Calcareous Concretions in Timber

Abstract

IN NATURE, vol. xxi. p. 376, I observe that in a remark of the reviewer, and also in an extract from Mr. Ball's “Jungle Life in India,” the occurrence of concretions of lime in trees is spoken of as a rare and novel phenomenon. That Terminalia tomentosa contains calcareous matter has long been known to natives, and a reference to Tennent's “Ceylon,” i. 99, will show that they make a practical use of their knowledge by using the ashes of the bark as a substitute for lime, to chew with betel. Another southern tree which contains an alkali in its bark is Avicennia tomentosa. It generally grows along the margins of backwaters, and has a most wonderful provision for preventing the erosion of the banks and for adding to the dry land. It is a squat bushy tree, and round the stem, to an extent equal to the spread of its branches, it sends up thickets of straight shoots a foot or two high. These, when the tide is up or the water in flood, catch all the stray branches, leaves, grass, &c., that may be floating about, and also promote silt. By this contrivance, therefore, not only are the banks protected from the distinctive action of water, but also raised and consolidated. Again, as regards Mr. Stoney's observation of calcareous masses in timber, which was brought to the notice of the Asiatic Society of Bengal in 1870 as a fresh discovery, it seems strange that the learned body in question did not know that the existence of such concretions, so far from being very rare, is an occasional and well-known phenomenon. Thus, in the Madras Journal of Literature and Science for April-September, 1858, page 142, Prof. Mayer gives a qualitative analysis of a concretion of the kind found in a teak log. It consisted chiefly of magnesia, with potash, lime, silica, and a trace of iron. The substance, he says, “Must be looked on as a mixture, and not a true chemical compound.” Again, he observes, “as a whole the substance thus hardened is insoluble in cold, and but slightly so in water of higher temperature. At 212°, however, there is sensible action after a time. In diluted hydrochloric acid solubility ensues, hastened by increased temperature. Solution is attended by slight effervescence, some carbonic acid being liberated.” He then proceeds to give an explanation of the process by which sach mineral matters may be taken up from the soil and deposited in the tree. So far as I know the occurrence of such concretions in India was first brought to notice by Lieut., now Col. Hawkes, of the Madras Army, in 1858. He had seen them only in teak logs, and remarked that they generally occur “in what carpenters call a shake in the wood, but with this exception the logs are perfectly sound, and no communication whatever with the external air has been observed.”