THE LIBRARY OF THE UNIVERSITY OF CALIFORNIA LOS ANGELES SANITAKY AND APPLIED CHEMISTET A TEXT-BOOK OF SANITARY AND APPLIED CHEMISTRY OR THE CHEMISTRY OF WATER, AIR, AND FOOD BY E. H. S. BAILEY, PH.D. PROFESSOR OF CHEMISTRY, UNIVERSITY OF KANSAS SECOND EDITION "Neto fforfc THE MACMILLAN COMPANY LONDON : MACMILLAN X 1 *<< o j^ ^. H .So g <1 E-i Springfield Mass Aver 1893 .009 .204 1 50 .001 .026 5 132 37 6 Boston " " 1894 .006 319 410 .001 .106 6.295 464 035 .140 70 1 525 70 050 .125 450 2 287 85 Rock Island 111 (Miss. E ) .025 .260 1.00 trace 6 000 1400 New Orleans La (Miss E) .040 325 14.50 o .080 5 724 3400 .300 040 130 00 .368 2 043 1170 .001 .085 13.50 16.000 64.0 Cincinnati Ohio (Ohio E ) .003 .108 14.00 .260 140.0 Philadelphia (Schuylkill E., average of 22) .010 .100 .460 133.4 New York, weekly average for 1894 .012 .082 2.47 .258 81.6 Water Supplies," Mason, p. 465. 74 SANITARY AND APPLIED CHEMISTRY DRINKING WATER AND DISEASE It should be noticed in the first place that while peaty waters contain quite large quantities of organic matter, this is not considered as injurious as other kinds of organic material. The best authorities seem to agree, however, that its presence does tend to induce diarrhoea and malaria. According to recent investigations the preva- lence of malaria in certain localities is due largely to the low land and numerous puddles where the mosquitoes that transmit the infection have a chance to breed. 1 It should also be said that though a water of this class may be harm- less at some stages of its history, at other stages it may be injurious on account of the decomposition that has taken place. Another water containing a large quantity of organic matter is the so-called sawdust water, which is obtained from wells sunk in " made " land in the vicinity of streams where sawmills have been located. This is, without doubt, injurious. In regard to hard waters, the opinion seems to be pre- dominant that the mortality is practically uninfluenced by hard or soft water. In many localities, waters that are extremely turbid are used for domestic purposes, and it is evident that they are used without serious injury, when we consider the popula- tion and the death rate in such cities as Cincinnati, Louis- ville, and St. Louis. This should be said, however, that while these waters are used with impunity by those who are accustomed to their use, strangers are frequently affected seriously for a time by the use of such waters. A much more serious class of impurities is those which come from the introduction of sewage into the waters, and 1 " Practical Hygiene," Harrington, p. 649. WATER 75 although they may be perfectly clear, transparent, and of good taste, such waters are often extremely dangerous. The question arises, Shall the water once polluted by sewage be again used for human consumption ? And if there is danger in such use, What is its extent, and can such danger be avoided ? A few examples of pollution of water by sewage will be of interest. In 1887 l the city of Messina, Sicily, was visited by an epidemic of cholera. Prom September 10 to October 25 there were 5000 cases and 2200 deaths. The government investigated this epidemic, and it was found that though the water which was supplied to the city left the gathering grounds in the mountain of good quality, part of it was diverted on its way to the city, and used by the washer- women of the vicinity for washing clothes, and was after- ward conducted back into the open canal which supplied the city. As soon as the authorities sent tank ships to the mainland and obtained pure water for use in the city, the plague ceased as if by magic. In 1890 there were two violent epidemics of typhoid fever in the valley of the Tees in England. The country which supplied the water was not thickly populated, and the water was apparently good. It was found, however, that many of the towns discharged their sewage into the stream, and in dry weather the stream receded, leaving its banks dry and exposed. Here the filth accumulated, and in times of high water this was swept into the stream, and was after- ward pumped into the reservoirs and used as the source of water supply. It was noticed that an " increase of rainfall was followed by an increase in the number of cases of typhoid fever among those persons using the Tees water, after an interval corresponding to the incubation period of the disease, while no appreciable result was noticed 1 Mason on "Water Supply," p. 24. 76 SANITARY AND APPLIED CHEMISTRY among those people of the district using other sources of supply." 1 One of the most interesting cases is that of the city of Plymouth, Pennsylvania, containing 8000 population. In a few weeks there were more than 1000 cases of typhoid fever and 100 deaths. The water supply was obtained from a mountain brook. There were but few houses on the banks of this brook, and it would seem that the water was well protected from sources of contamination. On investi- gation, it was learned that while the stream was frozen a man had been sick with typhoid fever, and had been cared for in a house near the source of this mountain brook. The discharges were thrown upon the snow, and when this melted in the spring the filth was swept into the stream. The inhabitants of the village of Plymouth were obliged to use this water for a time as their source of supply, instead of the Susquehanna River, so the typhoid poison was pumped to all parts of the city. It was noticed that whole groups of families using well water escaped entirely, while those using the city water were afflicted with typhoid fever. It was estimated that aside from the deaths that occurred, the money losses to this community in wages and care of the sick was over $100,000. All are more or less familiar with the conditions at the time of the terrible outbreak of cholera in Hamburg, Ger- many, in 1892. The city had a population of 640,000. The epidemic lasted for about three months, and the total num- ber of cholera cases was 17,000, with 50% mortality. Ham- burg is close to the city of Altona ; in fact, these two together with Wandsbeck are practically one city, but they obtain their water from different sources. Hamburg pumps water from the Elbe River, the intake being just south of the city. Altona pumps its water from the Elbe at a point about 8 1 Mason on " Water Supply," p. 27. WATER 77 miles below that at which the river receives the sewage of the three cities ; but in the case of Altona the water which has received the sewage from a population of 800,000 people was filtered with exceeding care before being delivered to the people. It was interesting to notice in this case that in some sections of the city, people supplied with the Hamburg water were afflicted with cholera, while those on the other side of the same street using the Altona water were not afflicted, and this immunity from cholera of those using the Altona water was noticeable all over the city. The analysis of the Hamburg supply showed in parts per million : Free ammonia 1.065 Albuminoid ammonia .293 Nitrates . 26.430 Chlorin 472.000 The case of the outbreak of typhoid fever at Lausen, Switzerland, is also very instructive. The source of the epidemic was traced to an isolated farmhouse on the oppo- site side of the mountain, where three cases of the fever occurred. The brook which ran past the house was after- wards used for irrigating some meadows, and then filtered through the intervening mountain to a spring in Lausen, from which all the people, except those in six houses, ob- tained their water supply. In the six houses no cases of fever occurred, but scarcely one of the other houses escaped. By dissolving a large amount of salt in the water on the other side of the mountain, and observing the great in- crease of chlorin in the spring water, the source of the in- fection was traced, and to show how thoroughly the water was filtered, a quantity of flour was mixed with the brook water, and not a trace was found in the spring water at the village. This showed that filtration through the rocks and soil of the mountain did not remove the dangerous infection. 