research on hydrogenium, Mr. Graham has shown, 

 •■- among other things, that palladium when it takes up hydrogen 

 expands, and, when the hydrogen escapes, contracts apparently more 

 strongly than it had previously expanded. A palladium wire which 

 originally measured 609*144 millims., and by absorbing hydrogen 

 had become longer by 9' 7 7 millims., after the hydrogen had been 

 expelled, was found to measure 599*444 millims., and had therefore 

 shortened to the extent of 9*7 millims. 



Where no exact numerical determinations are required, both phe- 

 nomena may be very strikingly demonstrated if palladium is charged 

 with hydrogen by electrolysis, a very thin plate being used. I used 

 a plate which was 118 millims. long by 23 millims. broad, and only 

 1 millim. thick, placed at a distance of 8 millims. from a platinum 

 plate in dilute sulphuric acid. 



If this be connected w T ith a small Grove's battery of two elements, 

 so that the palladium becomes charged with hydrogen, the following 

 is observed. 



Even after a few minutes the palladium plate begins to bend away 

 from the platinum, and gradually becomes greatly curved. After 

 about a quarter of an hour this has reached its maximum. A cur- 

 vature then commences in the opposite direction, so that the plate 

 first becomes straight, and then curves towards the platinum, which 



