Copyright NP COPYRIGHT DEPOSIT: GENERAL AGRICULTURAL CHEMISTRY BY EDWIN B.oART Professor of Agricultural Chemistry in the University of Wisconsin, AND Wiki VAM Ee: TOTTINGHAM Assistant Professor of Agricultural Chemistry in the University of Wisconsin MADISON, WISCONSIN 1910. he eas CopyriaHr 1910 BY EDWIN B. HART ann WILLIAM E.TOTTINGHAM. STATE JOURNAL PRINTING COMPANY PRINTERS AND STEREOTYPERS Maptson, WIs. ©cla275972 Pi CONTENTS. EN TROD UCLRION Pr ie ae a eo ne Gla ciel eevee ol Bish cae apace os Ram) AP MOSREIOR Re tarens eAtaay< cio eaiecscr eauecxecn be hyenas ANTS BRON BL Gio." 616 ir Rie OED. 6 SORE Ie LELG AEE RR een Per Hr yen ee INGA UAT WEAR Bt seen tetris nis ope hes cys. vik ye scence are SoM eonie Sela eholans HOOD) REQUIREMENTS OW ANTMAT Sian... cle ciae---2)so0 oacaee seals» Soe names 2.8 | Cane: SUger . + .p-s-snckon ee sees 4.0 | SS ee ey eee 7-6 | Cellulose ~...: . tnvde oe here eee 4.1 POO ds. Seieterig Blas « «isa soteaer ete 70 ]) OUALCH com ey ee Rieter orbs 4.1 CROE 2A ee ee SRS Introduction. 9 In ordinary eases of burning, the evolution of heat is readily evident, but in some eases the combustion is so slow that the heat evolved is carried away as fast as produced and very shght or no elevation of temperature is apparent. In some eases of slow combustion where the escape of heat is hindered from any cause, the temperature may rise so as to be perceptible or even dangerous. It may, under particularly favorable conditions, rise sufficiently to start a rapid combustion with oxvgen and flames then result. Such cases of ‘spontaneous combustion’’ frequently occur. Drying oils, as linseed or cotton-seed oil, especially when spread on cotton waste, and fermentation changes in vegetable matter as hay and tobacco are notable examples of these eondi- tions. Hydrogen (I). This element is rarely found in a free state in nature, but is combined with carbon and oxygen as in animal and vegetable matter, with oxygen to form water, and in a few cases with some of the base elements to form hydroxides. It is not found in large amounts in the soil and that which forms a part of the tissues of plants and animals comes largely from the hydrogen in water. It is a colorless, odorless gas and charac- terized by its lightness. This fact has led to its use for filling balloons, although coal gas is now more generally employed but is not nearly so efficient. In a free state it has been found in the gases escaping from volcanoes. Carbon (C) is the element most closely associated with plant and animal life. It forms a large proportion of the solid matter of all living beings; and the chemical processes of animal and plant life are mainly those in which carbon plays an important part. It exists in the combined state in many minerals as the carbonates of calcium, magnesium, iron, zine, and also in a small but very important constituent of the air, carbon dioxide. The carbon of the soil, where it exists as the main constituent of organic bodies, takes no direct part in forming the carbon com- pounds of the plant. It is not necessary to apply carbon fer- 10 Agricultural Chemistry. tilizers to produce the carbon compounds of the plant, because the carbon dioxide of the air is the source for crop production. It is estimated that there are about thirty tons of carbon dioxide in the air over every acre of the earth’s surface. This element occurs in three distinct forms: (1) as the diamond, (2) as graphite and (3) as charcoal, lamp black, ete. The diamond is crystalline and transparent; graphite is crystal- line but opaque; while lamp black and charcoal are non-erystal- line. The black carbon which is produced when animal or vege- table substances are strongly heated without access of air (char- ring) is due to the separation of free carbon from the various ear- bonaceous compounds present. Nitrogen (N) is much less abundant in nature than the ele- ments already described. A peculiarity of its occurrence is that it appears to be present only in the outermost portion of the earth. the greater portion being free in the air. No true minerals con- taining it are known except those which owe their origin directly to plant or animal life, as coal, and Chili salt-petre. All living matter, however, contains it as an essential constituent. In its - free state it is a colorless, odorless gas, showing little tendency to combine with other elements. It constitutes about seventy-nine per cent of the atmosphere and over each acre of land there is consequently about thirty thousand tons. Although in the free state it is so inert, the nitrogen compounds, as a rule, possess great chemical activity and many are very im- portant substances. Some powerful drugs and poisons as quin- ine, strychnine, and prussiec acid contain nitrogen, while most ex- plosives, as nitro-glycerine and gun cotton are also nitrogen com- pounds. It is an absolutely essential ingredient in the food of both animals and plants. It must be supplied to animals in com- pounds in which it is combined with carbon, hydrogen, oxygen, and certain other elements and which are known as proteins. while plants acquire it generally from nitrates, which are simple compounds of oxygen, nitrogen, and some base, as calcium, so- idum, and potassium. Only under very special. conditions can Introduction. tt some species of plants obtain their necessary nitrogen from the air. It will be seen in the later chapters that, although plants are surrounded by air, rich in free nitrogen, combined nitrogen is one of the essential and most valuable constituents of manures. A large part of the nitrogen in the food consumed by man and animals is eliminated as simple compounds in the excreta and un- fortunately, especially in our cities, sent down the sewers and rivers and finally discharged into the sea. To agriculture this valuable combined nitrogen is therefore wasted. This element is the most expensive of those necessary for plant growth and is among those liable to be most deficient in our soils. No other ele- ment takes such an important part in agriculture or in life pro- cesses. Sulphur (S) is found both free and combined in nature. The free element is found in voleanie districts, while in the combined state it occurs as hydrogen sulphide in mineral waters and as sul- phides of many metals, as for example iron, lead, and zine. The sulphide of iron, known as iron pyrites, is often mistaken for gold because of its yellow color; sulphur also occurs as sulphate of cal- cium, in which form it is very widely distributed in soils, and is the main source of the sulphur for crops. The element sulphur (brimstone) is a yellow, brittle substance and very inflammable. It burns in air with a pale blue flame, forming the suffocating gas, sulphur dioxide. Such forms of sul- phur are very poisonous to plants and animals, while sulphates are not only harmless, but necessary. Sulphur is present in the proteins of both plants and animals and when putrefaction of these substances occurs is often liberated as hydrogen sulphide. This substance is perceptible by its disagreeable odor as one of the chief products of the decay of eggs. There is generally less than 0.10 per cent of sulphur trioxide, as sulphates in ordinary soil, and it is now known that the amount required by crops is considerable ; for this reason it may be neces- sary to use certain sulphates occasionally as fertilizers and as sources of sulphur for the growing crops. 12 Agricultural Chemistry. Phosphorus (P) always occurs in a state of combination. Phosphorus compounds, chiefly phosphates, are very widely dis- tributed, but in small proportion, in the rocks of the earth. De- posits of calcium phosphate occur in certain localities and are one of the chief sources of our phosphate fertilizers. All fertile soils contain small quantities of phosphates, which are taken up by plants and through plants find their way into animals, where they accumulate in the bones or other hard parts, as teeth and shells. The element phosphorus, as usually prepared, is a yellowish waxy substance, which has the power of emitting a faint light when exposed to the air. This property was the origin of its name, which is derived from the Greek and means ‘‘the light bearer.’’ The emission of light is due to slow combination with the oxygen of the air, resulting in the production of heat. Phosphorus is a violent poison. -It is largely used in the man- ufacture of lucifer matches and rat-poison. For the farmer its chief importance lies in the use of its compounds, the phosphates, as fertilizers, and its occurrence in certain fats and protein com- pounds of feeding stuffs and in the bodies of animals. Soils are quite lable to be deficient in phosphates, as the latter are largely drawn upon by many crops, particularly grain crops, where the phosphorus accumulates in the seed and is sold from the farm. Calcium (Ca) is very abundant in nature, always occurring in a combined state. Calcium carbonate is found in enormous quan- tities, as chalk, limestone and marble, and contains the three ele- ments, calcium, carbon and oxygen. It also occurs as gypsum, a compound of calcium, sulphur and oxygen. The element itself is an easily oxidisable metal, difficult to prepare, and of no im- portance to the farther. Its oxide, or a compound of calcium and oxygen, is the important substance, quick lime. This is made by burning limestone, whereby the carbon and part of the oxygen are removed as a gas. Calcium is an essential constituent of Introduction. 13 plant food and in the soil is present in a variety of forms, as calcium carbonate, calcium sulphate and calcium phosphate. Potassium (K_) occurs in many minerals. It will be found in many silicates, as orthoclase or mica, which are complex com- pounds of potassium, silicon, aluminum, oxygen and other ele- ments. It also occurs in sea water, from which sea weeds accu- mulate large quantities of potassium compounds. The immense salt deposits at Stassfurth, Germany, furnish a large proportion of the potassium used in our potash fertilizers. The element is a lustrous metal, very soft, and so susceptible to change in the air that it must be kept away from contact with air or moisture by immersion in naphtha. By contact with water it reacts violently, producing much heat and floating on the sur- face of the water with a hissing sound. Potassium compounds are of the greatest importance in agri- culture and are necessary constituents of all fertile soils. They are intimately associated with the growth and increase of plants and are always found in greatest abundance in the twigs, young leaves and other rapidly growing portions. In some plants the potassium is in combination with certain organic acids, as citric and tartaric acids. In the ash of plants—that which is left after burning—it generally occurs as a carbonate. Potassium salts are very soluble in water, but are absorbed and retained by certain constituents of the soil, so that their loss by drainage from soil is little to be feared. Sodium (Na) is very widely distributed in nature and is a con- stituent of many silicates. In the form of sodium chloride—a compound of sodium and chlorine—it is very plentiful as rock salt and as the largest saline constituent of sea-water. Its properties resemble those of potassium. Sodium compounds are largely used in the arts and the preparation of sodium ear- bonate is one of the largest and most important of chemical in- dustries. Sodium is found in the ash of most plants, but, except in the 14 Agricultural Chemistry. ease of certain plants, does not appear to be essential to their development. ors 28.6 7.8 Oar 0.5 PAWVCT AGEL ache etek « 25.1 7.6 66.0 1:3 The inerease during the fattening stage of growth is seen to contain 8 to 9 parts of fat for one of nitrogenous matter. Important parts of the animal body. Blood consists of a colorless liquid—plasma—holding in suspension numerous small solid bodies, the red and white corpuscles. The red corpuscles give the blood its characteristic color. These corpuscles have a definite structure and make up 30 to 40 per cent of the blood. 212 Agricultural Chemastry. When taken from an animal the plasma quickly deposits one of its protein constituents, fibrin, which, entangling the corpuscles, causes them to separate as a clot from the yellowish liquid—the serum. Blood plasma is therefore the liquid portion of fresh blood, while blood serum is the liquid portion after clotting. The latter differs from the former by having lost its fibrin and a portion of its lime, magnesia and phosphorie acid. Blood is the nutrient fiuid of the body. It is the source of nourishment for all the cells. Out of its ingredients the tissues are built. It contains about 81 per cent of water, so that it easily holds in solution whatever soluble nutrients are furnished it from the digestive tract. The 19 per cent of solids consists of the following materials: 10 per cent of haemoglobin; 7 per cent of proteins; about 1 per cent of ash; the remaining 1 per cent consists of fats, sugars, lecithin, ete. The color of the blood is due to haemoglobin. This body is extremely complex in composition and contains about 0.4 per cent of iron. Haemoglobin is a dark purplish-red colored substance. It readily combines with oxygen to an oxy-compound which is bright red in color. The haemoglobin plays an import- ant part in respiration as the carrier of oxygen to the tissues. The red corpuscles consist of circular, bi-concave dises, though their shape and size vary in different animals. They are largest in reptiles. In man the average diameter of a blood corpusle is about 1/3200 of an inch, and its thickness about 1/12800 of an inch. These corpuscles contain the haemoglobin, the coloring matter of the blood. When they are treated with water or ether they loose their coloring matter and leave a nitrogenous residue which retains the shape of the original corpuscles. Bones consist of an earthy frame work composed mainly of ealeium phosphate, permeated by an albuminoid, called ossein, and by nerves, blood vessels, ete. In the hollow center of many bones is the marrow, which consists of fats and proteins. The relative proportion of mineral and organic matter in bones varies considerably. The amount of mineral matter in the green bone The Animal Body. 213 varies from 40 to 60 per cent. No definite percentage can be given, as the amount, up to a certain limit, will vary with the supply of lime and phosphoric acid in the food and also with the source of the bone. The ash of bone is not entirely phosphate of lime, but contains in addition carbonates, fluorides, chlorides and magnesia. The following analysis of bone ash is given by Ingle: Ralemmn phosphate. 2. cacti s clmalon sre anecece 86.0 per cent Merenestum, phosphate. oli wel Sou hess os 1.0 ¢ Calcium, as carbonate, chloride and fluoride... 7.3 ac (Opi oranelvon elas) 5 cain comomnr ne pee me cto mee 6.2 ee (O)nllorab ways ooo ou dec ane enne BO Cicer eee 0.2 oe TNINEKOReeVEre Sobel este rin tee A Oe anicen See cee SiN Gerees 0.3 ve Muscular tissue consists largely of proteins and water, but contains in addition small quantities of fat, glycogen (animal starch), and certain nitrogenous extractives, such as creatin, ereatinin, xanthin and guanin. Small quantities of dextrose are also contained in muscle tissue. The ash of muscle consists largely of potash and phosphoric acid compounds, but there are also present small amounts of sodium, magnesium, calcium, chlo- rine and iron. Muscle usually contains about 75 to 80 per cent of water, and 20 to 25 per cent of solids. When a muscle does work, the glycogen and sugar are burned at an increased rate and the blood, which bathes the muscle, re- celves an increased proportion of carbon dioxide. Fats are also sources of mechanical work for the muscle. When fats and carbohydrates are available for consumption, the nitrogenous waste of the muscle is not increased by exercise, and only the normal amount of waste nitrogenous products, as urea, uric acid, ete., appear as the result of the life processes. Fatty tissue is made up of relatively large, oval, or spherical cells. These cells consist of a nitrogenous membrane, filled with fat, which during life is fluid. The fats, which resemble in con- stitution the vegetable oils already described, are chiefly com- posed of stearin, palmitin and olein. The fat cells may be 214 Agricultural Chemistry. found deposited between the fibers or cells of muscular tissue, or may constitute almost the entire mass of adipose tissue. When the latter is the case, the fatty tissues will consist of water, membrane and fat in about the following proportions :— Ox Sheep Pig Water (per cent)..... 