78 SANITARY AND APPLIED CHEMISTRY The water of our ordinary domestic wells is also liable to be impure, especially in a thickly populated district. Ma- terial from cesspools or vaults or sewers or even from the surface may get in and contaminate the water. The chief trouble is that we cannot be sure of the water, for as a dis- trict becomes more thickly populated there may come a time when the soil is saturated with filth, and then every rain will cause some of this to flow into the well. In conclusion, then, any source of supply may be contami- nated, and there is danger in the use of well waters especially in crowded districts. Numerous diseases are distributed by impure waters, and in any case of an epidemic of these dis- eases that are propagated by germs, the water supply should be very carefully examined, and it is always advisable at such times to boil the water before using. CHAPTER VI PURIFICATION OF WATER SUPPLIES WATER is naturally purified by sedimentation, dilution, oxidation, filtration, vegetable growth, and bacterial action. The extent to which each of these agencies improves the water depends on a variety of circumstances. With the deposit of mud and silt there is often carried down a large amount of organic matter ; indeed, the presence of a certain amount of suspended matter in some of the Western rivers seems to assist in the removal of organic impurities. Sedi- mentation alone, however, will not purify an unsafe water. Dilution of a small stream carrying sewage by a large stream of purer water seems to make it of better quality, but really the organic matter is simply distributed through a larger volume of water, and not necessarily destroyed. Oxidation, by a rapid fall, or by exposure to the air in running over riffles, as in a shallow stream, has been depended upon formerly for a large amount of purification. There is a difference of opinion, however, as to the extent to which oxidation will destroy pathogenic germs, but it usually happens that these conditions are very favorable to purification. W. C. Young 1 states, as the result of his experiments, that the removal of dissolved organic matter from river water by natural means is extremely slow. The principal agent in this purification is the growth of vegeta- ble organisms, and atmospheric oxidation has little effect. 1 Jour. Soc. Chem. 2nd., Vol. 13, p. 318. 79 80 SANITARY AND APPLIED CHEMISTRY FILTRATION AND SOFTENING Water may be further purified by some artificial method of filtration, and this may be done on a large scale by a public water supply company in a much more economical and efficient manner than by household filtration. For the filtration of public water supplies, some of the most efficient means have been found to be, 1. Slow sand filtration. 2. Mechanical filtration. 3. The iron process. 4. Clark's process. In the slow sand filtration system, the water is run con- tinuously on to a filter made of coarse gravel, fine gravel, and sand, suitably underdrained. When a filter begins to clog, its surface is cleaned by paring off a fraction of an inch of sand. In the use of the filter it has been found that its efficiency increases for some time after it is first installed, as the mat or slime of bacteria and organic matter increases. The top layer, however, does not do all the work of filtra- tion, as was shown by Eiensch in the case of the Altona filters. He found that the unfiltered water contained 36,320 microbes per cubic centimeter, and after passing through the upper or slime layer of the filter it contained 1876 mi- crobes, and finally the effluent contained only 44 microbes per cubic centimeter. For the proper working of this system quite a large area of filter beds is required, as it must be so arranged that some beds can be cleaned while others are in use. The area of the beds in Hudson, New York, for instance, is 30,000 sq. ft. An average rate of filtration of about three million gal- lons per acre per 24 hours is usually attained. As to the efficiency of this system of filtration, attention may be called again to the Altona case, where ten of these PURIFICATION OF WATER SUPPLIES 81 filters are used. The average number of germs in the unfil- tered water was 28,667 and in the filtered water only 90; so 99.69% of the germs were removed. The removal of the bacteria is not due simply to straining, but the conditions within the filter are unfavorable to the life of the bacteria. The food material for bacterial growth is gradually taken away, and the water actually improves in quality as it flows through the pipes to the consumer. In Lawrence, Massa- chusetts, it is stated that the mortality from typhoid fever has been reduced 40% since this system of filtration was introduced. In order to avoid the great expense of erecting filtering basins, filtration galleries are sometimes built beneath the surface along the banks of a stream, and so arranged that the water that percolates through the sand into the gallery can be pumped into the service pipes. These galleries, however, are not easily inspected and are liable to get out of repair or become clogged. Mechanical filtration may be performed either with or without the use of alum or some other coagulant. Here the water is forced through a bed of sand contained in a tank, and after the filter becomes clogged it can be cleaned in about fifteen minutes by reversing the current of water. It is interesting to notice that in this process the " bacterial jelly" on the top of the filter beds is replaced by an artificial inorganic jelly of aluminum hydroxid, which entangles the bacteria and at the same time reduces the amount of organic matter in the water. The use of alum is applicable only to those waters possessing temporary hardness. In that case the calcium bicarbonate will cause the precipitation of the aluminum hydroxid. Experiment 53. The action of a coagulant may be illustrated by putting a few grams of alum into a sample of 82 SANITARY AND APPLIED CHEMISTRY water, and adding to it enough of a tincture of cochineal to give it a strong red color. Add to this ammonium hydroxid in excess, and allow to stand for some time, when the coloring matter will be precipitated with the aluminum hydroxid, A1(OH) 3 , leaving the solution colorless. In the iron process the water is brought in contact with spongy iron, and the result is the precipitation of ferric hydroxid, which carries down with it most of the organic matter. The precipitate may be removed either by sedi- mentation or by filtration through sand. In the Anderson process ferric hydrate is formed in the water by the combined action of iron scraps and air, and the precipitate is filtered out. Experiment 54. To a dilute solution of ferric chlorid, add an excess of ammonium hydroxid. The reddish brown precipitate of ferric hydroxid produced is similar to that in the iron process. Clark's process for softening water depends on the pre- cipitation of a large part of the carbonates by the addition of calcium hydroxid (limewater) in accordance with the reaction CaH 2 (C0 3 ) 2 + Ca (OH) 2 = 2 CaCO s + 2 H 2 0. The precipitate of calcium carbonate is then allowed to settle, or is filtered off. (See p. 67, also Soap.) A large proportion of the organic matter is carried down with this precipitate. Experiment 54 a. Pass a current of carbon dioxid through a dilute solution of calcium