Abstract
ANGELO BANIERI has made the following observations on the ammonio-ferric sulphate (sal ammoniacum martiale) collected on the lava of Vesuvius. Many naturalists believe that the hydrochloric acid evolved by lavas in their course, unites with the iron of the same lavas, forming ferric chloride, which, together with the ammonia of the air, gives rise to the compound of sal-ammoniac and ferric chloride found in the fumaroles. This view, however, does not appear to the author to be in harmony with facts observed in the Vesuvian lava-current of 1850. It was only in that part of the lava which had overwhelmed a cultivated and manured soil that fumaroles existed, and there they were so numerous as to yield more than loo measured quintals of sal-ammoniac, whereas, on the other part of the igneous current, which had passed over an older lava of the year 1834, in which there was nothing but dry rock and sterile sand, there were no fumaroles of sal-ammoniac. The silica of the lavas acts at very high temperatures on the common salt contained in the manured soil, liberating hydrochloric acid, which, on the one hand, reacts on the ferric hydrate contained in the same soils, producing ferric chloride, and, on the other hand, decomposes the ammonium carbonate eliminated from the organic substances of the soil, which are subjected to dry distillation by the heat of the invading lava. The hydrochloric acid which gives rise to the sal-ammoniac of the fumaroles of volcanic lavas, cannot be derived from the lavas themselves, inasmuch as its presence is only transient; but it is derived from the decomposition of the chlorides contained in the invaded lands. An inspection of the lava of 1850 shows indeed that the denuded soil has been completely burnt, and nothing is seen but scoria of a reddish sand, which have evidently been subjected to a very high temperature.—[Ann. di. Chim. app. alla Med., July, 1869, p. 61.]
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Chemistry: Sal-ammoniacum Martiale. Nature 1, 88–89 (1869). https://doi.org/10.1038/001088d0
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DOI: https://doi.org/10.1038/001088d0