262 Remarks on the principal Rocks 
colony the natural vegetation attains also its maximum luxu- 
riance on those mountain ranges and gullies displaying the 
older volcanic rocks; thus on the eastern slopes of the Dan- 
denong Mountains, and on some of the ranges of the Port 
Otway District, which are thug geologically constituted, the 
enormous dimensions and altitude of the trees are not sur- 
passed in any part of the globe. On the north-west coast of 
New Hoiland, Sir George Grey particularly noticed during 
his explorations there, the remarkable contrast between the 
refreshing aspect of the vegetation’on the few basaltic hills 
he encountered, and that of the general surface of the coun- 
try traversed by him. 
It would therefore, seem, from the experience of more than 
half a century in New South Wales, that some of the soils 
derived from the disintegration of volcanic rocks in Australia 
are able to bear, without apparent exhaustion, an amount of 
cropping that has, in America, been found by experience, 
sufficient to wear out some of the most fertile soils there. 
Soils displaying the extraordinary power of maintaining, 
without artificial renovation, their fertility unimpared by 
cropping, for a long series of years, are of very rare occur- 
rence in Europe, although a few very remarkable instances 
are recorded by Sprengel. : 
Thus he states that a field near the village of Nebstein, in 
Germany, has been cultivated for the last one hundred and 
sixty years without manure, and without being allowed to be 
fallow, and yet has produced good crops. 
The analysis of soil formed by the disintegration of volcanic 
rock analogous to that near Melbourne, has been found to be 
as follows :— 
Silica a ike ate Me 83°642 
Alumina sae Be hae .. 3978 
Protoxide and Peroxide of Iron a 5312 
Peroxide of Manganese ... a0 ..  0:960 
Lime a Baa ba My) 1:976 
Magnesia 300 dia 4 ...  0°650 
Potash in combination with Silica on 0:080 
Soda in combination with Silica ... xan 0-145 
Phosphoric Acid in combinatien with Lime 0-273 
Sulphuric ditto ditto ... a trace 
Humus, soluble in Alkaline Carbonates 1:270 
Chlorine de ps fh ... a trace 
Humus_... 5h Ate 30 0°234: 
Nitrogenous Matter 208 308 « -1:480 
The cultivation of wheat abstracts from the soil a larger 
proportionate quantity of silicate of potash than most agri- 
cultural products, and also demands an average quantity of 
