KNOWLEDGE & SCIENTIFIC NEWS. 



[Jl'LY, 1905. 



The New Tenth Satellite of Saturn. 



Very little has been published since the discovcn- of the 

 tenth satellite, but the details are now definitely stated in a 

 communication from the Hanard College C)bservatory. 

 The satellite was discovered by Professor \V. H. Pickering 

 at the Harvard College Observatory during the examination 

 of a series of several photographic plates taken with the 

 24-inch Bruce telescope, selected from the set used in deter- 

 mining the orbit of Phcebe, the ninth satellite. The new 

 satellite was detected on thirteen of these plates, and the 

 previous announcement of the orbital motion being direct with 

 a period of twenty-one days is confirmed ; it is now stated to 

 be nearer Saturn than Hyperion. 



Photography of the Canals on Mars, 



In a telegraphic communication to Professor E. C. Pickering, 

 Mr. Lowell announces that numerous photographs of several 

 of the dark canals on the planet Mars have recentl)' been 

 obtained at the Lowell Observatory by Mr. Lampland. 

 Amongst others the following are specially mentioned as 

 appearing quite distinctly, some being recognised ou as many 

 as twenty negatives: — Casius, N'e.xillium, Thotb, Cerberus, 

 Helicon, Styx, Chaos, Liedeus. 



CHEMICAL. 



By C. A. Mitchell, B.A. (Oxon.), F.LC. 



The Action of Light Upon Glass, 



Sir William Ckookes has communicated to the Royal Society 

 (Procicdings, April, 1903) the results of experiments upon speci- 

 mens of coloured glass sent to him by correspondents in 

 Bolivia and Chili. The pieces of glass, which had originally 

 been white, ranged in colour from pale amethyst to deep violet 

 black, and the colour was not superficial but permeated the 

 whole substance. It could be destroyed by heating the ghss 

 until it became soft, and restored again by exposure to the 

 rays of radium. Manganese was found to be present in each 

 case, and as the glass had been exposed to direct sunlight at 

 an altitude of 4000 metres above the sea, Sir William con- 

 cluded that it was possible that at that height there might be 

 specially active rays in the sunlight which would convert the 

 manganese present into the violet coloured manganic silicate. 

 In his opinion the colour produced in glass by radium was the 

 same as that caused by long exposure to the sun's ra}s. In 

 the discussion Professor Judd called attention to the fact that 

 the glass in some of the old greenhouses in Kew had changed 

 from its original green colour (due to iron oxide), and after 

 becoming colourless had gradually turned violet, and he 

 attributed this to the manganese in the glass. It is interesting 

 to note that Faraday, in 1825, recorded the occurrence of 

 similar colorations in the windows of certain houses, now pulled 

 down, in Blackfriars Koad, after nine months' exposure to sun- 

 light. Mr. W. H. Low, in a letter to the Chemical Scus, re- 

 ports that he has observed numerous instances of the same 

 kind in old window glass in many of the hoiises in Boston, 

 U.S.A., the colours ranging from pink to violet and almost blue. 

 The houses face east and are in low situations, so that the 

 altitude cannot be one of the factors in this case. He asserts 

 that a regular gradation in colour can be produced by covering 

 successive portions of window glass with black paper and 

 allowing each uncovered portion to be exposed to sunlight for 

 a month longer than the preceding portion. Herr F. I^ischcr 

 has also made experiments as to the influence of the light from 

 an incandescent mercury lamp of special construction, the 

 rays from which he concludes to be those of ultra-violet light. 

 Of the eight kinds of glass tried, four, including a (ierinan 

 lead glass and an English lead glass, were outwardly un- 

 changed, while four were coloured a decided violet within 12 

 hours, the coloration becoming visible after :5 minutes. All 

 of these contained manganese, whereas the uncoloured four 

 were nearly free from compounds of that metal. Heat de- 

 stroyed the colour, but if could be restored by a fresh exposure 

 to the light. When the glass was covered with thin sheets of 

 mica no coloration was produced, and it was therefore con- 

 cluded that the effect was due to radiations of short wave 

 length. Herr Fischer also suggests that the violet colours 



produced in glass by Rontgen tubes may be due to ultra-violet 

 light acting on the manganese in the glass, and that the similar 

 effect caused by radium may also be connected with radiations 

 of short wave length. 