chlorid till the precipitate at first formed is dissolved. Add to this solution an excess of limewater and notice the formation of the precipitate. Where household filtration is a necessity, some device of porous stone or tile, sand or animal charcoal, may be used. The filter should be of such construction that if of stone it can be readily cleaned with hot water and a stiff brush, or by thoroughly washing if of sand or similar material. PURIFICATION OF WATER SUPPLIES 83 The Pasteur-Chamberland filter, which is made of unglazed porcelain, is one of the most efficient filters, as bacteria are practically removed from the water by its use. The Worms, or Fisher, filter, made by the use of plates of artificial stone, has also proved efficient. It is of importance to remember that waters that are bad from the presence of organic matter may be made safe by thoroughly boiling, and also by distil- lation, and condensation of the steam. Ground water should be stored in dark reservoirs, as under these conditions the algae and other troublesome or- ganisms, which injure the water, do not develop as rapidly. Surface water often improves in quality when stored in clean open reservoirs where the sides have been thoroughly cleared of vegetation. The effect of mud deposits in storage reservoirs is not necessarily harmful. If, however, these deposits furnish food for and encourage the growth of organ- isms that by their development impart a disagreeable taste and odor to the water, they should be removed. The good effect of freezing has been very much over- estimated, according to Prudden. 1 Clear, transparent ice, from the surface of an open body of water, when melted, yields about 10% as many bacteria as were present in the original water. If a pond freezes solid to the bottom, all the impurities that were in the water will be in the ice. 1 Medical Secord, March 26, 1887. CHAPTER VII THE only practical methods that have been proposed for the disposal of the " wastes of animal life " are the " dry earth" system and the "water carriage" system. The former may be utilized in detached houses where no better method is available. The water carriage system is prefer- able, both from the standpoint of economy and that of sanitary efficiency. The organic material that accumulates in the waste of modern dwellings is of such a character that it must be very quickly removed or it will prove a menace to health. Sewage may be defined as " a complex mixture, with water, of the waste products of life and industry from densely settled communities." The only solids of importance which this sewage carries are those which are susceptible of solu- tion in water, or which become disintegrated in transit. Sewage consists very largely of water which acts as a vehicle to carry away a small quantity of other substances. In 1000 parts of sewage it is estimated that there is 1 part of mineral matter and 1 part of organic matter, leaving 998 parts of pure water. Now, the mineral matter con- tained in sewage is practically of no importance, so that all our efforts are directed toward the removal of the 1 part of organic matter in 1000 parts of water. The only really dangerous substances in sewage are the disease-producing organisms, but the gases given off as the result of decompo- sition are extremely disagreeable. Sewer gas is not as liable 84 SEWAGE DISPOSAL 85 to contain microorganisms, which will be injurious to the health, as was formerly supposed. The material which issues from the sewers of large cities contains no dissolved oxygen and no oxidized nitrogen. The reason for this is that the available oxygen of the water has been removed in oxidizing a portion of the carbon of the organic matter, but it has not sufficed, also, for the oxidation of the nitrogen, and further oxidation can go on only by the addition of more oxygen to the water. If the nitrogenous material in the sewers is represented by ammo- nia, then the following equation may be written : 2 NH 3 + 4 2 = 2 HN0 3 + 2 H 2 0. Now this nitric acid, coming in contact with the calcium carbonate of the soil and of the water is decomposed thus : CaC0 3 + 2 HN0 3 = Ca(N0 3 ) 2 + H 2 + C0 2 . The most modern theory for the purification of sewage is that it is carried on very largely by bacteria, and even this process of nitrification, as it is called, which the above equa- tion represents, cannot go on without the intervention of nitrifying bacteria, and this class of organisms must work in a medium containing a sufficient quantity of free oxygen. This purification may take place in water, when there is a sufficient quantity of the free oxygen in proportion to the filth handled. In soil this nitrification is of the utmost im- portance in the process of preparing it for the growth of plants, and in keeping up its fertility. DISPOSAL OF SEWAGE BY DILUTION If the stream into which the sewage is poured is small, and the current of low velocity, the result will be the pro- duction of a very disagreeable odor from the decomposition 86 SANITARY AND APPLIED CHEMISTRY of the sewage, but, if, on the other hand, the flow of the stream is large, this sewage will be distributed through so much water that we shall not find any offensive odor arising from it. It has been estimated that a stream which carries off sewage should have a volume of from twenty-five to thirty-five times that of the sewage ; the proportion, how- ever, depends on the amount of free oxygen that is carried by the stream and several other factors. The amount of water needed to carry off the sewage can be calculated readily, by knowing the amount of water supplied to the town, as it has been found under normal conditions, that the volume of sewage is practically the same as the amount of water supplied. In the case of the city of Milwaukee, as an illustration, for many years the sewage was turned into the Milwaukee River, a small stream, which became extremely foul, but arrangements were made to pump a large amount of water from the lake into the river 3^ miles inland, thus supplying 26 times as much water as the volume of the sewage, and by so doing the sewage was flushed out with the water, and the odor disappeared. To handle the sewage of Chicago it would be necessary to follow the same plan, and have 25 times as much water in the drainage canal as the sewage of the city. The objection to the disposal of sewage in this way is, of course, the rendering of a river water so impure. Although some experimenters have shown that water after running 20 miles is quite completely purified by the process of oxidation and nitrification, others claim that even by run- ning ten times as far, the pathogenic germs would not be re- moved, and there is a natural repugnance against using, for drinking purposes, water that has been at any time contami- nated by sewage. SEWAGE DISPOSAL 87 DISPOSAL OF SEWAGE BY IRRIGATION Another method for disposal of sewage is by irrigation. It is well known that there is a large amount of available fertilizing material in the sewage of the modern city ; for instance, the sewage of London is said to be worth annually $14,000,000 for fertilizing purposes. Some hold that sewage is not of such great intrinsic value after all, for it has been practically found that it is not possible to handle very large quantities of sewage upon a farm, and that the process cannot be applied upon a very large scale. Another disad- vantage is that when there is a large amount of rain, or when the water freezes, the process is very much interfered with, and the system to be. satisfactory must be carried on without any interruption day after day, so as not to allow any offensive matter to collect. The late Colonel Waring 1 states that an acre of land will be required to care for the sewage of from 250 to 500 persons, and when the question of growing crops is of secondary importance, and the soil is porous and sandy, the sewage of 1000 to 1500 can be purified on an acre of ground. The city of Berlin has set aside 20,000 acres for a sewage farm, and it is said that it actually receives a yearly profit of $60,000 from the operation. INTERMITTENT FILTRATION The next method for disposal of sewage is by intermittent filtration. This process is a natural one, because it depends for its success upon the prevalence of certain natural con- ditions; that is, the presence of oxygen and living micro- organisms. If we allow sewage to run, for some time, upon a filter bed composed of sand and gravel and then turn this sewage on to another filter bed and allow the water to run out of the first bed and the air to enter the spaces between the 1 Harrington, "Practical Hygiene," p. 496. 