Cheese, the curd of milk, separated from the whey and compressed into a solid mass. It consists of the caseine and butter and a portion of the water and saline constituents of the milk, and whatever salt may be added in the manufacture. The proportion of butter is subject to the greatest variation, depending as it does upon the richness of the milk, and the quantity which may have been abstracted by skimming, or which, as in Stilton cheese, may have been added by taking cream from other milk. Caseine (from Lat. caseus, cheese) is the coagulable constituent, and belongs to the group of albuminoids or proteine compounds which compose the principal part of the nitrogenous material of plants and animals. It is found not only in milk, but in other animal fluids. According to Berzelius, Braconnot, and others, it has two modifications, one soluble and the other insoluble in water; but later investigations have shown that its solubility depends upon its combination with a portion of alkali, and as found in milk it may be regarded as a natural alkali-albumen, similar to that found in the blood. As analyzed by Scherer, it consists, after deducting the ash, of carbon 52.7, hydrogen, 7.2, and nitrogen 15.6. Walther and Verdeil found one part of sulphur.

Mulder found 6 per cent. of phosphate of calcium, which is precipitated by adding an acid. It is concluded, therefore, that pure caseine can only exist in a soluble condition, and that when precipitated by coagulation it is deprived of a part of its constituents. The spontaneous coagulation of milk has been generally regarded as caused by the action upon caseine of lactic acid which has been formed by the fermentation of lactose or sugar of milk; but late investigations have created some doubt as to the extent to which lactic acid alone acts as the agent. Organic bodies have been found in new milk which are capable of being developed into a ferment, to which some have ascribed the power of causing caseine to coagulate. How far this ferment may act in conjunction with lactic acid, or the extent of its agency in generating lactic acid, has not been determined. Moist caseine exposed to the air soon putrefies, yielding sulphide and carbonate of ammonia, and an oily body having a disagreeable smell, together with butyric and valeric acids, the undecomposed caseine dissolving in the ammonia which is formed. Caseine plays an important part in the making of cheese, although as a constituent its quantity is often less than that of butter.

An analysis by Volcker of an average sample of good milk gave:

Water........

87.30

Butter..........

3.75

Caseine.........

831

Milk sugar and extractive matter.......

4.86

Mineral matters (ash).....

0.78

100.00

The cheese which was made from this milk had the following composition:

Water.......

37.85

Butter...................

2391

Caseine........

2500

Extractive matter, lactic acid,etc........

401

Mineral matter containing common salt.......

3.33

100.00

- In cheese making, the coagulation of the milk may be effected in either of two ways: by adding an acid, which is done in Holland, or by subjecting the caseine to a peculiar fermentation induced by the action of rennet, which is the usual mode. Rennet is usually prepared from the fourth stomach of the calf, by salting and drying. The stomach should not be washed, but turned and carefully wiped with a cloth, sprinkled with salt, and dried at a moderate temperature in the open air, stretched upon a small hoop or forked stick. It is prepared for use by steeping it either in whey or brine. Whey is preferred for the reason that it more readily assists in inducing lactic acid fermen-tion; but it should first be freed from the albuminous matter which it contains, by boiling and straining. The steeping occupies about a week, during which time the rennets should be squeezed and rubbed to extract the active principle. A wooden vessel should never be used, as it is almost certain to impart putrefactive properties to the rennet which are injurious to the cheese, but the steeping should be done in earthen jars. The English method is to steep the rennets in a brine strong enough to bear an egg, adding six rennets, one sliced lemon, and an ounce of saltpetre to two gallons of brine.

The brine liquor is usually prepared one or two months before it is used, as it is believed that this age improves its coagulating qualities. The theory of the action of rennet is not yet considered to be well established. Liebig, although admitting the necessity of the presence of a ferment to initiate by a catalytic force the fermentation of milk sugar and its conversion into lactic acid, rejects the theory of Pasteur that the process is the result of the constant development of a minute fungus which has been called micrococcus. W. Hal-lier, however, following Pasteur, has found that newly made cheese contains numerous ferment nuclei, which he considers as a kind of putrefactive yeast. According to his investigations, these nuclei are developed, as are the nuclei of beer yeast, from spores of penicillium, differing from them only on account of the difference in the fluid which affords them nourishment. In beer the penicillium, according to Hallier, is developed into cryptococcus, while in fresh milk it is converted into micrococcus, and when the milk becomes sour into arthrococcus. lie says that cows'milk contains ready-formed micrococcus cells, but that coagulation does not take place till the conditions for their development are favorable.

