xlviii Proceedings, fyc. 



other strata among the depositions of the Pleistocene epoch of the 

 tertiary era, there is every reason to believe that the aboriginal tribes 

 would not have been able to discover that which did not lie within 

 easy access. Even where clay occupies the surface or the first stra- 

 tum, some aboriginal tribes are known never to have taken any notice 

 of it. Our nearest example hereof we have in the aboriginals of 

 Australia, who Hterally have, in many localities, walked and still walk 

 on the clay ! With the fact before us, we view in the Post- 

 Pleistocene arrangements a providential circumstance of vital import- 

 ance for the benefit of man, and in this, at first sight, trivial distri- 

 bution of clay, we see the mysterious means by which one of the 

 greatest objects in creation was promoted, viz., the cultivation of the 

 human intellect ! 



During the last geological epoch, where water acted as the agent, 

 clay became distributed partly in a second or third stratum, as well 

 as presenting the last of depositions. Such superficial layers are 

 noticed all over the globe, where the floods acted on a favorably 

 situated locality, and where the silicate of alumina remained. The 

 substance clay, thus, as we see, gave the last touch to and crowned 

 the grand marvellous work of creation i 



Having observed the great importance of clay as an original 

 means of civilisation throughout the world, a glance at this sub- 

 stance, as known to modern science, will now briefly occupy our atten- 

 tion. Clay in its purer state, from pipe-clay to terra-cotta and kaolin, 

 encloses an elementary substance (a metal) combined with oxygen, 

 forming the Sesqui-oxide of aluminium, this again being chemically 

 combined with silicic acid. At the beginning of this century, 

 Oersted had the honor of being the first who obtained this metal, 

 and presented it to the chemical world as the chloride of aluminium. 

 Wbhler, availing himself of the properties of this chloride, succeeded 

 in procuring the metal in its free state, though in small quantities, 

 as a mere scientific curiosity. Still this was a great step towards a 

 result that might be anticipated. Such was lately arrived at by 

 improvements in the mode of producing this metal in quantity. 

 Science and the world at large are indebted to M. St. Clair Deville, 

 who has lately simplified the process and means for producing the 

 metal at a moderate expense. 



Though aluminium exists wherever clay is present, this substance 

 has, until lately, offered more difficulties in its extraction than 

 most other compounds containing it. An unexpected source was 

 discovered about three years ago, where a substitute for chloride of 

 aluminium was found to exist. Dr. Percy found this in the cryolite, 

 or fluoride of aluminium and of sodium, which exists in large masses 

 in Greenland. This is the most appropriate ore from which to extract 

 aluminium. Notwithstanding this natural aid for obtaining this 

 metal, its production must be viewed as one of the high results of 

 science. Another compound of alumina, the sky-blue " lapis-lazuli," 



