156 



ON THE CmCULATION OF THE BLOOP, 



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

 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 oxygene, 

 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 putrefaction will never follow. Of these the chief are rest, air, 

 moisture, and heat. 



Without itEST the putrefactive process in no instance takes place 

 readily, and in some instances does not take place at all : for animal flesh, 

 when exposed 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. 



Am must necessarily co-exist, for putrefaction can never be induced in 

 a vacuum. Yet we must not only have air, but genuine atmospheric air y 

 or, in other words, the surrounding medium must be compounded of the 

 gases which constitute the air of the atmosphere, and in their just propor- 

 tions. To prove this, it is suflicient to mention that dead animal sub- 

 stance lias been exposed by M. Morveau,* and other chemists, for five or 

 six years in confined vessels, to the action of simple nitrogene, hydrogene, 

 carbone, and various other gases, without any change that can be entitled 

 to the appellation of putrefaction. 



There must also be moistuke ; for, as I have already observed, putre- 

 faction 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 effective 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 

 lieat 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 assent of all the fluids in the animal substance towards its | 

 surface ; whence they will fly off in the form of vapour, before the putre- j 

 fying process can have had time to commence, and leave nothing behind | 

 but dry indurated materials, incapable of putrefaction because destitute of | 

 ail moisture. Our dinner tables too often supply us with instances of this | 

 fact, in dishes of roast or boiled meat too long exposed to the action of g 

 the fire, and hence reduced to juiceless and ragged fibres, totally devoid of 

 nutriment, and capable of keeping for weeks or months, without betraying 

 any putrefactive indication. 



In like manner, when bodies are buried beneath the hot and arid sands 

 of Egypt or Arabia, with a sultry sun shining, almost without ceasing, 

 upon the sandy surface, the heat hereby produced is so considerable as to 

 raise the whole of the fluids of the animal system to the cuticle, whence 

 ihey are immediately and voraciously drunk up by the bibulous sands that 



* See Memoire sur la Nature des Fluides elastiques aeriformes, qui se degagent de quelqnes 

 IVlatieres aniniales, &c. par M. Lavoisier, Mem. de i'Acad. 1TS2; as also, M. Brugnatelli's 

 5C3j)er m Crell's Chemical Annals for 1708, X^eberdieFauliingthierischertheiiein verfichiedep. 



