Suche löschen...
The chemical news
- Bandzählung
- 1.1860
- Erscheinungsdatum
- 1860
- Sprache
- Englisch
- Signatur
- A63
- Vorlage
- Universitätsbibliothek Chemnitz
- Digitalisat
- Universitätsbibliothek Chemnitz
- Digitalisat
- SLUB Dresden
- Lizenz-/Rechtehinweis
- Public Domain Mark 1.0
- URN
- urn:nbn:de:bsz:14-db-id507022629-186000010
- PURL
- http://digital.slub-dresden.de/id507022629-18600001
- OAI-Identifier
- oai:de:slub-dresden:db:id-507022629-18600001
- Sammlungen
- Projekt: Bestände der Universitätsbibliothek Chemnitz
- LDP: Bestände der Universitätsbibliothek Chemnitz
- Strukturtyp
- Band
- Parlamentsperiode
- -
- Wahlperiode
- -
- Digitalisat
- SLUB Dresden
- Strukturtyp
- Ausgabe
- Parlamentsperiode
- -
- Wahlperiode
- -
-
Zeitschrift
The chemical news
-
Band
Band 1.1860
-
- Titelblatt Titelblatt I
- Sonstiges Advertisement III
- Ausgabe No. 1. - December 10, 1859 1
- Ausgabe No. 2. - December 17, 1859 13
- Ausgabe No. 3. - December 24, 1859 25
- Ausgabe No. 4. - December 31, 1859 37
- Ausgabe No. 5. - January 7, 1860 49
- Ausgabe No. 6. - January 14, 1860 61
- Ausgabe No. 7. - January 21, 1860 73
- Ausgabe No. 8. - January 28, 1860 85
- Ausgabe No. 9. - February 4, 1860 97
- Ausgabe No. 10. - February 11, 1860 109
- Ausgabe No. 11. - February 18, 1860 121
- Ausgabe No. 12. - February 25, 1860 133
- Ausgabe No. 13. - March 3, 1860 145
- Ausgabe No. 14. - March 10, 1860 157
- Ausgabe No. 15. - March 17, 1860 169
- Ausgabe No. 16. - March 24, 1860 181
- Ausgabe No. 17. - March 31, 1860 193
- Ausgabe No. 18. - April 7, 1860 205
- Ausgabe No. 19. - April 14, 1860 217
- Ausgabe No. 20. - April 21, 1860 229
- Ausgabe No. 21. - April 28, 1860 241
- Ausgabe No. 22. - May 5, 1860 253
- Ausgabe No. 23. - May 12, 1860 265
- Ausgabe No. 24. - May 19, 1860 277
- Ausgabe No. 25. - May 26, 1860 289
- Ausgabe No. 26. - June 2, 1860 301
- Register Index 313
- Beilage No. 1. December 10, 1859 I
- Beilage No. 2. December 17, 1859 IX
- Beilage No. 3. December 24, 1859 I
- Beilage No. 4. December 31, 1859 I
- Beilage No. 5. January 7, 1860 I
- Beilage No. 6. January 14, 1860 I
- Beilage No. 7. January 21, 1860 V
- Beilage No. 8. January 28, 1860 I
- Beilage No. 9. February 4, 1860 I
- Beilage No. 10. February 11, 1860 I
- Beilage No. 11. February 18, 1860 I
- Beilage No. 12. February 25, 1860 I
- Beilage No. 13. March 3, 1860 I
- Beilage No. 14. March 10, 1860 I
- Beilage No. 15. March 17, 1860 I
- Beilage No. 16. March 24, 1860 I
- Beilage No. 17. March 31, 1860 I
- Beilage No. 18. April 7, 1860 I
- Beilage No. 19. April 14, 1860 I
- Beilage No. 20. April 21, 1860 I
- Beilage No. 21. April 28, 1860 I
- Beilage No. 22. May 5, 1860 I
- Beilage No. 23. May 12, 1860 I
- Beilage No. 24. May 19, 1860 I
- Beilage No. 25. May 26, 1860 I
- Beilage No. 26. June 2, 1860 I
- Beilage No. 27. June 9, 1860 I
-
Band
Band 1.1860
-
- Titel
- The chemical news
- Autor
- Links
- Downloads
- Einzelseite als Bild herunterladen (JPG)
-
Volltext Seite (XML)
THE CHEMICAL NEWS. Vol. I. No. 3. —December 24, 1859. SCIENTIFIC AND ANALYTICAL CHEMISTRY. Remarks on Parkes's Method for the Estimation of Copper by means of Cyanide of Potassium, toy ether with a brief Review of the Modes usually adopted for the Determina tion of Copper, by Fbedebick Field. [fikst pakt.] In one of the numbers of the Mininy Journal, in the year 1851, Mr. Parkes published a method for the volumetric determination of copper, by means of a standard solution of cyanide of potassium. The process is so well known, and has been so generally adopted, that a detailed ac count of the modus operundi would be unnecessary. The substance containing copper'is dissolved, ammonia added in excess, and solution of the cj'anide dropped carefully into the dark blue liquid until the colour disappears. Towards the latter stage of the process, however, the decolorisation is not very distinct, the solution assuming a delicate violet tint, which fades very gradually, leaving at length the liquid destitute of colour. Great caution and considerable practice are required to determine the necessary amount of cyanide. There can be no doubt that it is requisite to allow the liquid to stand for some time (a quarter of an hour or twenty minutes) towards the close of the operation; and if the colour is not ex pelled after that period a few drops more cyanide must be added, the flask well agitated, and the solution once more left