On some salts and products of decomposition of pyromeconic acid / by James F. Brown.

Date:
[1852?]
Catalogue details

Licence: Public Domain Mark

Credit: On some salts and products of decomposition of pyromeconic acid / by James F. Brown. 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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    ill crystals of considerable size. 3-41 grains aqueous solution of this salt at G0° gave 1-08 grain of residue at 312° = 0-31 per cent. 6-15 grains substance gave 10'26 carbonic acid and 1-5G water. G-34 grains substance gave 2-34 carbonate of lime. Calculation Experiment Carbon . . 42-94 42-85 C'o 60 Hydrogen . 2-60 2-85 II'' 4 Oxygen . . 34-02 34-30 0^ 48 Lime . . . 20-44 20 00 CaO 28 100-00 100-00 l40 00~ Hence the composition of the salt is represented by the for- mula CaO, Ci° 0^ + HO. Pyromeconate of Magnesia.—A warm aqueous solution of py- romeconic acid gives with acetate of magnesia a white amorphous precipitate, insoluble in water and alcohol. In its properties it closely resembles the other pyromeconates. The following is the analysis of the salt, the magnesia being determined by igni- tion of it, and weighing the residue. It loses nothing at 212°. 4-925 grains substance gave 8-735 carbonic acid and 1-235 water, 4-595 grains substance gave -76 magnesia. Experiment. Calculation. A Carbon . . 48-37 48-ol C'« 60 Hydrogen . 2-76 2-41 II'^ 3 Oxygen . . 32-34 32-37 0^ 40 Magnesia . 16-53 16-71 MgO 2067 10000 100-00 123-67 From which it appears that this is the only earthy salt of py- vomeconie acid which is anhydrous, the composition of it being expressed by the formula MgO, C^ H^ 0^ Pyromeconate of Lead.—When a warm concentrated solution of pyromeconic acid, made ammoniacal, is added to acetate of lead, it causes an immediate precipitate of a dense crystalline powder, which rapidly increases upon violent agitation of the fluid. This salt, as has already been mentioned, was prepared and analysed by Robiquet, who formed it by adding hydrated oxide of lead to a hot solution of pyromeconic acid; he found it to he anhydrous, and to consist of PbO, C'° H-'' O'. The crystals require a considerable quantity of hot water for their solution; they are not so soluble in alcohol either hot or cold. It is colourless when thrown down, but ra]iidly becomes yellow bv exposure for any length of time^o bright daylight.