572 Correspondence — A. R. Stmt. 



The term meteoric dust is used because it is commonly applied to 

 the materials forming the subject of this paper ; it is not intended 

 to state that the dusts are necessarily of cosmic or extra-terrestrial 

 origin. The specimens described and exhibited were from Moruya 

 (fell on Dec. 15th, 1880), from Uralla (fell on Dec. 14th, 1882), from 

 near Broken Hill (fell 1896), from Menindie (fellJune 17th, 1899), 

 and Pambula (fell Oct. 5th, 1899). Dust from the roof-beams and 

 •mud from a covered cistern at the University and from the roof of 

 the Observatory, Sydney, all three were collected in 1882. All the 

 dusts are of a reddish colour except those from the University and 

 Observatory, which are grey. The red dusts are mainly silicious 

 and argillaceous, and look as if they had come from dried-up water- 

 holes ; they contain a variety of organic and mineral matters such as 

 might be expected from such a source, and in addition magnetite 

 and metallic iron ; the latter contains cobalt and nickel, which 

 seems to indicate that the dusts contain some cosmic or extra- 

 terrestrial materials, part of which may have settled down and 

 become mingled with the undoubted superficial terrestrial deposits 

 and part may have been derived directly from the atmosphere. 

 The tJniversity and Observatory dusts also yielded magnetite and 

 metallic iron containing cobalt and nickel, and the University dust 

 yielded particles of gold ; the Observatory dust has yet to be tested. 

 The Moruya, Menindie, and Barrier red dusts yielded particles of 

 gold ; the others have yet to be examined. Fuller information is 

 given in the paper as to the constituents and chemical composition 

 of the dusts, and analyses of volcanic and other dusts for comparison. 



Professor Liversidge also exhibited under the microscope particles 

 of a malleable yellow metal, which have all the appearance of 

 gold, obtained from certain Australian and European meteorites 

 (siderolites). The presence of gold in meteorites bears upon the 

 presence of gold in ' meteoric ' dusts, and it is also of great interest 

 in connection with the presence of gold upon the earth and in 

 •sea-water, inasmuch as meteorites and the dust of meteorites are 

 constantly falling upon the earth to the extent of probably many 

 million tons a year. Further information upon the question of 

 Ihe presence of gold in meteorites will be given shortly in a sub- 

 sequent paper. 



GOK, I?, lEJSIPOIsr ID IB israjB. 



HYDROTHERMAL METAMOEPHISM. 

 Sir, — I crave a few words of explanation of my paper on 

 Hydrothermal Metamorphism noticed in your current number. 

 The ulterior object of the paper was to elicit a discussion on the 

 singular fact that in the Devon schists albite containing fluid 

 inclusions is intimately associated with chlorite and other water- 

 bearing minerals ; and this in rocks which show no sign of any 

 high temperature, far less of fusion. So far as I am aware, albite 

 lias only been produced artificially in the crucible at a high 

 temperature. After my little paper was written I found to my 



