to receive the knives, which are six or more pieces of tempered steel three-eighths of an inch thick and having one edge cut to form teeth three-eighths of an inch square with intervals of one-fourth of an inch between them. The knives are adjustable by set screws, and should be set so that the teeth project not more than three-sixteenths of an inch above the surface of the cylinder. One side of the cylinder housing is made up of the concave, which consists of three or four heavy curved iron plates, each attached by its top to the housing and adjustable at the bottom end by a heavy spring. The plates of the concave should be so adjusted that the tips of the cylinder teeth barely clear them (one-sixteenth of an inch or less) when the cylinder is rotated. The springs at the lower end of the concave plates permit them to give way and allow stones or other hard objects to pass through without injury to the knives. When properly adjusted, a grater is much more efficient than any roller-crushing device, since each apple is carried down against the concave and held there while it is very finely shredded or rasped by the knives. The fruit is much more finely divided and has a much larger percentage of cells broken than when crushed between rollers, with the result that the yield of juice from a given quantity of fruit is at least 10 per cent greater.

FIG. 4. Good and bad cheeses. That at the left is uniform in thickness, well covered by the cloth, and will not creep or spread in pressing. That at the right is too thick and will spread out beyond the racks when placed under pressure, making the proper extraction of the juice impossible. The two cheeses were pressed after being photographed. The yield from the thin cheese was 64 per cent of the weight of the fruit used and that from the thick cheese 52 per cent

Practically all power presses now in use are of the hydraulic type. (See fig. 5.) In most of these the ram chamber is beneath the floor of the press bed and requires an excavation in the floor of the room to receive it. In such presses the movement of the ram is upward, lifting the cheese against a press block at the top of the frame. In others, the so-called "inverted" press, the ram chamber is at the top of the press frame and the movement of the ram head is downward, the load resting on a stationary press block which is a part of the floor of the press bed. In this type of press all parts are readily accessible in case of need. No excavation in the floor of the pressroom is required, which is an advantage in keeping the room clean and in good sanitary condition.

A second advantage of power-operated presses, in addition to the more efficient grating of the fruit, lies in the fact that much greater pressure is developed upon the cheese than it is possible to get with the hand-operated press; also the pressure is maintained constantly at the maximum for any length of time desired, as the press automatically follows up the shrinkage of the cheese due to drainage. The combination of greater force and uniformity of pressure gives a considerably better extraction than can be obtained by hand. It

is impossible to determine the increase in yield due to these factors apart from that resulting from the more effective pulping done by the grater, but as a general statement it is true that 125 to 135 gallons of juice per ton of apples represent the average yield when a hand press is used, while yields of 150 to 165 gallons per ton are the average with power presses giving working pressures of 100 to 160 pounds per square inch.

SUGGESTIONS REGARDING HYDRAULIC PRESSES

A few suggestions derived from practical experience with hydraulic presses may be of service to inexperienced operators. Do not attempt to operate a press of the hydraulic type without equipping it with a pressure gauge, and do not risk damage to the

mechanism by forcing the pressure above the safety limit. Many small presses have no gauge, but have a safety valve, operated by a lever and counterpoise, which opens when the pressure has attained the maximum. It is not unusual to find weights added to the counterpoise in order to increase the pressure. Such a practice throws upon the hydraulic mechanism a strain that it was not designed to endure and involves serious danger of bursting the pressure chamber and possibly injuring the operator. The safe and practical way to increase the pressure is to cut down the size of the cheese by making a smaller form, thus exerting the full pressure of the ram head upon a smaller area. For example, a certain press had a form 40 by 40 inches in size, giving an area of 1,600 square inches, upon which it delivered a pressure of 100 pounds per inch, or a total of 160,000 pounds. By cutting down the form to 32 by 32 inches, giving

an area of 1,024 square inches upon which the same total pressure was exerted, the pressure upon each square inch of the cheese was increased to 156 pounds. The change reduced the load which could be handled at a pressing to two-thirds the former capacity, but also reduced the time necessary for pressing a load from 35 minutes to 25. Consequently, the quantity of fruit that could be handled through the press in a day was decreased less than 10 per cent, while the yield of juice obtained per ton of fruit was increased from 141 to 162 gallons, or 15 per cent.

Special care must be exercised in packing the cylinder of a press of the usual upward-thrust type in order to make sure not only that there is no leakage and loss of power but also that the ram is properly centered. If this is not done, the ram head will bear against one of the guides as it rises. The resulting friction not only cuts down the pressure delivered upon the cheese and reduces yield, but it strains the press frame and may result in breaking out the bolts by which the head is attached to the ram, or in other damage.

The oil chamber of the pump must be kept filled with oil of the type and grade recommended by the press manufacturer and kept closely covered in order to exclude water, juice, and dirt. Water or juice which gets into the oil chamber ultimately finds its way into the ram chamber, where it rusts the shaft, rots out packing, and causes leakage. When pressure is put upon a fresh cheese, allow it to increase until something like half or two-thirds the maximum pressure has been developed; then trip the valve and allow the press to maintain the pressure without increase for a few minutes. When rapid flow has ceased, set the counterpoise at safety and allow the press to develop maximum pressure. By following this method one avoids the strain on the cloths which would result from putting full pressure on the cheese before drainage had begun, and is freed from the disagreeable spurting of juice and oozing of pomace that would otherwise occur. Go frequently over the conveyer which elevates apples to the grater, looking carefully for split conveyer slats, loosened nuts, or broken bolts. Many breakdowns occur from the dropping off of a conveyer bolt or slat, which passes on into the grater and breaks the knives. A careful inspection of all set screws and bolts at frequent intervals will pay dividends in the increased life of any machine, and especially is this the case with a press.