88 SANITAEY AND APPLIED CHEMISTRY grains of sand, we furnish the means for the growth of the microorganisms. This is much more satisfactory than at- tempting to filter continuously through the same filter bed. As an illustration it was shown in one case that by the use of this process where 31,400 gal. of sewage per acre was fil- tered, 98.6% of the organic impurity was removed, and 99% of the bacteria. THE SEPTIC TANK There is a modification of the above method which is known as the use of the septic tank, in which the sewage is liquefied by being stored first in the sunshine or in the air, allowing the aerobic bacteria to work, and afterward in a closed tank where another class of bacteria (the anaerobic) carry on their purifying process. This material is then run upon filter beds, and a very pure effluent is the result. Some engineers prefer to run the sewage first into a closed tank, through which it requires from 12 to 24 hours to pass, and where a thick scum covers the surface, gases are given off, and very complete decomposition takes place. The effluent from this tank is then run on to filter beds. It is to be noted that both aerobic bacteria, or those which work in light and air, and anaerobic bacteria assist in the purification of sewage. PRECIPITATION OF SEWAGE Another method for sewage disposal is by chemical pre- cipitation. For this purpose such substances as ferrous sulfate, ferric sulfate, lime, or alum are used. It was at first proposed to utilize the precipitated material as a fertilizer, and considerable money has been spent in pre- paring this material and extracting the water from it by pressure. This process, however, has not been found to be very satisfactory, and improvements must be carried still farther before this method for disposal of sewage will be extensively adopted. SEWAGE DISPOSAL 89 To recapitulate, for the purification of sewage, we must depend largely upon the work of bacteria often in the pres- ence of oxygen, and any plan which utilizes the work of these organisms to the greatest extent, and furnishes the most complete conditions, for work in this way, will be successful. DISPOSAL OF HOUSEHOLD -WASTE A method for disposing of garbage or household waste economically has long perplexed the health authorities. Two conditions may be considered : that of disposing of it on the premises where it is produced, and that by the city authorities. Several methods have been used for disposal of refuse without removal from the premises. Among these the pro- cess of burning in the stove, range, or furnace, either with or without previous drying is suggested. This is efficient and practical if the amount of such waste material is not too large, and if a good fire is maintained. In summer, when there is naturally a larger amount of refuse, and the fires are not kept burning so continuously, it is often difficult to handle garbage in this way. A modification of the above method consists in having an enlargement of the smoke pipe of the stove at the elbow, and to introduce into this, through an opening in the side, a perforated basket containing the garbage. The material soon becomes dry and is partially charred, and then may be taken out and put into the stove, where it is useful as fuel. In some cities the plan of building brick or stone furnaces in the yard, for the sole purpose of burning rubbish, has been adopted with great success. Another method of disposal is by burying in the soil, and as the decomposition takes place rapidly, if only a few 90 SANITARY AND APPLIED CHEMISTRY inches of soil is placed over the material, no obnoxious odor arises to contaminate the air. When one hole is filled, it is covered and another is dug beside it ; but these holes must not be too deep or too large. If the city or village undertakes to dispose of the gar- bage, usually great expense is incurred, as the quantity is very large. For instance, in Manhattan alone the dry refuse amounts to 1,000,000 tons in a year, and the garbage is 175,000 tons per year. 1 Disposing of garbage to farmers for feeding of stock or swine is also practical. This involves a long haul of ill- smelling material through the streets, and is particularly objectionable if the material is not collected every day. In some localities garbage is loaded on to scows, towed out to sea and dumped, but here the incoming tide may throw the decomposing material back on the shore. There is a very valid objection to using such refuse, even if the more perishable material is excluded, for filling in the so-called " made land," as decomposition will continue for years in this soil, and the air of dwellings built upon it will be contaminated. Cremation has been adopted in many cities with good suc- cess. In 1899, 81 communities in Great Britain were em- ploying incineration as the chief means for disposal of refuse, and 76 of them turned the developed heat from the combustion of this refuse to some useful purpose, such as making steam to run electric lighting plants, for sewage pumping works, for grinding road material, and for use in the process of disinfection of clothing. 2 Another plan is by " reduction," in which method the gar- bage is dried in steam-jacketed cylinders, the dried residue then extracted with naphtha, and the grease thus removed is 1 Price, " Handbook on Sanitation," p. 49. 2 Harrington, "Practical Hygiene," p. 609. SEWAGE DISPOSAL 91 saved as a valuable product. The residue is again dried and worked up into a fertilizer. It is well to remember that such quickly decomposing material as garbage should be immediately removed under sanitary inspection, whether any financial profit comes to the city from its treatment or otherwise. CHAPTER VIII CLEANING: SOAP, BLUING WITH our modern knowledge of the means of transmitting disease, filth is something to be avoided, as it assists in the spread of infection from one locality to another. The love of cleanliness, which is considered a sign of a higher civili- zation, is, no doubt, the outgrowth of years of experience with the dangers of dirt. This abhorrence for filth is a sanitary safeguard: it protects the body, the air, the water supply, and the food supply. As man has advanced he has demanded some cleansing agent for the body, the utensils, and the clothing, and so a great industry has developed for the preparation of these agents. Substances used for cleaning act either mechanically or chemically to remove the offensive materials. In the use of soap and sand, for scouring, there is a combination of these methods ; and, in fact, when the chemical loosens up the fibers or sets free the dirt, some mechanical process is often required to remove it. Most of the polishing and cleaning powders on the market depend, for their efficiency, upon the action of a very finely divided substance like silica, precipitated chalk, or rouge. This is mixed with some fat or oil; thus, some "Putz Pom- ades" contain rouge, some finely divided silica, and a per- fumed fat. In the choice of a polishing material, one should be selected that is so finely divided that it will not scratch the metal. Dry sodium bicarbonate (baking soda) can be safely used for cleaning and polishing. 