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The chemical news
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- 1.1860
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The chemical news
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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 NEWS. Vol, I. No. 16.'—March 24, i860. SCIENTIFIC AND ANALYTICAL CHEMISTRY. On a Simple anil Expeditious Method of Estimating Phosphoric Acid and its Compounds, hy E. W. Davy M.B. M.E.I.A. Professor of Agriculture, Agricultural Chemistry, to the Royal Dublin Society.* The want of a simple and expeditious method of esti mating phosphoric acid and its compounds, has long been felt, most of the means devised being tedious and compli cated. After much investigation, the author has devised a method founded on the fact that phosphoric acid pos sesses a great attraction for peroxide of iron. When a persalt of iron is added to a solution containing phos- f ihoric acid an insoluble phosphate is produced. This fact las long been known, and different methods founded on it have been devised by Berthier, Kobell, Raewsky and others, for the estimation of phosphoric acid and its com pounds. But as each of those methods requires a con siderable time for the collecting, washing, drying, ig niting, and weighing of the precipitated phosphate of iron, the author proposes to dispense altogether with those operations by simply adding a solution of iron of known strength to the phosphate, and ascertaining' the point when enough has been added to combine with all the phosphoric acid present. The standard iron solution is made by dissolving clean pianoforte wire in pure hydrochloric acid, and sufficient nitric acid is added to convert the proto- intoper- chloride* of iron. Any free hydrocloric acid is then carefully neu tralised with caustic ammonia, which is added imtil a little peroxide remains undissolved on shaking the mixture. Acetic acid is now added to dissolve the precipitated oxide, and when the solution is effected the mixture is largely diluted with distilled water and graduated in the ordinary way, so that the amount of iron in a given quantity may be known. This solution may be kept a considerable time without undergoing change, and is therefore preferable to the acetate and other salts of iron which have hitherto been employed. The next step is to prepare the phosphate. If inso luble (as is generally the case) it is dissolved in an acid. Ammonia is added imtil the solution is decidedly alka line, but not in large excess, and then enough acetic acid to completely redissolve the precipitated phosphate, and leave a slight excess. The standard solution of iron is then carefully added from Mohr’s alkalimeter, or any other convenient form of volumetric apparatus, till the iron begins to bo in slight excess, which is ascertained by taking a drop of the mixture (after it has remained a few minutes with occasional Stirling) on a glass rod, and touching with it a piece of thick filtering paper, placed over another piece of paper which has been soaked in a solution of gallic acid and dried. The insoluble phos phate of iron is retained on the filtering paper and the Abridged from the L, E. and V. Phil. Mag. . solution which passes down to the lower shows at once by the purple stain when sufficient iron has been added and a minute excess exists in the mixture. If this excess is very minute, the stain will become more visible when the gallic acid paper is dried. The results should be controlled by repeating this experiment a second and third time, having the phosphate dissolved in a given quantity of solution, and taking a certain amount of it for each determination. The author’s experiments have clearly shown him that under the conditions in which the iron and phosphoric acid are placed, a compoimd having the uniform compo sition (Fe,,0,.P0 5 ) is produced, and therefore the objections hitherto made to the volumetric method of estimating phosphoric acid are obviated. Ex periments made with pyrophosphate of magnesia, tri- basic phosphate of lime, and anhydrous pyrophosphate of soda, all gave results agreeing closely with the cal culated composition, as will be seen by the following- table : Amount of iron required to combine with the P0 5 con tained in one grain of Ey calculation, 1*. parts of a grain, ^ By experiment. f o'jooo . ist experiment o'5ooo. Pyrophosphate of j „ . and „ „ Magnesia .1 „ .3rd „ L ff 4-th ,, ,, { C3589 , ist experiment o’36oo. „ . 2nd „ „ „ • 3rd „ „ ft • 4^^ ft a Anhydrous pyro- f 0 '™ ’ experiment o' 4 2oo. phosphate of I ” * , ” soda . . ” * ” ” L j) • 4 tn ft tt In all cases, however, bibasic salts must be converted into tribasic before the addition of the iron solution, which may be done by heating them with a little hydro chloric acid; and then the solution must be allowed to cool before the estimation is made, as heat alters the conditions and gives rise to a different compound of iron and phosphoric acid. The method appeal’s particularly useful for estimating the quantity of soluble and insoluble phosphates in superphosphate of lime as well as other manures, in.the ashes of plants, and in all cases in which an expeditious determination of the phosphates is required. Solubility of Mercury Precipitates in Alkaline Salts, by J. Attfield, Demonstrator of Chemistry at St. Bar tholomew's Hospital. The precipitates that are obtained on adding an alkali to tho solution of a mercuric or a mercurous salt, are described in the ordinary text-books as being insoluble in an excess of the reagent. Practically, however, this is far from being the fact; the acid with which the mercury was combined forming an alkaline salt in which in nearly all cases the mercury precipitate is move or less
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