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A wood that never rots
466
CURRENT TOPICS.
[J. F. I.
A Wood that Never Rots. A~oN. (Sci. Amer. Suppl., lxxvi, No. I978, 347.)---Engineers and others are annoyed by the rotting of railway sleepers, of piles, and of wood used to support galleries and in the building of ships, etc. Engineers, chemists, physicists, biologists, doctors, who for the construction of diverse apparatus, may need a wood possessing a maximum resistance to the causes of destruction, particularly humidity, are interested in this important question of the unputrescibility of wood. The ideal would be to find a wood able to resist putrefaction naturally. It appears from recent researches that the wood of the mangrove tree may be considered as absolutely unputrescible. Numerous samples of mangrove wood (Rhizophora racemosa) sent from French Guiana were, in 19o9, placed at Collonges (C6te-d'Or) in a soaking pit in the depot of sleepers of the Paris-Lyons-Mediterranean Railway Company. These samples were surrounded with all the elements capable of producing the decomposition and rotting of the wood in the minimum of time. In spite of this the samples still remain in an excellent condition and show no signs of alteration. Why has the mangrove resisted decomposition and whence the particular and excellent qualities of this too little known wood ? The grain of the mangrove is very close; hence it opposes a barrier to the invasion of water. The density of mangrove is about I IO, that of oak is 70, and that of fir is 40. Moreover, mangrove wood has an amount of tannin quite sufficient to prevent the attack of insects and the multiplication of germs, damp, mould, and all the various micro-organisms which constitute the flora of the woods of different climates. The wood of the mangrove is marvellously resistant to flexion; its resistance is double that of oak, quadruple that of fir; nevertheless it is not at all brittle. To crushing, either at the end or across the fibres, it offers a resistance double that of oak and three times that of fir. It resists all attempts at twisting far better than either oak or fir, and is superior to them in suppleness. It is easily worked, and is as easily sawn as oak. It may, therefore, be concluded that mangrove wood merits employment on a large scale for numerous and varied purposes. It might be used for posts of electric lines on account of its unputrescibility, its resistance, and its suppleness. It is valuable for sleepers of narrow railways for its resistance to putrefaction and to crushing. It could be advantageously used for the special woodwork of mines. There is always good use for a wood that never rots. Zirconium Hypophosphite, a Photo-sensitive Salt. O. HAUSER and H. HERZFELD. (Z. Anorg. Chem., lxxxiv, 92.)--The hypophos.phite is obtained by adding hypophosphorous acid to zircomum nitrate. The amorphous precipitate first formed redissolves in excess of the acid, and is precipitated by excess of alcohol as a colorless, crystalline precipitate, which, when dried over calcium chloride, has the composmon Zr(H,,PO,,) 4. In direct sunliffht the hypophosphite becomes deep violet. Microscopic examination of the colored crystals shows no evidence of decomposition.
CURRENT TOPICS.
[J. F. I.
A Wood that Never Rots. A~oN. (Sci. Amer. Suppl., lxxvi, No. I978, 347.)---Engineers and others are annoyed by the rotting of railway sleepers, of piles, and of wood used to support galleries and in the building of ships, etc. Engineers, chemists, physicists, biologists, doctors, who for the construction of diverse apparatus, may need a wood possessing a maximum resistance to the causes of destruction, particularly humidity, are interested in this important question of the unputrescibility of wood. The ideal would be to find a wood able to resist putrefaction naturally. It appears from recent researches that the wood of the mangrove tree may be considered as absolutely unputrescible. Numerous samples of mangrove wood (Rhizophora racemosa) sent from French Guiana were, in 19o9, placed at Collonges (C6te-d'Or) in a soaking pit in the depot of sleepers of the Paris-Lyons-Mediterranean Railway Company. These samples were surrounded with all the elements capable of producing the decomposition and rotting of the wood in the minimum of time. In spite of this the samples still remain in an excellent condition and show no signs of alteration. Why has the mangrove resisted decomposition and whence the particular and excellent qualities of this too little known wood ? The grain of the mangrove is very close; hence it opposes a barrier to the invasion of water. The density of mangrove is about I IO, that of oak is 70, and that of fir is 40. Moreover, mangrove wood has an amount of tannin quite sufficient to prevent the attack of insects and the multiplication of germs, damp, mould, and all the various micro-organisms which constitute the flora of the woods of different climates. The wood of the mangrove is marvellously resistant to flexion; its resistance is double that of oak, quadruple that of fir; nevertheless it is not at all brittle. To crushing, either at the end or across the fibres, it offers a resistance double that of oak and three times that of fir. It resists all attempts at twisting far better than either oak or fir, and is superior to them in suppleness. It is easily worked, and is as easily sawn as oak. It may, therefore, be concluded that mangrove wood merits employment on a large scale for numerous and varied purposes. It might be used for posts of electric lines on account of its unputrescibility, its resistance, and its suppleness. It is valuable for sleepers of narrow railways for its resistance to putrefaction and to crushing. It could be advantageously used for the special woodwork of mines. There is always good use for a wood that never rots. Zirconium Hypophosphite, a Photo-sensitive Salt. O. HAUSER and H. HERZFELD. (Z. Anorg. Chem., lxxxiv, 92.)--The hypophos.phite is obtained by adding hypophosphorous acid to zircomum nitrate. The amorphous precipitate first formed redissolves in excess of the acid, and is precipitated by excess of alcohol as a colorless, crystalline precipitate, which, when dried over calcium chloride, has the composmon Zr(H,,PO,,) 4. In direct sunliffht the hypophosphite becomes deep violet. Microscopic examination of the colored crystals shows no evidence of decomposition.