32 



UNDULATORY FORCES. HEAT. 



[VENTILATION. 



waste would bo at once removed. Although this can 

 rarely be carried out, still, if plates of clay are so arranged 

 as to completely euclo.se the burning fuel, a great saving 

 would result. As an illustration of this, we may remark, 

 that a rough fire-place, constructed of bricks, and only 

 having metal in the bars to hold the fuel in front and 

 beneath, will afford more heat for all domestic purposes, 

 at an expenditure of one hundredweight of coal in seven 

 days, than one of the same size, constructed entirely of 

 metal, would give at an expenditure of more than two 

 hundredweight of the same kind of coal, and for the like 

 period. The reason of this is obvious, for the bricks are 

 very imperfect conductors of heat, and, after a time, 

 they become red-hot, and so form, if we may term it, a 

 heat-jacket to the burning fuel, whilst the metal grate 

 has an exactly opposite effect. 



Several inventions have been patented and applied for 

 the purpose of diffusing the heat produced from the ordi- 

 nary fire-grate. Polished reflectors are sometimes placed 

 beneath the fire-bars; and, whilst forming a receptacle 

 for the falling ashes, they at the same time reflect a large 

 amount of heat into the apartment. The top of the 

 fire-place, or the metal arch over and in front of the fire, 

 is often made of polished metal. This, of course, is in 

 direct opposition to the laws of science; because, as this 

 portion of the arrangement is in front of the fire, it can 

 only receive heat by absorption, and throw it off by radia- 

 tion ; and, therefore, it should be of a dark or unpolished 

 surface, which, as we have already explained, forms the 

 best kind of radiator. It is, of course, very difficult to 

 retain that part of the grate forming its sides, above the 

 fire, in a polished state ; but just so far as this is managed, 

 so an additional amount of heat is reflected into the 

 room. 



It would be impossible for us to enter into detail with 

 respect to the construction of the various kinds of stoves 

 which have been proposed as substitutes for the open 

 fire. In every case, their heating power is obtained at 

 less cost than by means of the ordinary grate, because 

 the whole of the heated surface is placed bodily in the 

 apartment. In most instances, the employment of metal 

 stoves is decidedly prejudicial to health ; for not only is 

 the atmosphere dried, and a high temperature induced, 

 but there are certain obscure chemical changes which 

 take place between the atmosphere and the metal (iron), 

 which produce highly injurious effects. These are 

 entirely apart from those results afforded by the products 

 of the combustion of the fuel being allowed to escape 

 into an apartment. Indeed, this very rarely happens in 

 any stove to which a chimney is attached. 



With respect to the employment of gas stoves, wliich 

 have been lately introduced into such general use, it is 

 impossible to speak too strongly in their condemnation. 

 We of course refer to those from which the products of 

 combustion, together with the heated air, are allowed to 

 escape into the apartment. All coal gas contains arsenic, 

 sulphur, ammonia, and other impurities. During 

 the combustion of the gas, these substances are diffused 

 in a gaseous form ; and, being inhaled by the lungs, are 

 eventually absorbed into the blood. To speak of the 

 substance most commonly present arsenic is sufficient 

 to remind our readers that it is a deadly poison, and one 

 from the use of which we almost instinctively shrink. 

 There is, however, scarcely a room in the kingdom 

 wherein gas is burned, and no means are employed to 

 get rid of its products, that is not more or less a poison 

 propagator; and, by chemical tests, arsenic may easily 

 be detected in its gaseous form, floating in the air. If a 

 small portion of the solid poison is taken into the stomach, 

 we .at once seek for remedies with the utmost anxiety ; 

 whilst it is much to be feared, that there are thousands of 

 our countrymen, in our warehouses and shops, etc., who 

 are unconsciously and yet daily inhaling its gas, the 

 effects of which, whilst manifested in the decay of health, 

 are really ascribed to other but undue causes. 



Similar objections exist to the employment of any 

 source of heat when the products of the combustion 

 are permitted to escape into the apartment, and so to 

 mix with and vitiate the air. The ordinary chauffer in 



which charcoal is burned, and which is much employed 

 on the continent, has been the cause of numerous fatal 

 accidents. Whenever charcoal undergoes combustion, 

 carbonic acid gas is produced in great quantities. This, 

 if inspired into the lungs, produces speedy death not 

 perhaps from its poisonous qualities alone, but owing to 

 its containing no free oxygen, which is so essential to 

 animal existence. If a chauffer is used in an apartment 

 wherein abundant means of ventilation do not exist, the 

 carbonic acid gas, or fixed air, as it is sometimes called, 

 at first descends by its weight to the ground, and then 

 gradually accumulates, until, rising in the room to the 

 level of the mouths of persons who may be sleeping, is 

 inhaled into the lungs. It unfortunately produces no 

 painful effects, and some have even described the sensa- 

 tions as really pleasurable ; but a heavy sleep is eventually 

 induced, from wliich the sufferer never again rises alive. 

 It is a matter of great surprise, that, although cases of 

 this kind are continually occurring, the use of these instru- 

 ments of death largely prevails at the present day. It 

 may, perhaps, be not out of place to name, that a person 

 thus affected with the fumes of carbonic acid gas, may 

 be sometimes restored by removing him immediately into 

 the open air, and by dasliing cold water in the face. 

 Generally speaking, the patient should be treated as in 

 cases of drowning, inasmuch as that death occurs in fatal 

 cases from the same cause asphyxia taking place from 

 the gorging of the lungs witli carbonic acid gas. The 

 process lately introduced by Dr. Marshall Hall, for 

 restoring suspended animation (and which has been 

 adopted by the Humane Society of London), is of essen- 

 tial value in such instances. 



Having so far noticed the ordinary modes, as adopted 

 in our domestic arrangements, for the purpose of affording 

 heat, we shall next proceed to mention some facts in 

 reference to ventilation ; because the two processes that 

 of producing artificial heat, and of obtaining a supply of 

 pure air are so intimately connected. Indeed, as we 

 shall presently show, the only means of heating and 

 ventilating the apartments of many modern houses is that 

 of the fire-place, which at best is but a poor and inefl'cc- 

 -tual contrivance. After having explained some facts in 

 reference to the necessity of ventilation, the products of 

 respiration, &c. , we shall treat on the modes of producing 

 warmth by means of steam and hot- water apparatus. 



VENTILATION. 



WE have already stated, that the ventilation of an apart- 

 ment can only be carried on successfully so long as the 

 laws of expansion by heat are implicitly obeyed. We 

 now proceed to investigate in detail the application of 

 those laws. 



Our daily experience teaches us that a constant supply 

 of pure air is essential to our existence ; and, in the ab- 

 sence of this, that disease and death will take place. Like 

 many other generally received truths, to which we readily 

 give our assent, this, while believed in abstractedly, is 

 rarely put into full practice ; and hence, in most cases, 

 the complete ventilation of our churches, school-rooms, 

 houses, <fec., is at present, to a great extent, a desidera- 

 tum, and often a matter of chance. We liave already 

 suggested a very simple experiment,* which will 

 materially assist at arriving at a knowledge of those 

 general laws on wliich the principles of ventilation 

 depend. We have also observed, that hot air, being 

 light, ascends in a room, and should escape at its upper 

 part ; whilst cold air, being denser, remains, till heated, at 

 the lower part, and must also be admitted there. How- 

 ever, at ordinary temperatures, and in a room in which 

 no artificial heat is being produced, a double current of 

 air always exists, provided tliat openings, such as an open 

 door or window, are there. If any persons are present, 

 then the heat of their bodies and of their expired breath 

 tends to increase the flow of this current, and so to assist 

 the ventilation of the apartment. 



In ordinary circumstances, however, the doors and 

 windows of houses are kept closed, for the purpose of 



Sec ante, p. 2J Experiment 15. 



