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no volatile alkali. There is also much variety in the quantity and state of the combination of the saline and other matters in different secreted fluids.
Animal oils and fats, like the gross oil of vegetables, are not of themselves soluble, either in water or vi. nous spirit, but they may be united with water by the intervention of gum or mucilage. Most of them may be changed into soap by fixed alkaline salts, and may thus be rendered miscible with spirit as well as water.
The oderous matter of some oderiferous animal substances, as musk, civet, castor, is, as well as essential oil, soluble in spirit of wine, and volatile in the heat of boiling water.
It is said that an actual essential oil has been obtained from castor in a very small quantity, but of an exceedingly strong diffusive smell.
The blistering matter of cantharides, and those parts of sundry animal substances in which their peculiar taste resides, are dissolved by rectified spirit, and seem to have some analogy with any gummy resins.
The gelatinous principle of animals, like the gum of vegetables, dissolves in water, but not in spirit or in oils ; like gums also, it renders oils and fats miscible with water into a milky colour. Some insects, particularly the ant, are found to contain an acid juice, which approaches nearly to the nature of vegetable acid. There are, however, sundry animal juices which differ greatly, even in these general kinds of properties, from the corresponding ones of vegetables. Thus, animal serum, which appears analagous to vegetable gummy juices, has this remarkable difference, that though it mingles uniformly with cold or warm water, yet, on considerably heating the mixture, the animal matters separate from the watery fluid, and concretes into a solid mass.
Some have been of opinion, that the heat of the animal body in certain diseases might rise to such a degree as to produce this dangerous or mortal concretion of the serous humours, but the heat requisite for this effect is greater than it appears capable of sustaining. The soft and fluids parts of animals are strongly disposed to run into putrefaction; they putrefy much sooner than vegetable matter, and when corrupted, prove more offensive.
This process takes place, in some degree, in the bodies of living animals, as often as the juices stagnate long, or are prevented by an obstruction of the natural emunctories from throwing off their more volatile and corruptible parts. During putrefaction, a quantity of air is generated, all the humours become gradually thinner, and the fibrous parts more lax and tender; hence, the tympany, which succeeds the induration of any of the viscera, or the imprudent suppression of dysentries by astringents, and the weakness and laxity of vessels observed in the scurvy, &c.
The crassamentum of human blood, as well as that of quadrupeds, change by putrefaction into a dark livid colour, a few drops of which tinge the serum with a tawny hue, like the ichor of sores and dysenteric fluxes, as also the white of the eye, the saliva, the serum of blood drawn from a vein, and the liquid that oozes from a blister in the scurvy, and in the advanced state of malignant fevers.
The putrid crassamentum changes a large quantity of recent urine to a flame-coloured water, so common in fevers and in the scurvy. The mixture, after standing an hour or two, gathers a cloud resembling what is seen in the crude water of acute distempers, with some oily matter on the surface like the scum which floats on scorbutic urine. The serum of the
blood deposits in putrefaction a sediment resembling well digested pus, and changes to a faint olive-green. A serum so far putrefied as to become green, is perhaps never to be seen in the vessels of living animals ; but in dead bodies this serum is to be distinguished by the green colour which the flesh acquires in corrupting. In salted meat this is commonly ascribed to the brine, but erroneously, for that has no power of giving this colour, but only of qualifying the taste, and in some degree the ill effects of corrupted aliments. In foul ulcers, and other sores where the serum is left to stagnate long, the matter is likewise found of this colour, and is then always acrimonious. The putrefaction of animal substances is prevented or retarded by most saline matters, even by the fixed and volatile alkaline salts, which have generally been supposed to produce a contrary effect. Of all the salts that have been tried, sea salt seems to resist putrefaction the least; in small quantities it even accelerates the
process. The vegetable bitters, as camomile flowers, are much stronger antiseptics, not only for preserving the flesh long uncorrupted, but likewise somewhat correcting it when putrid : the mineral acids have this effect in a more remarkable degree.
Vinous spirits, aromatics, and warm substances, and the acrid plants, erroneously called alkalescent, scurvygrass, and horse-radish, are found to resist putrefaction. Sugar and camphor are found to be powerfully antiseptic. Fixed air, or the carbonic acid, is likewise known to resist putrefaction ; but, above all, the vapour of nitrous acid in the form of air is found to be the most effectual in preserving animal bodies from corruption. The list of the septics, or of those substances which promote putrefaction, is very short, and such a property has only been discovered in calca
reous earths and magnesia, and a very few salts whose bases are of these earths. It is observable, that notwithstanding the strong tendency of animal matter to putrefaction, yet broths made from them, mixed with vegetables, instead of putrefying turn sour.
It has been found that when animal flesh in substance is beaten up with bread, or other farinaceous vegetables, and a proper quantity of water, into the consistence of a pap, this mixture likewise, kept in a heat equal to that of the human body, grows in a little time sour, while the vegetable matters without the flesh suffer no change. Some few vegetables, in the resolution of them by fire, discover some agreeme in their matter with bodies of the animal kingdom, yielding a volatile alkaline salt in considerable quantity, with little or nothing of the acid or fixed alkali, which the generality of vegetables afford. In animal substances also, there are some exceptions to the general analysis ; from animal fats, as we observed before, instead of a volatile alkali, an acid liquor is obtained, and their empyreumatic oil wants the peculiar offensiveness of other animal oils.
The operation of milking, as well as many other operations in the dairy, require the most minute and unremitting attention. Hence, a small dairy is usually more profitably managed than a large one, for the farmer's wife and daughters can more readily superintend, or perhaps perform a great part of the dairy operations themselves, when the farm is of a moderate size,
and this is always better done by them than we can expect from a hired servant. Sir John Sinclair justly remarks, that no branch of husbandry requires such constant and unremitting attention.“ If,” says he, few spoonsful of milk are left in the udder of the cow at milking; if any of the implements used in the dairy be allowed to be tainted by neglect; if the dairyhouse be kept dirty, or out of order ; if the milk is either too hot or too cold at coagulation; if too much or too little rennet is put into the milk; if the whey is not speedily taken off; if too much or too little salt is applied ; if the butter is too slowly or too hastily churned; or if other minute attentions are neglected, the milk will be in a great measure lost. If these nice operations,” continues Sir John, “ occurred only once a month, or once a week, they might be easily guarded against ; but as they require to be observed during every stage of the process, and almost every hour of the day, the most vigilant attention must be kept up throughout the whole season. This is not to be expected from hired servants."
ANOTHER important branch of the dairy system, is the making butter; an art which appears to have been the invention not of the Greeks or Romans, but of the ancient Germans and Britons. With regard to the good or bad qualities of butter, a great deal has been always ascribed to the pasturage of different farms or districts. Recent observations and experiments, however, show that much less depends upon this than has been com