9.96 10.48 6.44 Membrane SP Maas «003 1.16 1.64 1.35 Fat Lt Pe ae 88.88 87.88 92.21 Fat is stored in the body as a reserve material from which the animal can draw in time of scarcity of food. It is the most con- eentrated form in which energy is stored in the animal. Connective tissue, of which tendons, ligaments, cartilage and skin are mainly composed, consists of substances which yield gelatine when heated with water. These are the albuminoid com- pounds and constitute the framework of the animal tissues. They are to the animal body what cellulose is to the vegetable kingdom. They are only slightly attacked by acids and alkalies and are insoluble in water and salt solutions. Several different bodies have been recognized, among which are elastin, collagen and keratin. The first is the principal constituent of the elastic tis- sues and contains but traces of sulphur. The second, collagen, constitutes the foundation of cartilage and may be extracted from these tissues with hot water. The product which goes into solu- tion is called gelatine and solidifies on cooling. It contains about 0.6 per cent of sulphur. The third substance, keratin, is the main constituent of hair, horn, hoof, feathers and wool, and contains 4 to 5 per cent of sulphur. It is insoluble in water, but by heat- ing with water under pressure to 150-200° C. it may be rendered soluble and then constitutes glue. ° Processes of nutrition. We have seen that the food of plants is of the simplest character and from such simple materials as earbon dioxide, nitrates, certain other inorganic salts and water. a plant is able to construct a great variety of complex compounds. It accomplishes these surprising transformations by a consump- tion of energy (sunlight) external to itself. An animal has no The Animal Body. - 215 such power. The animal tissues are built up from the complex substances existing ready-formed in the food. The animal de- rives no aid from external energy. The temperature of the animal body (about 100° F.) is maintained by heat generated within the body and by the combustion of the material consumed as food. The energy by which all the mechanical work of the animal is performed, comes from the same source. The source of heat and force in the animal is thus purely internal. It is apparent from what has been said that the food of animals has duties to perform which are not demanded of the food of plants. In plants the food chiefly provides material for build- ing up the vegetable tissues. In the animal, besides constructing tissue, the food must furnish the means of producing heat and performing mechanical work; to accomplish this result, it must be burned in the animal body. Functions of food constituents. The solid ingredients of vegetable food may be classed, as (1) proteins; (2) fats; (3) car- bohydrates; (4) salts. Besides these general classes of food constituents, we have in immature vegetable products, as hays, roots, ete., a fifth class—the amino-acids and amides—which also take part in animal nutrition. They are the simple intermed- lary nitrogenous substances, formed from the nitrates absorbed by the plant, and eventually take part in the construction of the complex proteins of seeds and plant tissue. The proteins occurring in seeds, roots and other forms of vegetable food, have a general similarity in composition to those found in milk, blood, and flesh, but are by no means identical. From the proteins of the food are formed not only the proteins of the soft tissues of the animal, but also such a class of proteins as the albuminoids, which differ so materially in properties from the proteins of blood and muscle. It is also very probable that fat, a non-nitrogenous body, may be formed from protein. This is still a much disputed question and it remains for future in- vestigations to definitely decide this point. Proteins can also serve as a source of energy. In the case of 216 Agricultural Chemistry. a dog eating exclusively a meat diet, probably a greater part of the protein eaten is not stored but is used as fuel. We see from this that the proteins can serve most of the requirements of the animal, a statement which cannot be made of any other food constituent. They are the true tissue builders. An animal, even when not increasing in weight, will always require a certain constant supply of protein in its food to replace the waste of nitrogenous tissue, which is always going on even during rest. The cell proteins are constantly undergoing de- composition and reconstruction. When the nitrogenous tissues of the animal, or the proteins consumed as food are decomposed in the body, the nitrogen they contain is largely excreted in the form of a simple nitrogenous substance, urea. This is eliminated by way of the kidneys in the urine. There are small quantities of other nitrogenous products, such as uric acid, creatin, creatinin, and in the case of herbivora, hippurie acid, voided in the urine, but they constitute but a small proportion of the total nitrogen eliminated. The urea pro- duced is rich in nitrogen, containing about 46.6 per cent. It represents about one-third the weight of the protein oxidized. The amides and amino-acids consumed as food are burned in the body and their nitrogen excreted as urea. It is very prob- able that they can, in part, take the place of proteins as tissue builders. In addition, by their combustion, they serve as sources of heat and force. The fats are free from nitrogen. Those contained in food are similar to those found in the animal body. It appears possible for a vegetable fat to become deposited in the animal without essential change. Small deposits occur in every organ and cell. The fat reserves'‘vary much in size, depending on nutritive con- ditions, so that no definite statement can be made regarding the fat content of the individual organs. The fat of the food is either burned in the animal system to furnish heat and mechan- ical energy or is stored up as reserve material. With their larger content of carbon and smaller proportion of oxygen, fats are less The Animal Body. © 217 easily oxidized than sugars and require a larger intake of oxygen for their combustion; but when oxidized they yield more heat per pound than any other food ingredient. The carbohydrates of the food are chiefly starch, sugars, cel- luloses and pentosans. Various other non-nitrogenous constit- uents of food, such as the pectins, lignin and vegetable acids, are generally included under this title, though they are not, strictly speaking, carbohydrates. Carbohydrates form the larg- est part of all vegetable food. They are not permanently stored in the animal body, but serve when burned in the system, for the production of heat and mechanical work. If a fattening steer were consuming 16 pounds of digestible organic matter and gaining two pounds of live weight daily, the body increase and urine would contain not over 2.5 pounds of dry matter, leaving not less than 13.5 pounds to be oxidized, of which 12 pounds might consist of carbohydrates and fat, mostly the former. The carbohydrates are also capable, when consumed in excess of immediate requirements, of conversion into fat. The well- recognized value of corn meal as a fattening food, a feeding stuff nearly seven-tenths of which consists of starch and similar strue- tures, is a practical illustration of this truth. The carbohydrates and fats are the natural fuel food stuffs of the body. They cannot serve for the renewal or upbuilding of tissue, but by oxidation they constitute an economical fuel for maintaining body temperature and for power to run the bodily machinery. Proteins may likewise serve as fuel, but this is ap- parently confined to a non-nitrogenous part of their molecule. When fats or carbohydrates are available the proteins of the tis- sue are not normally consumed for production of heat and force. Only when the former are lacking will the animal increase its protein metabolism and nitrogen output for purposes of main- taining the body temperature. A moderate quantity of protein supplied to a growing animal will thus produce a much larger increase of muscle when accompanied by a liberal supply of car- bohydrates or fats. In this case, the non-nitrogenous constit- 218 Agricultural Chemistry. uents of the food supply the demands for heat and work and the protein can be devoted to the rebuilding or increase of tissue. If an adult animal receives the small amount of protein and salts necessary to repair the daily waste of tissue, it would be expected that the whole of the remaining wants might be met by supplying carbohydrates or fats. This is to some extent true; but a ration very poor in protein is not found to be consistent with real bodily vigor. There is some specific action of proteins not as yet understood. They,.appear to stimulate cell activity, a property not possessed by fats and carbohydrates. The ash constituents present in food are the same as those found in the animal body. The animal simply selects from the digested ash constituents those of which it is in need. The tissue. the blood, digestive fluids, and the bony framework contain a variety of these bodies, which are as essential as any of the other substances considered for the building and maintenance of the animal body. Without lime and phosphoric acid there can be no bone formation, and the digestive juices would cease to be active if deprived of chlorine. A cow from which common salt is withheld will, in time, die. Not only must the growing calf have ash material for constructive purposes, but the mature ox must be supplied with them in order to sustain the nutritive processes. The milech cow, which stores combinations of lime. phosphorie acid, potash and other salts in the milk, must have an adequate supply of these materials. Nothing else can take their place. Lime and phosphoric acid, stored in abundance in the framework of the animal, may at times of deficient supply in the food, act as internal sources; but ultimately all ash ele- ments must have been contained in the food. Digestion. We have accepted so far without discussion the self-evident fact that the food is the immediate source of the energy and substance of the animal body. It is now necessary to consider the way in which the nutrition of the animal is accom- plished. Digestion is the important process by which the food of an animal is rendered capable of being absorbed into the sys- The Animal Body. 219 tem and utilized in building up or renewing the tissue of the body. Hay and grain cannot directly be transferred to the blood, but must first be brought into soluble and diffusible con- dition before they can pass out of the alimentary tract into the blood and lymph. This is accomplished partly by mechanical means, but mainly by chemical changes, which are produced chiefly by the action of bodies called enzymes. Enzymes are a peculiar class of substances produced by living cells which constitute the various secreting glands. They are of unknown composition and are peculiar in that the chemical changes which they induce are the result of what is called eat- alysis, or contact. That is, during the solution of the food stuffs, the enzyme is not used up or destroyed, but by its mere presence sets in motion or quickens a reaction between two other sub- stances. For example, the enzyme of the saliva causes the starch of the food to combine with water, with the result that the soluble sugar maltose, is formed. An enzyme that acts upon starch, for example, cannot act on proteins or fats. Some digestive fluids have the power of producing changes in different classes of food stuffs, but when this occurs, it is assumed to be due to the presence in the same fluid of different enzymes. Again, enzymes are sen- sitive to their environment, and ‘a proper temperature and re- action must be maintained for their activity. The activity of saliva is extremely sensitive to the nature of the reaction and ceases when that becomes acid. Enzymes are thus seen to be more or less unstable substances, endowed with great power as digestive agents, but sensitive to a high degree and working ad- vantageously only under definite conditions. Digestion in the mouth. The first step is mastication, by which the food is subdivided and crushed by the action of the teeth and thoroughly mixed with saliva. This special secretion has its origin in several secreting glands, and from these this liquid is poured into the mouth through ducts, opening in the eheek under the tongue. Saliva is a highly dilute liquid of faint- ly alkaline reaction and contains an enzyme, ptyalin, which has 220 Agricultural Chemistry. the power of bringing about the same changes as are produced by plant diastase, that is, the conversion of starch into the sugar, maltose. This change begins in the mouth and continues for a limited time in the stomach, or until the gastric secretions es- tablish an acid reaction in the stomach contents. When this is established, salivary digestion ceases. The proteins and fats are not attacked by the salivary secretion. Ruminants, whose feed usually contains much starchy material, secrete enormous quantities of saliva. It is estimated that oxen and horses secrete from 88 to 122 pounds daily. This serves the additional important function of properly preparing the food for swallowing. Gastric digestion. The food after mastication passes down the gullet into the stomach. In the case of the horse and pig the stomach is a single sac, and true gastric digestion begins at once. In ruminants, as the ox and sheep, the stomach consists of four divisions, or sacs, and not until the fourth is reached, does gastric digestion proper begin. These sacs may be considered as en- largements of the oesophagus and primarily for the storage of the bulky materials consumed by these classes of farm animals. The four divisions are the paunch, honey-comb, many-plies and rennet, or what the anatomist has called the rumen, reticulum, omasum and abomasum. The capacity of these cavities in the ox is, on the average, not far from 50 to 60 gallons, about nine- tenths of the space belonging to the paunch. It is in the paunch that the food is first stored, only the finer portions being carried by what is known as the oesophagal groove to the third stomach, and finally from this compartment into the fourth and last di- vision. From the paunch the food is returned to the mouth where it is more finely ground before passing to the fourth stom- ach for digestion. This is what is termed ‘‘chewing the eud.”’ In the pauneh salivary digestion probably continues, as well as other fermentations induced by various micro-organisms. Here possibly a partial fermentation of cellulose by bacterial enzymes begins. The Animal Body. 221 When the food reaches the fourth stomach, it meets with the characteristic secretion of that organ, the gastric juice. This juice is secreted by glands located in the mucus membrane of the stomach. It is a watery fluid, containing various salts, as chlorides and phosphates of calcium, magnesium, sodium and potassium, free hydrochloric acid and the two enzymes, pepsin and rennin. The combination of pepsin and the acid is the ef- On the left—stomach of the horse. A, end of the oesophagus; B, pyloric end, or beginning of the intestine. On the right—stomach of the sheep. O, oesophagus; P, rumen; R, reticulum; F, omasum; C, abomasum; I, commencement of the small intestine; 1, oesophagal groove; 2, opening between omasum and abomasum. fective agent in the digestion. They are secreted by different gland cells in the stomach walls and the amount of hydrochloric acid secreted during 24 hours by a normal man, under ordinary conditions of diet, amounts to what would constitute a fatal dose of acid, if taken at one time in concentrated form. The main action of gastric juice is exerted on the proteins of the food, which under its influence, are gradually dissolved and converted into soluble products, known as proteoses and peptones. This enzyme, like the ptyalin of the saliva, is influenced by tem- 222 Agricultural Chemistry. perature, maximum digestive action being manifested at about 38° C., the temperature of the body. Further, a certain degree of acidity is essential for procuring the highest degree of effi- ciency. Pepsin acts best in the presence of from 0.1 to 0.3 per eent of free hydrochloric acid. It is said that the gastric juice of the sheep has a low acidity, while that of the dog has the high- est recorded among mammals. Chemically, the results are the same in the stomachs of all farm animals, that is, the proteins are changed to the soluble forms known as proteoses and peptones. The utilization of coarse fod- der by the horse is not as complete as in the ox for the reason that in the case of the former there is no preliminary remastica- tion and trituration before the food material comes in contact with the gastric juice. Another important function of gastric juice is that of curdling milk, due to the presence in the secretion of the peculiar enzyme known as rennin. This is present in the stomach of all mammals and it is the ealf’s active secretion, which is the source of com- mercial rennet used in cheese making. The purpose of this enzyme can only be conjectured. As the sole nutriment of the young, milk occupies a peculiar position as a food stuff, and be- ing a liquid, its protein constituents might easily escape complete digestion were it to pass too hastily through the digestive tract. Experiments have shown this to be true of liquid foods. But when curdled by the rennin, the proteins of the milk in their clotted state, must remain for a longer time in the stomach, and their partial digestion by gastric juice made certain. Among other factors in gastric digestion, the muscular move- ments of the stomach walls are to be emphasized, since we have here a mechanical aid to digestion of no small moment and like- wise a means of accomplishing the onward movement of the stomach contents. From the stomach but little absorption of the soluble food materials takes place. It is in the intestine that both digestion and absorption are at their best. The Animal Body. 223 Digestion in the intestine. When the food leaves the stomach it enters the small intestine. At this point it is only partially digested. The fats of the food have not as yet been changed, and undoubtedly a considerable proportion of the proteins and carbohydrates susceptible to solution is still to be acted upon. Immediately after passing from the stomach, the partially di- gested mass comes in contact with the pancreatic juice, the bile and intestinal juice, and the changes which began in the mouth and stomach, together with others which set in for the first time, proceed at a vigorous rate. The bile is secreted by the liver and stored in the small sae attached to that organ and called the ‘gall bladder’’ and from which it is brought to the intestine by a duct opening near the orifice leading out of the stomach. Bile is a reddish-yellow (in carnivorous animals) or green (in herb- ivora) liquid, with an alkaline reaction and bitter taste. It con- tains complex salts, which in conjunction with the fat splitting enzyme of the pancreatic juice, reduces the fats to an emulsion, a form in which they can be absorbed into the blood. When bile is prevented from entry into the intestine, the fat of the food largely passes out in the feces. Besides this important relation to fat digestion, the bile also acts in some degree as an anti- septic, preventing putrefaction in this part of the intestine. The pancreatic juice is of strongly alkaline reaction due to its content of sodium carbonate, and is characterized by the pres- ence of at least three distinct enzymes; these are trypsin, a pro- tein digesting ferment; lipase, a fat splitting enzyme; and amy- lopsin, a starch digesting enzyme. This juice comes from the pancreas and enters the intestine through a small duct, which in some animals is confluent with the bile duct. By the action of this juice, the acid chyme from the stomach is rapidly converted into an alkaline mass and the enzyme pepsin is quickly destroyed . in the new environment. Trypsin, effective