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< SCIENCE' G OS SI P. 



CONDUCTED BY C. AINSWORTH MITCHELL, 

 B.A.OXON., F.I.C., F.C.S. 



Old Egyptian Platinum. — M. Berthelot has 

 recently examined an ancient Egyptian -metal box 

 covei'ed with hieroglyphics. It was discovered at 

 Thebes, and apparently belonged to Queen Shapen- 

 pit in the 7th century B.C. It was covered with 

 designs and inscriptions, in gold oir one side and 

 in silver on the other. Within the box was a small 

 metallic plate which from its colour was at first 

 regarded as silver. On being analysed, however, 

 it was found to consist of a peculiar alloy of gold 

 with platinum and several other allied metals. 

 The occurrence of platinum has not hitherto been 

 recorded in any of the metallic articles fomid in 

 Egypt. It was probably obtained from the alluvial 

 deposits of the upper regions of the valley of the 

 'Nile. 



A " Eain of Blood."— On March 10th, 1901, a 

 meteorological phenomenon, which caused great 

 consternation throughout Sicily, occurred near 

 Palermo, and indeed over most of Southern 

 Europe. The sky was darkened by a red cloud, 

 from which fell drops resembling coagulated blood, 

 and soon the soil, roofs of the houses, and leaves 

 ■of the trees all acquired a red tint. This curious 

 " rain of blood " was examined by M. St. Meunier, 

 who found it to consist of a fine reddish, gritty 

 powder, hard enough to scratch glass. It was 

 impregnated with air, which adhered firmly to the 

 grains. When gently heated in a glass tube it 

 became so mobile as to appear liquid ; and when 

 •exposed to a red heat it became dark grey, and 

 finally almost black. On analysis it was found to 

 Jiave the following percentage composition : — 



Water 5-20 



Organic matter . . - . . 3"17 



Sand 59-14 



Calcium carbonate .... 23-91 

 Clay (by difference) ... . 8'58 



Another specimen of the same dust was examined 

 independently by F. Jean and J. Bruhat, who give 

 its composition in a more elementary form : — 



Moisture 0-974 



Organic matter and substance vola- 

 tile at a red heat 

 Chlorides and sulphates of sodium 

 and potassium . , . . 

 Carbonates of iron, calcium, and 



magnesium . . . ' . 23-051 

 Oxides of iron and aluminium . 4-545 

 Silica (sand) 59-732 



9-740 



1-948 



99-990 

 Under the microscope it was possible to distinguish 

 siliceous fragments of different shapes, vegetable 

 fibres and other debris, spores of various mould - 

 fungi, fragments of diatoms, and irregular poly- 

 hedral bodies which gave a blue coloration with 

 iodine. The composition of the dust excludes the 



possibility of its being of volcanic origin, and all 

 of these chemists agree in attributing it to the 

 desert of Sahara. We have here, without doubt, 

 the explanation of the ominous " rains of blood '' 

 mentioned by Livy and other Latin authors. 



Hy'drogen in the Atmosphere. — The pre- 

 sence of traces of free hydrogen in the atmosphere 

 has been demonstrated by Professor A. Gautier, of 

 Paris, in a series of investigations. He suggests 

 that it may be derived not only from volcanic 

 action, but also from the action of water upon old 

 granitic rocks. Thus when a portion of the in- 

 terior of a large block of granite is powdered in an 

 atmosphere of carbon dioxide, and then heated 

 with water at 280° C, a considerable quantity of 

 gas, chiefly hydi-ogen, is liberated ; whilst, if an 

 acid be used instead of water, a still larger pro- 

 portion of gas is obtained. 



Passive State of Iron. — When drawn iron is 

 immersed in strong nitric acid it assumes what is 

 known as the passive state, and remains unattacked 

 for a considerable time, though eventually it is 

 gradually dissolved. If, however, the strong acid 

 be diluted by the addition of water the iron 

 rapidly passes into solution. This passive state in 

 concentrated nitric acid can be converted into the 

 active condition in several ways. Thus, the change 

 is_ accelerated by stirring- the liqiiid, and by placing 

 the iron in a concentrated solution of potassium 

 nitrate or potassium hydroxide. If a rod of pas- 

 sive iron immersed in concentrated nitric acid be 

 touched with zinc under the liquid, an active zone 

 is developed at the point of contact and passes 

 along the iron, which, however, soon becomes 

 passive once more. The phenomenon has recently 

 been studied by H. L. Heathcote, who has come to 

 the conclusion that the passive state cannot be 

 attributed to a protective film of liquid or gas, and 

 that some external stimulating influence is required 

 to transform it into the active state. 



The Papaya Tree. — The papaya or papaw 

 {Carioa papaya) grows most abundantly in Asia, 

 Africa, and America, between the isothermal lines 

 of 77°. It is used in the most varied manner, the 

 bark making excellent rope, whilst the fruit is 

 eaten both in the raw and cooked state. Its most 

 remarkable property, however, is the power which 

 the juice possesses of dissolving- meat and other 

 albuminous substances. In the Antilles the natives 

 are said to use the pulp of the fruit as a cosmetic, 

 and are certainly noted for their beautiful com- 

 plexions. If these are really due to the use of 

 the papaw, it will probably be found that the 

 digestive action of the juice plays a part in the 

 process. In tropical countries meat has to be 

 eaten at so early a period after slaughter as to be 

 very tough and flavourless, and it is therefore a 

 common practice to rub it with a slice of the fruit 

 and thus render it more tender and digestible. 

 The ferment or enzyme which is the active agent 

 in this preliminary digestion is known as papayo- 

 tin. It has been separated from the juice of the 

 plant in the form of a white powder, which, how- 

 ever, has not yet bee:i obtained in a pure state. 

 In many respects it resembles the pepsin isolated 

 from the stomachs of animals, though it differs 

 from it in being rendered inactive by acid of the 

 strength of that in the gastric juice. In commerce 

 the juice of the papaw is used in the manufac- 

 ture of various peptonised food products, such as 

 Cibil's " Fluid Extract of Beef " and Antweiler's 

 " Peptone." 