The addition of rennet, which contains cells of a similar character ready to take on an active condition, produces a development of the micrococcus cells. Volcker and others have demonstrated by numerous experiments that milk is often coagulated by the action of rennet before it becomes sour; and although it is undoubtedly true that caseine owes its solubility to a combination with an alkali, it does not follow that that combination may not be broken up even while the fluid in which it is dissolved is alkaline. It cannot therefore be maintained that the coagulation of the caseine in the ordinary use of rennet is due to the action of lactic acid. When an acid is added to milk, it does not coagulate till there is decided acidity. It would seem therefore that the alkaline constituent of the caseine is not immediately abstracted, because of the slight acidity of the milk in which it is held in solution. It is not unlikely that the coagulation of caseine by rennet has much similarity to its coagulation by the gastric juice, which by a catalytic action has the power of coagulating soluble caseine, and of again dissolving it in a condition which Maihle calls albuminose, as he does the digested product of all the albuminoids, but which Leh-mann calls peptones.

The juice of the gastric tubules never effects this transformation unless it contains a free acid, but it is possible that the mucous coat of the stomach when converted into rennet may possess the power of coagulating soluble caseine, although not of digesting it. The antiseptic properties of gastric juice are probably owing to the combined action of the pepsine and lactic acid, and it is not improbable that the development of lactic acid in cheese making arrests putrefactive fermentation upon the same principle. But whatever may be the result of the investigations that are in progress, it is admitted on all hands that the transformation of sugar of milk into lactic acid is hastened by the action of rennet, although coagulation of caseine may precede the lactic acid fermentation. (See Fermentation.) In the practice of cheese making the subject of ferments is one that requires to be constantly borne in mind if satisfactory results are to be secured. The spores of various fungi are constantly floating in the air and attaching themselves to and developing in any matrix capable of yielding them nourishment; and as milk is one of the most delicately sensitive of all fluids, the most scrupulous cleanliness should exist in every part of a cheese dairy.

The vessels for containing the milk and its products must always be scalded with boiling water as soon as they are emptied, and all the utensils should regularly be subjected to the same treatment. The pastures and all the food and drink of the cows ought to be free from all products of fungoid putrefaction or fermentation of whatever kind; therefore stagnant water or low, sour land should not be suffered in pastures devoted to the grazing of milch cows, and mouldy food should be strictly excluded from their diet. Most of the cheese in the United States is now made at factories, which are carried on by associations of farmers who employ a manager. The usual practice is to send the milk to the factory every night and morning, keeping it as cool as practicable during transportation. - The process of making cheese with the use of rennet which will now be described is that which is followed by the best cheese makers in this country, and is very nearly the same as that by which the celebrated Cheddar cheese is made, in Somersetshire, England. The evening's milk is placed in cooling vats so that it will be brought to a temperature of about 60° by the following morning, when the morning's milk is added and the temperature raised to 80°. This is effected in a manner the most efficient, at the same that it avoids overheating any portion of the milk.

A large vat contains the milk, which is gently and equally heated by a water bath, which receives its heat from the circulation of warm water furnished from a cylindrical reservoir heated by a concentric flue placed beneath the vat, or by water contained in a coil of pipe, and heated in a fire box near by. When the milk has reached 80° a sufficient quantity of rennet is stirred into it to produce coagulation in about 40 minutes. It is customary with the Cheddar cheese makers to add sour whey in quantity according to the condition of the milk, adding little or none if any acidity has been developed in it. The whey is used for the purpose of hastening the development of lactic acid, because it is then found that there is less liability to that species of fermentation which results in gaseous and other objectionable products. It is a practice that has not been general in this country, but many of the best cheese makers are now adopting it. When the curd has become sufficiently firm, which may be known by its dividing with a smooth fracture when the finger is passed through it, it is cut with curd knives, one set of which have perpendicular and the other horizontal blades, into small cubes of from a quarter to a half inch in diameter.

