1853.] A few Remarks on the Rangoon Laterite. 199 



The analysis of a proportion of a black stratum in its neighbour- 

 hood bearing quite the appearance of a carbonaceous or vegetable 

 mould, gave moisture 13.3 in 100 parts, and on being calcined to a 

 red heat, animal or organic matter 1 .6 only, the remainder having the 

 colour and appearance of powdered brick. 



Particles taken carefully out, having more than usual the appear- 

 ance of concretions of lime, gave however on trial with sulphuric-acid 

 no indication of it. 



Erom the foregoing, this rock appears to be chiefly silica and iron 

 bound together, by some agent acting chemically on it, although at 

 the same time, there can be no doubt that the clay of the rich alumi- 

 nous soil, in which it rests and is formed, is in some way necessary to 

 the process. In some of the rising grounds near the Rangoon stock- 

 ade, I have found a plain soft clay-slate which gathering the ochreous 

 tint or infusion, seems to swell into lumps or small masses, and from 

 that to pass into the regular concretionary or gravelly form in which 

 I have described the stone itself as being found in its first stages, and 

 which we use for roads, and in this pebbly form it may be found 

 covering the surface of most of the hillocks and mounds about 

 Rangoon. "What the infused agent may be I am unable at present 

 with my imperfect means to ascertain. If this rock be then, as it has 

 all the appearance of being, true laterite, we have it here forming 

 under our feet, and laterite cannot be supposed to be igneous, but is 

 evidently, like other rocks which have been erroneously attributed to 

 volcanic sources, of chemical origin. 



I have found in it myself small shells, but no sufficiently decided 

 specimen as yet to pronounce confidently on, and the superintending 

 Surgeon here informed me that he had seen at Moulmain, in the 

 side of an excavation for a dry dock, pieces of pottery imbedded in it. 

 Quartz and other pebbles are common in it. It may be perhaps 

 that as the flints in chalk and our kunkur are nodular formations of 

 silica and of lime, so this represents a similar nucleous concretionary 

 form of a richly aluminous soil, and that flints, kunkur and laterite 

 are the results of a similar chemical process acting respectively upon 

 calcareo-silicious, silicio-calcareous and alumino-silicious earths. 



Specimens of rocks of various kinds are found at Eangoon, but the 

 only one in situ is the plastic clay-like pipe-clay which occurs to the 