at rest. Indeed, it is always safer to leave a very slight tint, as it disappears after the lapse of twelve or fourteen hours. Since the publication of Mr. Parkes’s method, I have made considerably more than fifteen thou sand estimations of copper by the cyanide process, com paring it with many other well-known modes of deter mination, in order to test its accuracy, and to observe the influence which solutions of other metallic oxides possess when in conjunction with that of oxide of copper. In the case of copper ores, containing copper either combined with sulphur, as disulphide or protosulphide; with sulphuric acid, as brochantite or cyanose; with oxy gen, as suboxide or protoxide ; with carbonic acid, as the blue and green basic carbonates; with chlorine, as ataea- mite; with phosphoric acid, as tagilite, &c.; as arsenide in Domeykite or algodonite, and with arsenic or arsenious acid, provided no iron be present; in alloys of copper and tin or copper and antimony; double sulphides of copper and iron, either as yellow or blue pyrites, the copper can be estimated with exactness by cyanide of potassium. Now, in all copper ores containing iron, it is far better to add the cyanide to the ammoniacal solution, without filtering off the suspended peroxide of iron. Every chemist knows with what tenacity this oxide holds an ammoniacal solution of copper. Even after several hours washing with warm liquid ammonia, the copper cannot be sepa rated; and although the liquid may pass through colour less, on rewashing, after a day or two, the filtrate will have a decided blue tint. The test first proposed, I believe, by Mr. Warington (and which, decidedly, is the most delicate one for the presence of copper which we possess), viz. ferro-cyanide of potassium, never fails to show the presence of copper in the peroxide of iron, even when hydro-sulphuric acid or ammonia are unable to detect it. If a small quantity of copper with a large excess of iron be dissolved in nitric acid, a considerable quantity of ammonia added, and the two metals separated by filtration, after washing for several days, on taking a small portion of the oxide of iron, dissolving in hydro chloric acid, adding ammonia and filtering, a drop of the ferrocyanide added to the filtrate in a white capsule, is sure to give a pink stain on the porcelain, when the excess of ammonia has been expelled by a gentle heat. There is no need whatever for filtering oft' the oxide of iron, and the estimation of copper can be effected in a very satis factory manner without undergoing filtration. I11 copper slags, for example, which generally contain from o'2 to o-8 per cent, of copper, and from 40 to 50 per cent, of iron, it is impossible to determine the former metal, with any degree of accuracy, by the addition of ammonia and subsequent filtration. Cyanide of potas sium added to the liquid in which the oxide of iron re mains suspended, is capable of estimating the amount ot copper with considerable exactness. A rim of liquid, more or less blue, gradually appears above the precipitating oxide, a few drops of the standard decolorising solution are added, the whole well agitated, and allowed to rest, until the clear liquid reappears. If still strongly co loured, more cyanide is required, and this operation is continued until the liquid lias a pale violet, or rather, rose-coloured tint. It is then left for some time, and if the shade do not seem to fide, a small quantity more is added. The result of numerous estimations prove, that small quantities of copper can be determined very suc cessfully by this means; and when several slags or other metallurgic products have to be examined, the method is very convenient, as, while the oxide of iron is subsiding in one flask, another assay can be undergoing decolori sation from the burette, and so on. In order to test the accuracy of the process, two or three experiments may be cited from among a great many which have been made. A mineral containing simply sulphur, iron, and copper, with a little quartz, gave in five determinations: — 31-4 per cent. Cu. • 3i'5 3i'3 3i’4 3>'4 >. .. or a mean percentage of 31’4. Four estimations were made by precipitating the cop per from the solution of its oxide in hydrochloric acid, by means of metallic iron: — 31-38 per cent. Cu. 3 r 4 z .. ». 3 >'47 .. .» 3>’44 .• ..
- Aktuelle Seite (TXT)
- METS Datei (XML)
- IIIF Manifest (JSON)