TiCHBORNE — Laboratory Notes. 81 



XIY. — Laboeatort Xotes.* By Chaeles E. C, TlCHBOE^"E, Ph. D,, \/ 



F. C. S., &c. 



[Eead December 14, 1874.] 



3. — On the Solution of Alloys and Metals ly Acids. 



Hating to form a number of estimatioBS of tin, in alloys of tin and 

 lead, I found it necessary to effect solution of the mixed metals in 

 Hydrochloric Acid, and to devise a quick and expeditious method of 

 bringing this about withoutloss of substance. The alloys were dissolved 

 in the ordinary manner and according to the usages of laboratory 

 experience, that is to say — in each case a weighed quantity of the 

 alloy was coarsely rasped by a clean plumber's file, and placed into 

 a rather capacious flask, with the necessary quantity of pure Hydro- 

 chloric Acid ; an Indian-rubber stopper was inserted, through which. 

 passed a short tube. The flask was placed upon a sand bath at an 

 angle of about 45 degrees, so that no loss from spitting could take place 

 up the neck. Platinum was introduced for the purpose of making an 

 energetic voltaic circuit and to assist the solution. The action with . 

 the alloy itself is energetic enough at first, but it gradually subsides and 

 becomes languid after the Hydrochloric Acid has become in any degree 

 saturated. If the platinum, however, be inti'oduced, this sluggishness 

 is avoided. Prom the nature of the experiment time was an object of 

 considerable importance, and yet a great excess of acid was not 

 desirable. The introduction of platinum foil to facilitate solution of 

 other metals is no novelty, but I found it convenient to use a modifi- 

 cation, which I consider sufficiently important to note. 



From the electrical condition of the platinum foil and its great 

 attraction for the electro-positive hydrogenium, an intermittent and 

 rather curious reaction is set up in the flask where solution is effected. 

 The platinum foil sinks on its introduction until it touches the particles 

 of metal lying upon the bottom of the flask, when it instantly becomes 

 covered with the electro positive hydrogenium, and the foil rises to the 

 surface of the liquid, and there discharges the hydrogen gas, and then 

 sinks again until it comes in contact with the alloy, when the pheno- 

 menon is repeated, as long as any alloy remains. It is therefore self- 

 evident that this intermittent process must greatly retard the consumma- 

 tion of perfect solution. 



To remedy this, I substitute small spheres of platinum about the 

 size of swan shot. The rounded particles of platinum act perfectly, the 

 hydrogen being much more readily illiminated from the spherical 

 surface, and in no case does the platinum float. If the operation is 

 performed in a flask as recommended, from the shape of the vessel these 

 particles of platinum are also in actual contact with the aUoy during 

 the whole of the process. 



Solution is effected in nearly half the time, and the loss upon the 



* Continued from Ser. II. Yol. I. Science, p. 105. 



Jl. I. A. PROC, SER. II. VOL. II., SCIENCE. M 



