11 Mr. T. Bayley on the Analysis of Alloys 



hypothetical ; it is extremely improbable that two cosmical 

 bodies should move in the same straight line ; and of two 

 moving in different lines, it is improbable that either should 

 impinge against the other." In reply, if there are stellar 

 masses moving in all directions, collisions are unavoidable. 

 It is true they will be of rare occurrence : but it is well that it 

 is so ; for if they had been frequent the universe would be in 

 a blaze, and its store of energy soon converted into heat. 



II. On the Analysis of Alloys containing Copper, Zinc, and 

 Nickel. By Thomas Bayley, Assoc. R.C.Sc.l* 



THE analysis of these alloys can be very rapidly effected 

 by a combination of colorimetric and volumetric methods. 

 The alloy is dissolved in nitric acid, and the solution then eva- 

 porated to dryness with excess of sulphuric acid to expel nitric 

 acid, which must not be left in the solution. 



Determination of the Copper. — The solution is mixed with 

 excess of potassic iodide, which causes the formation of cuprous 

 iodide, according to the following well-known reaction : — 



2CuS0 4 + 4KI=2K 2 S0 4 + Cu 2 I 2 + I 2 . 



The solution containing the precipitate is then titrated with a 

 standard solution of sodic thiosulphate. The free iodine present 

 is an exact measure of the copper, each gram of copper being 

 equal to two grams of iodine. The following is the result of 

 a series of determinations of copper made under various cir- 

 cumstances by this method : — 



Cu taken. Iodine. 



•0635 Cu -1275 



•1250 Cu (free HC1 present) -2500 



•2531 Cu -5100 



•1408 Cu (free H 2 S0 4 present) .... -2740 



•1408 Cu (NiS0 4 present) -2755 



•1408 Cu (ZnS0 4 and free H 2 S0 4 present) -2760 



The solution, after the titration, is filtered and the precipi- 

 tate washed. The filtrate is free from copper and contains the 

 nickel and zinc. The absence of copper was proved in several 

 experiments by evaporating to dryness and gently heating the 

 residue, after which it was dissolved in a little dilute sulphuric 

 acid and excess of ammonia added. In no instance was any 

 blue colour perceptible. 



Determination of the Nickel. — The fact will have been ob- 

 served by chemists, that solutions of nickel and cobalt salts 



* 



Communicated by the Author. 