The Prevention of Poisoning by Mercury 

 Vapour. 



The workmen in the quicksilver mines and, to a less extent, 

 those engaged in the manufacture of barometers and other 

 instruments in which mercury is used, are liable to suffer from 

 a peculiar form of poisoning produced by continually breathing 

 mercury vapour. The disease, which is known as " the 

 trembles," or " mercurial tremor," affects the nervous system, 

 so that the sufferer is attacked by fits of trembling whenever 

 any attempt is made to use the muscles, and it eventually 

 ends in death. In the mines in Sp.iin, Austria, and America 

 it is usual to remove workmen to other parts of the works 

 comparatively free from the vapour, so soon as they show the 

 characteristic signs of poisoning ; but the Spaniards in South 

 America did not pay even this amount of attention to their 

 miners. A mining community was founded towards the close 

 of the i6th century at Hunncavelica, in Peru, to work the 

 celebrated mine of St. Barbara, in which is a subterranean 

 village with a church cut out of the cinnabar. This mine was 

 a great source of profit to the Spanish, and it is estimated 

 that during their rule thousands of the Indians driven to work 

 there died of mercury poisoning. No serious attempt appears 

 to have been made to grapple with this evil except that in 

 certain mines better systems of venlilation have been adopted, 

 and it has been left to an Italian chemist to devise a simple 

 means of prevention. Dr. Tarugi has found that aluminium 

 in a finely-divided state immediately absorbs mercury even 

 when only traces of the metal are present in a large volume 

 of air. The amalgam produced is very stable, and can be 

 heated (o 200° C, or twice the temperature of boiling water, 

 without losing the slightest trace of mercury. This absorptive 

 power of aluminium is so great that the reaction can be used 

 as an extremely sensitive test for mercury. In order to utilise 

 this property cf aluminium in the prevention of mercury 

 poisoning. Dr. Tarugi has devised a respirator containing 

 several layers of very fine aluminium gaiue, which will allow 

 the air to pass whilst retaining every trace of mercury vapour. 

 This respirator has been patented in Italy, Austria, and 

 Spain, and will probabh' before long be adopted in all quick- 

 silver mines. 



Tlie Consun\ption of Odoriferous 

 Constituents by Pla-nts. 



The results of interesting cxperimtnis jii basil plants have 

 been published by MM. Charahot and Htoert. One set of 

 plants were kept in the dark for six weeks and another under 

 normal conditions for the same period. The amounts of 

 essential oils (to which the perfume is due) were determined 

 before and after the experiments, and it was found that they 

 had increased twenty-fold in the plants kept under ordinary 

 conditions, while there was a notable decrease in the case of 

 the plants kept in the dark. Hence it appears that the 

 odoriferous constituents of basil are not fimply products of 

 excretion, but that under certain conditions they can be 

 utilised to supply some of the energy not given by the light or 

 to form tissue. 



GEOLOGICAL. 



By Liav.\j;d A. M.\i<tin, F.G.S. 



Coal. 



The Report of the Royal Commission on Coal Supplies has 

 served to emphasize one fact very clearly, namely, that in 

 spite of all fears which have possessed the British people for 

 forty years as to the p<issible exhaustion of our coalfields, 

 such fears have very little reason for their existence, and at 

 least for half a niillenniuin, even with the present rate of con- 

 sumption, there will be no shortage of supply. We are, in 

 fact, only just at the beginning of the "coal-using age." In 

 1820 Britain raised but 20 millions of tons of coal. Now she 

 raises 230 million tons a year. If she continue to use coal to 