92 CLEANING: SOAP, BLUING 93 Borax, Na 2 B 4 7 , added to water, greatly aids in the removal of dirt, in special cases. Ammonium hydroxid (aqua am- monia) is also used for the same purpose, and as it forms a soap with the oily matters of the skin or of the fabrics washed, it is a convenient cleaning agent. A teaspoonful of ammonia to a quart of water is an excellent wash for wood work, and may be used to brighten carpets or rugs. Much of the "household ammonia" on the market is of a very low grade, and so it is always advisable to purchase ammonia from a druggist. A cleaning material should not only remove the grease or dirt, but it must be of such a nature that it will not injure the article cleaned. From the recent work of Mrs. Rich- ards, 1 many of the following suggestions are taken. In some cases, as with wood, leather, metal, etc., the dirt does not penetrate into the interior, but remains on the surface; in other cases the whole fabric is filled with dust and grease. All polished wood surfaces, except those finished with wax, may be cleaned with a weak solution of ammonia, or soap, but they should never be treated with a strong alkali. As solvents for grease, either kerosene or turpentine may be used, and should be applied with a soft cloth. Painted surfaces, especially if white, may be cleaned with a little " whiting," CaCOg, which can be applied with a piece of cheese cloth. The wood is afterward washed with water and wiped dry. Painted walls if painted with oil paints can be cleaned in the same way, but "tinted" walls, since water colors are used, are disfigured by this treatment. Leather may be kept bright and clean by the use of kerosene, or occasionally a little oil. Marble may be scoured with sand soap, and finally polished with a coarse flannel. It should not be forgotten that marble is calcium 1 Richards and Elliott, "The Chemistry of Cooking and Cleaning." 94 SANITARY AND APPLIED CHEMISTRY carbonate, CaC0 3 , and consequently should never be treated with an acid, or even an acid fruit juice. Metals can usually be cleaned with a hot alkaline solution or a little kerosene. To clean glass, .it may be covered with a paste of whiting, ammonia, and water, and after it is dry this may be rubbed off with a woolen cloth or with paper. Kerosene is excellent for this purpose, especially in the winter when the water would freeze. Household fabrics are often washed with alkaline solu- tions or with soap. In some cases naphtha may be used for washing such fabrics. As some of the solvents, such as naphtha, benzine, turpentine, and gasoline are frequently used for cleaning, and removing grease, it is extremely important to remember that they are all very volatile, and that the vapors may take fire from a lamp, gas jet or stove, even if at some distance. On this account work of this kind should be done by daylight and out of doors, if possible. Many serious burns occur from lack of these precautions. In the use of the volatile solvents like gasoline, enough should be used to cover a large portion of the goods, and if possible afterwards wash thoroughly with water. To remove stains, spots, and tarnish, a little knowledge of chemistry will serve an excellent purpose. Since grease is readily absorbed by blotting paper, spots may often be re- moved from fabrics by placing the goods between two pieces of blotting paper, and then heating with a warm iron. French chalk will sometimes absorb the grease, especially if the spots are fresh. Grease may also be removed by the use of hot water and soap, ammonia, or even borax. If there is danger that these solvents will injure the goods or the colors, it is better to use some solvent such as chloroform, ether, alcohol, turpentine, benzine, or naphtha. Ether and chloroform are better adapted to the more delicate CLEANING: SOAP, BLUING 95 fabrics. " The troublesome ' dust spot ' has usually a neg- lected grease spot for its foundation. After the grease is dissolved the dust must be cleaned out by thorough rinsing with fresh liquid or by brushing after the spot is dry." 1 Since paints consist of oil and some coloring matter and lead or zinc oxides, paint spots should be treated with a sol- vent for the oil, and then the coloring matter can be brushed off. Fresh spots may be treated with turpentine, benzine, naphtha, or gasoline, but old paint spots must be softened with oil or grease, and may then be removed by the appro- priate solvent. Pitch, tar, or varnish may be treated with oil, and then be dissolved out with turpentine. Sugar deposits are soluble in warm water. If acids have destroyed the color of goods, this may usually be restored by ammonia, and dilute alcohol may be used in the same way for the stains from fruit. Ink spots would not be so difficult to remove if we knew in advance the composition of the ink. Fresh ink usually dissolves in cold water, though sometimes sour milk is more efficient. Ink stains may also be removed with blotting paper or some absorbent. Ink stains on marble may be treated with turpentine, baking soda, or strong alkalies, or a paste may be made with the alkali and turpentine, and this may be left for some time in contact with the spot, and finally washed off with water. A dilute solution of oxalic acid may often be successfully used to remove either ink stains or iron- rust spots. If there is much iron in the water supply, this may be removed from bowls or other porcelain ware by the use of hydrochloric acid, then rinse with water, and finally with a solution of soda. Silver is readily tarnished by sulfur, either from eggs, or from rubber bands or elastic, or sometimes from the 1 Richards and Elliott, loc. cit. 96 SANITARY AND APPLIED CHEMISTRY sulfur compounds in the illuminating gas. The sulfid of silver thus formed is grayish to black. Silver thus tarnished should be rubbed with moist common salt before washing, thus forming a silver chlorid, which is then washed in am- monia, in which it is soluble. For cleaning and polishing brass and copper, nothing is better than oil and rotten-stone, and most of the good pol- ishes on the market are made from these materials, with al- cohol, turpentine, or soap. Kerosene is useful in keeping metals bright, as well as glass and wood. Aluminum may be cleaned by the use of whiting or any silver polish, but alkalies should not be used upon this metal. Aluminum does not readily tarnish. As it does not rust, with ordinary care it will, in a kitchen utensil, last for many years. Experiment 55. To remove an iron-rust spot from a piece of goods, stretch the cloth over a dish containing hot water, then as the steam arises and the goods become moist, drop a little muriatic acid, HC1, upon the rust spot with a medi- cine dropper ; after a moment lower it into the water. If the spot is not removed, repeat the operation, then rinse in clear water, and finally in a dilute solution of ammonia to neutralize any acid that might remain and injure the goods. 