Oct. 19, 1888.] 



SCIENTIFIC NEWS. 



407 



General &ott$. 



Pollax Island. — According to advices received at 

 New York from Yucatan, this island, on the coast of that 

 Republic, disappeared during the recent cyclone in that 

 region. 



The Propagation of Cholera. — Dr. Otto Riedel, in 

 a recent work, admits that insects — he should have stated 

 more precisely two-winged insects (Diptera) — constitute 

 an important agency in the distribution of the cholera- 

 bacillus. 



The Chlorides of Iridium. — M M. Nilson and Petter- 

 son have communicated to the Comptes Rendus an 

 account of three well-defined chlorides of iridium. They 

 remark that a metal of the third group of the natural 

 system of the elements is thus found capable of acting 

 either as a univalent, divalent, or trivalent body in 

 definite compounds. 



Frozen Milk. — According to La Nature, M. Guerin, of 

 Grandvilliers, has devised a practical method of freezing 

 milk, so that it may be kept for weeks unchanged, and 

 transported to any distance in the solid state. It may 

 then be re-converted into a liquid by a simple rise of 

 temperature, and is fit for consumption, not having lost 

 any of its natural properties. 



The Fertilising Effects of the Nile. — Prof. A. 

 Muntz recently undertook to show that the perennial 

 fertility of Egypt was due not so much to the mud 

 deposited by the Nile as to the properties of the water. 

 But on analysis he found that the water of the Nile was 

 poorer in nitrate of potash than that of the Seine. The 

 Nile conveys only 3 to 7 milligrammes per litre of nitrate 

 of potash, whilst the Seine contains n. 



Formation of Hair-Silver. — Opificius (Chemiker 

 Zeitung) shows that on igniting powdered sulphuret of 

 silver in a current of hydrogen, the silver is obtained in 

 the form of fine hairs, which shoot up out of the mass, form- 

 ing a dense thicket of fine threads of metallic silver. 

 Sulphuret of silver yields the same product in a current 

 of carbonic acid. Copper may also be obtained in the 

 form of hairs or threads on heating the sulphuret of 

 copper in a current of hydrogen. 



A Lunar Rainbow.— M. de Valois, Mayor of Aumatre, 

 writes in La Nature, that on Monday, September 24th, 

 he observed at Aumatre, about 9.45 p.m., during stormy 

 weather, and whilst a slight rain was beginning to fall, a 

 well-marked lunar rainbow, having the appearance of a 

 very luminous halo on a dark ground, and which extended 

 in the form of the arc of a circle over about 100 lo no degs. 

 It rose at first almost vertically in the north-west and 

 terminated at the west near its highest point. 



Chemical Reactions between Solids. — A Belgian 

 chemist, M. W. Spring, finds that certain solid bodies, if 

 submitted to intense pressure, can act upon each other 

 and enter into combination. Thus, when a mixture of 

 sulphate 01 Saryta and carbonate of soda was exposed to 

 a pressure of 6,000 atmospheres n per cent, of the 

 sulphate was transformed into carbonate. Hence the old 

 adage of the chemists, " Substances act upon each other 



only when in solution " {Corpora non agunt nisi soluta), 

 no longer expresses an exact truth. 



Effects of Petroleum upon Health. — M. Wiecyk 

 has studied the effects of petroleum vapours upon the 

 workmen in the Carpathian oil region. These men have 

 to breathe an atmosphere tainted with hydrocarbons, 

 ethylene, carbonic acid, carbonic oxide, and sulphuretted 

 hydrogen. Cases of asphyxia are not rare. The affec- 

 tions ordinarily incident to long-continued work are 

 tinglings in the ears, dazzling, throbbing of the arteries 

 in the head, syncopes and hallucination, palpitations and 

 general weakness. Consumption and epidemics are rare. 



Glacier Dust. — The holes with which the great in- 

 terior glacier of Greenland is studded (Le Steele) were 

 found by Prof. Nordenskiold and his companions to con- 

 tain each a quantity of mineral dust, to which their 

 origin, on well-known physical principles, is supposed to 

 be due. As to this dust, the question arises whether it 

 has come from the realms of space, or whether it has 

 been projected from volcanoes. The similarity of the 

 composition of this dust with that of meteorites causes 

 the majority of eminent authorities to incline to the 

 former opinion. 



Profits of Timber Growing. — Mr. G. Cadell (Mac- 

 millan) shows that the revenue of the Government 

 forests in India in 1886-87 showed a profit of 41,017,000 

 rupees. This has been built up " from not only an 

 entire absence of income but from a rapidly decreasing 

 capital." The means used have been simply " restraining 

 the destruction of the forests by the wood merchants, 

 guiding, without checking, the cutting of trees by the 

 peasantry for their farming and building necessities," 

 and taking a middle course between reckless waste and 

 oppressive restriction. 



The Speed of Light. — The following figures, quoted 

 by La Nature from the results of independent observers, 

 show that there exists comparatively little disagreement 

 on this important point. The velocity, in kilometres per 

 second, is given by 



Foucault, in 1862 .. .. .. 298,000 



Cornu, 1874.. .. .. .. 298,500 



Cornu, 1878 .. . .. .. 300,400 



Cornu, according to Listing . . . . 299,920 



Young and Forbes, 1 88 1 .. .. 301,382 



Newcomb, 1882 . . . . . . 299,860 



Influence of Aluminium upon Cast-Iron. — Messrs. 

 Keep, Mabey, and Vorce give an account, in the Journal 

 of the Franklin Institute, of the value of small proportions 

 of aluminium as an addition to cast-iron. It appears 

 from their experiments that fused wrought-iron, a mix- 

 ture of cast-iron and steel, or steel alone, either of which 

 would yield castings full of blow-holes, will make solid 

 and homogeneous castings if as small a quantity of 

 aluminium as i\,th of a per cent, be added just before pour- 

 ing. Great benefit is promised to the iron-founder from 

 the rapidly falling price of aluminium. 



Influence of Drinks upon Digestion. — Dr. A. Heney- 

 r.oki, assistant at the Rostock Medical Klinik, has recently, 

 according to the Naturwissenschaftliche Wcchenschrift, 

 made experiments on this question. Water in quantities 

 up to 22 to 23 fluid ounces has no appreciable effect. 



