KNOWLEDGE & SCIENTIFIC NEWS. 



[October, 1906. 



Finally, there are the Burmese glass mosaics, or the art 

 of wall decoration by coloured glasses imbedded in the 

 s-pecially prepared varnish. In many instances most elabor- 

 ate designs have been traced on walls or around pillars, 

 and as the material sets firmly it is very durable. 



In conclusion, the author remarks that the varnish is of 

 great merit and immense possibilities, and up to the present 

 practically lakes no part in the arls and industries of Europe 

 and .America. 



Rate of Growth of a Seaweed. 



The giant kelp, Xereocystis luetkeana, common on the 

 shores of North-VVest .America, sometimes reaches a length 

 of 50 to 80 metres, and the rate of growth as recorded by 

 T. C. Frye, in the Botanical Gazette, is as follows : — " The 

 plant lives for two years; during the first vear it attains a 

 length of 1 .25 to 2.5 m. ; during the second year an average 

 increase of 18 ni. in length is made between the middle of 

 March and the first of June, a period of about 70 davs, 

 which woii<s out at an average of over 25 cm. a dav, and 

 about 0.175 mm. per minute." 



This rate of growth is between one-third and one-fourth 

 as rapid as that reported for the bamboo, and far above that 

 of ordinarv plants. 



CHEMICAL. 



By C. AiNswoRTH Mitchell, B.A. (Oxon.), F.I.C. 



Upas Arrow^ Poison. 



The upas tree, Antiaris toxicaria, which grows in Borneo 

 and other East Indian islands, has long had an evil reputa- 

 tion, and it is still a common belief that birds flying within 

 the influence of its poisonous vapours instantly perish, and 

 that it is fatal for animals or men to rest beneatli its shade. 

 .As is the case with many another fable of natural history, 

 there is some groundwork for the exaggerated reports of 

 the evil effects of the upas tree, for it resembles certain 

 lihus plants in emitting a volatile substance which afTects 

 the skins of certain susceptible persons coming near it, 

 though others are quite unaffected. There is no question, 

 however, as to the poisonous nature of the sap of the tree, 

 and it is the chief substance used by the Dyaks of Borneo 

 for poisoning the tips of their darts. .An interesting ac- 

 count of their method of preparing and using the poison 

 has been given by Mr. John .Allen to the Manchester 

 Literarv' and Philosophical Society. .An incision is made in 

 the bark of the tree and the milky exudation collected on a 

 palm leaf and dried first in the sun and then over a fire 

 until a thick brown mass is left. In this state it can be 

 kept without the poison deteriorating, and when required 

 for use it is made into a thin paste with the juice of " tuba " 

 root (which is used to stupefy fish), or with tobacco or lemon 

 juice, and the ends of the darts dipped into the mixture and 

 dried. These darts are made from the middle stem of the 

 palm leaf and are about six or eight inches in length and of 

 about the thickness of a knitting-needle. They are used 

 with a wooden sumpiian, or blow-pipe, which is about seven 

 or eight feet in length and has an internal diameter of 

 about } inch. A bird struck b)' one of these little darts is 

 instantly killed, and a pig dies in about 20 minutes. The 

 fresh juice of the upas tree, whether swallowed or injected 

 into the blood, acts as a-violent poison, causing convulsions 

 and death from paralysis of the heart. It was shown some 

 years ago by MM. Pelletier and Caventou that the active 

 principle in the juice was a substance which they termed 

 antiarin, Cu Hm O5. It was . crystalline and soluble in 

 alcohol, and when heated with dilute acid was decomposed 

 into glucose and a yellow resin. .Another poison prepared 

 from the roots of Uj)as tieute, a climbing plant, is in less 

 common use as an arrow poison. Its action is still more 

 deadly than that of Upas aniinris, and its effects resemble 

 those produced by strychnine. 



Early English Gunpow^der. 



