OF ZINC AND ANTIMONY. 



361 



quite cover the differences between the first ten numbers of column 1, excepting the 

 first, so difficult is it to granulate the alloys to a uniform size, and submit them during 

 the experiments to precisely similar conditions. The numbers of column 3, from which 

 the variations due to difference of surface have been eliminated, are probably, relative- 

 ly to each other, very nearly correct. 



Table of the Amounts of Hydrogen Gas evolved hy 200 Grammes of Different Alloys 

 of Antimony and Zinc, in Ten Minutes, at \0(f C. measured at about 2(f C. 



A mere glance at the table will discover two facts : — 



1st. That up to 40 per cent no great increase in the amount of hydrogen evolved is 

 obtained by increasing the amount of zinc in the alloy. 



2d. That at the alloy containing 42 per cent of zinc there is an immense maximum, 

 which is confined at most between two per cent on either side. 



It is a well-known fact, that the rapidity of the evolution of hydrogen from dilute 

 sulphuric acid and zinc can be very greatly increased by adding to the materials a few 

 drops of a solution of bichloride of platinum. The platinum, being immediately de- 

 posited over the zinc, forms with it a galvanic pair, and thus increases the affinity of 

 the zinc for oxygen. The same increased action can be produced by the same means 

 in the decomposition of pure water by the antimony and zinc alloys. Column 2 of the 

 table gives the results which were obtained by boiling with pure water in a small flask 

 200 grammes of the granulated alloys previously treated, witli the same amount in each 



VOL. V. NEAV SERIES. 49 