in alkaline media, now continues the protein digestion, splitting the proteoses and peptones, as well as unattacked proteins, into simpler structures. In this act it is aided by another enzyme, known as erepsin, 224 Agricultural Chemistry. secreted by the mucus membrane of the intestine. These two enzymes are powerful agents and under their combined action the proteins are reduced, in part at least, to simple fragments, the amino-acids. The fatty foods undergo little or no alteration until they reach the intestine. While in the stomach they become liquid from the heat of the body and the neutral fat is liberated from the eell structures by the action of the gastric juice. Most of the neutral fats must be decomposed into the fatty acids and gly- eerine, of which they are composed, before absorption into the blood ean take place. Under the influence of the fat splitting enzyme of the panecreative juice, lipase, and the bile salts, the neutral fats are partly decomposed, with formation of soaps. These soaps aid in the formation of an emulsion of the rest of the fats. Such an emulsion is really a suspension of the fat in a very finely divided condition. Soap, free acid and glycerine are then absorbed from the intestine and are found again com- bined in the lymph as neutral fat. In this way the fats are ren- dered available for the nourishment of the body. The transformation of starch into maltose is again taken up by the amylopsin of the pancreatic juice. The maltose is further exposed to an enzyme of the intestinal juice, termed maltase, and decomposed into the simple sugar, dextrose. Other carbo- hydrates, as the lactose of milk, and cane sugar, meet with special enzymes in the intestinal juice, capable of converting them into simple sugars, the final form in which the carbohydrates are absorbed. No special enzymes fermenting the celluloses and pentosans, which constitute a large proportion of hays and straws, have as yet been prepared from the normal secretions of the intestinal tract. Possibly their partial solution is effected by bacterial fer- ments and other low forms of life. Such solution may have its beginning in the paunch, where active fermentations are in progress, and continue in the lower portions of the digestive tract. The Animal Body. 225 Absorption of food. In the ways mentioned above, the pro- teins, fats and carbohydrates of the food are gradually digested. Throughout the length of the small intestine absorption proceeds rapidly; water, salts and the products of digestion pass out from the intestine into the circulating lymph and blood. There are two pathways by which absorbed material reaches the blood. In the intestinal wall are numerous projections, called villi. Im- bedded in these structures are the minute branches of two sys- tems of vessels. One set is the lacteals, belonging to the lym- phatic system and the other the capillaries of the blood system. Materials passing into the lacteals reach the thoracic duct and by it, in a roundabout way, are carried into one of the main blood- vessels at the neck. Asa general truth it may be stated that the fats are largely absorbed through this channel, and it is impor- tant to observe that when they reach the lacteals they are again in the form of neutral fats. Materials absorbed by the capillaries of the blood system are carried directly to the liver through the portal vein, and there subjected to the action of that organ before they enter the gen- eral circulation. Most salts and the carbohydrates and proteins follow this course. In the liver the soluble sugars are converted into glycogen, the animal starch, and as such temporarily stored. The amount of sugar in the blood is a constant but small quan- tity and as this is required in the tissue, the glycogen is recon- verted back into soluble sugar to maintain the supply in the blood. ' The fragments of protein digestion, the proteoses, peptones and amino-acids, are not found as such in the blood or at least only in traces. Hither in passing through the intestinal wall, or after reaching the liver, they are reconstructed into complex proteins before being cast loose into the circulatory system. These reconstructed proteins are the serum albumin, serum glo- bulin and haemoglobin of the blood, which serve as sources of protein for the various body tissues. The processes of absorption 226 Agricultural Chemistry. and blood regulation are wonderfully and delicately balaneed and are by no means completely understood. Feces. The portion of the food which has escaped solution and absorption, together with certain substances already absorbed but re-excreted by way of the intestines, constitute the feces. Epithelial cells from the intestinal walls, parts of the digestive juices, bile, bacterial cells, ete., will make up a large portion of the fecal matter. . Respiration. The nutrients, prepared by the various process- es of solution and reconstruction in the intestines and intestinal wall, enter the blood on its return to the heart, coming into the venous circulation by way of the thoracic duct and liver (hep- atie vein), as already deseribed. By this route, the blood, laden with nutrients, passes to the right side of the heart. It is then carried to the lungs, by way of the right ventricle, to be returned to the left side of the heart, and from which it is pumped to all parts of the body. In the lungs the blood is supplied with oxy- gen. The purple of venous blood is changed to a scarlet, due to the absorption of oxygen by the haemoglobin, with the forma- _ tion of oxy-haemoglobin, the important oxygen carrier of the blood. At the same time, a considerable quantity of carbon dioxide, most of which was in solution in the blood plasma, pos- sibly as a bi-carbonate, is given up to the air within the lungs. Inspired air contains about 21.0 per cent of oxygen and .03 per cent of carbon-dioxide, while expired air carries approx- imately 16.5 per cent of oxygen and 4.4 per cent of carbon-diox- ide. Though the absorption of oxygen takes place in the lungs. it is not there that the processes of combining the oxygen with the carbon and hydrogen of the body tissues takes place. The blood, through the haemoglobin of the red-blood corpuscles, acts as a carrier of oxygen and the actual combustion of the products derived from the food occurs in the tissues themselves. The rate of combustion in the tissues is a variable one, dependent upon the amount of work the animal is doing and the temperature to The Animal Body. 227 which it is exposed. And it is through this oxidation of the nutrients in the cells of the body that heat and mechanical work are produced. Elimination. As has already been noted, the undigested resi- dues of food, together with certain excretory products eliminated by way of the intestines, constitute the feces. The products, which result from the metabolism of the body cells, or of the food consumed, are removed from the body by the lungs, the kidneys, the skin and the intestine. The carbohyd- rates and fats, which are oxidized in keeping up the animal heat or in furnishing energy, are broken down into carbon-dioxide and water and removed as such from the blood in the lungs, and to a smaller extent by the skin. Water and salts are removed by both intestine and kidney, while the perspiration may also serve to carry considerable quantities of these materials. The elimina- tion of the products of protein degradation in the tissues is al- most entirely by way of the kidneys. The larger part of the nitrogen is eliminated in the form of the simple body, urea. There are other forms of nitrogen occurring in the urine, such as uri¢c acid, creatin, creatinin, ammonia, etc., but they constitute only a small proportion of the total nitrogen eliminated. The sulphur of the protein molecule is also removed as sulphate through the kidney, while the phosphorus passes out of the body in the form of a phosphate by both the intestines and kidney ; by far the larger proportion is removed through the intestine in the herbivora. The quantity of nitrogen in the urine is taken as a measure of the amount of protein decomposition in the tissue. This may be only partly true. It is now believed that a considerable part of the nitrogen of ingested protein has not been built into body tissue, but is eliminated from the protein molecule as ammonia in the intestine, carried to the liver, and from there finally ex- ereted through the kidney as urea. The carbonaceous part of the protein molecule from which this nitrogen has been removed 228 Agricultural Chemistry. may now be used, through combustion, as a source of energy for the animal body. When an animal is supplied with known quantities of food per day, it is possible, by collecting the feces and subjecting it to the same chemical analysis as was applied to the food, to determine how much of each constituent of the food has been digested by the animal. This applies particularly to carbohydrates, fats and proteins, although not strictly accurate for these. It does not apply to the mineral salts, as they are partly excreted through the intestine. But by such means the digestibility of feeds is measured and such results are of enormous value to the knowledge of animal feeding. CHAPTER X FEEDING STANDARDS We have traced in the preceding chapter the processes of solu- tion and the destination of the various nutrients of feeding ma- terials. It will now be necessary to consider briefly the develop- ment of our knowledge leading to the establishment of feeding standards and the present status of such information. In 1810 Thaer, in Germany, formulated the first standard, publishing a table of hay equivalents, using meadow hay as the standard. It had little experimental foundation and soon fell into disuse. In 1859 Grouven published the first standard based upon the quan- tity of proximate constituents in feeding materials. The work of Liebig, Boussingault, and others, with the new tools of a rapidly developing chemistry, was paving the way for standards based on chemical analysis. But the tables of Grouven did not meet the requirements, since they were based on the total, instead of the digestible nutrients. In 1864 the feeding standards of Wolff, the eminent German scientist, first appeared. They are based upon the amounts of digestible protein, carbohydrates and fats, required by the va- rious classes of farm animals. These standards have been pub- lished annually in the Mentzel-Lengerke calendar down to 1896; for the next ten years they were issued by Lehmann of the Berlin Agricultural High School, and since 1907 by Kellner, modified to a starch equivalent basis, to be described later. The Wolff standards have seen wide use by practical stockmen because of their simplicity and definiteness. Co-efficient of digestibility. The nutrients of feeds are not wholly digestible. A part passes through the animal without having been dissolved by the digestive juices and thereby made available to the animal. The general method of measuring the digestibility of feeds has been to supply the animal with weighed 230 Agricultural Chemistry. quantities of the feed, the composition of which has been de- termined by chemical analysis. During the experiment the solid excrement is collected and weighed and finally analyzed by the same methods as those previously applied to the feed. From the data thus collected the digestion co-efficients are calculated. Example: Digestion Experiment with Sheep (From Henry). ee Nitro- Dry . rude gen Ether Matter Protein fiber free |extract extract | Grams | Grams | Grams | Grams| Grams Fed 700 grams of hay (con-) PALIN! Sais cre earhacii cess | 586.1 Clete \Obs eadoen 10.7 Excreted 610.6 grams dung! | (ContaInine)) ities nd enels | 288.6 | 40.4 | 101.5 | 119.4 7.9 WAGERIOD vigatt' ose en cm eer 29725. |) “Sine 90.0 | 157.3 2.8 Per cent digested............. 50.8 | 48.0 47.1 56.8 26.2 From the example it will be seen that the digestion co-efficient is the proportion of each food constituent digested out of 100 parts by weight supplied. The figures secured are not absolutely accurate, due to intestinal secretions which become reckoned as undigested food. The co-efficients for proteins and fats suffer most in this regard. In experiments with oat straw the fecal nit- rogen has been found to be more than that in the food, although the protein of the straw must have been digested to a considerable extent. Jordan states: ‘‘It is probably safe to affirm that at least 10 should be added to the co-efficients of digestibility of the protein of coarse fodders, as usually given in the tables that have been compiled.’’ With fat co-efficients, an error is introduced through the seeretion of bile into the intestine. This material contains products soluble in ether, the usual reagent used in de- termining the fat content of the feeding stuff. Consequently the undigested fat appears larger than it réally is. Feeding Standards. 231 Conditions affecting digestibility. Animals differ in their power of digesting any given food or food constituent. For ex- ample, the ruminants, by their more thorough and repeated mas- tication, are better able to digest bulky fodder than are pigs and horses. This is illustrated in the following table taken from Jordan :— Dry Substance Digested from Meadow Hay (Per Cent). Samples Best Medium Poor BEEP fire tere nail 42 67 61 55 Okemo Cae. Se 10 67 64 56 JE Kordseisiigecicneke achat a arcecl ae 58 50 46 On the other hand the power of digesting bulky feeds by dif- ferent classes of ruminants is very similar. Steers have been compared with sheep, and cows with goats, with no uniform dif- ference in their digestive power for this class of feeds. With the grains, the differences in digestibility with the various classes of farm animals are not greatly unlike. Comparative trials of oats with sheep and the horse gave nearly identical di- gestibility of the dry matter. With cows the result was similar. In other trials where beans were used the advantage was slightly with the ruminant. Swine digest the concentrated feeds as com- pletely as do ruminants or the horse. Nor are they incapable of digesting vegetable fiber when presented in a favorable condi- tion. Pigs fed on green oats and vetch digested 48.9 per cent of the fiber supplied. However, the digestive apparatus of the pig is not adapted for dealing successfully with bulky fodder. So far as the influence of breed is concerned, this does not be- come a factor in the digestibility of feeds. A Jersey is as effi- cient in this capacity as a Holstem. Young animals appear to digest as efficiently as older ones of the same species. There are, ~ very probably, differences in individuals, but the data so far collected do not definitely show this. The influence of quantity of food on digestion is an unsettled point. The old experiments of Wolff indicated that a full ration was as completely digested as a scanty one. More recent ex- 232 Agricultural Chemistry. periments in Europe, as well as in this country, give opposite results, indicating a higher rate of digestibility with smaller rations. The difference is not large and with appetite regulating the consumption, it is fair to assume that variations in food in- take, incidental to normal feeding, will not markedly influence the power of digestion. Influence of the quality of feed on digestibility. It is a popu- lar belief that curing a fodder decreases its digestibility. This is probably true, especially where the drying has been conducted in a careless manner. The loss of leaves and the finer parts of the plant, and the washing out of soluble matter by rain are factors which will depress the digestibility of the fodder. For this reason, field cured corn fodder is considerably less digestible than silage coming from the same source. On the other hand, where the curing is done in such a manner as to exclude these losses, it is doubtful if it, in itself, has any appreciable effect upon digestibility. The stage of growth of a fodder plant will influence its di- gestibility. That stage where there is a relatively high propor- tion of starch and sugar and a minimum of cellulose and lignins, will show a higher digestibility. As the grasses mature, the fiber increases; on the other hand, the corn plant furnishes a rela- tively higher proportion of digestible nutrients when the ears are full grown than before the ears have formed. Influence of methods of preparation. Steaming, wetting and cooking the feed have received considerable attention. The gen- eral concensus of opinion of feeders, as well as the results of scientific experiments, do not indicate that these practices are of great advantage; beans, corn and bran are not better digested by the horse or ox when previously soaked in water. Barley. corn and pea meal have been found more nourishing for pigs when given dry than when previously cooked. Cooking certainly depresses the digestibility of the proteins. This has been ex- perimentally demonstrated with steamed hays, silage, corn meal Feeding Standards. 233 and wheat bran. However, when cooking or steaming the feed renders it more palatable, and secures a larger consumption of material which otherwise would be wasted, the influence on di- gestibility is of less importance. Grinding increases the digestibility of feeds. Mechanical divi- sion is an important factor in the rate and completeness of solu- tion of material in the digestive tract. A single experiment with corn, fed to the horse, showed about 7 per cent increased digesti- bility from grinding, and with wheat, in one trial the increase was 10 per cent. With ruminants, the danger from imperfect mastication is less than with horses and swine. Whether it will pay to grind the grain will depend upon the cost of grinding and the loss of nutritive material from not grinding. Influence of one feed on the digestibility of another. It is generally stated that the addition of a considerable quantity of protein to a ration of hay and straw consumed by a ruminant, is completely digested, without affecting the digestibility of the original feed. Pigs have been fed potatoes to which variable quantities of meat flour were added. The proteins of the meat were completely digested, while the proportion of potatoes di- gested remained unchanged. It is also claimed that the addition of fat or oil to a basal ration of hay and straw was without influence on their digesti- bility. On the contrary, Dietrich and Koenig state that if a carbo- hydrate, as starch or sugar, is added to the extent of more than 10 per cent of the dry substance of a basal ration, or if roots or potatoes, equivalent in dry matter to more than 15 per cent, are fed, a diminution of digestibility occurs. It is further stated that the depression of digestibility is reduced, when, accompany- ing the high starch intake, there is a corresponding increase in protein consumption. From these considerations, it is stated that highly nitrogenous feeds may be given with hay and straw without affecting their digestibility ; but feeds rich in carbohyd- 234 Agricultural Chemistry. rates, as potatoes and mangels, cannot be given in greater pro- portion than 15 per cent of the fodder (both caleulated as dry food) without diminishing the digestibility of the latter. Lindsey of the Massachusetts Station has, in part, confirmed the work of Dietrich and Koenig. He found that when Porto Rico molasses fed together with hay, constituted from 10 to 15 per cent of the total dry matter of the ration, little if any de- pression oceurred. But with molasses constituting 20 per cent of the dry matter of the ration, a depression of 4.5 per cent was noted in the digestibility of the hay. He concluded that molasses and hay would not make a satisfactory combination for farm stock. A more suitable ration would consist of hay, together with one or more protein concentrates and molasses. Even in a ration of hay and gluten feed and in which molasses composed 20 per cent of the dry matter, there was a depression of 8 per cent in the digestibility of the hay and gluten. The nutritive ratio. We have seen that the formulation of feeding standards must be based on a knowledge of the relative digestibility of the several nutrients contained in the feeding material. Such knowledge has been secured by many experi- menters, working with various classes of farm animals, and has given us our tables of co-efficients of digestibility available in books on animal feeding. (See table in Appendix.) It has been found in practice that the feed of an animal may be varied within fairly wide limits, provided the ratio of digest- ible protein to all other digestible organic matter is kept within certain limits. Protein has special and peculiar functions and less than a certain minimum would limit production by just the amount of the deficiency. In order to get this ratio it is neces- sary that some carbohydrate be taken as a standard for express- ing the non-protein portion of the ration. Starch is the sub- stance always chosen, and it becomes necessary, in order to ex- press the fats and other carbohydrates in terms of starch, to ob- tain the equivalent in heat producing power of the other food constituents. ‘This has been secured (1) by burning a weighed Feeding Standards. 235 portion of the various materials in a calorimeter (an instrument for measuring heat production), and (2) by direct experiments upon animals placed in a respiration calorimeter (an apparatus for measuring both gas and heat production), and fed with known weights of the various feeding-stuffs. As an average of several experiments it may be taken that one part of fat evolves as much heat as 2.4 parts of starch, sugar, cellulose or of protein. To express the non-protein, other than carbohydrates, in terms of starch, it is therefore necessary to multiply the quantity of di- gestible fat by 2.4 and add this product to the quantity of digest- ible carbohydrates present. The nutritive ratio thus becomes: : digestible protein digestible carb. + (dig. fat x 2.4) The nutritive ratio of corn meal is obtained as follows: 100 lbs. contain 7.9 lbs. digestible protein 66.7 lbs. digestible carbohydrates 4.3 lbs. digestible ether extract (fat) 7.9 as! Tots, 1 MiGs eee ae 66.7 0825 76.02 9.6 The nutritive ratio for corn meal is therefore 1:9.6. This means that for every pound of digestible protein in corn meal there are 9.6 pounds of digestible carbohydrates and ether ex- tract (fat) equivalent. The term ‘‘wide’’ ratio is used when there is a very large proportion of carbohydrates contained in a feed in proportion to the protein. Oat straw, with a nutritive ratio of 1:33.7, is an example of a very ‘‘wide’’ nutritive ratio. With corn the ratio is ‘‘medium,’’ while with oil meal, with a ratio of 1:1.7 the expression ‘‘narrow’’ is used. The Wolff-Lehman feeding standards. In 1864 Wolff pro- posed certain feeding standards, which have been largely used in framing rations. In order to eliminate the size of the animal, the proportion of the various feed constituents, to be supplied daily for 1000 pounds of body weight, are given. For ilhustra- tion, a few standards are given here. (See full table in Ap- pendix. ) 236 Agricultural Chemistry. For 1000 Pounds Live Weight Daily. Digestible Dry Nu- * Sub- | tritive stance -_ | Carbo- Ratio Protein hydrates Fat, Lbs Lbs. Lbs. Lbs. Cow, milk yield 22 lbs...... 29 2.5 13 0.5 SSC Fattening steer, 1st period. . 30 2.5 15 0.5 1:6.5 Horse, medium work....... 24 2.0 11 0.6 1:6.2 In formulating standards for ruminants it is better to start with two kinds of roughage, furnishing from 16 to 20 pounds of dry matter, and about 10 pounds of carbohydrates (nitrogen free-extract), and then add concentrates, which will on first cal- culation bring the total digestible protein somewhat under the standard. The additional requirements can then be easily com- puted. The term ‘‘fat’’ is identical with the ‘‘ether extract.’’ It is not necessary that a ration agree mathematically in all nutrients with the standard. To attempt to do this is to avoid the individual possibilities of the animal. The tables of digestion co-efficients and feeding standards are but averages and approx- imations. ‘They are not to be followed blindly and absolutely, but if taken as guides, they can become extremely helpful. For example, the Wolff standards are quantities to be fed per thou- sand pounds of live weight. It is known that the food demands of an organism are not proportional to its size, but rather to its surface. This is because of a difference in demand on the heat producing function of a food. A small animal has a propor- tionately greater suface to its weight than a larger animal. Con- sequently it does not require the same proportional amount of digestible food to maintain a 1700 pound steer as one weighing 1000 pounds. For instance, Kuhn of the Mockern Station, found that a 1900 pound ox could be maintained on 0.7 pound of di- gestible protein and 6.6 pounds of digestible carbohydrates. Feeding Standards. 237 Other investigators have found that the Wolff allowances may be too high. Haecker of the Minnesota Station maintained a dry, barren cow of a 1000 pounds weight on 0.6 pound of digestible protein, 6 pounds of digestible carbohydrates, and 0.1 pound of digestible fat (ether extract). Energy value of feeds. The function of food, as has already been pointed out, is not only to repair waste and promote growth and increase, but also to furnish heat and energy. For this reason, attempts have been made by several investigators to assess the relative value of feeds by a determination of their heat pro- ducing power. Heat units are expressed either in starch equiv- alents or calories. The German investigators, Kellner and Zuntz, have used starch as the basis for expression, while Armsby of this country is using the calorie. The calorie represents the quantity of heat required to raise the temperature of one gram of water from 0° to 1° C. A large Calorie, one thousand times larger than the small calorie, is usually employed for the ex- pression of large quantities of heat and will be used here, gen- erally. However, the new term, therm, which represents 1000 large Calories, is now in use by Armsby and is the quantity of heat required to raise the temperature of 1000 kilograms of water 1° C. The value in large Calories of one gram of the several classes of nutrients, is given in the following table: Wihhestrelmten J... vec 2. oct sm: Fea MOOUM ORE a terete gee oictes wal eae 4.1 SAUIATTIT al eIMAOIS CLE erate es tess y-ray eal @AN Gc SU ae. ete cys) excess sein 4.0 Starcliecch tarecr nr etcuster wets fue Amaia ly Arma ateiti event eet tcisstecs cis eno = 9.4 Available energy. The data in the above table is secured by complete combustion of the material in the calorimeter. Such does not obtain in the animal body. It should be remembered that only part is digested, and as only the digested portion fur- -nishes available energy, the available fuel value of a ration must depend primarily upon the amount which is dissolved out of the digestive tract and passes into the blood. There is fuel waste in the solid excrement of the feces, in the incompletely burned gases 238 Agricultural Chemistry. escaping from the alimentary canal, and in the unoxidized com- pounds of the urine. It has been estimated by Kuhn that the loss of energy in the gas, methane, which has its source in the fermentations of the digestive tract, amounts to over one-seventh of the energy of the digested crude fiber and carbohydrates. From this we see that the available energy of a ration represents the fuel value of the dry matter digested from it, minus the energy in the dry matter of the urine and that lost in excreted gases. Such data have been secured on a number of materials by the use of the respiration apparatus—an air tight compart- ment in which the animal could live and from which the gases could be removed for analysis. At the same time the urine and feces could also be collected for a complete chemical analysis and for a determination of the energy still contained in them. Net available energy. We have seen that food is not applied to use until it reaches the blood. It must have work done upon it before it is in solution. The processes of mastication, of mov- ing it along the digestive tract, and of bringing it into solution all require the expenditure of a certain amount of energy. Zuntz, ' working with a horse, has attempted to measure this. His method has been to determine by various devices, how much more oxygen is consumed during mastication and digestion than before or after these operations are accomplished. From this measure of oxygen consumption, he calculated the following heat units, rep- resenting the energy used in chewing certain feeds: Cal. L pound, corns (454:oramigi tse is asi ore os peace eee 6.3 DOUN GLOBUS ine Wm Shaitee ode eee rae aa tyekey ete re ear alent 21.0 l pound hay. Ao ee ae sete hen ade eee ar ae 76.0 This is an important finding. Zuntz calculates that in general the coarse feeds have 20 per cent less net energy value than the grains and that the work of mastication and digestion combined is about 48 per cent of the energy value of the digested material from hay and 19.7 per cent of that from oats. We must remem- ber, however, that the wastefulness of fibrous foods shown in Feeding Standards. 239 these determinations on the horse are not true to an equal extent in the case of ruminants. In the latter the fiber is softened in the paunch and its digestion has begun before it reaches the intestines. Net available energy then, is the available energy minus the energy of digestion and preparation of the food for use. This internal work furnishes heat, and provided it is not in excéss of the heat requirement of the animal, should not be regarded as waste. The waste of heat has begun when that produced bv the work of digestion exceeds the animal requirement. But if it is produced in the digestive tract and not in the tissues of the animal, it cannot appear as useful work. We learn from this that it is not the total chemical energy in a feeding stuff which measures its value to the body, but that which remains after deducting the energy losses in the unburned material of the excreta, the energy expended in digesting the real fuel materials from the food, and in addition, the energy used in transforming them into substances which the body ean use or store up. This gives us what Kellner calls the productive value of feeds, and is identical in meaning with the term net available energy of feeds. » Productive value of feeds. [From elaborate experiments with the respiration chamber and mature oxen Kellner has determined the productive value of certain feeds. For this purpose he chose rather lean oxen, giving them a fixed moderate ration which re- sulted in a small increase in weight. He then added to the ration the feed to be experimented with, and determined the amount of increase produced. This was not done by weighing the animal, but by determining the amount of nitrogen and carbon retained by the animal. The protein tissue stored, was calculated from the nitrogen retained and the fat from the carbon left after deducting the carbon required to build the increase in protein. Kellner’s results are shown in the following table. The available energy of these feeds had already been deter- mined and is given in the first column. In the second column appears the percentage of loss in the process of digestion and 240 Agricultural Chemistry. assimilation and production of tissue. The last two columns ex- press the energy value of the increase and the comparative pro- ductive value of the different materials, with starch as a unit. We see from this that 56.3 per cent of the digested fat (peanut oil) was stored, and 44.7 per cent of the digested protein (wheat gluten), while but 17.8 per cent of the digested wheat straw was available for useful energy or increase. This gives us a scien- tific explanation of the fact that coarse feeds are not adapted to rapid production. From such data Kellner concludes that 1 pound of digested Heat Values of Digested Feeds and of the Increase Obtained in a Fattening Ox. | Heat value | Z Loss of Comparative digested | PTO uctive | obtained value. substance | Processes Starch 100 | Jals. | Per cent Cals. SLENTO Wee Misatnokeratls aac oll 41.1 2.2 100 Molasses’ 97.5 a8 ant Bro 36.4 2.3 104 Straw pullp’s... sehen: 3.6 36.9 2.3 104 Wheat gluten......... 4.7 hase 21 101 Peantt olla. ce een 8.8 43.7 4.9 | 224 Meadow hay.......... 3.6 56D 15 68 Oab AUPE Wf a.tcntine a a Solids Animal Fat | Casein | Sugar Ash | oe det Per cent|Per cent|Per cent|Per cent|Per cent NMOINAT SS, oe hoses eerie iis 3.3 15 6.8 0.2 8.5 NT iene Pena pane e ha TO De a ea 1.0 eal d.5 0.4 7.8 Ginatitea 5. af ito A eo ce 6.5 4.3 520. One 10.2 IWC dey ie at oilers eee croton avers waxes FO) (heel 4.2 0.8 12.4 11 Eo ae ea ers Pic Sinn RA a bce ys ye 6.0 0.4 8.6 Si GS Ride oho hc ee ae en lee 4.6 pers Sud 0.8 11.4 ers yay 2b Relea RO a li pa ae 2.9 3.8 Pat 0.6 10.2 Hippopotamus . 2. o.)..20. oc... 4.5 Trace 4.4 0.1 4.5 Bitch cee 215 oe a tose 9.6 9.9 Bev tea 13.8 GP i eee Soni ket a= Sve rain. aoe 3358) 9.5 4.9 1.0 15.0 Bab bit Ae hk eee eee 10.5 tS 2.0 2-5 Wh Zoek Blephant: Js. 3.2acendeay hoe 19.6 3.1 8.8 0.6.2 |. 1236 PGnpOise= var cecni.c ee heer 48.5 1h.2 igre 0.5 | Isa Wihdlevie che cae See Re eee 43.7 TOR Neches O45" m= 7a operation of milking and during subsequent exposure to the air, bacteria, molds and yeasts find admission. They may find their way into the milk from the hands of the milker, the teats and hair of the cow, and often from the vessel in which the milk is collected. The ordinary souring of milk is produced by various species of bacteria, which during their growth convert the milk- sugar into lactic acid. This formation of acid induces the eurd- ling of the milk. This generally occurs when the amount of acid reaches about 0.7 per cent. Curdling is produced by less acid if the milk is heated. Other organisms, and often of a more dangerous character. Milk and Its Products. 279 sometimes find their way into milk. Outbreaks of diarrhea, ty- phoid and cholera have been traced to contaminated milk. It has also been shown that milk can act as a earrier of tuberculosis. Milk, too, has the property of absorbing gases and vapors and in consequence readily acquires odors and flavors from the air. All these facts emphasize the necessity of cleanliness in milk production and precautionary measures to check bacterial devel- opment should the milk become seeded. Their growth can be checked by cooling the milk as soon as it is produced. This pre- vents a rapid development of the organisms already in the milk, but will not entirely prevent their development. It will prolong the sweetness of the milk. In order to destroy the organisms which have gained access to the milk, heating or the use of anti- septics must be resorted to. Where the process of heating is carried on at a temperature high enough to completely destroy all organisms and their spores—a process known as sterilization and requiring a temperature above 100° C.—undesirable chem- ical changes are produced in the milk. The sugar is turned brown, the albumin partly precipitated, and the milk acquires a burnt or cooked flavor. To avoid these disadvantages the process known as Pasteurization is often substituted. The milk is heated to only 60 to 80° C., whereby the flavor is little affected and most of the active bacteria are killed. The keeping qualities are thus materially increased. ) Antiseptics. By adding various substances to milk, the growth of micro-organisms can be impeded, if not entirely pre- vented. When, however, such quantities of an antiseptic are added as will prevent bacterial growth, then there is little doubt that the milk is made unsuitable for human consumption. The chief preservatives in common use are boric acid, salicylic acid, formaldehyde and benzoic acid. Their use in any quantity is reprehensible, allowing uncleanly methods in milk production to be practiced, as well as endangering the health of the consumer, and should be absolutely prevented. 280 Agricultural Chemistry. Products derived from milk. Cream. The fat of milk exists in globules and is specifically lighter than the aqueous portion of the milk. This makes the globules tend to rise to the surface, where they form a layer of cream. The specific gravity of fat at 15° C. is .930, while the serum in which the globules float has a specific gravity of about 1.036. The globules are of various sizes. They are considerably larger in the milk of the Jersey and Guernsey breeds than in the Ayrshire and Holstein breeds. The Devons and Shorthorns hold an intermediate position. The smaller the globule, the larger is its surface in proportion to its volume, and the greater the resistance to its rise. For this reason Jersey milk creams easier than that from breeds with smaller elobules. Cream can be separated from milk by gravitation or by sub- stituting for gravity the much greater force produced by rapid rotation. When milk leaves the cow it will have a temperature of about 90° F., and where set for cream should be cooled as quickly as possible. There are two methods in use for the separ- ation of cream by the gravity processes, namely, shallow setting and deep setting. In the former the milk is placed in shallow vessels to a depth of 2 to 4 inches, cooled to about 60° F. and kept at that temperature for 24 or 36 hours. The cream layer is then removed by a shallow spoonlike vessel, or sometimes by running off the milk into another vessel through a hole at the bottom of the creaming pan. Under these conditions of cream- ing a large surface is exposed, the milk may receive a great num- ber of bacteria, and decomposition of a part of the protein and sugar may rapidly take place. The cream obtained in this way is liable to be contaminated with various strongly flavored pro- ducts of decomposition, resulting in a poor quality of butter. The process is not efficient, as only about 80 per cent of the milk fat is removed. By the deep-setting system, the milk, while still warm, is placed in cylindrical vessels, usually about 8 to 12 inches in Milk and Its Products. 281 diameter and 15 to 20 inches deep, which are then immersed in ice-cold water. The cream rises quickly and the process will be practically complete in 12 hours. By this process 90 to 95 per cent of the fat can be removed, dependent upon conditions of cooling, manipulation, and the breed of the cow. It has been found that by this process twice as much fat remains in the skim milk from Holstein cows as in that from Guernseys and Jerseys, owing to the slower rising of the small fat globules in Holstein milk. Many explanations of the efficiency of this system have been attempted. Since fat expands and contracts with changes of temperature more rapidly than does water, the effect of cooling upon milk would be to lessen the difference in specific gravity between fat and water; it would also increase the viscosity of the milk, both conditions working against a rapid rise of the fat globules. Perhaps the most satisfactory explanation is the one given by Doctor Babcock. There exists in milk a substance sim- ilar in character to blood fibrin, which, when formed produced more or less of a network throughout the body of the milk. By rapidly cooling the milk, the formation of fibrin threads is checked. This allows the fat globules a free path of movement, with the resultant rapid formation of the cream layer. The ex- istence of fibrin in milk has been definitely proven. Separators. A third plan of separating cream is by subject- ing the milk to extremely rapid horizontal revolution in a cen- trifugal machine. Under this condition the serum, being the constituent of heaviest specific gravity, is thrown to the outer side of the revolving vessel while the fat globules rise into the center of the mass. The milk should be warmed to about 85° F. previous to separating, for the purpose of lowering its viscosity. By providing suitable outlets, the skim milk can be directed into one channel and the cream into another. By adjusting the size of one of these openings, thick or thin cream can be obtained at will. Both the cream and skim milk thus obtained, are, of course, perfectly sweet. The separation of the fat is far more complete 282 Agricultural Chemistry. than by either of the other processes, from 97 to 98 per cent being recovered in a good machine. Composition. Cream varies enormously in composition, the proportion of fat varying from as low as 10 per cent to as high as 60 or 70 per cent. By shallow setting, a product contaiming from 15 to 40 per cent is usually obtained; at low temperatures about 20 per cent of fat is usually present. In the deep-setting process the cream obtained will contain about 20 to 25 per cent of fat. Cream separated by the centrifugal process will vary according to the mode of working. It may be quite poor, or it may contain 50 to 60 per cent. Generally speaking, thin cream will contain 15 to 25 per cent of fat, and thick cream 30 to 50 per cent of fat. Devonshire-‘‘clotted cream’’ is prepared by setting the milk in shallow pans and at a fairly cool temperature for 12 hours. It is then heated to a temperature of 70 to 80° C. until the surface becomes sharply wrinkled. It is then set in the cold for 12 hours and skimmed. Such clotted cream usually ‘contains about 58 per cent of fat, 34 per cent of water and about 8 per cent of solids not fat. Skimmed milk varies in composition according to the more or less complete removal of the fat. Milk thoroughly skimmed after shallow setting will contain about 1 per cent of fat. With deep setting and ice, the per cent of fat left in the milk will vary from 0.15 to 0.40. When the centrifugal machine has been used the percentage will be from .05 to .15. Milk of average quality may be expected to yield with a good centrifugal machine, skim- med milk of about the following composition :— Per cent Per cent Water uit odd tating 90:54 |\Casein= sc Ast soe 8.1) eats Os ec, were cas ate ees 0210) |: Albumin 2 as semen 0.42 UQAr oc vest tnore siaiee ce oreerette A O48) ASD CLC ie ey ras sonra eye 0.89 Skimmed milk contains a valuable amount of food stuffs, and should be utilized on the farm for feeding pigs or in other ways. Though poorer in fat, machine separated milk has the advantage Milk and Its Products. 283 of being sweet and of keeping better than the product from other processes of skimming. Butter. When cream or milk is agitated for some time, the fat globules coalesce and butter separates out in irregular masses. While these masses are not continuous fat, very few of the original globules remain. The spherical globules visible in but- ter under the microscope consist of minute drops of butter-milk or water, enclosed in the fat. Churning is a methanical process. The fat globules collide, adhere, and the large irregular masses thus formed become cen- ters of growth, to which other fat globules adhere. Portions of the aqueous liquid, butter-milk, are enclosed in the masses of fat. During the ‘‘working”’ of the butter, the butter-milk is partly pressed out. For butter to be of good quality, it must possess a certain texture and grain and be neither hard nor greasy. This desirable result can only be attained by careful churning at a favorable temperature. If the temperature of the cream is too low the butter will be long in coming and will be hard in texture. If the temperature is too high, the butter will come very speed- ily, but the product will be greasy and destitute of grain. No temperature can be fixed as the best at which churning should always take place. The proportion of solid and liquid fats in the milk varies somewhat with the breed and feed of the cow, and this necessitates a change in the temperature. From 45 to 65° F. is the greatest range usually employed and in most eases from 50 to 60° F. is chosen. ‘‘Ripened’’ or sour cream must be churned at a higher temperature than that required for sweet cream. The exact temperature most suitable for churning may be ascertained, by recording every day the temperature employed, the length of time occupied in churning and the character of the product. When this is done the experience gained can be used in selecting the most suitable temperature. The temperature may rise during churning, work being con- verted into heat. This causes an expansion of the air in the churn. In addition, the carbon-dioxide in solution in the serum 284 Agricultural Chemistry. of a ripened cream is driven out by the agitation. These two factors give rise to the pressure observed within the churn. Churning should always be stopped as soon as the butter appears in fine grains. This allows a more complete separation, by wash- ing, of the butter-milk, and removes one of the important factors in the production of mottles in butter. Further, the more com- pletely the butter-milk is removed, the better will be the keeping qualities of the butter. Freshly separated cream is sometimes churned, but it is gen- erally admitted that the best flavor and aroma for butter can only be obtained by the use of properly ripened cream. This is, cream to which lactic acid organisms have either gained access spontaneously, or, as is preferred in modern practice, have been added in the form of a ‘‘starter’’ of sour skimmed milk or some pure culture of the lactic organisms. The degree of ripeness which is probably best, corresponds to about 0.5 per cent of lactie acid; but the acidity most suitable depends to some extent upon the flavor desired in the butter. If the cream is over ripe, the casein present may be hardened and on churning is found as white specks or flakes in the butter, spoiling its appearance and endangering its keeping qualities. Salt is usually added to butter, serving both as a condiment and as a preservative, the proportion varying from a mere trace to 5 or 6 per cent. Composition of butter. The main constituent is of course fat, but in addition, water, casein, milk sugar and ash are also present. The amount of fat is usually about 80 to 86 per cent, water about 11 to 12, casein from 0.6 to 1.5 and salt from 0.1 to 4.0 per cent. Under the present pure food law of the United States it is unlawful to sell butter containing more than 16 per cent of water. So called ‘‘milk-blended butters’’ prepared by kneading butter in milk, usually contain an excessive quantity of water and a high proportion of casein. Renovated butter. In this country old and rancid butter is sometimes converted into what is known as ‘‘renovated,’’ ‘‘pro- Milk and Its Products. 985 cess,’’ or ‘‘aerated’’ butter. This is done by melting the butter, separating the fat from the casein, water, ete., blowing air through the fat to remove the unpleasant odors, and then churn- ing the liquid fat with milk until an emulsion is formed. This is then quickly cooled in ice and a granular mass results. It is then worked, salted, and made up as butter. Oleomargarine is also known as ‘‘margarine’’ or ‘‘butterine.’’ This product, which is intended as a substitute for butter, is made by churning so called ‘‘oleo oil’’ with lard, milk, sometimes a little butter, and occasionally cotton-seed oil or peanut oil, in a warm state. After the churning the mixture is quickly cooled, salted and ‘‘worked.’’ Where coloring matters are used, with the intention of imitating butter, a tax of 10 cents a pound is imposed. On uncolored ‘‘oleo’’ a tax of 1% cent per pound is levied. The ‘‘oleo oil’’ is made from beef fat by melting, carefully clarifying, and allowing it to stand at a temperature of about 30° C. The semi-solid mass which results is then separated by a press into solid stearin and a liquid composed of olein and palmitin. Pure butter can be distinguished from ‘‘renovated’’ butter and from ‘‘oleo’’ by its behavior when heated in a test tube or spoon over a flame. Oleomargarine and renovated butter boil with much sputtering and produce no foam, or very little, while genuine butter in boiling produces more foam and less noise. Butter-milk. The liquid remaining in the churn after the separation of butter from the cream varies a good deal in com- position. With good churning of ripened cream, the percentage of fat in the butter-milk may be 0.3 or less. When sweet cream is churned 1.0 per cent of fat may be expected. The average composition of butter-milk will be about as follows:—Water, 90.9 per cent; proteins, 3.5; fat, 0.5; sugar and lactic acid, 4.4; ash, 0.7. The chief use for butter-milk has been as food for pigs, but there is a growing demand for it as human food. The finely ‘ 286 Agricultural Chemistry. divided condition of its protein makes it readily and easily di- gestible. The preparation of a new product, butter-milk cream, will probably increase the consumption of this material as human food. This product is prepared by holding the butter-milk at 75 to 78° F. for about 2 hours, and finally heating to 130 to 140° F. for a short time. This treatment induces an aggregation of the finely divided protein, allowing the material to be strained and collected, which etherwise could not be done. The following table shows how the various constituents of 100 pounds of milk are distributed when the milk is creamed and made into butter :— Distribution of Milk Solids in Butter Making. Products from 100 lbs. of milk, in Ibs. | lb | lb Ss d | tl B 100 lbs. 20 Ibs. kimme utter of milk | of cream milk Butter milk Otalesolvas ..ceeee ee 13.00 5.18 7.82 4.00 1.18 Rattner anions ae 4.00 3.88 0.12 3.83 0.05 Casein and albumin 3.50 0.50 3.00 0.10 0.40 Sugar and acid..... 4.75 0.75 4.00 0.05 0.70 AHS ini thee 0.75 0.05 OMe Misc Jaen 0.03 The 4 pounds of solid matter recovered in the butter, which contains 3.83 pounds of fat, together with the salt and water present, make about 4.6 pounds of marketable butter. Condensed milk and milk powders. Condensed milk is pre- pared by evaporating milk in vacuum pans until its volume is reduced to about one-third or one-fourth of the original, and then sealing the condensed product while hot. In many brands cane sugar is added in large proportion. This aids in preserving the product, even after the cans are opened. To other brands, often known as ‘‘evaporated cream,’’ no sugar is added. The composition of these products varies, the fat being liable -Milk and Its Products. 987 to considerable variation. The following analysis may be taken as typical :-— Sweetened Unsweetened Per cent Per cent Via beret eee ina oer s oye Sits Dail FNS Bie Sete tg yeh sieve (i Sree chon cieke mace ehiles i Jar 10.7 8.1 Proteinby Eris cise Oe ESS ee ee Seer 8.5 8.7 INTUUIR Se ipa Gees o> Sacedob ooon moda op 11.9 9.9 CELI QATSE 2S) ae ya tee ROR eee aS 41.9 PASINEY ee aes pti cis ioverk ors tc aie Reeas Sarcvsrgeed. = es 1.6 Milk powders are made by several processes. One of the earliest was to evaporate the milk in a thin layer, on a heated revolving drum. By this process the evaporation of water takes place rapidly and the dried film of milk drops, or is scraped, from the rolls, appearing as a thin yellow scale. Another proc- ess, of recent date, consists of atomizing the milk under pressure into a moving volume of warm dry air. The moisture is in- stantaneously absorbed and by the use of centrifugal force, the vapor charged air is made to give up the minute particles of suspended matter. The product is a fine flour, possessing, in common, with some other brands prepared by other methods, the properties of milk when again stirred up in water. There are preparations on the market which do not have these prop- erties, probably because they have been subjected to too high heat in the drying process. Of the several milk powders examined by the authors, only one contained any appreciable quantity of fat. It appears that most, if not all of these powders are prepared from skimmed, or partially skimmed milk. This-is probably necessary, in order that dessication may be more complete and the keeping qualities of the product well insured. One product examined. and rep- resented as a preparation from whole milk, contained but 9 per eent of fat. A milk powder prepared from average whole milk should contain at least 25 per cent of fat. Various other dry foods are prepared from the casein of milk, 288 Agricultural Chemistry. among which are ‘‘plasmon’’ and ‘‘nutrose.’’ ‘‘Plasmon’’ is made by treating the curd of skimmed milk with sodium bi- carbonate and drying the thoroughly mixed product in an at- mosphere of carbon-dioxide. ‘‘Nutrose’’ is also a sodium com- pound of casein. Cheese. The principal varieties of commercial cheese are pre- pared from milk by the action of rennet. Rennet is made by extracting the fourth stomach of the calf with a 5 to 10 per cent solution of common salt. Its power to coagulate milk is due to the presence of an enzyme called rennin, which plays a similar part in the process of digesting milk in the calf’s stomach. Ren- nin coagulates the casein of the milk, forming a curd which mechanically entangles almost all the fat of the milk, leaving the albumin and sugar in the whey. Rennin acts more rapidly at about 102 to 104° F. In cold milk it is slow in its action, while at temperatures above 120° F. it is retarded, its action en- tirely ceasing at 130° F. In milk containing some acid, but not enough to curdle it, rennin action is hastened. It is impossible in a work of this scope to describe the varieties of cheese and their methods of manufacture. The common practice followed in the preparation of American cheddar cheese is to ‘‘ripen’’ the milk to an acidity correspond- ing to about 0.25 per cent of lactic acid. This is done by adding to it a starter consisting of sour milk or a pure culture of lactic organisms. The necessary rennet is then added, the milk being previously warmed to 82 to 85° F. After the curd is sufficiently firm, requiring about 30 minutes, it is cut into cubes and the temperature of the vat raised to 100° F. It is maintained at that temperature for 1 to 2 hours, during which time the curd shrinks and the acidity increases. After proper acidity is de- veloped, the whey is drawn, the curd piled in one end of the vat and kept warm. In this condition it mats into a solid mass. It is finally passed through a grinding mill, salted, and pressed into molds. The cheese is then placed in a curing room at a tem- perature of 50 to 60° F. and allowed to ripen. A lower tem- Milk and Its Products. 289 perature than this can be used, with great improvement in the quality of the product. In the manufacture of Swiss cheese the milk must be in a sweet condition. No acid is developed and the curd is cooked at a temperature of 125 to 130° F. The curd is placed in molds and the salting done by surface application. In making soft cheese the curd is not cut or pressed, but simply allowed to drain on a cloth or frame. Reckoning that the fresh cheese which goes into the cheese room contains about 36 per cent of water, the products from 100 Ibs. of normal milk will be as follows :— Products from 100 Lbs. of Normal Milk. == | | fee Water | Protein | Fat Sugar Ash i Lbs. Lbs. Lbs. Lbs. Lbs. Lbs. NV Tillis ciers ae sete 100.0 87.10 3.40 3.90 4.85 1h) @Mecsee co. sss te | O40 3.94 | 2.57 3.59 0.17 0.13 WYRE Pio dite aSiee a's 6 89.60 | 83.16] 0.83 0.31 4.68 0.62 Ripening. Cheddar cheese ripens quickest at a moderately warm temperature, 50 to 60° F. being usually employed. It has been shown that it will also ripen at a much lower temperature— even at 30° F.—and the product will be of excellent quality. The time of ripening is necessarily longer when conducted at the lower temperature. During this curing process many complex ehanges occur. The sugar is converted to lactic acid, some water evaporates, and the insoluble proteins are partly converted into water soluble products. Ammonium compounds are also pro- duced during the ripening process. Experiments have shown that fresh cheddar cheese contains but from 5 to 10 per cent of its protein in water soluble form, while at the end of 5 months, 35 to 40 per cent will be found in that form. These changes, ac- cording to one view, are produced primarily by the lactic acid organisms. Another theory ascribes them to enzymatic action, the enzymes being galactase, which is present in all milks and 290 Agricultural Chemistry. possesses the power of peptonizing casein, and pepsin, contained in the rennet extract used. Whatever may be the cause of these changes, there can be no doubt that during the curing process the flavor and aroma are developed and that a considerable por- tion of the insoluble nitrogenous bodies are converted into water- soluble forms. The fat of cheese undergoes slight change during ripening, a small proportion of the neutral fat beimg decomposed and butyric and other fatty acids formed. The sugar which was present when the cheese was first made also disappears after a period of 7 to 10 days. Lactic acid is the main product formed from the sugar, although other products, probably of great im- portance to flavor development, are produced. The ripening of special kinds of soft cheese, such as Roquefort and Camembert is attributed to such special ferments as molds, introduced during the process of manufacture. The average composition of various cheeses is given in the following table :— Composition of Cheese. Water Protein Fat Ash l Per cent | Per cent Per cent Per cent Cheddante cee sores 34.4 26.4 Aa | 3.6 @Gheshires 5.00 s8ccone 32.6 32.5 26.0 aac Gavia. : Pa esoe ee kc eee Ba. Bo) Tae 37.4 2.4 Ped gna yk ese see pia pareve | bo YG aded 30.3 4.9 ROGUGIOTE 5 cjca.p ais. Bills. 31.2 27.6 33.2 6.0 Pie hg: SC ee | 50.4 Te aoe Rene 5.4 Rime ois. hay ace 39.6 28.5 | 29.8 5.9 Under the United States pure food act, the following defini- tions of cheese were established. (1) Whole milk or full cream cheese is cheese made from milk from which no portion of the fat has been removed. (2) Skim milk cheese is cheese made from milk from which any portion of the fat has been removed. (3) Cream cheese is cheese made from milk and cream or milk containing not less than 6 per cent of fat. Milk and Its Products. 291 Standard. Whole milk or full cream cheese contains, in the water-free substance, not less than 50 per cent of butter fat. The term ‘‘full cream’’ simply means that in the manufacture, whole milk has been used. It gives the impression that cream has been added, but such is not the case. In some eases, cheese is adulterated by the addition of foreign fat, as lard. Such cheese is usually known’ as ‘‘filled’’ cheese. Whey. As already stated, whey contains almost all of the milk sugar and albumin originally present in the milk, as well as a portion of the ash. The amount of fat in the whey will de- pend upon the treatment the curd has received. If the milk has been rich, the temperature of cooking high, and the curd roughly handled, considerable quantities of fat will be present. Where whey is rich in fat, it is customary to recover it for the manu- facture of whey butter, either by allowing it to rise by gravity or through the use of the separator. The average composition of whey is about as follows: Water, 93.3 per cent; protein, 0.9: fat, 0.3; sugar, 4.9; ash, 0.6. The cheese yield of milk. As has been seen, the two milk con- stituents that must determine the yield of cheese are casein and fat. The percentage of these varies in milks from different in- dividual cows. They are not always in the same relation in two different milks. Milks of high fat content are not proportionately richer in casein than milks of low fat content. As a rule, for 100 pounds of fat in Jersey and Guernsey milk, one may expect 55 to 65 pounds of casein, while in the milk from the Ayrshire and Holstein breeds, there will be 65 to 75 pounds. There will be individual exceptions to this general statement. In herd milks, although the relation of casein to fat is more constant, nevertheless variations in the proportion of these two constituents exist. The general rule that high fat milks do not yield in proportion to their fat, as much cheese as low fat milks, finds its explanation in the fact that high fat milks have pro- portionately less casein. This is illustrated in the following 292 Agricultural Chemistry. table, which represents some work done by Babcock at a number of Wisconsin cheese factories. Relation of Composition of Milk to Cheese Yield. Average Hverage Lbs. of No. of No. of Range yield of groups reports , of fat Lee aot cheese per weet hag sng o 100 Ibs. milk| “OF * °- "8% 1 24 | Under 3.25 3.12 | 9.19 2.94 2 90 3.25-3.50 3.38 9.28 2.73 3 134 3.50-3.75 3.60 9.40 2.61 4 43 3.75-4.00 3.83 9.80 2.56 5 46 4 00-4. 25 4.09 10.30 2.51 6 20 Over 4.25 4.44 | 10.70 2.40 It will be seen that the yield of cheese in proportion to the fat is less in the rich milks than in the poorer milks. A milk testing 6 per cent of fat will not make twice as much cheese as one testing 3 per cent. Making out dividends at cheese factories. While the inequal- ity of the cheese-yielding capacity of milks, and of the distribu- tion of dividends, based on their fat content alone, has been recognized, it has been quite generally asserted that such in- equality disappeared because of the improved quality of the product made from the milks of higher fat content. This is true when we consider cheese made from skimmed or partly skimmed milk and from milk very rich in fat or re-inforeced with cream. But within the range of normal factory milk testing in fat from 3 to 41% per cent, the quality of the product, as judged by buyers for the market, does not show uniform improvement with increase of fat in the milk. This has been shown by the work of the Canadian Experiment Station at Guelph and by the Wisconsin Station. No grading in the price of cheese, made from normal whole milk, based on its fat content, is at present practiced. Other factors, as the sanitary condition of the milk from which the cheese is made and the subsequent ripening processes, play an important part in determining the quality of the product. Milk and Its Products. 293 Normal factory milks may vary in their cheese-yielding capac- ity, and the quality of the product from such milks is not deter- mined by those variations that may occur in the fat and casein content. It is clear that the most complete and equitable method for the distribution of dividends at a cheese factory, is to allow for the amounts of both fat and casein delivered by the patron. In its simplest form this consists in allowing equal values for both the fat and the casein, the amounts of which can be de- termined by methods applicable to factory conditions. Such tests are the Babcock fat test and the mechanical casein test devised by one of the authors. A patron delivering 100 pounds of milk, containing 3.5 per cent of fat, and 2.4 per cent of casein, should be paid on the basis of 5.9 pounds of cheese solids deliv- ered. The price per pound of cheese solids would be determined by the price received for the cheese in the market. CHAPTER XIII INSECTICIDES AND RELATED SUBSTANCES. A number of miscellaneous substances used in the agricultural industries depend primarily upon their chemical composition for effectiveness. Prominent among these substances are various preparations for the control or suppression of parasitic pests upon plants and animals and the restriction of contagious dis- eases. Brief consideration will be given here to the composition and action of the more important of these substances. For their practical applications, reference should be made to special books and bulletins on these subjects. The following classification of these substances will be followed for the sake of order and convenience :— I. Insecticides. IJ. Fungicides. III. Disinfectants, deodorants and antiseptiecs. IV. Ineidental materials. Insecticides are substances used for destruction of insects feed- ing upon the fruit, foliage or bark of vegetation and for the re- moval of ticks and similar pests from animals. These materials have won general recognition as essential factors in the produc- tion of high grade fruit. They may be classed as stomachic, contact, or gaseous poisons, according to their mode of action. Such insects as the codling moth of the apple and the ‘‘potato bug,’’ which are surface feed- ers, may be reached by poisons of the first class; the aphides or plant lice and other sucking insects must be attacked by poisons of the second class; and the resistant scale insects and other pests are most efficiently destroyed by fumigation with a poison- ous gas. Stomachic poisons for insects are generally dependent upon arsenic for their poisonous effects. Arsenic does not enter these. Insecticides and Related Substances. 295 substances as the free element, but as a constituent of ‘‘ white arsenic,’’ technically called ‘‘arsenious oxide’’ or ‘‘arsenious acid.’’ Soluble compounds of arsenic were at first tested as in- secticides, but they were found to cause serious injury to foliage. Later experiments have demonstrated that arsenical compounds insoluble in water produced the desired effect, probably by virtue of the solvent action of the juices of the digestive tract of the insect. The resulting effort to furnish the arsenic of insecticides in insoluble form has been stimulated also by the passage of state laws restricting the amount of arsenic permissible in soluble form. Paris green has been a leading insecticide in America for fifty years. It was first used, apparently, in an attempt to controi the Colorado beetle or ‘‘potato bug’’ which had made its ap- pearance in the western United States. This stomachic poison contains arsenious acid, acetic acid and copper in a definite chem- ical structure known as ‘‘Schweinfurt’s green,’’ and technically known as ‘‘copper aceto-arsenite.’’ It is prepared by adding a hot solution of arsenious oxide to a hot solution of copper acetate. Paris green separates from the mixture and settles out as a rather fine powder of a clear, green color. The pure compound is prac- tically insoluble in water, but readily soluble in ammonium hyd- roxide, or ammonia water, and has the following composition: Per cent Wepper Oxide ct 6 ind 2 iia eS arn aay ete 31.29 APRCTATO USHA CIO. > or elae eau heats Sieve lust ec coe haa dew ebtons 58.65 AANCCEELICR EXT lise dal eater oo I nen CSTE EN Ne er 10.06 Scorching of foliage by applications of Paris green suspended in water was frequently observed during its early use. Gillettte showed, in 1890, that the use of lime water or Bordeaux mixture with Paris green prevented this injury. A year later, Kilgore found that the scorching effects were due to soluble forms of arsenic and concluded that the preventive substances acted by virtue of their lime, which fixed the soluble arsenic in insoluble compounds. Experiments at the New York Experiment Station with Paris green and sodium arsenite applied to potatoes led to 296 Agricultural Chemistry. the conclusions: ‘‘That Paris green is not injurious to potato foliage if applied in moderate quantity with lime water or Bor- deaux mixture evenly distributed ;’’ and ‘‘That sodium arsenite should not be applied to potatoes except with Bordeaux mix- ture.’’ Adulteration and the manufacture of impure Paris green were more or less prevalent previous to the passage of insecticide laws. Gypsum or sulphate of lime was one of the most common adulter- ants. This has little if any insecticidal value and was added to increase the bulk. Other impurities may result from the use of crude materials or careless methods in preparation. Wood- worth has given some simple tests to detect common forms of adulteration. The ammonia test is performed by taking an amount of Paris green that can be held on a five cent piece, transferring it to a drinking glass and adding about six tablespoonfuls of household ammonia or ‘‘spirits of hartshorn.’’ Keep the contents of the glass well stirred for five minutes. If the ‘‘green’’ is pure, it will then form a clear, dark-blue solution and leave no solid residue. If gypsum is present, it will form a white suspension in the liquid and finally settle to the bottom of the glass. This is not a conclusive test since impurities soluble in ammonia may be present. The glass test often enables one to distinguish adulterated samples not detectable by ammonia. Take such an amount of Paris green as can be picked up readily on the point of a pen knife and place it on a small rectangular piece of clear glass. Holding the glass in an inclined position, gently tap the lower edge and the Paris green will move down the inclined plane leav- ing a track of dust behind. In the case of a pure ‘‘green,’’ the dust will be of a bright green color. If the sample is impure, it may leave a white, pale-green or other-colored streak, depend- ing upon the color of the adulterating substance. This test is best used for comparing unknown samples with a sample known to be pure. Like the ammonia test, it is not infallible. Varia- Insecticides and Related Substances. 297 tions in the color of samples in bulk, especially an abnormally pale shade, and a tendency to dampness or lumping, indicate almost certain adulteration. Microscopic examination offers the most certain and satisfac- tory of simple methods for testing the purity of Paris green. The sample is prepared for this test as in the ‘‘glass test’’ just described and the dust is then examined under a medium power objective. The Paris green will be seen in the form of clean On the right—pure Paris-green; on the left—adulterated Paris-green. round balls; and in perfectly pure samples these are all that can be seen. Impure samples will exhibit also a considerable quan- tity of material of erystalline or irregular shapes, and usually white in color. Excess of free arsenious oxide is not so readily distinguished by this test. "When mixed with the prepared Paris green it is as easily recognized by the microscope as is any other form of adulterant, but when added in the process of making. it adheres firmly to the particles of true green and causes them to stick together in clusters. Chemical analysis is the only absolute means of determining the purity of this insecticide. One of the most important of the chemical determinations, is that for estimating the soluble ar- senic in Paris green and other insecticides. Two procedures are 298 Agricultural Chemistry. in use. In one case the sample is extracted with a hot 33 per cent solution of sodium acetate, while in the other case it is extracted for several days with cold water and the amount of arsenic in solution estimated. The former method apparently shows more nearly the amount of soluble arsenic that may be present, while the latter treatment more nearly simulates conditions to which the insecticide is exposed in the field. Control laws have been passed by some states to regulate the composition and sale of insecticides as has been done in the case of commercial fertilizers and feeding stuffs. In some cases, spe- cial stipulation is made with regard to the amount of free ar- senious oxide permissible in Paris green. Idaho allows a max- imum amount of six per cent for this constituent and California allows but four per cent. Green arsenoid is the trade name for a compound resembling aris green in composition and effects. It contains no acetic acid but is formed from copper oxide and arsenious oxide, and is technically known as copper arsenite. The pure compound contains about 53 per cent of arsenious oxide. Sodium sulphate or Glauber’s salt is a by-product in the process of preparation and may occur together with sand and other impurities in such an insecticide; they should, however, be present in only smal! amounts. The following data from an analysis of green arsenoid illustrates the relative effect of sodium acetate solution and cold water upon the arsenic of insecticides : Free arsenious acid Per cent (extracted with sodium dacetate)...... 2... 6. . eee ee auee (extracted: with cold: water). 4. i cac dere oe ee ee This insecticide has given excellent results when mixed with lime to ‘‘bind’’ the soluble arsenious oxide. London purple was imported from England by Bessey in 1878 as a substitute for Paris green in destroying the potato beetle. It is prepared by boiling a purple residue from the dye industry. containing free arsenious acid, with slaked lime. Calcium ar- senite is formed at first. but by subsequent boiling and exposure Insecticides and Related Substances. 299 to the air, this may be partly oxidized to calcium arsenate. This _ insecticide carries some impurities brought over from the dye- making process, and as a result of insufficient addition of lime or incomplete boiling some of the arsenious acid may be present in free condition. Haywood examined four samples with the following results: Per cent AVL GISUUT Ox sted eae Ey elo ehate Vay itp Paraecys oa eereece 12 ounces Whee 65 eit ite a asian Ses cee Fa eee ete 100 gallons The soap is said to increase the retention of the dip on the fleece and aloes renders it distasteful to the animal and prevents poisoning. Sodium arsenate has been used against locusts by adding it to sugared water and spraying the grass in the infested region. Lead arsenate was recommended as an insecticide in 1892 and was first used against tent caterpillars. It is prepared by adding © lead acetate to sodium arsenate in water. These substances dis- solve readily in the cold and react to form sodium acetate and lead arsenate. the latter remaining suspended as a fine white powder. This insecticide should be handled im the form of a paste, for once dried it is suspended with difficulty. Recent ex- periments show that lead nitrate is to be preferred to the acetate in making the arsenate because the product remains in suspension better and contains more lead-hydrogen-arsenate. carrying a higher percentage of arsenic than is the case with preparations from the acetate. This is apparently the most insoluble of all the arsenical insecticides and least likely to scorch the foliage. Headden has shown, however, that care should be taken to use pure water in the preparation of even this spraying mixture. Solutions of 0.1 per cent sodium sulphate or 0.05 per cent com- mon salt dissolve considerable amounts of arsenic from lead ar- senate. Practical spraying tests with lead arsenate in distilled water showed that sodium carbonate or sodium chloride at the rate of 10 grains per gallon in the spray finid produced severe injury and 40 grains of the latter salt per gallon injured about 50 per cent of the foliage. Salt waters and alkali surface waters must therefore be avoided. Insecticides and Related Substances. 