The contraction of the curd then takes place more rapidly, expressing the whey; and in about 20 minutes it becomes quite firm, when it is broken up by means of an instrument called a wire shovel breaker into smaller pieces, and the temperature is raised to 98°, the contents of the vat being gently stirred to prevent packing of the curds upon the bottom. When the curd has become sufficiently firm for the operation, and the whey has attained a certain degree of acidity, conditions which can be learned only by experience, it is drawn off by a large spout as rapidly as possible, and the curd is heaped in one end of the vat, which is elevated to facilitate the draining. Exposure to the air hastens the development of lactic acid. In 15 or 20 minutes the particles of curd will have become coherent and form a partially solid mass, which is then cut into pieces and turned over and left until firm enough to break into pieces without danger of expressing the buttery particles, which would be the case if the process were attempted too soon. It is then taken out, placed in a cooler, broken into thin flakes, and spread out to cool still further. In about 20 minutes it is turned over and left until it attains a peculiar mellow and flaky condition, well known to the experienced cheese maker.

By this time its temperature has been reduced to about 70°, and it is put into a hoop and pressed gently for 10 or 15 minutes, to express more of the whey, by which a too rapid fermentation is prevented. It is then taken out and cut and broken into pieces about the size of peas by means of a curd mill, after which it is salted. In England 1 lb. of salt is used to 56 lbs. of curd; but in the United States more salt is used - from 21/2 to 3 lbs. to 100 lbs. of curd - partly because American dairy men do not drain their curds or express the whey from their cheeses as much as the English. The changes that produce the aroma and flavor of cheese may be produced in less time, or at least may to a certain extent be imitated, by using a large amount of salt and keeping the curing rooms warm. The flavor, however, is always rendered inferior by such means, and irritating and unwholesome properties are engendered. After the salt has been well incorporated the curd is again put into the hoop, a cloth being placed upon the top and bottom, and sometimes around it. It is kept under pressure for 20 or 24 hours, and is then taken out, and any sharp edges that may have been made in pressing pared off.

It is then turned and placed in the press again, and generally, especially if the cheese is a large one, bandaged, and kept there for one or two days longer. In many of the factories in this country, however, only 24 hours is allowed for pressing, because of the number that are made. The temperature at which it goes to press is a matter of great importance, because if too high, fermentation with evolution of gas is liable to take place and make the cheese porous. The temperature at which Cheddar cheese goes to press is between 60° and 65°. Care should be taken during the operation that the buttery particles are not squeezed out, and at the same time the retention of too much whey should he avoided, as that will injure its keeping properties. Much of the excellence of the Cheddar system lies in the proper management of the conditions which affect the different processes of the manufacture. The following are the chief points requiring attention: 1, the early initiation of lactic acid fermentation by using, when indicated, sour whey; 2, the employment of sufficient heat to cause the curds to contract and express the whey; 3, such an exposure to the air as will to the proper extent convert the micrococcus into arthrococcus cells, or which will, upon any theory, carry the formation of lactic acid to that degree which, with proper care, will prevent future putrefaction; and 4, to cool the curds enough to prevent loss of butter in pressing.

After the cheese is pressed it is taken to the curing room, rubbed with melted fresh butter, and turned over once a day until it is ripened. The curing room should be dimly lighted, to avoid flies as well as the chemical action of light, and sufficiently ventilated to keep the air pure. The temperature should be well regulated, being kept for the most part at about 70° both in summer and winter. A higher degree produces too rapid ripening, and below 60° the necessary chemical changes will not take place. It sometimes happens that the milk when it is poured into the vat has some taint that will cause it, after the rennet is added, to take on a fermentation which will result in gaseous products and an offensive flavor and smell. This condition of the milk may be caused by the overheating of the blood of the cows, or from their having partaken of improper food. The effect will be, unless the difficulty is anticipated, the production of what is called floating curds, in consequence of the reduction of their specific gravity by the bubbles of gas. This floating occurs when the curds are broken and the temperature is raised previous to drawing off the whey.

When this phenomenon is seen to be taking place, the temperature of the vat should be raised to 100° to cause greater contraction of the curds, and after the whey is drawn off the draining and exposure to the air should be continued longer than usual in order to develop an increased amount of lactic acid. This will be likely to arrest the putrefactive fermentation, and to get rid of the obnoxious products which have already appeared. When a bad condition of the milk is known or strongly suspected, it should be aerated and cooled as much as possible before going into the vat, and enough more rennet than usual should be used to produce coagulation in 30 minutes, and a larger quantity of sour whey than usual should be stirred in at the same time. - Some very fine cheeses are made in England by skimming the night's milk and adding it to that of the morning. Such are often called skim-milk cheeses, although the term more strictly applies to those made of milk all of which has been skimmed, leaving only a small percentage of butter. Some made in Wiltshire and Gloucestershire of partly skimmed milk are said by Dr. Volcker to compare favorably with good Cheddar, the deficiency in butter being made up by other good qualities.

