XxXil Proceedings. 
In reference to the paper of Mr. Hodgkinson, a letter was read 
from R. B. Smyth, Esq., one of the hon. secretaries, who was 
unable to attend. 
Melbourne, July 9th, 1855. 
Drar Srr—I have to thank you for having permitted me to peruse a 
manuscript of yours on the soils, and general agricultural properties of 
the lands in Victoria. You have handled the subject so carefully, and 
displayed such a large amount of practical knowledge in that department 
of science, that I dare not venture to offer a criticism. 
Your analysis of the volcanic soils is borne out by the facts elicited by 
Klaproth, Vauquelin, Rose, and others, in reference to the minerals 
which these rocks contain; and you have done great service to agricul- 
ture by pointing out the causes of the remarkable fertility of soils of 
such a character. 
Let me offer a few remarks, in addition to what you have stated in 
your paper, in elucidation of the facts there put forth. 
One great cause of the fertility of volcanic soils is due to the colour, 
consistency, and the consequent comparative rapidity with which such 
soils radiate heat absorbed during the day. Experiment has shown that 
the general temperature of rich black mould is some degrees higher than 
wet clay during the solar heat; and a regular scale of temperatures is 
found between white clay saturated with moisture and black earth. Now, 
in addition to this, it is found that a rich black soil, radiating heat as it 
does with such rapidity, necessarily condenses a larger amount of dew 
than a clay soil, thus supply the plant with an absolute necessary in com- 
parative abundance. This property is really an objection in a climate 
such as England, if in excess; but in this climate it must be held asa 
prime consideration in choosing land for agricultural purposes. 
I do not hold that this applies in strictness, or with equal force, to all 
voleanic soils. It is, however, the characteristic of the volcanic soils in 
this country. For the growth of cereals—wheat for instance—where 
the roots are fine and radiating, and the stalk high and heavy, possibly 
volcanic soil of the richest kind is not to be chosen. Itis perhaps better 
adapted to horticultural products. 
Another cause of the fertility of this soil is to be found in the vast 
amount of decaying and decayed vegetable matter which it contains.— 
This, I need not remind you, has the property of absorbing carbonic 
acid from the atmosphere, and in itself, almost indestructible, is a never- 
failing storehouse for this essential ingredient in vegetable substance.— 
When engaged in experimenting in England, in 1850 and 1851, I re- 
peatedly raised crops from pounded charcoal. The plants were kept in 
pots, regularly watered, and subjected to different temperatures, and the 
results were most satisfactory. I may venture to say that almost any - 
soil may be rendered productive by the addition of pounded charcoal, or 
coal dust, or soot. 
It is the vulgar opinion of agriculturists that charcoal in this shape is 
really appropriated by the plant, but this is now utterly exploded where- 
ever experiment has taken the place of vague conjecture. 
Having devoted a considerable portion of my leisure time in England, 
some three or four years ago, to the consideration of these questions, 
