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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![if they are very dilute and cold, it forms only after some time ; in the latter case it is more distinctly ciystalline, and consists of a mixture of the above salt with 2CaO,C,Og + 6aq [CaC,0„3H.p]. Oxalate of lime dissolves readily in hydrocldoric and nitric acids, but not appreciably in acetic or oxalic acids. 6. Neither cliromate of potassa nor dichromate of potassa pre- cipitates solutions of salts of lime. 7. When soluble salts of lime are heated with dilute spirit of wine, they impart to the flame of the latter an orange-red colour, which is liable to be confounded with that communicated to the flame of alcohol by salts of strontia. 8. If salts of lime are held in the fusing zone of the Bunsen gas flame, or in the inner spirit blowpipe flame, they impart to the flame an orange-red colour. This reaction is the most distinct with chloride of calcium; sulphate of lime shows it only after its incipient decomposition, and carbonate of lime also most distinctly after the escape of the carbonic acid. Compounds of lime with fixed acids do not coloui- flame; those which are decomposed by hydrochloric acid will, however, show the reaction after moistening with that acid^ The reaction is in such cases promoted by flattening the loop of the platinum wire, placing a small portion of the lime compound upon it, letting it frit, adding a drop of hydrochloric acid, which remains hang- ing to the loop, and then holding the latter in the fusing zone. The reaction is most distinctly seen at the instant the drop evaporates and disappears; this takes place, as in Leidenfrost's phenomenon, without ebullition (Bunsen). Viewed through the green glass, the lime coloration of the flame appears finch-green on letting the sample moist- ened with hydrochloric acid spirt in the flame (difierence between lime and strontia; the latter, under similar cii'oumstances, shows a very faint yellow. Merz). In presence of baryta, the lime reaction is only seen on the first introduction of the sample into the flame. The lime spectrum is shown in the plate of spectra. The intensely green line /3 is more particularly characteristic, also the intensely orange line a. It requires a very good apparatus to show the indigo-blue line to the right of G in the solar spectrum, as this is much less luminous than the other lines. 9. With monocarbonates and bicarbonates of the alkalies, as also with a solution of carbonate and sulphate of potassa, sulphate of lime shows the same reactions as sulphate of strontia. §98. d. Magnesia, MgO [MgO]. 1. Magnesium is silver white, hard, malleable, of 1*74 sp. gr.; it melts at a moderate red heat, and volatilizes at a white heat. When ignited in the air, it burns with a dazzling white flame, forming mag- nesia. It preserves its lustre in dry air, but gradually becomes coated with hydrate of magnesia when exposed to moist air. Pure water is not decomposed by magnesium at the ordinary temperature, but m water acidified with hydrochloric or sulphuric acid, magnesium dissolves rapidly with evolution of hydrogen. 2. Magnesia and its hydrate are white powders far more bulky](https://iiif.wellcomecollection.org/image/b21966953_0122.jp2/full/800%2C/0/default.jpg)