It is the opinion of many good cheese makers that milk may be too rich in butter for the best quality of cheese that will keep well. If nearly all the cream is skimmed from milk, it will not be possible to make it into good cheese, at least by the ordinary English process. At creameries and in the butter-making districts in this country, as well as in England, the making of skim-milk cheeses is practised to a certain extent. The process differs but little from that of making whole-milk cheeses; but as they do not ripen or cure as soon or as evenly, they are made smaller and thinner. - The coagulation of milk by means of hydrochloric acid, as it is practised in Holland in making the most excellent cheeses, deserves more attention than it has hitherto received in other countries. The process is attended with much less difficulty than when rennet is employed, and the coagulation is more complete, yielding an increased product. All the butter is retained in the curd, and the danger of after fermentation is also greatly diminished by avoiding the use of fungous ferments, whose control is always more or less difficult. The principal objection seems to be an ascribed want of flavor, which among most cheese fanciers, especially in England, requires to be somewhat gamy.

The Dutch cheese has a sharp taste and high keeping qualities, and notwithstanding it may lack what is called mellowness, its flavor is preferred by many. It probably possesses the advantage of being less liable than cheese coagulated by rennet to contain deleterious or poisonous principles. - There are more varieties of cheese made in Europe than in America, which may be in part attributed to the greater attention which is paid there to economy in food. They may be classified into cream cheeses, whole-milk cheeses, and skim and sour-milk cheeses. To the first class belong Neufchatel, Vaschrein, Brie, cream Cheddar, and Cotherstone. Neufchatel is made of pure cream thickened by heat and compressed in a mould. It is made at Neufchatel-en-Bray, a small town in the department of Seine-Inte-rieure, France, 25 m. N. E. of Rouen. It is esteemed as a great delicacy, but, from the difficulty of preserving its good qualities, can scarcely be appreciated for from the locality where it is made. Brie, which is also a French cheese, and the Vaschrein of Switzerland, are also made of the purest cream. Both Neufchatel and Brie cheeses are now largely made in the state of New Jersey, and can be brought to the New York and Philadelphia markets in a better condition than if imported.

Stilton and cream Cheddar are made by adding the cream of one milking to the whole milk of the next, in the proportion of one quart of cream to ten quarts of milk. After stirring, the mass is put into a tub in which a linen strainer has been laid. Coagulation is produced by rennet, the curd is cut into cubes, and without breaking is carefully lifted into a strainer, to allow the whey to drain off, after which it is placed in a hoop seven or eight inches in diameter and eight or nine inches high, having a follower pierced with holes at each end. When fitted, the hoop is placed upon a shelf and turned four or live times a day, the only pressure applied being its own weight. When sufficiently firm, which can only be known by experience, it is bandaged and taken to a curing room whose temperature is about 70°, where it receives its salting, which is performed externally and not by salting the curds. After a time it is sometimes placed in a warmer room for the purpose of developing blue mould, which gives it a peculiar value to some cheese fanciers. Of the second class, or whole-milk cheeses, Cheddar, Cheshire, best Gloucester, and Wiltshire of England, Gouda and Edam of Holland, Gruyere of Switzerland, and most of the American cheeses are examples.

The famous Gruyere cheese, made in the canton of Fri-bourg, Switzerland, which is said by the Swiss to have been the first cheese made by the factory system, is of whole milk, which, to the amount of 100 or more gallons, is heated while fresh in a caldron to blood heat, and rennet added to effect coagulation in about half an hour. The curd is then sliced with a knife and broken with a blunt stick armed with wooden pins, and the heat raised to about 135°. Stirring is continued half an hour after, by which time the curd is divided into small, elastic pieces of the size of peas. A strainer cloth is then drawn under the curds, and they are laid upon a rack to drain, after which they are placed in a peculiar hoop, formed of a thin piece of board bent into a circle, with the ends lapping, but left free to slide over each other to allow the cheese to spread in pressing. The press is a simple lever loaded with a weight at one end. The salting is done after the pressing, the cheese hoop being replaced after each application of salt for a few days, to preserve the form.

