The principal animal fluids are blood, milk, and bile. The blood, soon after it is taken from the living animal, separates into two parts, one called the crassamentum, which is red, and the other serum, which is a fluid, and of a pale straw-colour; the crassamentum is a more firm and consistent mass than the serum, by which it is usually, when cool, surrounded. Milk consists of serum or whey, butter, which while floating on the milk is called cream, and curd or cheese, which has the leading properties of coagulated albumen. The bile, as has been before stated, is a saponaceous fluid consisting chiefly of albumen, soda, a bitter resin, water, and some other saline matter. Fat, in the dead animal, is merely animal oil in a concrete or hardened state.
The principal animal solids besides bone, are albumen, gelatine, and fibrin. These substances, in certain states of concretion and combination, form all the solids of animals, and are separable from each other by easy analysis.
By whatever means we deprive animal substances of their nitrogen, we reduce them to a state similar to that of vegetables. The muscular fibre, or flesh as it is usually called, when excluded from the air, but particularly if in contact with water, parts with its nitrogen, and is converted into a substance resembling spermaceti, which in its analysis agrees with vegetable expressed oil.
When vegetables and animals are deprived of life, their various parts, and especially their fluids, sooner or later, spontaneously assume processes which terminate in their total decomposition. The earlier stages which lead to their decomposition are termed fermentation. Of this there are three kinds; the first, or vinous fermentation, takes place in vegetable juices which contain a considerable quantity of sugar, such are the juices of the grape forming wine, of the apple forming cyder, &c. In this fermentation a considerable quantity of carbonic acid gas is disengaged; this gas is very destructive to animal life, no one can live for a minute in it. If, after the vinous fermentation is completed, the liquor be exposed for some time to atmospheric air, another fermentation takes place, oxygen is absorbed, and the liquor becomes vinegar, hence called the acetous fermentation. The putrid fermentation generally takes place in animal bodies very soon after death, so that neither of the other processes, certainly not the vinous, the acetous rarely, becomes a condition of animal matter.
The chief product of the vinous fermentation is an intoxicating, colourless, volatile, and highly inflammable liquor called alcohol; in common language rectified spirits of wine. It may be obtained by distillation from wine, cyder, perry, brandy, &c. &c.; and from whatever liquor it be obtained, when freed from extraneous matter, it is in every case the same. Alcohol consists of hydrogen, carbon, and oxygen. Its usual specific gravity is 825, water being 1000.
After vegetables have passed through these fermenting processes, the decomposition continuing, unless checked by extraneous means, the remainder of their constituents become separated, many of them being volatilized in the form of gas, and nothing remains but a black or brown residuum called mould, consisting of carbon, some salts, a little oil, and extractive matter.
In the decomposition of animal substances, we perceive the union of hydrogen and nitrogen forming ammonia; the combination of carbon with oxygen produces carbonic acid; and nitric acid arises from the union oxygen and nitrogen. A quantity of hydrogen is also extricated in the form of gas, carrying off with it sulphur and phosphorus, which produce together the disagreeable smell arising from animal putrefaction. Nothing now remains but a portion of carbon mixed with phosphate of soda and phosphate of lime.
Hence we see that, by the processes of fermentation, complex bodies are converted into more simple substances, and that nature restores, in the new combinations, the principles which she had borrowed from the atmosphere for the formation of both animals and vegetables; and that she accomplishes a perpetual circle of ever-changing being, at once demonstrating the fecundity of her resources, and the grandeur and simplicity of her operations.
On substantive and adjective colours, and the mordants, &c. used in dyeing; and on the leading facts of chemical science as connected with this art.
The substances commonly dyed are either animal, as wool, silk, hair, leather, and skins of all kinds; or vegetable, as cotton, flax, hemp, &c. Great differences exist between the affinities for colouring matter possessed by these substances, so that a process which perfectly succeeds in dyeing wool may fail when applied to cotton. Wool has generally the strongest affinity for colour; silk and other animal substances come next; cotton next, and hemp and flax last.