Of preparing Dung for the Beds.
NO dung answers the purpose so well as that of the horse, the dung and urine of this animal, together with the wet straw litter of the stalls in the stables, being of a hot quality, ferments, and acquires a strong degree of heat of long duration; but as this heat generally proves too violent at first for the growth of vegetables, the dung should always be previously reduced to a proper temperature, by casting it up in an heap, and turning it once or twice, in order to evaporate the rank burning steam before its fermentation. A quantity, in proportion to the size or extent of the intended bed must be procured. For a bed of twenty feet long, three or four large cart-loads will be necessary; and so in proportion to any length intended; as a bed may be made of almost any extent, from ten feet to fifty if required; four or five feet wide at bottom, drawing into a sharp ridge at top four or five feet high; which will allow for settling.
For private use, a single bed of about ten or fifteen feet in length may be fully sufficient. But for the supply of the London markets, long parallel ranges are made, from twenty to fifty feet in length.
Provide therefore a proportionate quantity of the best fresh horse-stable dung and litter, warm and moist, rejecting such as is dry and decayed, and such as has already exhausted its fermenting property. Let this be taken long and short as it comes to hand; and as it is brought in, toss it up together in an heap, carefully mixing, that the whole mass may acquire an equal degree of heat.
Thus let it remain together three or four weeks, according to the quantity and strength of heat, in order that it may meliorate, by discharging the rank obnoxious steam; and if it is turned over once every week, it will still incorporate the parts more effectually, and give an additional vent to the fierce ferment.
This preparation of the dung is absolutely necessary, as without such precaution, when formed into a close bed, it is apt to acquire such a vehement degree of heat, as to burn and exhaust its vegetative power, without being able to effect the purpose intended; for the spawn requires a bed that only gradually advances to its full heat, and declines in the same gradual manner; till reduced to the low, kindly, growing warmth that is peculiar to the nature of the spawn, and the growth of the Mushroom: