CHKMISTRY. 



fvi.NTir.VriON 1 ! 



pen*, unless either gas is present in great excess. On the 

 rry, by the action of gaseous diffusion they inter- 

 mingle, and M> form a homogeneous combination in all 

 ordinary circumstances. In a doted room, tlu-rcfore, 

 every part will soon arrive at a literally stagnant state. 

 H>e only motion of the impure air will be produced by 

 the animal heat, which causes it to rise, and the cooling 

 effect of the window* and walla, which has a contrary 

 influence. On opening a door, however, a fro-h series of 

 physical cause* comes uit A draught of cool, 



and therefore heavy, air Kit into the room at the lower 

 part, whilst nno of hot iuid light air tfrajxi out tran/ji, at tho 

 top. This may be readily noticed by holding a lighted 

 candle successively at the bottom, middle, and top of an 

 open doorway, when these currents will be noticed ; the 

 middle part, however, affording no current. This simple 

 experiment teaches us the philosophy of ventilation in tho 

 most effective manner; and every ventilating an 



'. which has yet been, or is likely to be proposed, 

 rests for iU basis on this fact 



YA hen open fires are found in a room, of course a con- 

 stant draught is maintained ; and this, doubtless, di- 

 Uiinixhes the unhealthy character of apartments in which 

 we often see men, women, children, cats, dogs, &c., <tc., 



ing together. A firo must be kept for cooking pur- 

 ]>oses; and all the animals we have named generally 

 sleep on the floor, or but little removed above it. They 

 then, to some extent, enjoy a constant change of air when 

 at rest ; whilst to a person entering such a room the 

 effluvia would be intolerable, because his head would be 

 urn. h above the chimney opening, through which the 

 lower stratum of impure air passes away. On these 

 \ital and interesting subjects, however, we must not 

 enlarge. We commend them to the study of all our 

 readers, as a matter of duty on their part. A little 

 sound practical advice to a poor man, earning his weekly 

 wages and supporting a large family, is of much greater 



uiary value than a lilieral donation of money. The 

 last he will soon upend ; the former will save him, in 

 medicine and loss of time (his money) by illness, some 

 ].IUII<IK pnduuMM in the year. Indeed, we never see a 

 broken pane of glass in the window of a working man's 



. without being thankful that the brittle nature of 

 the material most mercifully provides for him one of the 

 greatest blessings of nature free air, and also ventilation 

 both of which he wilfully denies himself, to his own 

 loss of health and resources. Well would it bo if tin- 

 city missionaries, so usefully employed in our large 

 towns, would, in such a manner of giving sanitary ad- 

 vice, completely follow the pattern of the Great Physician, 

 who "went about doing good," not to the souls alone, but 

 generally first to the bodies of men. However much we 

 may endeavour to raise the moral condition of man, we 

 must not neglect his physical state. Our relationship, as 

 beings, is threefold moral, mental, and physical. At 

 no instant in this life do they exceed each other in their 

 exigencies. They have been united by the Creator from 



loineiit man was created, and they are not put 

 minder until He commands, and death becomes the 

 means of their dissolution. 



Distantly connected with the subject of ventilation is 

 that of clothing, in so far as it concerns the removal of 

 those gaies which paas from the skin. It is a remark- 

 able fact, that animals may be as readily poisoned 1 

 absorption of poisonous gases through the skin as if such 



inhaled by the lung*. Some years ago, when tho 

 : edition was first proposed, an inquiry was made 



the causes of the unhealthiness that prevails in 

 regions surrounding the Niger and other tropical rivers. 