1 Iron-rust stains may often be completely removed from delicate fabrics by the use of lemon juice and common salt. SOAP Water, and a few other solvents, are used to remove dirt, or, as it is sometimes called, "matter out of place." Some of these foreign substances readily dissolve in the water ; others, like the fats, will dissolve in ether or gasoline; and still others, as the resins, will dissolve in alcohol. Some form of alkali, such as wood ashes, was formerly used with 1 Richards and Elliott. CLEANING: SOAP, BLUING 97 the water, to assist in removing the dirt. It was found, however, that this had a very destructive action on the goods, so a " saponified " fat, the product produced by the action of an alkali on a fat, or what we call soap, came into use. This, when well made, does not injure the goods. Soap was used instead of the lye from the lixiviation of ashes, long before the chemistry of the process became known. It was not till 1813 that Chevreul published his scientific researches on the composition of fats and the process of soap-making. The raw materials used in soap manufacture are an alkali known as " caustic alkali," which may be either sodium hy- droxid (NaOH), which makes a hard soap, or potassium hydroxid (KOH), which makes a soft soap. These are made by boiling the carbonate with slaked lime, in accord- ance with the equation : Na 2 C0 3 +Ca(OH) 2 =CaC0 3 +2 NaOH. From this mixture the calcium carbonate settles out, and the solution of the caustic alkali is boiled down to a solid, and is put upon the market under the name of "concentrated lye," or the concentrated solution is used directly by the soap maker. More recently caustic soda has been made directly by the electrolysis of sodium chlorid, NaCl. The sodium deposited at one pole is dissolved in water, and the chlorin is used for making bleaching powder. The second ingredient of a soap. is either a vegetable or animal fat or oil or a resin. Such oils as that of palm nut, cocoanut, olive, hemp seed, linseed, cotton seed, fish, or lard may be used, and fats like beef tallow, mutton tallow, lard, or house grease. The process of "saponification" may be brought about either by the action of water or steam at high temperature and pressure (especially in the presence of a dilute mineral SANITARY AND APPLIED CHEMISTRY acid), by the action of caustic alkalies, or sometimes by the use of lime (see Candles, p. 49). The fats may be briefly described as consisting of ethers of the triatomic alcohol-radicle, containing glycyl, C 3 H 5 . By treatment with alkalies or high-pressure steam, they yield gylcyl alcohol (glycerin) and stearic or other fatty acid. 1 The name given to the compound of the acid and glycerin is stearin, palmitin, or olein. In the case of stearin, the saponification equation would be: C 8 H 5 (C 18 H3A)s + 3 KOH = C 3 H 8 (OH) 3 + 3 KC^H^. Stearin Caustic Potash Glycerin Soap With palmitin or olein, the reaction is similar. If the fat or oil is solid, it contains a preponderance of stearin or palmitin, but if liquid, there is an excess of olein. In making soap on a large scale, 2 a kettle, provided with both a closed and open steam coil, so that the soap may be boiled either by the heat or the free steam, is used. A ket- tle that will hold 100,000 Ib. of soap is 15 ft. in di- ameter and 21 ft. high, and is made of f -in. boiler plate. The melted fat and lye are run into the kettle and mixed by the aid of free steam and boiled for some time, or until the soap has a dry, firm feel between the fingers ; it is then "salted out " by adding common salt. In boiling, the saponi- fication represented in the above equation has taken place, and when salt is added this causes the soap to separate from the caustic lye and glycerin. After boiling, to mix thor- oughly, the mass is allowed to stand in the kettle till the soap rises to the top, and then the lye may be drawn off at the bottom of the kettle. Some more strong lye is then added, and the boiling is continued till the material is fully saponified, which the experienced soap boiler knows 1 Allen, " Commercial Organic Analysis," p. 183. 8 Thorp, "Outlines of Industrial Chemistry," p. 340. CLEANING : SOAP, BLUING 99 by sight, feel, and taste, and then the contents of the kettle is again allowed to stand for a while, and the addi- tional lye is drawn off. The soap is then boiled with some water, and is allowed to settle again, to allow the separation of more alkali, dirt and impurities, called "nigre." After standing several days, the soap is pumped into the "crutcher," which consists of a broad, vertical screw work- ing within a cylinder, which is placed in a larger tank. Here it is thoroughly mixed, and any perfume or scouring material may be added. The soap is then drawn off into rectangular "frames," holding about 1000 lb., where it is allowed to solidify. The sides of these frames are re- moved and the soap is cut, by means of a wire, into slabs and then into bars. If put on the market in the form of cakes, the bars are pressed into the desired shape. For making white soaps, tallow, palm oil, and cocoanut oil are used. Castile soap, if genuine, is made from olive oil, sometimes with the addition of cocoanut or rape seed oil. It is useless to attempt to make a good soap out of inferior material. In making lower grades of soap, cheaper fats are used, and frequently those that have a rancid odor. This is sometimes "corrected" by the addition of a strong perfume, like oil of " mirbane," nitrobenzene, made from coal tar. Yellow soaps almost always contain considerable rosin; that is, they are made by the usual process, except that quite a large proportion of rosin is used to replace the fat. This has valuable soap-making qualities, and would not be classi- fied as an adulterant of soap. Cocoanut oil saponifies with- out boiling, so it is used in making the "cold process" soap. This material also admits of the use of a larger quantity of water, so that the soap will be hard and still contain as much as 70 % of water. Soap is mottled by stirring into it, while warm, some coloring substance, such as copperas, ultramarine, or an aniline color. 100 SANITARY AND APPLIED CHBMI8TEY Sand soap, pumice soap, and compounds of a similar character are made by incorporating sand or powdered pum- ice, with the ground soap, and this ought to lessen the price of the soap very materially. These substances can act only mechanically ; that is, they sandpaper off the dirt. A silicated soap is made by mixing with the ordinary soap some silicate of soda or soluble glass, as it is called. Into most laundry soaps both sodium silicate and sodium car- bonate are " crutched," as a filler to soften hard water and to give additional detergent properties. Toilet soap is made either by melting raw soap, by per- fuming an odorless soap, after cutting in fine shavings and drying, or by making the soap directly by the use of pure materials. In either case the mass is colored by metallic oxides or aniline colors, and is perfumed by the use of essential oils, and then it is pressed into molds while yet fresh. To make a transparent soap it is necessary to dissolve an ordinary soap in alcohol, allow the insoluble residue to settle out, and distill the alcoholic solution to jelly. This may then be pressed into molds and dried. Another method very frequently employed is to make a cold process soap, with coloring matter and perfume added, and then to add to the mass more glycerin, or a strong sugar solution, which renders it still more transparent. Soft soap is made directly by the use of potash lye, or by the use of soda lye and considerable water. The glycerin and the excess of lye, if any, remain in the soft soap. This is used in "fulling" or shrinking cloth and in other manu- facturing operations, probably on account of the excess of alkali which it contains. The salt lye which is drawn off from the kettle in which soap is boiled is used for the manufacture of glycerin. In this process the soluble soap and impurities are taken out CLEANING: SOAP, BLUING 101 by chemical treatment, and mineral salts are separated by evaporation and crystallization. The purified crude residue containing about 80 % glycerin