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.

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    solution must then be boiled for some time, adding a little water from time to time, to replace that which is evaporated. To the solution, which must not be filtered even if a preci- pitate has been formed, is added, when it is cold, sulphuric acid slightly in excess; if in some hours after the acid has been added a precipitate appears, nickel is present; if no precipitate appear, or at least only a crystalline one which —redissolves in water, nickel is absent. 167. Nickel may also be detected in the presence of cobalt by the two following methods. 1st method:—“The acid solution which contains cobalt and which may contain nickel, must be evaporated nearly to dryness, nitrite of potash must then be added in not too small a proportion, then acetic acid to strongly acid reaction, then let the mixture stand for at least several hours in a moderately warm place, when cobalt will separate as nitrite of sesquioxide of cobalt and potash; the nickel may then be readily precipitated from the filtrate by soda or sulphide of ammonium. 2d method:—Saturate with chlorine the very dilute solution of the two metals in hydrochloric acid, having the acid slightly in excess; add carbonate of baryta in excess, and let the fluid stand twenty-four hours. The cobalt is entirely pre- cipitated in this process as black sesquioxide, whilst the nickel remains in solution, and may, after the removal of the baryta by sulphuric acid, be thrown down with solution of soda.” * 168. The following precautions are to be attended to in the analysis of this group :—When manganese is present, care must be taken to expel all the sulphuretted hydrogen from the hydrochloric acid solution, before carbonate of ammonia is added to separate the manganese from the zinc. Before * The student ought to state all the different methods which could be adopted for the separation of the members of this group.