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HARD WICKE ' S S CIE NCE-GO SSI P. 



their daring. For ages the most valuable precious 

 stone in the world has been the diamond. Of course 

 it was known that this crystallised bit of carbon 

 could be burnt like an ordinary piece of coal, if it 

 were subject to a sufficiently high temperature, for 

 Sir Isaac Newton demonstrated this more than two 

 hundred years ago. Apart from this fact, however, 

 the diamond was regarded'as peerless amongst precious 

 stones. It was the hardest object in the whole world 

 of matter. Nothing could corrode it or destroy it. 

 Alas ! a German chemist, Mr. Luzi, has just demon- 

 strated that diamonds can be corroded by heating 

 them for half an hour in the melted matrix or " blue 

 ground," in which they are usually found in the 

 South African diamond-fields ; and . it is thought 

 that the process depends upon the reduction of the 

 melted matrix or magma at the expense of the 

 carbon of the diamond. 



One of the most wonderful places in the whole 

 world, for number and variety of metallic minerals is 

 the "Broken Hill" district of New South Wales, 

 recently noted for the bitter losses of the strike 

 quarrel there. We possess at least a score of small 

 specimens of various minerals from one particular 

 mine in that neighbourhood. When the geological 

 formation of all these various minerals, their origin, 

 mode of occurrence, etc., comes to be written (as one 

 day it must be) it will prove as interesting as the 

 volume issued by the United States Government 

 upon the Sierra Nevada district of Western America, 

 out of which one of the owners, Mr. Mackay, is 

 taking ,£25,000 a week. A new form of silver ore 

 has just been discovered in the Broken Hill district. 

 It consists of hard, horny particles of ore, containing 

 traces of gold and silver, associated with traces of 

 iodide, bromide and chloride. It has long been 

 suspected by some eminent mineralogists that sea- 

 water, in a highly heated form, or otherwise, has had 

 a good deal to do with the deposition of precious 

 metals, and the composition of this new silver ore 

 will undoubtedly strengthen the belief. The water 

 of the sea contains a good many metals, which its 

 chlorides have enabled it to dissolve. How many 

 people know, [for instance, that every cubic mile of 

 sea-water contains fifteen tons of silver ? The new 

 silver ore above referred to is found disseminated 

 through beds of fine clay, which have been subter- 

 raneously heated, so as to resemble baked kaoline or 

 biscuit-ware. 



More than a quarter of a century ago a book was 

 written by the Hon. Mr. Marsh, United States 

 •Consul at Florence, entitled "Physical Geography 

 as Influenced by Human Action." It gave a long 

 list of instances in which the indiscriminate cutting 

 down of forests had affected the rainfall of countries. 

 Climate is an exceedingly sensative thing, and every 

 leaf on every tree, shrub, and plant influences it. 

 Vegetation is a marvellous regulator of climatic 



conditions, particularly of rainfall. The latter is 

 stayed and checked by the influence of the former. 

 Cut down the forests of a country, and the rainfall 

 becomes irregular ; so, of course, does the volume 

 and velocity of rivers, floods, and torrents. Such 

 altered conditions bring about extremes of dryness 

 and wetness. Let all the vegetation be cleared away 

 and perhaps general aridity, and therefore sterility, 

 are the results. 



The subject of the earliest eruptions of Mount 

 Etna has recently been discussed before the Paris 

 Academy of Sciences. They commenced in the 

 Upper Pliocene period, represented in England by 

 the shell beds which form the Suffolk and northern 

 Essex cliffs. From that particular period, before the 

 appearance of man on earth, right through the great 

 northern ice age, Etna has been a living volcano, 

 through long periods of time, which, although a mere 

 skin-deep part of the antiquity of our planet, 

 probably extend over a quarter of a million of years ! 



A very interesting paper by Mr. Dickson has just 

 been published, in which he shows how the ebb and 

 flow of tides in the English Channel are affected by 

 the shapes or main features of the coast-lines. Thus, 

 bays with a western side run nearly from south to 

 north, turn at a sharp angle, and lie open to the east. 

 Even the circulation of the water as well as the tem- 

 perature Mr. Dickson found was largely influenced 

 by the conditions. 



One of the most important physical discoveries of 

 our generation was demonstrated by Professor Dewar 

 before a brilliant audience assembled in the Royal 

 Institution. This was no less than the liquefaction 

 of atmospheric air. All gases except hydrogen have 

 now by compression and extreme cold been artificially 

 liquefied. The air we breathe was the last to hold 

 out, but now we are in front of the possibility of a 

 liquefied atmosphere. In addition to the pressure 

 used to produce atmospherical liquefaction, a cold 

 equal to 327 of frost had to be employed. The 

 liquefied atmosphere is of a faint blue colour. 



A very destructive earthquake occurred in the 

 island of Zante on January 31st. The shocks were 

 frequently repeated. 



Australia is about to grow its own tobacco. 

 It is surprising the colonies never thought of it 

 before ! 



We are pleased to draw the attention of our 

 archaeological and geological readers to Mr. John 

 Allen Brown's paper (illustrated) reprinted from the 

 "Journal of the Anthropological Society," entitled 

 "The Continuity of the Palaeolithic and Neolithic 

 Periods." Mr. Browne is well known as an excellent 

 observer and ardent collector, and he makes out a 

 very good case. 