RE-PRESSING THE POMACE

Whether re-pressing the pomace will prove profitable depends upon the thoroughness with which the first pressing has been done and upon the use which is to be made of the pomace. If the plant in addition to making cider manufactures apple jelly, the pomace may profitably be used for this purpose without re-pressing. If it is to be discarded or used as stock feed, it may be found worth while to re-press it, especially if the press used is one which develops a working pressure of 100 pounds or less per square inch.

For preparing pomace for re-pressing, a pomace picker, a device for tearing the compact cakes into pieces, is a necessity. Press manufacturers offer them in several sizes, but an ordinary mechanic can make a very effective device. The picker consists of a wooden cylinder, 10 to 14 inches in diameter, of a length equal to that of the

press cakes with which it is to be used. Teeth made of an iron rod. one-half inch square and finished with a point or screw thread at one end, are driven into the surface of the cylinder in rows or lines extending spirally around it, with the square ends projecting 11⁄2 or 2 inches above the surface. The cylinder is mounted at the base of a wide feed hopper, and the side of the hopper toward which it revolves is studded with similar teeth. The apparatus may be set near the press and geared to the main power shaft and the cakes of pomace dumped directly into the hopper as they come from the press, the broken cakes being received in a bin, from which they can be shoveled to the press platform for re-pressing.

In re-pressing pomace, particularly with a small press or one which has a maximum pressure of 100 pounds per square inch or less, it is an excellent plan to have a smaller form to use especially for this purpose. It should be made enough smaller to give a working pressure of 150 to 160 pounds per square inch, as the increased yields of juice obtained will pay for the longer time required to handle the material with the lowered capacity.

OBTAINING COLOR FROM THE POMACE

Many consumers express a decided preference for deeply colored golden brown ciders over others of equal quality but of lighter color. It is within the power of the cider maker to control in some degree the depth of color which the juice possesses. The color of cider is due to chemical changes in the fruit which set in as soon as the material is brought into contact with the air by crushing. Some of the colored products, together with the colorless compounds from which they are formed, are carried into the juice in pressing, and the deepening of the color of the liquid continues for some time when in contact with the air. The same changes go on more rapidly in the pomace, as shown by its change of color, by reason of the large surface which is exposed to the air. When pomace is re-pressed after standing a few hours, the juice obtained is much deeper in color than that from the first pressing and at the same time somewhat more astringent by reason of its higher tannin content. The maker who finds that his customers show a preference for deeply colored juices may meet the demand by re-pressing a part or all of the pomace after allowing it to stand for some hours exposed to the air and using the juice thus obtained to blend with the first pressed juice to deepen the color. If this is done, great care must be taken to protect the pomace by storing it in a covered bin until it is re-pressed, and re-pressing must never be delayed until fermentation of the pomace has begun. If the weather is quite cool, pomace may be held for 24 hours without danger. In warm weather it can be held only a few hours, but the higher temperatures accelerate the oxidation processes which produce the coloration, so that the same degree of color may be obtained in the shorter period.

If it is difficult to obtain the desired suggestion of astringency in the product, it will be found advantageous to place some of the pomace in a suitable vessel or tank, add enough freshly pressed cider to wet the mass thoroughly, allow it to stand for an hour or two, and re-press. This treatment extracts color and tannins more thoroughly than merely re-pressing without the addition of juice. It is to be

preferred to the practice of some makers, who grind the fruit and allow it to stand in tanks or barrels overnight, or for 24 hours, before pressing. This method of handling the material is said to "bring out the flavor," but it is not clear that it accomplishes this more effectively than the treatment here suggested, while it is open to several objections. The repeated handling of the crushed fruit is laborious and difficult, and unless the temperature is low and can be kept under control fermentation will set in; consequently such treatment can not be recommended.

USES OF APPLE POMACE

Under ordinary working conditions a ton of apples yields about 700 pounds of pomace. In most cases no systematic attempt is made to utilize this material; some of it may be consumed by stock, but in large part it is allowed to decay unused, either near the plant, where it constitutes a nuisance, or at a distance after the proprietor of the plant has been put to the expense of having it hauled away.

While the subject can not be discussed in detail, it may be briefly pointed out that apple pomace has a number of uses. One of these is as a food for stock. For feeding purposes it is most nearly comparable in composition and digestibility to corn silage and is regarded by authorities as having a feeding value approximately equal to that of corn silage. As it may be kept in good condition for several months in a silo, covered pit, or compact covered pile, its value for feeding purposes justifies attempts to preserve it for such uses when no other means of utilization is feasible.

If the plant, in addition to cider, also manufactures apple butter and marmalade or cider jelly, more profitable use can be made of the pomace. When cooked until soft and passed through a colander or cyclone the pomace is freed from peels, seeds, and cores, and the resulting pulp may be used in making apple butter or marmalade. As pectin, the constituent of fruits that causes their boiled extracts to set into jellies upon the addition of sugar, is only very slightly soluble in fruit juice, the pomace from a ton of apples contains a large part of the pectin of the entire fruit. Consequently, pomace may be cooked with water, re-pressed, and the water extract added to cider preparatory to boiling it down into jelly. There is a limited demand for dried apple pomace for use in the manufacture of commercial concentrated pectin, and the cider maker who does not make other profitable uses of his pomace and has a drier available may find it advantageous to dry his pomace for sale to such manufacturers, provided his production is large enough to enable him to ship in carload lots.

HANDLING THE JUICE

SEDIMENTATION

As rapidly as the juice is expressed it should be placed in temporary storage vessels to permit sedimentation. Sedimentation is always necessary, since the freshly pressed juice contains considerable quantities of finely divided pomace which will separate out on standing, and it is necessary to free the juice from this material as completely