is distilled with steam under diminished pressure. It is not economy to use a cheap soap, as on account of the excess of alkali which it usually contains it injures the fabrics washed, by causing the fibers to disintegrate and readily fall apart. There is a great advantage in using a well-dried soap, as it does not so readily become soft in the water and there- fore does not wash away so qxiickly. A laundry soap will lose 25 % of water if the bars are piled and allowed to remain for some time where they are freely exposed to the air. In his researches on soap, Chevreul said that the cleaning action was because the soap was decomposed, when brought in contact with water, into fatty acid and alkali. The impurities are set free by the alkali and entangled by the fat acid salts, and thus removed with the lather. Thus it will be seen that vigorous rubbing is not necessary to remove the dirt, though, of course, it aids the process. Ordinary soaps are readily soluble in water, but if the water is " hard " from the presence of lime or similar mineral substances, the alkali soap is decomposed and an insoluble lime soap is precipitated, thus forming a dis- agreeable scum on the water. Not until all this lime is thrown down by the soap will the latter begin to have a detergent action. The equation for the formation of the lime soap would be: 2C 1 H< B 0,Na + CaS0 4 = CaCCuHjA). + Na^SO* On account of the necessity for using hard water in some localities "washing soda" NaaCOs + 10 H 2 is used to 102 SANITARY AND APPLIED CHEMISTRY "break" the wafer; that is, to precipitate the lime so that less soap will be required, thus : CaH 2 (C0 3 ) 2 + Na 2 C0 3 = CaCO 8 + 2NaHC0 3 . (See Hard water, p. 67.) In order to make a laundry soap fit for hard water, sodium carbonate is added to it in the crutching. Experiment 56. To make a hard soap, dissolve in a medium-sized beaker 15 grama of caustic soda (sticks) in 120 cc. of water, and pour one half of this into a porcelain evaporating dish of at least 500 cc. capacity, add 60 cc. of water and 50 grams of tallow. Boil this solution for three quarters of an hour, carefully replacing, from time to time, the water that has been lost by evaporation ; then add the remainder of the solution of caustic soda and boil for at least an hour more. Water should be added as before, but the volume of the liquid may be allowed to decrease about one third. Add 20 grams of salt, boil for a few minutes, and allow the liquid to cool. The soap will rise to the top, and the glycerin, excess of lye, and salt will remain in solution. Experiment 57. Slightly acidify the water solution sepa- rated from the soap in the above experiment with dilute hydrochloric acid. If any fatty acids or impurities separate out, filter. Pour the solution into a porcelain evaporating dish, and evaporate to dryness on a water bath. Dissolve the residue in strong alcohol, filter or decant from the un- dissolved crystals of salt, and evaporate the alcohol. The slight residue will be sticky, and give the sweet taste of glycerin. Experiment 58. Cut a good quality of soap into shavings and mix with hot water on a water bath, until well dissolved. Add dilute sulfuric acid until the solution is acid. Note CLEANING: SOAP, BLUING 103 that if the soap is " filled," the sodium carbonate will cause an effervescence on adding acid. Heat on the water bath for some time or boil slowly, and the fatty acid will separate, forming an oily layer on the top. When clear this may be separated from the water by pouring on a wet filter, and the sulfuric acid removed by washing on the filter with hot water. Washing soda, Na2C0 3 10H 2 0, is often used, not only to soften hard water, but as a stronger washing agent than soap. This is a much better material than most of the so-called washing powders of the grocer. It should always be dissolved in a bottle or other vessel, and used as a solu- tion in the quantities necessary. An excess disintegrates the fabrics, or "rots "the goods. Sometimes the washing powders or liquids on the market contain in addition to the washing soda, a little soap or ammonium carbonate or a small per cent of borax, but they are much more expensive than the common washing soda, and no more efficient. Experiment 59. To test a washing powder for sodium car- bonate, put a little of it in a test tube and add a few drops of hydrochloric acid. If there is a brisk effervescence, it will indicate the presence of a carbonate, and if the gas that is given off colors the flame of a Bunsen burner yellow, it indicates sodium. BLUING Bluing is the process resorted to in the laundry to over- come the slight yellow color of the clothes, and for the same purpose in the bleacheries where new goods are finished. Indigo was one of the substances most commonly used some years ago. It was known to the ancient Egyptians as a dye and to the Komans as a pigment. The method of using it for bluing, as it is insoluble in water, is to tie up a lump in a cloth, and when soaked in water the finely divided precipitate which is in suspension will give a blue 104 SANITARY AND APPLIED CHEMISTRY color to the water, and to the clothes, which are immersed in it. Prussian blue (ferric ferrocyanid), Fe 4 (Fe(CN) 6 ) 3 , is also used for bluing. It is insoluble in water and in mineral acids, but is decomposed by alkalies and dissolved by oxalic acid. It is generally used as a solution or " liquid blue," but this imparts to the goods a greenish blue color. On account of the ease with which it is decomposed by alkalies, there is danger that " iron rust " will be deposited on the goods if this form of blue is used. ^ Experiment 60. Make Prussian blue by the action of ferric chlorid, FeCl 3 , upon potassium ferrocyanid, K 4 Fe(CN) 6 , in the presence of a few drops of hydrochloric acid. Treat this blue precipitate with an excess of sodium hydroxid, and heat to boiling. Notice the reddish brown precipitate of ferric hydrate, Fe(OH) 3 . Experiment 61. Make some Prussian blue, as in the pre- vious experiment, and add to the precipitate, in the test tube, a few crystals of oxalic acid, and warm the mixture. Notice the intense blue solution obtained (liquid blue). Ultramarine is an interesting artificial compound which is put upon the market in the shape of small " bluing balls." It is similar to the native mineral called " lapis lazuli," and is a double silicate of sodium and aluminum containing sul- fur. Like indigo, it is insoluble in water and is simply held in suspension in that liquid. There is difficulty in preventing the formation of blue spots and streaks with the solid blue. This blue is extensively used for coloring wall paper and for " bluing " white sugar. '"~ Experiment 62. To show the presence of sulfur in ultra- marine, place a part of a bluing ball in water in a test tube, and add to it enough hydrochloric acid to make the solution acid. Notice the odor of escaping gas when the solution is CLEANING : SOAP, BLUING 105 warmed, and test it for hydrogen sulfid, by holding in the gas a paper dipped in lead acetate solution. The paper turns black on account of the formation of lead sulfid. Aniline colors made from coal tar are the basis of most of the liquid blues on the market at the present time. The soluble blues from this source are very numerous, and they are probably as satisfactory as anything for this purpose. CHAPTER IX DISINFECTANTS, ANTISEPTICS, AND DEODORANTS SINCE the health of the body depends so largely upon sanitary surroundings, it is important to consider what assistance modern science can offer to bring about the most hygienic conditions in the household. Infection, in general terms, is something capable of producing disease that comes to the body from without, and this infection usually reaches the system by the aid of certain lower forms of life known as microorganisms. These microorganisms may be distrib- uted by impure water, by house flies, by flying dust, or by personal contact between individuals. We may try to check the progress of a disease within the body, where it becomes a very difficult problem, or, what is better, the attempt may be made to prevent the disease from invading the body by keep- ing the dangerous microbes out, or destroying them before they have an opportunity to enter it. Those substances which are capable of checking the growth of the microorganisms, but without necessarily killing them, are known as "anti- septics"; so all "disinfectants," or destroyers of infection, are also antiseptics, but antiseptics are not necessarily disinfectants. (The surgeon of to-day deals with wounds in such a way as to have the conditions aseptic, that is, to have all germs excluded in the operation, which is far better than attempting to destroy them when once intro- duced into the wound.) 