301 Haywood gives the following directions for preparing lead arsenate; for each pound of lead arsenate to be made, use— Ounces Formula A. Sodium arsenate (65 per cent)............... 8 Lead acetate (sugar of Jead).:............... 22 Formula B. Sodium arsenate (65 per cent)................. 8 Tpea climate terns se ch tesstheaste ciate els tad dnecateiets 18 Dissolve each salt separately in 1 to 2 gallons of water, using wooden vessels. When dissolved, pour the lead solution into the sodium arsenate, stirring thoroughly until the mixture just turns a potassium-iodide test paper to a bright yellow. The lead salt is then in slight excess. A large excess should be avoided. AI- low the lead arsenate to settle, and pour off the liquid. These ‘chemicals are extremely poisonous and should be plainly labeled and handled with care. Pink arsenoid is a commercial preparation made by -adding lead acetate to sodium arsenite and coloring the insoluble product with a dye. It is composed chiefly of lead arsenite, only a small proportion of the arsenic being soluble, and has given satisfae- tory results. White arsenoid was the product of an attempt to put barium arsenite upon the market as an insecticide. Contrary to expec- tation, all the arsenious oxide of this preparation was found to be soluble in cold water. It gave poor results and was short- lived. White arsenic, or the simple arsenious oxide, has been used as a constituent of ‘‘dips’’ and various insect and animal poisons. It is volatile at a comparatively low heat and mixed with sulphur, it has been successfully used against ants by forcing the vapors into the nest. Arsenical poisoning may occur in the case of trees heavily sprayed with arsenical insecticides. Headden found arsenic in diseased fruit trees and this condition was correlated with an accumulation of arsenic in the soil in compounds from which it was rendered gradually soluble by the salts of the soil solution. 302 Agricultural Chemistry. Paige found, in connection with reported poisonings associated with combating the gypsy moth, that the amount of lead arsenate consumed by herbivora with the grass from beneath sprayed trees might Jead to serious results. These findings emphasize the need of care in the use of poisonous spraying mixtures. Hellebore, from the root of the pokeroot plant, and Pyrethrum or insect powder, from the flower heads of certain plants, have poisonous insecticidal properties attributed to alkaloids. Both deteriorate with age. Purity and efficiency of insecticides can only be insured by purchasing them under guarantee or under recommendations from reliable authorities, such as the state experiment stations, or by the purchase of simple constituents to be combined by the purchaser. Contact poisens may act by their caustic properties and by absorption from the surface of the insect, or by closing the tra- cheae or breathing tubes. These will now receive our consid- eration. Lime-sulphur wash is typical of the former class of insecti- cides. It was used in California as a sheep dip, where it was first applied also to the San José scale in 1886. The wash was prepared by boiling sulphur and slaked lime in equal parts. which produced first a simple sulphide of lime (CaS) of a white color. Prolonged boiling causes the color of the wash to pass through shades of yellow to a deep orange color with the forma- tion of poly-sulphides of lime carrying increasing proportions of sulphur. The chemistry of lime-sulphur wash has been inves- tigated at the New York Experiment Station. The chief com- ‘pounds were found to be calcium penta-sulphide (CaS,), caleium tetra-sulphide (CaS,) and calcium thiosulphate (CaS,O,). Boil- ing converts the last-named compound into calcium sulphite and free sulphur, and the calcium sulphite then oxidizes by exposure to the air into ealeium sulphate. The specific gravity of the wash and the amount of caleium and sulphur in solution increased with the amount of lime used. Insecticides and Related Substances. 303 The higher amounts of lime produced more calcium tetra-sul- phide, while with the smaller amounts, the mixture was more nearly penta-sulphide. The largest amount of soluble sulphides was formed by boiling about one hour, especially when the largest amount of lime was used. The amount of sediment in- creased with increased boiling, due to the formation of calcium sulphite. It was found that the addition of extra lime to the diluted lime-sulphur solution might seriously decrease its in- secticidal value as a result of the decomposition of the higher sulphides of calcium with formation of free sulphur. Where pure lime was used, the sediment, found to consist of calcium sul- phite, free sulphur and hydroxide and carbonate of lime, formed suitable material to add in the making of a new wash. It was also found that magnesium oxide when present in the lime, as in dolomitic limestone, tended to decompose the sulphides of eal- cium with evolution of hydrogen sulphide. The importance of pure lime for this insecticide is thus emphasized. An examina- tion of commercial lime-sulphur preparations revealed great. variations in composition. Since field experiments have demon- strated that this insecticide derives its chief value from the soluble ime-sulphur compounds, commercial preparations should be bought on the basis of the strength and composition of their supernatant liquid. Stewart states that the problem of making concentrated lime- sulphur solutions is essentially one of: preventing crystallization and securing a storable product of high density. He finds that the formation of crystals is largely due to an excess of lime and exposure to the air when cold. Exposure to the air may be avoided by covering the surface of the wash with oil. Arsenite of lime, as a supplementary insecticide. has been found to pro- duce least decomposition of the sulphur compounds of this wash. Haywood found that a one hour period of boiling dissolved practically all the sulphur used for this wash. The addition of common salt was found to have no effect so far as the sulphur compounds of the wash were coneerned. 304 3 Agricultural Chemistry. On theoretical grounds, Haywood recommends the following formula for preparing, at minimum cost, a wash with the max- imum amount of sulphur in solution and a moderate excess of lime: PMG! Fi, $4 Pie ee reg ae cet Pak oe pre ie 20-2216 pounds Sulphur: .0.s ios eivace Pane eee ae ae 20 pounds Water. 42 556 Sock eae cigs See eas 50 gallons The mixture is best when boiled by passing steam through it. Moderate slaking of the lime was found to have no influence, but a comparison of flowers of sulphur and erystallized sulphur showed that the crystalline form, even when finely ground, re- quired much longer boiling for maximum solution and gave a product of variable composition, apparently dependent on the size of the particles. To determine what changes take place after the wash is ap- plied to trees, measured quantities of the clear liquid were ab- sorbed on filter papers and dried in the open air exposed to sun- light. Analyses at successive stages showed the gradual oxida- tion of calcium penta-sulphide into calcium thiosulphate, calcium sulphite and finally calcium sulphate, with deposition of free sulphur. Wetting the paper daily to simulate the daily wetting of branches by dew greatly increased the rapidity of the process. Indications were, that after four to six months only free sulphur and ecaleium sulphate would be left. Haywood believes that the excess of caustic lime loosens the scale insects from the tree, and that the active agents in killing are sulphur in finely divided form, thiosulphate, for a time, and sulphite, which is gradually formed by the slow oxidations. Self boiled washes, in which the heat for solution is produced by the cheinical reaction incident to slaking the lime, are un- satisfactory, even when a maximum amount of heat is so gen- erated. Lime, sulphur, salt, soda-wash, in which caustic soda is used in addition to lime, has nearly the same composition and action as the simpler wash already described. It is less effective, how- Insecticides and Related Substances. 305 . ever, because it decomposes more slowly and the sodium sulphite formed is more subject to loss by washing than is calcium sulphite. Kerosene has been used as a contact insecticide against scale insects. It is applied as a spray to the dormant trees, but is frequently injurious. Applied to stagnant pools, it effectually suffocates the emerging pupae of mosquitoes; and in the ‘‘hop- per-dozer’’ it destroys grasshoppers which are trapped in it, by forming an oil film over the trachee. Kerowater sprays were the result of attempts to dilute kero- sene before applying it to trees. Kerosene is not miscible with water but by forcibly mixing these liquids at the nozzle of the spray pump the kerosene was temporarily diluted. Kerosene emulsions are comparatively permanent suspensions made by mixing kerosene oil with soap solutions. They are not true solutions, for the oil can be observed under a microscope as droplets suspended in the soap solution. Well made emulsions persist for several hours, and even for days, and facilitate an even distribution of the kerosene. Crude petroleum oils, which are closely related to kerosene but less volatile than the latter, have taken its place to a great extent because of the greater efficiency and safety attendant upon their use. Miscible oils are preparations of this nature. They are based on a standard soap solution with which various proportions oi different oils are emulsified. Crude oil, a mixture of petroleum oils heavier than kerosene; paraffin oil, a lubricating oil from petroleum; and resin oil, from the distillation of resin, are used. The crude oils are efficient in 6 2/3 per cent strengths, whereas kerosene is inefficient below 20 per cent strength. Penny gives the following formula for a standard miscible oil: The “Soap Solution.” Menhaden ail (5, osc. coarse sect to riots eer se es aan acc we 10 gallons GENS] GT (Ur 0 Eire a Sel ne ey RP Pom Bins Wausticpotarh...a7 set eciadoae sre beret es Sse Se Toke Heat to 290° or 300° F., then edd kerosene........ inn co NIGH lacs Bath oS Bas ees nh We eslarn Mie ga ane Maes a Deis 306 Agricultural Chemistry. From the above soap solution, the miscible oil is prepared ac- cording to the following formula: Soap: AGMblOn ssa.i 1+ osk ee cis ee aeeles eels er 32g gallons Para Site Onl sees e tars ska atale cesnete to oiede s teats Crea mae 40 nS FROST I Olle k or ls ae role ved a site otNeatanbalaen rane 6 ae Water, as required by test. In the process of making the soap solution the kerosene should be added while the soap is hot. The heavier oils should be stirred into the soap solution at moderate temperatures. Freezing tem- peratures should be avcided. The amount of water to be added is a matter of experiment but it should be used in quantity suffi- cient to produce an emulsion of creamy consistency. One gallon of the soap solution or emulsifier will make 8 to 14 gallons of miscible oil and these 8 to 14 gallons will make from 100 to 210 gallons of spray material, according to dilution. Resin soaps, efficient against orange scale insects, are prepared by boiling resin with carbonate of soda and diluting the solid product with water. Fish oil soap and whale oil soap, prepared by boiling the oils in potash lye and diluting with water, are effective against plant and animal lice, but the commercial preparations are subject to great variations in composition. Tobacco decoction depends for its value upon the poisonous properties of nicotine. This alkaloid is soluble in water, and hot water extractions of the stalk and waste of tobacco are used as an insecticide. Gaseous insecticides are used against insects particularly dif- ficult to attack. Tydrocyanie acid gas is by far the most effec- tive substance in this class. It is produced from :— Potassium ,cyani@e; Pure-sa. ..s06 Sie beeah.a eee 1 ounce Sulphuric acid, commercial................+..-++. Bere Worthen siaoe ecie che hcp aon Sateen a giiete arctan cey arena Ae This is the quantity recommended for each 100 eubie feet of space. The eyanide should be added last, having the mixture in Insecticides and Related Substances. 307 an earthen-ware vessel. Potassium sulphate is formed and the poisonous hydrocyanic acid is rapidly liberated as an invisible gas. This is an extremely powerful poison, a single breath being fatal, and by no means should it be inhaled by the operator. To retain the gas and secure efficient action, it should be applied in tightly closed rooms or buildings, or in tents specifically pro- vided for the purpose, allowing it to act for an hour or more. The enclosure should then be opened from the outside and thor- oughly aired before being entered, and the strongly acid residue from the reaction should be carefully disposed of. Carbon bisulphide is a colorless, volatile liquid formed by pass- ing sulphur vapors over red hot charcoal. The gas evolved from the liquid is heavier than air, inflammable and fatal to insects breathing it. Its chief use is for the destruction of weevils in grain. One teaspoonful for each cubic foot of space should be placed in a shallow dish at the surface of the grain, and one hour allowed for the evaporation of each teaspoonful used. The heavy vapors sink through the grain to the bottom of the bin, where they may be released by boring holes through the wall. Ants, moles, prairie dogs and similar pests are exterminated by placing cotton saturated with carbon bisulphide in the heaps or runs and covering tightly. Carbon bisulphide should never be brought near flames. Fungicides are materials utilized for the destruction of para- sitic plants. Hyposulphite of soda, lime-sulphur and sulphur alone were used in this capacity as early as 1885 against apple scab and leaf blight. Bordeaux mixture has been the premier fungicide since 1883, when Millardet used it against the downy mildew of the grape. It was accidentally discovered by observing the flourishing con- dition of vines to which lime and copper salts had been applied to prevent the theft of grapes in the province of Bordeaux, France. Several formule have been superseded generally by 308 Agricultural Chemistry. the so-called ‘‘normal’’ formula, or 1.6 per cent Bordeaux, which consists of : Copper: sulphate... .4)-0.tG; 2ipdis Fie emo eee 6 lbs. Qaiek dime. dS a. whe dt ee ae eee eee ee 4 lbs. WY Ger hice tpl che als he aticer ope haben raped et spent 50 gallons The lime should be slightly in excess. This may be accom- plished by weighing the pure salts for the mixture, or by testing the product. SPRAYED. Note the beneficial results from the control of potato diseases by Bor- deaux mixture. The litmus test depends upon the fact that so long as copper sulphate is in excess blue litmus will be turned red when moist- ened with the Bordeaux mixture. Enough lime should be pres- ent so that red litmus is turned blue. The ferro-cyanide test may be used also for this purpose. A teaspoonful of the clear liquid, obtained by straining if necessary, should be added to a few drops of potassium-ferrocyanide solu- Insecticides and Related Substances. 309 tion in a white porcelain dish. A reddish brown precipitate or color indicates the presence of soluble copper salts, and lme should be added to the mixture until this no longer appears. The fungicidal properties of Bordeaux mixture are chiefly due to the insoluble compounds formed and it is important to keep these thoroughly in suspension. To facilitate this, the copper sulphate and lime should be dissolved separately, each in one-half the water, and when the lime is cool, they should be poured to- gether with constant stirring. In this way, the dilute solutions react to form a fine suspension which will not settle for several hours. The chemistry of Bordeaux mixture has not been thor- oughly investigated. According to Lodeman, when the copper sulphate is just neutralized, most of the copper is probably pre- cipitated as a hydrate; but excess of lime added to a concentrated ‘‘mixture’’ forms another compound which may be a basic sul- phate of copper and lime. Soda Bordeaux, made with caustic soda in place of lime in the regular formula, has given satisfactory results. Copper ammonium sulphate, a clear blue solution formed from copper sulphate and ammonia, also called ‘‘eau celeste,’’ has been applied as a fungicide, but its caustic action renders it unsafe. Copper carbonate dissolved in ammonia, however, has given good results. It should be freshly prepared, as the am- monia may volatilize on standing, causing the copper to fall out of solution. Copper sulphate has been applied to dormant trees and green- house plants as a dilute solution, but it possesses a strongly acid reaction and should be used with care. Smut on grains is de- stroyed by this fungicide. A one to two hour immersion of oats in a 0.5 to 1.0 per cent solution may be safely practiced, but stronger applications retard germination. Potassium sulphide is used against mildews at the rate of one-half ounce to one gallon of water. Strong solutions are destructive to plants. Potash lye and formaldehy4de-glycerine 310 Agricultural Chemistry. mixture, properly diluted, have proved valuable fungicides under certain conditions. Formalin or formaldehyde, is a most efficient agent for destroy- ing smut spores on grain. The seed should be immersed for ten minutes in a solution of 1 pint of ‘‘40 per cent’’ formalin to 20 gallons of water. Stronger solutions have been found in- jurious to the germinating power of barley. The seed should be spread and finally mixed so as to dry with not more than two to three hours contact with the formalin. Disinfectants are substances which aceomplish the total de- struction of the germs of infectious diseases. They may also act as deodorants or destroyers of foul odors. Antiseptics prevent decomposition or putrefaction by arrest- ing the development of germs, but do not necessarily destroy them. Disinfectants in weak solutions may act as antiseptics. Refrigeration, common salt and sugar, all of which are largely used in preserving fruits, meats, ete., are good examples of anti- septics. Formaldehyde is perhaps the most commonly used chemical disinfectant. It is a product of the oxidation of wood alcohol and is put upon the market in a 38 to 40 per cent solution in water. — —_— COD DOROR HR DBD HWOTDKRNHD ASURRONNANR]” | i wn of St CRODR SO SH NOOCARD RANARHDROMNANO Oo bo bo 0 bo = bo D> Potash |Dry matter Ibs. lbs. 8.0 1, 764 13.6 1,818 9.8 0.6 1,844 10.0 1, 732 12.6 1,748 10.8 1,714 9.6 1,714 32.6 1,760 8 1,810 10.6 1,734 17.4 1,823 19.8 1,720 28.0 1,816 18.0 1,726 44.0 1,684 24.4 ae 26.2 1,672 33.6 1,850 7.4 441 24.8 1,710 41.8 1,716 9.2 500 8.8 245 926 360 9.8 218 7.8 184 8.6 220 7.2 290 Appendix. 