14 
ALUMINIUM AND THE CLEVELAND KAOLIN. 
PROGRESSIVE MODIFICATIONS OF AMBULATORY i 
LEGS IN ANIMALS INT'O OTHER ORGANS. j , 
BY 
Joseph Lautekeb, M.D, 
(Read on 16th June, 1892). j 
^ [A'oig. — The substance of this paper was communicated on ; 
8th April, 1893, to the Eoyal Society of Queensland: vide “ Proc}^ 
Boy. Soc. vol. x, pp. 19-20. — Ed.] \ 
ALUMINIUM AND THE CLEVELAND KAOLIN. * 
BY 
Henry G. Stokes, F.G.S. 
(Read on 7tli July, 1892). 
Several letters having of late appeared in the daily papers '' 
bearing on the discovery of a supposed valuable clay in the',' 
Cleveland district, termed by some of the writers thereof alumina,^ 
and by others kaolin, containing aluminium ; and as apparently’ 
a good deal of misunderstanding appears to exist concerning the^ 
importance or otherwise of this discovery the accompanying facts" 
are submitted in the hope that they may serve to remove it. i 
I 
Now, this difference of opinion to which allusion is madejl 
relates to the value of the so-called kaolin as a source of the earth \ i 
alumina and so of the metal aluminium ; also on its value as a ' 
china clay. 
It is convenient at the outset to consider what alumina is. ! 
This mineral, then, is an oxide of the element aluminium, and 
is in fact the only oxide of that metal known. In nature it | 
occurs in two states or conditions— when it may («) be • 
anhydrous or [b) contain water of constitution ; and (2) in a ! 
comhmed state. As illustrations of the former of these modes of | 
occurrence we have the mineral corundum and its varieties— ■] 
ruby, sapphire, — which is an anhydrous oxide ; whilst as j 
