468 



METALS. 



be instantly obtained by the following method, 

 without any mixture of protoxide : Before re- 

 ducing the precipitate produced by the pot- 

 ash in the sulphate solution, by means of the 

 inverted sugar, neutralize the acidity of the 

 sugar solution, and, when the precipitate of the 

 copper hydrate is almost entirely redissolved, 

 filter it, and boil the limpid liquid thus ob- 

 tained ; the metallic copper will then be seen 

 to fall, but its color is not quite so bright as in 

 the former experiment. 



Refining Copper. Dr. Le Clerc, of Paris, 

 has recently devised a new process for refining 

 copper. He subjects black copper, in a more 

 or less impure condition, to heat in a reverbe- 

 ratory furnace. After it has reached a suffi- 

 ciently high temperature to begin to soften, 

 water is projected on the heated metallic mass, 

 in the form of very fine jets, until the complete 

 fusion of the metal is obtained, when the sup- 

 ply of water is stayed. Supposing the copper 

 to contain iron, sulphur, arsenic, antimony, 

 lead, or tin, the water coming in contact with 

 the mass is decomposed, and forms sulphuret- 

 ted, arseniated, or antimoniated hydrogen, 

 which disengages. The oxygen of the water 

 then acts on the copper, iron, and other, fixed 

 metals, and forms oxides, which derive silica 

 from the sides of the furnace, and pass into 

 scoria. A small amount of sulphuric, arseni- 

 ous, and antimonious acid is produced, which 

 disengages in the form of vapor. When the 

 copper is completely fused, a tube of refractory 

 clay is placed in the metallic bath, the diameter 

 of which tube is proportionate to the quantity 

 of copper forming the bath. A large amount 

 of atmospheric air is then projected through 

 the tube, when a lively reaction takes place, 

 and the refining is completed in a very short 

 time, often in a few minutes, when the copper 

 to be refined is not very impure. The best way 

 to pass the air into the midst of the copper 

 bath is through the tube at the centre of the 

 roof of the furnace. It is essential that the 

 treatment should extend beyond the period 

 of oxidation, and, when the metal on examina- 

 tion is found to be of a deep or brick-red color, 

 the refining is complete. By extending the 

 oxidation, as directed, a large quantity of oxide 

 of copper may be obtained, which has the 

 property of giving up its oxygen to foreign 

 matters, and in this manner conduces to the 

 reduction of the copper. The production of 

 the protoxide of copper in superabundant quan- 

 tity causes a considerable loss of copper, unless 

 th precaution is adopted of adding to the bath 

 a mixture of from two to five per cent, of char- 

 coal and lime, which should be well stirred in. 

 By this means the complete reduction of the 

 silicate is effected, and the loss of copper en- 

 tirely prevented. 



Tinning Copper Vessels. In France, says 

 the Journal of the Society of Arts, the police 

 regulations require that nothing but pure tin 

 shall be used in coating copper saucepans ; but 

 that metal is dear, while lead is cheap, and 



therefore a mixture of the two metals is too 

 often made use of. When the lead forms a 

 considerable part of the mixture, the vessels 

 become dangerous to use. In consequence of 

 information obtained, the Minister of War re- 

 cently ordered an inquiry to be made into the 

 subject by the directors of the military hospi- 

 tals. The result of the investigation has been 

 read before the Academy of Medicine, and 

 brings out the startling fact that some manu- 

 facturers of copper utensils and some tinners 

 mix 25 and in some cases 50 per cent, of lead 

 with the tin ; and that, besides this, antimony, 

 another dangerous metal, is added. From the 

 facts thus presented, M. Gobley, a member of 

 the Academy of Medicine, has recommended : 

 1, that the metal used to line copper drinking- 

 vessels shall contain no more than 1 per cent, 

 of lead ; 2, that not not more than 5 or 6 per 

 cent, of lead be mixed with the tin used for 

 saucepans or other cooking-vessels, that amount 

 offering no serious danger; 3, that eVery maker 

 shall be required to mark his productions with 

 a special stamp ; 4, that the travelling tinmen 

 shall be strictly watched. 



Crystallized Tin-foil. Ym-foil having a 

 crystallized surface, and coated with transpar- 

 ent varnishes or gelatine of various colors, has 

 lately come into large demand for the fancy- 

 goods business in Paris and Germany. Puscher, 

 of Nurnburg, publishes this process of getting 

 the crystalline surface on the tin. A solution 

 is made of two parts of chloride of tin in four 

 parts of hot water, and to this are added one 

 part of nitric acid and two parts of hydro- 

 chloric acid. The foil is dipped in this mixture 

 and left until the crystals appear. As soon as 

 they appear, the foil must be rinsed with cold 

 water, and its surface well sponged. When 

 the solution is applied to cold foil the crystals 

 are small, but very brilliant. Large crystals can 

 be obtained by heating the tin-foil before the 

 solution is applied. This can best be done by 

 placing the foil on a hot plate and brushing on 

 the solution when the melting-point of the tin 

 is nearly reached. After the rinsing the foil 

 is attached to paper, and then the colored 

 varnish or gelatine is applied. Some beautiful 

 specimens of this manufacture are coated with 

 varnishes colored with the aniline dyes. The 

 solution mentioned may be used as a test for 

 the" purity of tin, inasmuch as tin containing 

 only as little as one per cent, of lead or copper 

 will not give a crystalline surface. 



The Eeaton (or Nitrate) Steel Process. The 

 merits and alleged defects of the Heaton pro- 

 cess have undergone a searchiug examination 

 at the hands of the iron-masters and chemists 

 of Great Britain. So fierce has been the disr 

 pute over this subject, that it is impossible to 

 determine, after much reading of the contro- 

 versy, whether the process is or is not one of 

 the great discoveries of the age. The chief 

 opponents of Mr. Heaton's plan are the Besse- 

 merites, who are rivals of his. Mr. Bessemer 

 himself has taken a conspicuous part in the 



