198 A few Remarks on the Rangoon Laterite. [No. 2. 



The fragments of this are neither, irregular masses of two or more 

 minerals intimately blended, nor, secondly, are they fragments of pre- 

 existing rocJcs united by a cement . These are generally considered, 

 as the only two classes, I believe, of breccias. 



Analyses of the various parts of this rock and of the soils about it, 

 give the following results. 



The aluminous soil generally contains 50 per cent, of clay, the 

 richer kinds as much as 65 to 70. 



A detailed analysis of specimens of the rock made by Captain 

 James. 32nd N. I.* of the Museum of Economic Geology gives the 

 following result. 



Mean Result of three Analyses of Laterite from Burmah. 

 Soluble lis Acids. 



Peroxide of Iron, 46.279 



Alumina, 5.783 



Lime, 742 



Magnesia, 090 



Silica, 120 



Insoluble in Acids. 



Silica (dissolved by Potash,) 6.728 



Silica (by fusion,) 30.728 



Lime, Iron and Alumina, 2.728 



Combined Water Alkalies and Loss, 6.802 



100.000 



* The following is an extract from Capt. James* letter : — 



,l I send you an analysis of the Laterite which I have made very carefully. 



" It is the mean result of three analyses, all of which came within a fraction 

 one of the other. You will perceive by the quantity of iron it contains, that it 

 would he well worth smelting if coal and limestone could be obtained in its vicinity. 



" It yields about 32 per cent, of metallic iron, and I shall smelt a small piece I 

 have remaining to see what quality of iron it is. 



44 The quality of hardening by exposure which the laterite possesses, is doubtless 

 due to the silica which exists in a soluble state by potash, and to which the same 

 property is due in all hydraulic limes. Iron also when it exists in such quantities 

 has the power of hardening. 



" I have shown the analysis to Sir Henry de la Becke who considers it very in- 

 teresting, and I think I shall publish it in the Chemical Journal. 



44 Water also exists in it chemically combined, and which I was unable to drive 

 off at 212° . This would also assist it in hardening. 



44 I have been assisted in my analysis by an assistant of Lyon Playfair's who is a 

 very clever chemist, so you may depend upon the result being quite correct. 



4< I have sent the analysis of the laterite to Col. Sykes, requesting him to let me 

 have one that was made for him some time ago." 



