Animal Chemistry is the department of organicchemistry which investigates the composition of the fluids and the solids of animals, and the chemical action that takes place in animal bodies. There are four elements, sometimes distinctively named organic elements, which are invariably found in living bodies, that is carbon, hydrogen, oxygen, and nitrogen. To these may be added, as frequent constituents of the human body, sulphur, phosphorus, lime, sodium, potassium, chlorine, and iron.
The four organic elements are found in all the fluids and solids of the body. Sulphur occurs in blood and in many of the secretions. Phosphorus is also common, being found in nerves, in the teeth, and in fluids. Chlorine occurs almost universally throughout the body; lime is found in bone, in the teeth, and in the secretions; iron occurs in the blood, in urine, and in bile; and sodium, like chlorine, is of almost universal occurrence. Potassium occurs in muscles, in nerves, and in the blood-corpuscles. Minute quantities of copper, silicon, manganese, lead, and lithium are also found in the human body.
The compounds formed in the human organism are divisible into the organic and inorganic. The most frequent of the latter is water, of which two-thirds (by weight) of the body are composed. The organic compounds may, like the foods from which they are formed, be divided into the nitrogenous and non-nitrogenous. Of the former the chief are albumen (found in blood, lymph, and chyle), casein (found in milk), myosin (in muscle), gelatin (obtained from bone), and others. The non-nitrogeneous compounds are represented by organic acids, such as formic, acetic, butyric, stearic, etc by animal starches, sugars; and by fats and oils, as stearin and olein. Research Animal Chemistry
Casein is a protein found in milk. It can be separated by the action of acid, the enzyme rennin, or bacteria (souring); it is also the main protein in cheese. Casein is used as a protein supplement in the treatment of malnutrition and is used commercially in cosmetics, glues, pigments and as a sizing for coating paper. Casein is insoluble in water, but is freely soluble in alkaline solutions. Casein is neither coagulated spontaneously, like fibrin, nor by heat, like albumen, but by the action of acids alone, and constituting the chief part of the nitrogenized matter contained in it. Cheese made from skimmed milk and well pressed is fully half casein. Casein is one of the most important elements of animal food as found in milk and leguminous plants. Research Casein
A cream separator is a machine for extracting cream from milk. Up to about 1877 the only method of separating the cream from the milk was by allowing the milk to stand in shallow pans until the cream rose and formed a layer on the surface by the action of gravity, being lighter than the milk. After about 1877 macjines employing centrifugal force were developed and by 1905 were in use in all large dairy establishments in the UK.
There have been various forms of separator in use, but the principle is the same in all. A steady stream of milk is allowed to run into a drum or cylinder, which is the essential part of the machine, and which is made to revolve at the rate of several thousand revolutions per minute. The force thus exerted upon the liquid drives the heavier milk to the outside and leaves the lighter cream in a layer next to the revolving axis, which may be vertical or horizontal. The exit for the cream is placed near the axis, that for the skim milk necessarily nearer the periphery. Separators have been made in sizes suitable for all dairies, and have been driven by hand, horse, steam-power, etc. Cream seperators have various advantages over the old manual method of extracting cream: the greatest quantity of cream is obtained, and in a fresh condition; no casein is left in the cream; and dairy working is greatly facilitated. Research Cream Separator
Galalith (erinoid) is a synthetic plastic material manufactured by the interaction of casein and formaldehyde. It is odourless, insoluble in water, and only with difficulty inflammable. Research Galalith
Milk is a secretion from modified skin glands of female mammals.
Cow's milk is the most popular form of milk consumed as a food by humans. All milks will vary in composition depending upon the diet and nature, but cow's milk is remarkably stable in constitutents so long as the diet is relatively stable. However, cow's milk does vary noticeably between milk taken in the morning and milk taken in the evening. This difference in milk has long been exploited by cheese makers to produce cheeses with distinct characteristics and taste. Morning milk being more water than evening milk which has a noticeably greater proportion of fat and solids. The last milk taken from the udder is likewise the richest in terms of fat content.
Unpasteurised cow's milk is generally reckoned as neing comprised of 86.3 percent water; 4.1 percent casein; 3.7 percent milk-fat; 5.1 percent lactose; and 0.8 percent mineral matter. Research Milk
Butter, a fatty substance produced from milk, especially cows' milk. When the milk is first drawn this fatty matter is disseminated through it in minute clear globules inclosed in membranous sacs or bags which in a short time rise to the surface and form cream. The cream is then skimmed off to undergo the operation of churning, which by rupturing the sacs effects a separation of the cream into a solid called butter and a liquid called butter-milk, the latter consisting of whey and other caseous matter. In many cases, however, in order to save time, the churning is done before the cream has separated from the milk, and machines for effecting the process of separation are frequently used.
The quality of the butter depends much upon the treatment of the cream at this stage. Its temperature in warm weather ought to be between 53 and 55 degrees Fahrenheit; in colder weather several degrees higher. If too cold the fat is hard and does not coalesce, and if too warm it becomes semi-liquid. The butter, being formed into lumps, is washed well in cold water, and kneaded until all the butter-milk has been expelled.
Butter of good quality has a faint sweet odour and a soft delicate flavour. Its composition varies somewhat according to the way in which it is made. It has usually from 80 to 90 per cent of pure fat, the rest consisting of casein, water, and salt. The water should not amount to more than 10 per cent, nor the salt to more than 2 per cent of the whole weight, but butter was frequently adulterated by the excess of these two elements.
Before refrigeration, where the butter was to be preserved only for a short time, keeping it in a cool place and covering it with pure water daily was often sufficient. More certain methods were to use water mixed slightly with tartaric acid or vinegar, or to salt it lightly, thus making what was known as powdered butter. Butter which was to be thoroughly cured, so as to keep for some length of time, was usually prepared with from 5 to 8 per cent of common salt. In preserving butter it was important to exclude the air as much as possible. When exported to warm climates it was packed in 1 lb. or 2 lb. bottles, with mouths about rwo inches across, and fitted with glass stoppers and cemented so as to be air-tight. Or hermetically sealed tins were sometimes used. Research Butter
In painting and decorating, distemper is properly a composition of common white bound with either glue size or casein. The term is loosely, and inaccurately, frequently applied to any form of water paint or water thinned material. Research Distemper
Abbreviations
Research Dyspeptone
