OF THE HORSE. 1-2.5 



of jiroper drainage or neglect. To make the subject cleai'ly understood, 

 we will briefly describe the composition of the atmosphere and the changes 

 which are brought about in it, by the function of respiration. The air 

 which surrounds us, in its ordinary state, consists of two principal gases 

 named oxygen and nitrogen, in the proportions of about a tifth by bulk of 

 the former to nearly four-fifths of the latter ; besides these there are also 

 very small quantities of carbonic acid and some watery vapour. Either 

 oxygen or nitrogen gas, in a separate state, or combined in any other pro- 

 portions, would prove destructive or otherwise injurious to life, but by a 

 beautiful arrangement, they are blended together in such proportions that 

 the destructive properties of each are neutralised and made one of the 

 chief means by which the life of men and animals is sustained. The func- 

 tion of respiration consists of two distinct parts, viz. inspiration and 

 expiration. At each inspii'ation made by the animal a considerable 

 quantity of air passes into the lungs, and having penetrated to the remotest 

 parts of the bronchial tubes, enters what are called the air-cells. Ai'ound 

 these cells ramify great numbers of very minute blood-vessels called 

 capillaries, containing the blood which has been rendered impure in its 

 passage through the system of the animal. A pecuHar change here takes 

 place between the air and the blood. The oxygen of the air conibines 

 with the blood, and uniting with the carbon contained in it, and Avhich 

 renders it impure, forms carbonic acid, thus rendering it again fit to pass 

 on and supply the wants of the system, while the carbonic acid and nitrogen 

 (both in their present state destructive poisons) are exjoelled from the lungs 

 by the process of expiration into tlie suiTOunding atmosphere. From the 

 above it Avill be seen that an abundant supply of pure air is necessary for 

 the maintenance of the health and life of the animal. The effect of several 

 horses being shut up in the same stable is completely to empoison the air; and 

 yet, even in the present day, there are too many who carefully close every 

 aperture by which a breath of fresh air can by possibihty gain admission. 

 In efiecting this, even the key-hole and the threshold are not forgotten. 

 What, of necessity, must be the consequence of this ? The breathing of 

 every animal contaminates the air, and when in the course of the night, 

 with every aperture stopped, it passes again and again through the lungs, 

 the blood cannot undergo its proper and healthy change, digestion will 

 not be so perfectly performed, the brain and nervous system will suffer, 

 and all the functions of life be more or less injured, and one need not feel 

 surprised at finding sore throat, inflamed lungs, diseased eyes, grease, 

 mange, and glanders, at times making their appearance in such stables. 

 One other chief source of impurity to the air in stables, is the jiresence of 

 certain deleterious gases resulting from the decomposition of the urine 

 and dung of the animal, and also of other vegetable substances, caused 

 either by defective di-ainage or neglect. The principal gases evolved are 

 the compounds of sulphur and carbon with hydrogen and ammonia, all 

 more or less injurious to health. When a person first enters an ill-man- 

 aged stable, and especially early in the morning, he is annoyed, not only by 

 the heat of the confined air, but by a pungent smell, resembling hartshorn. 

 It has been ascertained by chemical experiments that the ui'ine of the 

 horse contains in it exceedingly large quantities of compounds easily con- 

 verted by decomposition into ammonia ; and not only so, but that influ- 

 enced by the heat of a crowded stable, and possibly by other decompositions 

 that are going forward at the same time, this ammoniacal vapour begins 

 to be rapidly given out almost immediately after the urine is voided. 

 When disease begins to appear among the inhabitants of these ill-venti- 

 lated places, is it wonderful that it should rapidly spread among them, and 

 that the plague-spot shoixld be, as it were, placed on the door of snnh a 