A bucket containing bullets and gunpowder has been dis- 

 covered in the roof of Durham Castle, where it is believed to 

 have been walled up about the year 1641, when the castle 

 was being prepared to withstand a Scottish raid. The 



bullets are moulded spheres of two sizes, and, according to 

 the analyses of Messrs. Silberrad and Simpson, consist of a 

 little over 99 per cent, of lead, with iron and silver and 

 traces of bismuth, arsenic, and antimony. The gunpowder 

 is not granulated like that of the present day, and was 

 evidently prepared by simply mixing the ingredients. It 

 contains about 1 per cent, of moisture, and the proportion 

 of the constituents calculated on the dry powder is practicallv 

 identical with that of the black gunpowder of to-dav, viz., 

 nitre, 75 per cent. ; carbon, 15 per cent. ; and sulphur, 10 per 

 cent, it is pointed out by Messrs. Silberrad and Simpson 

 that this is a remarkable fact, since the gunpowders made 

 in England at that time contained a considcrablv larger 

 amount of sulphur. The only gunpowder with the modern 

 proportions in use in the 17th century was Prussian musket 

 powder, and hence it is suggested that the Durham powder 

 was probably of Prussian origin. 



Calcium Hydride. 



.A new method of preparing calcium hydride, which will 

 find its chief use in the production of hydrogen for balloons 

 (see " Knowledge & Scientific News," this vol., p. 542), 

 has been patented in this country. The metallic calcium is 

 melted in an iron pot, and hydrogen conducted into it while 

 it is in a state of fusion. The gas is absorbed rapidlv, and 

 the resulting product, which contains about 84 per cent, of 

 pure calcium hydride, is cooled and broken into large lumps. 



The Blue Colour of Water. 



The intense blueness of the water in the reservoirs near 

 Purley Station must have puzzled man\' who have looked 

 down upon it from the adjacent downs, and have given rise 

 to various guesses as to its cause. The real explanation, 

 however, of the blue and green colours found in natural 

 waters has been supplied by the experiments of M. Spring, 

 of Liege. He finds that lime compounds impart no colour 

 of their own, and are not the cause of the brilliant blues 

 often seen in chalky waters, but that the colour is due to 

 diffraction of the light by invisible particles still present in 

 the w'ater after the removal of all colouring matters. Yet 

 the lime compounds play an active part in eliminating iron 

 compounds and humic substances, which prevent the natural 

 blue colour of the water from being seen. The fact that all 

 calcareous waters are not blue is due to there sometimes 

 being formed a state of equilibrium betv.een the ourifving 

 action of the lime salts and the constant influx of humic 

 and iron compounds, which mask the blue colour bv their 

 own brown tint. 



GEOLOGICAL. 



By Edward A. Martin, F.G.S. 



Pliocene Beds in Iceland. 



There is a fossiliferous deposit on the west coast of Tjornes. 

 northern Iceland, which has been known to geologists for 

 nearly 160 years. The molluscs found in it indicate a 

 much milder climate than now, and the deposit was con- 

 sidered by Gwyn Jeffen,s and Searles Wood to be not 

 younger than Sliddle Red Crag. Dr. H. Pjetursson now 

 finds that at a height of above 500 feet above the sea, 

 these beds are overlain by the " eastern basalts," being 

 indurated and altered by them, and resting on some of the 

 ''older basalts." Thus there is an intercalation of a 

 fossiliferous deposit of over 500 feet thick, occupying part 

 of the great gap between tertiary and pleistocene rocks, 

 whilst the latter contain indurated ground moraines. The 

 oldest basalts of Iceland are thought to date from earlv 

 tertiary times, and the occurrence of glacial deposits 

 amongst the younger lavas, together with the fact that 

 the island is still a centre of volcanic disturbance, furnish 

 evidence of a remarkably protracted period of volcanic 

 activity. 



Trilobites from Bolivia. 



Some interesting trilobites were obtained by Dr. J. W. 

 Evans in Bolivia in 1901-1902, and these have been re- 

 cently described by Mr. Philip Lake. 



.Several horizons are represented by these fossils. Two 

 specimens of Peltura, probably from the Upper TAiuiula- 



