TRANSACTIONS OP THE SECTIONS. 5\ 



The authors hope to find, between this date and the next Meeting of the Associa- 

 tion, a practical method of preparing this desirable alloy, which would render eminent 

 service to manufacture. 



The following alloys were also described, one composed of one equivalent of alu- 

 minium and five equivalents of copper ; one other of iron and zinc composed of one 

 equivalent of iron and twelve equivalents of zinc ; and what is interesting respecting 

 this last alloy, is not only its extreme hardness, but that it is produced at a temperature 

 of about 800°, it being formed hi a bath of zinc and tin containing 14 tons of metal, 

 and through which iron-wire is passed when coated with zinc or galvanized. 



The authors took advantage of having large melted mass of metals (zinc and tin) 

 at their disposal, to inquire into the following question, viz. if two metals, when 

 melted together, separate according to their respective specific gravity, or form a 

 homogeneous mass combined in definite proportions. 



They consequently analysed three samples taken from the melted bath, one near 

 the top, one in the middle, and one at the bottom. Strange to say, they all presented 

 a different composition ; and what is not less remarkable is, that the upper layer con- 

 tained the largest proportion of the heaviest metal. These three samples oSered the 

 following equivalents and definite composition: — 



m (I equivalent of tin, 

 •P' \ 11 equivalents of zinc. 



TW-1J1 / 1 equivalent of tin, 

 Miame-j^ jg equivalents of zinc. 



„ f 1 equivalent of tin. 



Bottom -^ jg equivalents of zinc. 



The authors also prepared several alloys of zinc and copper ; copper, zinc, and tin 

 and copper, zinc, tin and lead, having definite and equivalent composition; but they 

 intend to enter more fully into this subject next year. 



The action of acids on these alloys of copper, zinc, &c. presents this curious 'fact, 

 viz. that although hydrochloric acid attacks zinc and tin violently, still, in alloys con- 

 taining these metals with copper, they are not, or very slightly attacked by this power- 

 ful acid. Similar results were also obtained with sulphuric and nitric acids. 



On the Action of Sulphuretted Hydrogen on Salts of Zinc and Copper. 

 By F. Grace Calvert, F.C.S, 



In all our treatises of analytical chemistry, it is stated that the process to be fol- 

 lowed to separate zinc or its compounds from those of copper, is to render the liquors 

 acid which contain salts of these metals, and to pass a current of sulphuretted hydro- 

 gen, when the copper will be precipitated in the state of sulphuret, leaving the zinc 

 in solution. 



Having had lately to analyse several alloys of zinc and copper in connexion with some 

 researches on allovs, the author found it impossible to make two analyses of the same 

 alloy correspond satisfactorily. To ascertain the cause of error, he made several trials, 

 and soon found out that zinc, even in very acid liquors, was freely and sometimes 

 completely precipitated from them by sulphuretted hydrogen. He also remarked that 

 the facility with which zinc was precipitated from an acid solution depended in a 

 great measure on the peculiar salt of zinc which was in solution, and the nature of 

 the acid employed to acidify the liquor. The results contained in this paper are so 

 conclusive on this point, that the old method (which is still recommended in recently 

 published works on quantitative analysis) for the separation of salts of zinc from those 

 of copper must in future be rejected as completely inexact. 



The experiments were made by employing 18 grains of crystallized and pure sul- 

 phate of zinc, dissolving them in 400 grains of distilled water, and adding to the 

 liquor equivalent quantities of an acid; for example, as there existed in the quantity 

 of sulphate of zinc used for the experiment (18 grains) 5 grains of sulphuric acid, 2-5, 

 5, 10, 12*5, or 15 grains of sulphuric acid were added, after being previously mixed 

 with such a proportion of water as to give in each jar of an experiment 1500 grains 



4* 



