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Band 1.1860
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- 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
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THE CHEMICAL Vol. I. No. z6. — June 2, i860. SCIENTIFIC AND ANALYTICAL CHEMISTRY. On the Detection of Chromium in Presence of Iron, by F. H. Stokee. (Concluded from page 266,) Sevekai, experiments have also been made in order to ascertain whether the presence of peroxide of iron would interfere with the oxidation of the sesquioxide of chro mium. Weighed portions of protosulphate of iron were hoiled with nitric acid in order to oxidise the iron, and mixed with weighed portions of chrome alum ; the solu tions were then treated with a slight excess of caustic ammonia and boiled. After washing the precipitates formed, they were subjected to the action of oxidising agents. I have oporated upon mixtures composed of— No. r. Grammes. Grammes. Per cent., poo FeOS0 3 + 7-aq | FeO,^ o 86$; or 84 81 4- > ==s I 00 K0S0 3 ; Cr 2 0 3 .3,S0 3 -r *4aq) Cr 2 0 3 0*1556 or 1579 No. a. poo FeOS0 3 A* 7<aq ) FeO : ^ 0*8633 or 9178 o'50 K()SO, : Cr 2 0 3 , pSQ 3 +24 :l q ) Cr 2 0 3 0-0773 or 8-22 No. p 5'ooFeOSO* +-7aq ) FeO,j 1-4389 or 97-38 0'*5 KOS0 3 j Cr 2 0 3 , pS0 3 +a4aq) Cr 2 0 5 0*0387 or l6z No. 4. io'oo FeOS0 3 + 7aq V FeO^ 2 8777 or 9873 0*25 K0S0 3 ; Cr 2 0 3 , pS0 3 +*4aq J tr 2 0 5 0:0387 or 127 No 5. *0-00 FeOSQ„ 4* 7 aq ) FcOjj 5*7554 or 99*33 o*2S KOSO5 ; C(* 2 0 3 , 3S0 3 4.24aq j Cr 2 0 3 0*0387 or 0 67 Portions of the precipitate produced by ammonia in each of these solutions were dissolved in chlorhydric acid, and a part of this solution was treated with an excess of cold potash lye of sp. gr. = 1*305 ; an excess of caustic soda of sp. gr, T = 1 *07 being added to another piortion. After standing in the cold, out of contact with the air, during eighteen hours, the alkaline mixtures were filtered, and the filtrates thoroughly boiled. No precipitate of sesquioxide o.f chromium was produced in any of them, nor did these filtrates afford any chromic acid when hoiled with peroxide of lead. Other portions of the moist original precipitates were dissolved in chlorhydric acid, and these solutions treated with a slight excess of dilute caustic soda, A small quantity of peroxide of lead was now added to the mix ture, and the whole thoroughly hoiled during two or three minutes. On filtering, yellow-coloured solutions were obtained in every instance, and on testing these with peroxide of hydrogen the characteristic reaction of chromic acid was very distinct in each. The oxide of chromium in other portions of all of the original precipitates was also readily oxidised by boiling them with bromine in presence of free alkali, as well as by dissolving them in concentrated nitric acid, and boil ing this solution with chlorate of potash. The presence of chromium was, moreover, readily detected in Nos. I and 2 by boding a mixture of precipitate and alkali with eroxide of manganese, or with permanganate of potash ; ut as these substances, are evidently less conveniently applied than the others which I have mentioned, no. further experiments were made with them. It should perhaps be stated that the experiments upon the precipitate from mixture No 5, were made upon portions of it weighing two or three grammes, the entire weight of the moist precipitate being something more than a hundred grammes. Among the various agents capable of oxidising oxide of chromium, when in presence of sesquioxide of iron, it is not at first sight easy to decide -which one should be preferred to, the others for common use. Bromine in presence of the alkalies appears to he the most powerful of them, but since the acid solution of peroxide of hy drogen, which, is used in testing, would react upon any bromide which might have been formed in the alkaline solution, bromine would be liberated, and, by imparting its colour to, the ether, would obscure the reaction* A similar objection applies of course to iodine. This difficulty is easily overcome by neutralising the alkali with nitric acid, and: boiling for a few minutes to. expel the bromine: an objection to this process, how ever, is the fact that the solution is considerably diluted thereby. Chlorate of potash, with concentrated nitric acid, is in some respects a very convenient agent: obj ections to it are, that some of the products of the decomposition of the chlorate which remain in the solution, appear to interfere with, the formation of perchromic acid ; more over, if any nitrate of chromium remain unoxidised in the solution, it will impart a bjujsh purple tint to the aqueous solution of peroxide of hydrogen, which, though insoluble in ether, often interferes very materially with the detection of the colour of pgrclpromip acid, if only traces of the latter are present. This remark applies to any process of oxidation in which nitric acid is employed. Both of these difficulties can generally he avoided by diluting the nitric acid solution with water, and using a quantity of ether somewhat larger than is usually neces sary. In any case where hyponitric acid is generated, it dissolves in the ether, and may conceal the blue colour of perchromic acid. Black oxide qf manganese is not only a less energetic oxidising agent than peroxide of lead, but the chromate formed in its presence does not colour the solution so strongly. The latter remark applies also to perman ganate of potash, another objection to which is the neces sity of destroying its own colour whenever it has, been used in excess, before testing for chromic acid. On the other hand, the reagent of Chancel, peroxide of lead, is capable, as I have shown, of oxidising sesqui-
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