 After much dispute on tho subject, it was considered that 



presence of free sulphuretted hydrogen was the 

 proximate cause ; and that not only would danger arise 

 from ii, -piring the tainted air, but that tho entire surface 

 of the body was also predisposed to absorb tho fatal 

 exhalations. To prove this, rabbits were enclosed in air- 

 tight vowl,, filled with sulphuretted hydrogen, in such 

 a manner that the heads of tho animals were left free in 

 the open air ; so that the poisonous gases could not pats 

 into the sysUuu by means of tho lungs. It was found 



that a rapid absorption took place through tho skin, 

 which IKK>II proved I'.Ual. If, h<.\\,, 



well oiled, then thn porps of the skin being tilled up. al>- 

 sorption did not take place ; and so the animals, placed in 

 tho circumstances referred to, were compmtiTMy unin- 

 jured. Applying, to some extent, such principles to the 

 question of the human subject, we shall see that, unless 

 the clothing permits a certain amount of ventilation of 

 the body, either by its being porous, or oulycoverin 

 skin loosely, the animal exhalations will IMS retained on 

 the surface of tho skin, and will be reabsorbed, to the 

 manifest detriment of the individual. Hence the dan- 

 ger which arises in part from the use of what is term. -d 

 " water-proof" clothing. The gaseous and liquid secre- 

 tions are kept in contact with the skin, and art) thus pro- 

 ductive of serious consequences. The nie of water-proof 

 shoes hence frequently IM ," for tho 



ammonia or acetic acid secreted, according to tho physi- 

 cal constitution of the person, acts as an irritant of the 

 skin ; and thus, for the same reason, tho nonporosity of 

 tho leather new shoes always hurt the feet, preventing, 

 as they do, the escape of the perspiration. 



It is thus found that flannel worn next the skin, and 

 woollen clothes generally, are the most healthy. They 

 retain, through their non-conducting power, the heat of 

 tho body ; and yet, by their porosity, permit of a con- 

 stant circulation of the air they inclose, into which tho 

 excreted gases, etc., pass off. They have also another 

 advantage, which is that of acting as an irritant to the 

 skin. They stimulate the nerves on its surface, and thus 

 the pores are kept continually open. 



CLEANLINKSS. The remarks just mado bring us to 

 another subject of great importance that of personal 

 cleanliness ; and in tliis, chemistry and chemical manu- 

 factures play a most important part. It is well known 

 that the body of a human being contains some millions 

 of outlets, through which water, A'c. , continually pass out. 

 The liquid and gaseous substances escape, or else are 

 absorbed by the clothing; whilst some portion of tho 

 solid is retained in the skin and in tho pores. This solid 

 matter consists of animal fat, common salt, acids, and 

 i ther substances, which, if not removed, will close tho 

 perspiratory pores, and prevent that relief to the sy 

 which those pores are intended to all'ord. In removing 

 the matter, water alone is not sufficient. This may be 

 readily noticed on any one taking a bath, either hot or 

 cold, after violent exercise. The water will flow frum 

 tho skin without really wetting it, simply because tho 

 fatty matter, deposited on the surface, intervenes between 

 the skin and the liquid. If, however, an alkali, either 

 free or in the form of soap, be used, then the fatty sub- 

 stances are easily removed. Soap, indeed, is simply a 

 convenient method of applying an alkaline solution in 

 such a way that, whilst its detergent properties maybe 

 employed, its caustic ellects, which would destroy the 

 skin, are avoided. Washing powders, and other sub- 

 stances of tho class, arc those generally containing 

 either potass, or soda in a free state; and from their 

 known power of combining with the animal fatty acids, 

 their value as detergents ari>cs. Of course, what is ro- 

 i (i M red to cleanse the skin, is equally useful in the ope- 

 ration of washing articles of clothing. If such are not 

 rli-uis.'d from the impurities which they have absorbed 

 from the skin, they soon not only acquire a fu-tid Mnoll, 

 but become positively dangerous. Kept near the ab- 

 sorbing pores, they alTord a constant supply of impure 

 matter, which, if realism-bed, is productive of any kind 

 .rder of tho typhoid class. We are, perhaps, not 

 wrong i:i applying a similar observation to ragged clothes 

 as wo have done to broken windows ; for what one does 

 to ventilate the room of tho poor man, the other does to 

 his body each allowing an unwelcome, but necessary 

 supply of fresh air. 



WATER. Wo have already stated that we do not in- 

 tend to enter into the question of the supply of water, 

 but we may make a few remark ug its chemical 



relations to sanitary questions. I'nro water, in the che- 

 mical sense, never occurs in Nature. Th 

 , approach to it is rain ; which, however, is always 



