40 
managed with regard to keeping out the rain, there will be no 
necessity for thatching, as the vret penetrates this kind of soil 
with difficulty. If housed, it becomes totally desiccated, and 
is very awkward to manage in such state on the potting bench. 
It should lie for several months before being used, as the fibre 
of heath is unusually tough. If well piled up it will be preserved 
for several years; and when used it should, like loam, be well 
chopped with the spade, but not riddled. 
265 Charcoal. Any sort of charcoal will do for potting purposes, 
as almost everything depends on the size of the particles, which 
should be regulated in a considerable degree by the size of the 
“shift” given to the plant. Thus, for a three-inch pot, I would 
use charcoal in the compost in pieces of a quarter of an inch or 
less; in seven-inch pots, their size may be nearly half an inch; 
and in very large shifts, say pots of thirteen or fourteen inches 
diameter, I would increase them to nearly an inch. The species 
of plant under culture will, however, vary these circumstances. 
Charcoal is said to act as a manure, by condensing carbonic 
acid gas within its pores. Be this as it may, it is extremely 
useful as a mere transmitter of moisture, and its chemical 
characters are, doubtless, considerable. I burn my own, and 
prefer it from its mixture with the ashes; it is readily produced 
by covering up with earth the smouldering heap of brush-wood 
with all the weeds, hedge prunings, and other refuse of the 
kitchen garden, which is reserved for the purpose. See Auc- 
tarium 218. After burning, I pass the whole through a very fine 
sieve, to separate the dust or wood-ash, which I reserve by itself 
for dressing onion, carrot, and turnip ground, in the kitchen 
garden. The whole should be kept under cover until wanted. 
266 Sharp Sand. I need say little on this head, as most persons 
are familiar with the kind of sand used by gardeners, or rather 
nurserymen, who are sure to select the best. Everything 
depends on its sharpness and cleanness, and in order to ensure 
the latter quality, if pit sand, it should be washed, to divest it of 
all extraneous matter, as it is wanted chiefly, if not entirely, for 
its mechanical properties, in facilitating the steady and uniform 
escape of moisture. Two kinds should be kept if possible, the 
one extremely fine, for cuttings and plants in very small pots, 
and the other very coarse — as large as grains of raddish seed, 
if it can be obtained. Both should be equally sharp. 
