RESPIRATION, AND ANIMALIZATION. 149 



Of these gases I have already observed, that azote or nitrogen is by far 

 the largest in respect of quantity, and it appears also to be by far the most 

 active." Hence, on the cessation of the vital principle, the azotic corpuscles 

 very speedily make an advance towards those of oxygen, and generally in the 

 softer and more fluid parts of the system ; the confol of the vital principle being 

 here looser and less powerfully exerted. A union readily takes place between 

 the two, and thus combined they fly oft' in the form of nitric acid ; while at the 

 same time another portion of azote combines with some portion of hydrogen, 

 and escapes in the form of ammonia or volatile alkali. A spontaneous de- 

 composition having thus commenced, all the other component parts of the 

 lifeless machine are set at liberty, and fly off either separately or in dif- 

 ferent combinations ; during which series of actions, from the union of hy- 

 drogen with carbon, and especially if conjoined at the same time with some 

 portion of phosphorus or sulphur, is thrown forth that offensive aura which 

 is the peculiar characteristic of the putrefactive process, and which, accord- 

 ing to the particular mode in which the different elementary substances com- 

 bine, constitutes the fetor that escapes from putrid fishes, rotten eggs, or any 

 other decomposing animal substances. 



In this manner, then, by simple, binary, or ternary attractions and combi- 

 nations, the whole of the substance constituting the animal system, when 

 destitute of its vital principle, flies off progressively to convey new pabulum 

 to the world of vegetation; and nothing is left behind but lime or the earth 

 of bones, and soil or the earth of vegetables: the former furnishing plants 

 with a perpetual stimulus by the eagerness with which it imbibes oxygen, and 

 the latter offering them a food ready prepared for their digestive organs. 



In order, however, that putrefaction should take place, it is necessary that 

 certain accessaries to such a process should be present, without which putre- 

 faction will never follow. Of these the chief are rest, air, moisture, and heat. 



Without REST the putrefactive process in no instance takes place readily, 

 and in some instances does not take place at all : for animal flesh, when ex- 

 posed' to the perpetual action of running water, is often found converted into 

 one common mass of fat or spermaceti, as I shall presently have occasion to 

 observe more minutely. 



AIR must necessarily coexist, for putrefaction can never be induced in a 

 vacuum* Yet we must not only have air, but genuine atmospheric air ; or, in 

 other words, the surrounding medium must be compounded of the gases 

 which constitute the air of the atmosphere, and in their just proportions. To 

 prove this, it is sufficient to mention that dead animal substance has been 

 exposed by M. Morveau,* and other chemists, for five or six years in confined 

 vessels, to the action of simple nitrogen, hydrogen, carbon, and various other 

 gases, without any change that can be entitled to the appellation of putre- 

 faction. 



There must also be MOISTURE ; for as I have already observed, putrefaction 

 commences in the softer and more fluid parts of the animal system. On this 

 account it rarely occurs during a sere harmattan or drying wind of any kind, 

 and never in a frost so severe as to destroy all moisture whatsoever; the 

 power of frost exercising quite as effectual a control over the elements of 

 animal matter as the living principle itself. 



For the same reason there must be HEAT ; since in the total absence of 

 heat frost must necessarily take place, together with an entire privation of 

 moisture. On this last account, again, the heat made use of must only be to 

 a certain extent, as about 65^ of Fahrenheit; for, if carried much higher, the 

 rarefaction which takes place in the surrounding atmosphere will induce an 

 ascent of all the fluids in the animal substance towards its surface ; whence 

 they will fly off in the form of vapour, before the putrefying- process can have 

 had time to commence, and leave nothing behind but dry indurated materials, 

 incapable of putrefaction because destitute of all moisture. Our dinner - 



* See Memoire sur ia Nature des Fluides lastiqnes afiriformes, qui se dgagent de quelques Matures 

 animates, &c. par M. Lavoisier, Mem. de 1'Acad. 1782 ; as also, M. Brugnatelli's paper in Crell's Chemical 

 Annals for 1708, Ueber die Faulung thierischer theile in verschiedeii Luttarten. 



