Manual of qualitative analysis / by Robert Galloway.

  • Galloway, Robert.
Date:
1861
Catalogue details

Licence: Public Domain Mark

Credit: Manual of qualitative analysis / by Robert Galloway. Source: Wellcome Collection.

    37/272 (page 19)
    lead is deposited to a great extent when the acid is diluted, sulphate of lead being less soluble in dilute than in con- centrated sulphuric acid. The dilute acid is prepared by adding four parts of water to every one of the concentrated acid. 5. Tartaric acid is generally sufficiently pure for analytical purposes. As it undergoes decomposition in solu- tion, a small quantity only should be prepared at a time. For use, dissolve one part, by weight, of acid, in two parts, by measure, of water. 6. Bitartrate of soda is prepared by dissolving a quantity of tartaric acid in water, dividing the solution into two equal parts, and neutralizing one exactly with carbonate of soda, and then adding the neutralized portion, and after- wards evaporating the whole solution until the bitartrate crystallizes. For use, make a saturated solution. 7. Acetic acid, when employed in analysis, ought to be free from non-volatile matter and sulphuric acid. Dilute one part of the acid with four parts of water. 8. Hydrosulphuric acid (sulphuretted hydrogen) is pre- pared by adding to sulphide of iron, in an appropriate apparatus, dilute sulphuric or hydrochloric acid. The sul- phuretted hydrogen is liberated in its gaseous state, and may be passed through any solution under examination; or a solution of the gas may be obtained by passing it through pure water. As this solution very soon decomposes by contact with the atmosphere, it ought to be prepared very frequently, and kept in well-stoppered bottles. Sulphide of iron, from which hydrosulphuric acid is. ob- tained, is prepared by projecting a mixture of thirty parts of iron filings with twenty-one of flowers of sulphur, in small portions at a time, into a red-hot crucible, replacing