317 COMPOSITION OF FERTILIZERS. Composition of fertilizer materials supplying nitrogen. Per cent Percent Per cent . Nitrogen deed Ae Potash ——— — —— — na —_ prt — INIGRADEM OM SOG As oe. sepals ol papal tie sielasesls oleae N55 = GE la eee elec en ras Salpuate ul ammoniaen. 0. cross guts. == 2s 1G BOSS se oles bus eet Dried blood-(hiph grage) 5... 022 se sashes - UT Aas Es eS ARAN faa ke wee Concentrated! tankage, .)o. 2: .ccc ce ccna e ts as ite 12.5) 9 eG ee ear. Mommies ee (OME is sy ak'n es cis sidstes © Se aie sce 5 -6 SL Se A | eee Niframenoun. SOA, . or... a0 3. 0hs Se valine 3 .-7 9-19 2-4 Composition of fertilizing materials supplying phosphoric acid. Per cent . | Per cent eee Nitrogen S. Carolina rock (ground) (floats)..........:..... iea| 20.3 Petal x BeCaroinasrock. (dissolved ).1).-. Aen. eine ol ees ae cee rai ed Ao Al ero oe PONG Rit RIOR AO LOC ae eon cota eis pia ne DA b weeats & Vis) eae lA licsayieg ook ARav ThE CCE. (5) TUONO te Pe RO tpt et ea ae Sa Nora epee sae (CHRON! loves es Goce ube ue DOG he Ntlorta st Beaaicees cnn 20 — 25 |2.5 - 4.5 Sen onverel |OOINaL bis edsioe Bag eG omte ato acco CRE ts RpEaDI CAEN 22 — 29 {1.5 — 2.5. IBOMer Dl aclu cere eer wre cunso ears Moat ssi vlciahs wyaiahe.5 G2 = 15Gb Moss ae Composition of fertilizer materials supplying potash. Per cent) Per cent Preetoric Potash | Nitrogen anid Muriate of potash (80-85 per cent pure)....| 50 — 53).........].....-.---- Sulphate of potash (high grade)........... BS OT ens eee lh icra alee c Sulphate of potash (low grade)............ DOV BO iene irate ane ee oe Weeettita tee re Seat ene, ari alae ost nis whale Wale tessa « NDR UB Re teeh sescveie | easing here GUA CONELE IIR crite spate wixrsnoini wen atop ep eta 3- 8 2-8 3-5 GRD El SSR en) stetn a cya pene aye 1s bpaeome nage 6) hie APA, Nat vane 1-2 318 Agricultural Chemistry. COMPOSITION OF FEEDING STUFFS. The following brief table gives the composition of some typical feeding materials (taken from ‘‘The Feeding of Animals,’’ Jordan, Appendix) : 2 ~ |o 3 | = ~ 2 = = ey gos oer '88|28| 28 | Gs |e28|] #8 S Oo no fa) © o aS oO oe FS |g 195/38 |o8s| s8 <- Beau & BIS °a) oo rae 5 Z es FopDDERS Corn fodder (green)........... e412) 8 bale 5 ne S|) c(Heldvenred)) 7.575% 42.2| 2.7.) 4.6 | 14.3") 34.7 eh a6 Corn'silage: 23. Sis. cts eee 79.1 1.4 7 | 6704 a0 8 “umothy (green) tc dess sso ds 61.69) (2.1) 322] UL 87) 20225) Fae ee BY Piratn-siauise enarese ete 13:2 4.4 5.9 | 29.0 | 45.0 2.5 Alfalfa (aweon Jerks. sacs 71,8.) 257 | 4.8.1 4) eee ‘i TRA eA upreiaic, ween we olen 8.4 0.4 | T4235) 25.50%) 42 eee Glover hay (fei) 3 ss. ea al 18.3°| 6.2 | 1273°| 24°8°) SB.dap ges Roots fet | oer ee eee, 90.5 8) 2.1 8 62 2 ERICA DAP ARS 25) rade ea tca i vartaae 68.61 1.9) 1212 e ste .2 GRAINS Comys 22 Oa. 2. cee ee ae eae 109°) 1-5.) AOs5|) 2 A606 ieee Barley.) Acct e cae oc Stee 10.9. |: 2:4 | 12:4 1° 3.7 1 60.8 oe Onterrn see e ies ccc eet es Hoe Oe 3. 11.8 9.5 | 59.7 5. W eat ie gl Beb 0.5 Severe work..............- 28 st lg) fey eS} 0.8 Fattening bovines | Hirst: period... <...ci..:.. 30 2.5 |) 15.0 0.5 Second period............. 30 3.0 14.5 0.7 CHEE Period . 5. ..enceest 26 2.7 15.0 0.7 Milch cows Daily milk yield11]bs.| 26 1.6 10.0 0.3 Daily milk vield 22]bs.; 29 Ae gad be Pe 0.5 Sheep Coarse Wool..........s.000 20 1.2] 105 0.2 HINO. WOOL, cciececnccnse ace 23 1.5 | 12.0 0.3 Ewes, suckling Jambs..... 25 2.9 15.0 0.5 Fattening sheep First period................ 30 3.0 15.0 0.5 Second period............. |. 28 3.5 14.5 0.6 Horses TBI WOT Ke orc noes (o 20 15 9.5 0.4 Heawy works. ;5.: inmrrenacae nq ¢p ‘urTeIs 48Q > | 2°02 | 6°@ | 2°6 BO Gz cee ie EIGOr- \eLG Aide el wal nip, Rallis e oe cease “dora [BO], ea | OS) OR | OB 6 Ge 22 Vio | TE 1080S | rb gs (ee ee OG | OOO. eho) VEL Re 8 ee Or eee hy) SO8Olgs | [oss adiggs ules Katine Bl tale | 2 es | 9°S | 8°83 [2ST] OF | SLT iest'y | seer eeecanihiea staan, CEO tt AOR TGC OP O86 8 OS | OL 6 Ob err: ech ale Shee leas eo oe FM BTIS yy OP oar. e-e N01 ee | $6 |P'9 | F& | OF jOSGT | OOSTT NG Og UTeId gvoq A rd | | b- Jer Ss o csc Saleen eee oe toe oath eS lange lege See ihr ree. 08 a eee 6 jo) & Ea oe 5 a 5 -] | 4% IOS it fone 4 Ss 5. om | (eel e aie @ O° D : | 2 > | a ee ee 8. | @ | dog yo 345104 | © ler ‘SdOdO AOVAAAY AG GHAOWAY ANOV YAd GOOA INVId AO SANNOd Agricultural Chemistry. 324 a 6°&g seeecceee £°6 6°OL 1°&Z 9'T 8°8 seeee 6g 99[ C16'S eecceccccdececs eocesece palate 1-01 yea] = Aaa eee ween Co | rE 6°ZL 8 0 ZF ween OL 9% 2E3'S . 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LOT...) 2OT = (ORS | ONT e ere Se eek SL dowd [BJO], 69 |e leo | ae | eo] at leer le | 6c 66 |\sES't | oFg'g foe oy oe P Oe) Tubal Sas, |-o 8x6 oe. POO 7G ra. |F°O-| BL > BO. ISTO | OsGsb lees nq Og ‘UleIs suveg as) > S al = Per marie ti Se) oe See clay |, Be Pies = 5 = be) 0g B FS S$ |Se0| 8 po, 5 5 a 5 > 5 @ 7) os| © “< os =a fe fae A ee) oe g 5 2 a” 5 2 = 8. @ | dory yo yy 310, : = =z ‘(penurju0)) —'SqOUO AOVYAAV AD GHAOWAY AYOV UAd GOO LINVId AO SGNQAOd 325 Appendia. I~ 8°¢ a0 1d sereeeree! G G 6 verses] 9 sete eeee 008 “F 000°¢ 002‘ 008‘T 62‘ UPS‘ F88'% O9F ‘81 0&3 ‘LT 868 ‘F G8 ‘ZI ee iri) See ee eee ewes eee sores upid afouM ‘adeqqey tteteeerececeescceeeoseed rg [VIO], Tce OBIS a ee ee EP CCL gor Rood Je) OdIBQOT, Cie een. F141 0) 0 Col [BO], pooner Nii Jeo] i see eeseecescece rene seb Eneae CWA ‘suid yayoog Abomasum, 220. Acid, definition of, 16. Acids, organic in plants, 99. Adult animal, 253. Aerobic organisms, 128. Albumin, definiton of, 100. in plants, 101. in animals, 207. in milk, 271. Albuminoids, definition of, 207. in animals, 207. Alinit, 60. Alkali, “black,” 76. tolerance of plant to, 77. “white,” 76. Aluminum in plants, 108. Alkaloids, 103. Amides, in plants, 102. in animals, 208. Amines, in plants, 103. Amino-acids, in plants, 102. in animals, 208. Ammonia, in the air, 31. in water, 32. loss from manure, 127. Ammonium sulphate, 149. Amylopsin, 223. Anaerobic organisms, 128. Animal, constituents, 206. manure, 112. action on soil, 42. composition of bodies, 209. INDEX Antiseptics, 310. in milk, 279. Ants, in soil formation, 43. Apples, 195. Apatite, 38. Argon, 30. Armsby’s feeding standards, 242. Arsenic, as insecticide, 294. Artificial manures, 146. Ash, in animal products, 210. in feeds, 103, 218. importance to animals, 218. Assimilation of carbon dioxide, 86. Ass’s milk, 278. Atmosphere, 23. Available phosphoric acid in fer- tilizers, 155. energy, 237. Avenin, 258. Ayrshire milk, 270, 280. Bacteria, action in digestion, 224. action in milk, 278. assimilation of nitrogen, 30. Barium, in plants, 109. Barley, grain composition, 183. straw composition, 184. Base, definition of, 16. Basic slag, 157. Beans, grain composition, 187. field, 187. soy, 187. 328 Agricultural Chemistry. Beets, 194. Bile, 223. Bleaching powders, 311. Blood, 211. dried for manure, 150. Boiler scale, 71. Bone ash, 156. Bones, 156, 212. Boracic acid, 279. Bordeaux mixture, 307. Bran, wheat, 181. Bran, corn, 186. Brewer’s grains, 184. Buckwheat, 189. Butter, 283. Butter milk, 285. Cabbage, 196. Calcium, function in plants, 106. occurrence, 12. carbonate, 37. in soils, 38. cyanamide, 150. nitrate, 150. Caliche, 149. Calf, composition, 210. Calorie, definition, 8. Cane sugar, 90. Capillarity, 53. Carbohydrates, in plants, 89. in animals, 208. function in animals, 217. Carbolic acid, 311. Carbon, occurrence, 9. dioxide in air, 30. assimilation, 86. in decay, 47. respiratory, 226. in soil gases, 60. as a solvent, 43. Carbon disulphide, 307. Carcase, composition of, 209. in increase, 211. Cartilage, 214. Casein, 271. Castor bean, 189. oil, 189. Cellulose, 93. Cereals, 173. Chalk, 38. Cheese, 288. Chemical changes in soil, 55. Chemical manures, 147. Chili saltpeter, 149. Chlorine, bleaching action, 15. as a disinfectant, 311. function in plants, 108. occurrence, 14. Chlorophyll, 86. Churning, 283. Clay, occurrence and composition, 45. physical and chemical proper- ties, 48. Climate, influence on plants, 200. Clovers, 191. Collagen, 214. Colloids, 53. Colostrum, 249. Cooking food, 232. Combustion, spontaneous, 96. Condensed milk, 286. Connecting tissue, 214. Constituents of plants, 22. Copper sulphate, 309. . Corn, composition, 185. stover, 139. silage, 192. Cotton seed meal, 151, 188. oil, 188. Cow, digestion in, 220. ration for, 263. Cream, 280. Index. 329 Creosote, 312. Creatin, 227. Creatinin, 227. Cresol, 312. Crops, classification, 173. residues, 180. Crude fiber of feeds, 174. Dairy, 267. Denitrification, 59. Dent corn, 185. Dextrine, 93. Dextrose, 89. Diastase, 80. Diffusion in soils, 52. Digestibility of feeds, 231. Digestion, 218. coefficient of, 129. energy consumed in, 237. Dips, 312. Disinfectants, 310. Dissolved bones, 156. phosphate rock, 154. Dolomite, 37. Drainage, 63. Eggs, 210. Elastin, 214. Elements, 7. Elimination from animal, 227. Energy, lost in digestion, 238. utilized in labor, 255. Ensilage, 192. Enzymes, 79, 219. Ether extract of foods, 175, 236. Evaporation, from plants, 85. soil, 54. Ewe’s milk, 249. Excretion, in animals, 227. in plants, 83. Fallow, 54. Farmyard manure, 112. composition, 113. decomposition of, 122. preservation of, 129. Fat, digestion of, 2238. heat producing value of, 216. in animal body, 218. in feeds, 95. of milk, 269. Fat globules in milk, 270. Fats, nature of, 96. Fatty acids, saturated, 96. unsaturated, 96. Fat production, from proteins, 265. from carbohydrates, 265. stareh equivalent, 240. Fattening animals, 258. rations, 259. Feathers, 206. Feeding standards, 229. Feldspar, 36. Fermentation, of manure, 127. in) silo; 193: Fertilizers, 146. laws, 171. selection of, 165. Flax, 188. Flowers, 87. Fluorine, 206. Fodder crops, 190. Food constituents, function of, 215. composition, 174. digestibility, 231. economy of, 264. influence on butter, 275. influence on milk, 275. manurial value, 115. production value, 2389. Formaldehyde, 310. Frost, action of, 41. Fruits, 195. 330 Agricultural Chemistry. uel value, animal products, 8. food constituents, 237. Fumigation, 306. tobacco, 306. Fungi, 307. Fungicides, 307. Galactase, 289. Galactans, 93. Galactose, 90. yases, in soil, 60. Gastric juice, 220. Germination, of seeds, 79. Glaciers, action of, 39. Globulins, 100. Glucose, 89. Glutamin, 102. Glycerine, 95. Glycogen, 208. Goats, digestion in, 231. Grapes, 77. Grasses, composition, 190. digestibility, 231. Green manuring, 143. yravel, 53. Grits, 38. Guano, bat, 157. fish; 157. Gypsum, 162. Haemoglobin, 212. Hair, 152. Hardness, of water, 71. Hay crop, 190. composition, 191. digestibility of, 197. Heat, of animal, 254. of combustion, 8. relation to plant, 87. relation to soil, 48. Hellebore, 302. Hemp seed, 189. Hoof meal, 152. Horn meal, 152. Horse, digestion in, 220. labor ration, 255. manure, 113. Humus, function in soil, 46. physical properties, 48. Hydrated silicates, 37. Hydrates of iron and aluminum, 37. Hydrocyanic acid, 306. Hydrogen, occurrence, 9. Igneous rocks, 35. Increase, while fattening, 211. Indian corn, 185. Insecticides, 294, Iron, function in plant, 107. in soils, 36. occurrence, 14. Irrigation waters, 76. Jersey milk, 270, 280. Kainit, 159. Keratin, 207. Labor ration, 255. Labradorite, 36. Lactic acid, in milk, 278. in silage, 193. Lactose, 271. Lead, action of water on, 72. arsenate, 300. Leaves, function of, 87. Leather, 152. Lecithin, 97. Leguminous crops, 191. Leucine, 102. Lentils, 260. Light, action on plants, 86. Lignin, 93. / Lime, as a manure, 161, in foods, 266. in soil, 38. Limestone, 46. Linseed, 188. Lipase, 80, 223. Litter, 118. Loco-weed, 109. London purple, 298. Lupines, 144. Lysol, 312. Magnesium, functions of, 106. occurrence, 14. silicates, 37. Maintenance ration, 253. Maltose, 90. Malt, 183. Maltsprouts, 183. Mangolds, 194. Manure, farmyard, 112. application, 134. composition, 113. decomposition, 127. yield by animals, 114. Manurial value of feeds, 115. Maple sap, 90. Marl, 45. Marrow of bones, 212. Margarine, 285. Meadow hay, 191. Metamorphic rocks, 35. Methane, production in digestion, 238. Mica, 36. Milk, albumin, 271. ash, 272. cows, 274. composition of, 273. fat of, 269. physical properties, 273. powders, 286. Index. preservation, 278. souring, 278. sugar, 271. of various animals, 268. Milking cows, rations for, 263. Mineral phosphates, 153. Minerals, 36. Miscellaneous materials, 313. Muscular tissue, 213. Muriate of potash, 159. Nitrate, of potash, 149. of soda, 149. Nitrates, conservation of, 128. loss by drainage, 66. produced in soil, 57. Nitric acid, in air, 31. in rain, 32. Nitrification, 57. Nitro-bacter, 29. Nitrogen, in air, 27. assimilation, 27. fixation, 27. occurrence, 10. stored up, by animals, 207. by plants, 205. voided by animals, 216. Nodules on legumes, 45. Nucleins, 100. Nucleic acid, 100. Nutrition, of animals, 214. of plants, 18. Nutritive ratio, 234. Oat, grain, 184. hay, 191. straw, 185. Oil meal, 189. Oils, influence on milk fat, 276 drying and non-drying, 96. essential, 98. nature of, 98. ) Bod 332 Oleic acid, 96. Olein, 96. Oleomargarine, 285. Omasum, 220. Organic acids in plants, 99. Oxidation, 16. slow, 96. Oxen, ration for fattening, 258. ash stored up, 116. comparison with cow, 264. Oxygen, in the air, 29. occurrence, 7. Ozone, 31. Palmitin, 96. Pancreatic juice, 223. Pace, influence on food require- ment, 256. Pasteurizing, 279. Paris green, 295. Pears, 195. Peas, 188. Peat, 118. Pectins, 94. Pentosans, 94. Pentoses, 94. Pepsin, 222. Peptones, 207. Perspiration, 227. Petroleum emulsion, 305. Phosphates, loss by drainage, 66. Phosphatic fertilizers, 153. Phosphorus, function in 107. occurrence, 12. in animals, 210. in foods, 218. Phytin, 110. Pigs, ration for fattening, 260. rations for growing, 248. manure of, 1138. plants, Agricultural Chemistry. Plants, assimilation, 86. constituents, 88. respiration, 87. Plums, 195. Pop corn, 186. Potash, loss in drainage, 66. fertilizers, 158. Potassium, function in plants, 106 occurrence, 13.- Potassium nitrate, 149. Potatoes, 195. Preservation of milk, 278. “Process” butter, 284. Proteins, classification, 100. kinds of, 101. Ptyalin, 219. Putrefaction, 17. Quartz, 36. Quick lime, 161. Raffinose, 91. Rain water, 69. Rape, 189. Rechnagel’s phenomenon, 273. Reduction, 16. Reverted phosphates, 154. Rennin, 221. Rennet, 288. Renovated butter, 284. Resin soap, as insecticide, 306. Respiration, in animals, 226. in plants, 87. Reticulum, 220. Rice, 186. Ripening, of cheese, 289. cream, 284. River water, 69. Rocks, classification of, 35. Root, crops, 193. pressure, 83. Index. Rotation of crops, 208. Ruminants, digestion by, 231. Rye, 182. Salicylic acid, 279. Saliva, 219. Salt, common, 163. Sand, properties of, 45. Schweinfurth’s green, 295. Sea water, 77. Season, influence on plant compo- sition, 198. Seeds, germination, 79. Sedimentary rocks, 35. Separated milk, 282. Sewage as manure, 75. Shales, 38. Sheep, nutritive ratio for, 262. digestion of foods, 231. manure, 113. production of wool, 261. Silage, corn, 192. clover, 192. Silicon, function in plants, 108. occurrence, 15. Silicates in soil, 37. Size of animal, influence on ration, 254. Skimmed milk, 282. Soap, action on hard water, 70. nature of, 97. Sodium, occurrence, 13. Softening of hard water, 71. Soils, composition of, 61. definition of, 35. fixation of nitrogen in, 44. formation, 40. gases in, 60. retention by, 55. Soil, sedentary and transported, 39. relation to heat, 48. relation to ‘water, 52. 3O9 tenacity of, 50. water in, 50. weight per acre, 61. Sorghum, 191. Specific heat, 48. Spontaneous combustion, 96. Starch, in plants, 91. influence on digestion, 233. part in nutrition, 217. productive value, 240. Steapsin, 223. Stems of plants, 83. Stearin, 96. Sterilization, 279. Stomata of plants, 85. Stomach, digestion in, 220. Straw as litter, 118. energy consumed in digestion of, 240. Sucrose, 90. Sugar beets, 194. Sugars, 90. Suint, 262. Sulphate of ammonia, 149. Sulphur, function in plants, 107. occurrence, 11. Sulphur and lime wash, 302. dioxide, 34. Sunflower, 190. Super-phosphates, Swede/crop, 194. Sweet corn, 202. 154. Temperature of soils, 50. Terpenes, 98. Therms, 237. Thomas slag, 157. Tillage, 63. Timber, composition of, 179. Tobacco, 196. Transpiration from leaves, 81. Trees, food requirements, 195. 334 Agricultural Chemistry. Trypsin, 223. Tubercles on legumes, 29. Turnips, 194. Urea, 227. Uric acid, 227. Urine, 227. Vetches, 171, 205. Warp soils, 76. Water, action of on lead, 72. action of on rocks, 41. hard, 70. mineral, 69. natural, 68. organic matter in, 73. physical properties of, 68. rain, 69. SoOLt, (i. spring, 69. typical good and bad, 74. Waxes, 98. Wheat, 181. Wheat bran, 181. Wheat straw, 182. Whey, 291. White ants, 43. Wind, action on rocks, 42. Wolff's feeding standards, 235. Wood ashes, 160. Wool, production, 261. Woolen waste, 152. Work, production of, 255. Worms, in soil formation, 42. Xanthin, 213. Yolk, of wool, 262. Young animals, nutrition of, 248. Zein, 101. Zine, in plants, 109. 7 ¥5h One copy del. to Cat. Div. ul BIS Gideids t LI OF CONGRESS UU OO0eb?1La?sa