Jura cheese, made in the Alps, is much like the Gruyere, and they are both known in this country as Schweitzerkuse. A factory for making it is established in Oneida co., N. Y., which uses the milk of more than 200 cows; and it is also made in Ohio. It is said, however, that the American Gruyere lacks the flavor of the Swiss, because of difference in the grass upon which the cattle feed. The process for making Parmesan, the cheese of Parma, is said to be precisely similar to that for Gruyere, the difference in the cheese being that the Parmesan is made of skimmed milk. Sour-milk cheeses are made in various parts of Europe. They are often of an inferior quality in consequence of the improper manner in which they are made and the extent to which the fermentation is carried.

Cottage cheese is nothing more than newly prepared curd, drained, broken, slightly pressed, and salted to suit the taste, and is usually eaten in this condition. If kept for some time at a warm temperature, putrefactive fermentation takes place, and ammoniacal gases of an offensive odor are given out. There are persons whose palates are pleased with this product, and it is erroneously supposed by some that this is genuine Dutch cheese. Properly cured sour-milk Dutch cheese is as free from offensive odors as Cheddar, the fermentation having been carefully conducted until all gaseous products cease to be formed; a sharp, clean-flavored, appetizing condiment is the result. It is sometimes flavored with sage and other garden herbs. Roquefort, a French cheese, is made of goats' or sheep's milk; after coagulation by rennet, the curd is subjected to great pressure, and the cheeses are bandaged with coarse cloths and placed on shelves to dry, after which they are taken to caves, where the bandages are removed and they are salted.

In 15 or 20 days they become covered with mould, which is scraped off with a knife, the operation being repeated every fortnight for two months, during which the color of the mould is said to be successively white, green, and red, the last color indicating that they are fit to use. Schabzziegerkase is made in the canton of Glarus, Switzerland, of curd which has been fermented. It is mixed with the pulverized dried flowers of Schabziegerklee (meliotus cceruleus, not M. officinalis, as is sometimes stated), and pressed in a mould. It is usually eaten grated, spread upon buttered bread, and has a sharp and peculiar flavor much relished by many. In Limburg, Belgium, a cheese is made which is eaten while in a high state of putrefaction. Large quantities are also made in New York, Ohio, Illinois, and Wisconsin. Oneida, Lewis, and Jefferson counties are the principal seats of its manufacture in New York. In 1872, as nearly as can be estimated, about 20,000 boxes were made, of 100 lbs. each, containing from 50 to GO "bricks," each weighing from 1 3/4 to 2 lbs. - Annotto, a vegetable coloring matter of an orange red, is often used to color cheese; but it is a disagreeable substance, whose use should not be encouraged. (See Annotto.) - Cases of poisoning by cheese are not infrequent, and have lately been sufficiently investigated to show that they are analogous to sausage and salt meat poisoning, and take place from the use of cheese which has been hastily cured, and generally when considerable salt and warmth had been employed.

The cases are usually not fatal, but present symptoms of all degrees of violence. It is natural to suppose that a proteine body like caseine, in the presence of fats, would be likely to generate during fermentation substances of a character highly irritating to the mucous membrane, and therefore great caution should be observed in the use of cheese which has an unpleasant odor. Cheese, either new or old, is not an easily digestible article of food, but when well made is not unwholesome, and may sometimes suitably form quite a large share of the diet of laborers. For further practical and theoretical information, see Willard's "Practical Dairy Husbandry" (New York, 1872), and Watts's "Dictionary of Chemistry." - According to the census, the whole amount of cheese produced in the United States in 1870 was 162,027,382 lbs., of which 100,435,229 lbs. was made in factories and 53,927,382 lbs. on farms. The principal states producing cheese were New York, 100,776,014 lbs.; Ohio, 24,153,856; Vermont, 7,814,879; Illinois, 5,734,004; Massachusetts, 4,131,300; and California, 3,395,074. There were 1,313 factories devoted to the manufacture of cheese, employing 4,607 hands.

The capital invested amounted to $3,690,075; wages paid during the year, $706,566; gallons of milk used, 116,-466,405; value of all materials used, $14,080,-284; of cheese produced, $16,710,569; other products, $61,006. The number of cows supplying one factory ranges from 100 to more than 1,000, the average being about 400. In 1871 a factory in Chautauqua co., N. Y., had registered as the whole number of cows, 1,734. During the year ending June 30, 1873, 66,204,-024 lbs. of cheese, valued at $7,752,018, were exported from the United States, of which 52,-056,026 lbs. went to England, and 8,428,306 to Germany.