There is much reason to think that the agitation of the ocean, by its waves and tides, is not more favourable to the preservation of the purity of its waters, than the movement of the atmosphere, by winds and currents, is to the maintenance of its wholesome condition, and when this is lost, to restore it; and in the absence of winds, and when pestilence is raging, the use of combustion on a large scale may with advantage be adopted; but in this climate, where the weather is seldom long calm, the occasions for the employment of that agency can be very rare indeed. Heat is much used for the purpose of dissipating effluvia, and purifying goods, clothes, letters, &c., which are supposed to be impregnated with contagious matter, or other unwholesome impurities; and there is good evidence to shew that this agent is perhaps the most powerful instrument which is ever employed for the purpose in question. Heat when applied to an atmosphere containing effluvia will rarefy it, cause it to become lighter, and dissipate it, amid the atmosphere above, where any opportunity is afforded for its egress; and when the heat is employed in the sick chamber, much good is effected by the dissipation of the damp and condensed vapour which cannot fail to be frequently present in that situation. In the sick chamber, the presence of a fire for even an hour daily is highly useful where there is little opportunity for ventilation, and when the external atmosphere is damp and motionless, for the heat issuing from it, will dislodge and dissipate any effluvia which may have become condensed, and have fastened on the furniture of the apartment. The condensation of effluvia, &c., is thus depicted in the “Mussulman.” The apartment is that of a prison. —— The pestiferous breath of the surviving was mingled with the effluvia from the dead, and the empoisoned exhalation was condensed on the damp walls, and was seen trickling down in drops of poison to the ground.[10] Footnote 10: The Mussulman by Madden. Heat, when applied to clothes which are impregnated with specific contagious matter, or merely impurities or condensed effluvia, is calculated to be highly useful, and where washing cannot be adopted, should never be neglected. Clothes which are thus tainted will be deprived in a great measure of their power of doing mischief, by placing them before a fire for a considerable time, for there is good reason to think that specific contagious poisons will be decomposed, and it is ascertained that condensed effluvia may be dissipated by the application of a smart heat.