Licence: Public Domain Mark
Credit: Qualitative chemical analysis / by C. Remigius Fresenius. Source: Wellcome Collection.
Provider: This material has been provided by the Royal College of Physicians of Edinburgh. The original may be consulted at the Royal College of Physicians of Edinburgh.
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![OXIDE OF LEAD. of lead is ignited in the air, part of it volatilizes, and leaves behind oxychloride of lead. 4. Sulphuretted hydrogen and sulphide of ammonium produce black precipitates ot sulphide of lead, PbS [PbS], which are in- soluble in cold dilute acids, in alkalies, alkaline sulphides, and cyanide of potassium. Sulphide of lead is decomposed by hot nitric acid. If the acid IS dilute, the whole of the lead is obtained in solution as nitrate of oxide of lead and sulphur separates-if fuming acid is used, the sulphur IS also completely oxidized, and insoluble sulphate of lead alone is obtained;—if the acid was of medium concentration, both reactions take place, a portion of the lead being obtained in solution as nitrate of lead, whilst the remainder separates as sulphate of lead, together with the unoxidized sulphur. In solutions of salts of lead containing a large- excess of a concentrated mineral acid, sulphuretted hydrogen produces a precipitate only after the addition of water or after partial neutraliza- tion of the free acid by an alkali. If a solution of lead is precipitated by sulphuretted hydrogen in presence of a large quantity of free hydro- chloric acid, a red precipitate is occasionally formed, consisting of chloride and sulphide of lead, which is, however, converted by an excess- ot sulphuretted hydrogen into black sulphide of lead. 5. Potassa, soda, and ammonia throw down basic salts in the form of white precipitates, which are insoluble in ammonia but soluble- m potassa and soda. In solutions of acetate of lead, ammonia (free from carbonic acid) does not immediately produce a precipitate, owing to the formation of a soluble di- or triacetate of lead. 6. Carbonate of soda in the cold throws down neutral carbonate^ and m a hot solution a more or less basic carbonate of lead as a white precipitate, which is not quite insoluble in a large excess of the pre- cipitant, especially on heating, but is insoluble in cyanide of potassium. 7. Hydrochloric acid and soluble chlorides produce in concen- trated solutions a heavy white precipitate of chloride of lead, PbCl [PbCI,], which is soluble in a large amount of water, especially on heat- ing : ammonia converts this into basic chloride of lead, PbCl,3PbO + 4II0, [PbCl2,3PbO,4H,0], which is also a white powder, but almost absolutely insoluble in water. Chloride of lead is more sparingly soluble in dilute nitric or hydrochloric acid than in water. 8. Sulphuric acid and sulphates produce a white precipitate of sulphate oi lead, PbO,S03[PbSO,], which is nearly insoluble in water- and dilute acids. From dilute solutions, especially from such as contain much free acid, the sulphate of lead precipitates only after some time,, frequently only after a long time. It is advisable to add a considerable excess of dilute sulphuric acid, as this tends to increase the delicacy of the reaction, sulphate of lead being more insoluble in dilute sulphuric acid than in water. The separation of small quantities of sulphate of lead is best effected by evaporating, after the addition of the sulphuric acid, as far as practicable on the water-bath, and then treating the residue with water; or, if allowable, with spirit. Sulphate of lead is slightly soluble in concentrated nitric acid; it dissolves with difficulty in boiling concentrated hydrochloric acid, but more readily in solution of potassa. It dissolves also pretty readily in the solutions of some of the salts of ammonia, particularly in solution of acetate of ammonia; dilute sulphuric acid precipitates it again from these solutions.](https://iiif.wellcomecollection.org/image/b21966953_0166.jp2/full/800%2C/0/default.jpg)