1 1 Sedgwick, " Principles of Sanitary Science and the Public Health," pp. 326, 327. 106 DISINFECTANTS, ANTISEPTICS, AND DEODORANTS 107 Those substances that destroy foul odors are often called disinfectants. This may be true or it may not. Some things destroy foul odors, or, in fact, simply cover them up without in the least going to the source of the trouble, and they are not disinfectants but simply "odor killers." The American Public Health Association's committee defines a disinfectant as, "An agent capable of destroying the infective power of infectious material." This does not, however, represent the popular view of the subject. Deo- dorants, though they may be of great value in their place, are not disinfectants or antiseptics. Many people are in the habit of relying on the sense of smell to prove the presence of injurious as well as dis- agreeable substances in the air. The nose is, no doubt, an excellent watchman to protect the body, but whether we destroy a foul odor or simply overcome it by a more pungent one is not for the sense of smell to distinguish, for germs that render the air poisonous are not necessarily destroyed when no vile odor can be perceived. Because a substance is put on the market as a "microbe killer" or a "perfect disinfectant," it is not a proof that it is of any value, any more than the fact that a patent medicine is advertised as a specific for all the ills of the flesh is a proof that it will have that effect. TESTS FOR DISINFECTION These tests may be of three kinds : l First. From the practical experience of those engaged in sanitary work. Such diseases as smallpox, diphtheria, and scarlet fever have in many instances been contracted after months, from the use of clothing that has been about a patient, or from the occupancy of rooms where he has been 1 Dr. Sternberg, American Public Health Association. 108 SANITARY AND APPLIED CHEMISTRY sick. (Books that have been in the sick room have commu- nicated disease months after they were removed from the room.) If, after an attack of the disease, the rooms have been thoroughly disinfected, the disease has been completely stamped out in that place. Second. Inoculation experiments have been made upon animals with infected material, and with the same material that had previously been subjected to the action of disin- fectants. In the former case the disease was transmitted, and in the latter it was not, and thus the efficiency of the disinfectant was shown. It is known that in many infec- tious diseases the infecting agent is a germ, and in these cases the effect of disinfection is to destroy the germ. Experiments have been tried upon man with disinfected vaccine virus, and with the same virus that has not been thus treated, and the vaccination with the first was not successful while that with the latter was. In this way the efficiency of a disinfectant was shown. Third. Experiments are made directly on the disease germs, culture experiments as they are called. Here the germs are allowed to propagate in such fluids as extract of beef, or bouillon, and thus it is possible to study the life- history of these germs outside the body, and to learn what agents are efficient in destroying them. Some bacteria multiply by "division" and others by "spores" also, and the latter are more difficult to destroy, because the organism is at that time in what may be called a resting stage. Often it is possible to prevent the growth and development of germs by the use of antiseptics or dis- infectants; the germs are not destroyed, but the disease is arrested. "An ideal disinfectant is one which, while capable of destroying the germs of disease, does not injure the bodies and material upon which the germs may be found ; it must DISINFECTANTS, ANTISEPTICS, AND DEODORANTS 109 also be penetrating, harmless in handling, inexpensive, and reliable. 1 This ideal disinfectant has not yet been discov- ered." There are, however, some inexpensive and common substances which can be used to destroy the germs of disease with good effect. Among the substances used as disin- fectant and antiseptic agents, the following may be noted: Sunlight is an excellent disinfectant, if the material can be exposed to the direct rays of the sun. It has been shown that the bacillus of tuberculosis is killed by direct sunlight, and that of typhoid fever also under certain conditions. Even diffused light is of value as an adjunct to the other methods for the destruction of germs, so there is reason in the common practice of "airing" bedrooms, and letting in all the sunlight possible for a time every day. Dry air is an excellent purifier, especially if accompanied by sunlight, chiefly on account of the large number of oxidizing bacteria which are present. It will remove moisture and often prevent decomposition in this way, for moisture is usually the friend of disease and decay. Dry earth also allows oxidation and arrests foul odors. This fact is utilized in the dry earth closet. Charcoal, especially that made from bones, is an excellent deodorizer and will remove foul odors quite readily. A handful of boneblack sprinkled on a piece of putrefying flesh will, after a short time, prevent any foul odors from escaping from it. Wood charcoal acts less effectively in the same way, but on account of its porosity absorbs gases very quickly. Experiment 63. Into a bottle containing 200 cc. of dilute hydrogen sulfid water, which has the character- istic odor, put about 30 grams of boneblack and shake for some time. Filter, and, if the conditions have been care- 1 Price, " Handbook of Sanitation," p. 223. 110 SANITARY AND APPLIED CHEMISTRY fully observed, the filtrate will have no odor of hydrogen sulfid gas, as it will have been absorbed by the animal charcoal. Quicklime is also used for purposes of disinfection. On account of its cheapness, " milk of lime," Ca(OH) 2 , is recom- mended, especially in camp sanitation, for destroying foul organic matter. Some physicians regard it as efficient as chlorid of lime. A variety of substances are used to cover up vile odors, while they do not pretend to destroy them. The bad smells in the house may be overcome by burning sugar, cotton clofch, or coffee. (The lack of personal cleanliness may be made less noticeable by the free use of perfumes, but this is a method belonging to an earlier kind of civilization rather than to our own.) More effective than any of the methods above noticed are the following in the absence of spores : Heat, at a temperature of 302 F. (150 C.), may be used for disinfecting, and should be continued for at least two hours. A higher temperature, continued for a shorter time, will also destroy the bacteria. Sometimes clothing that would be injured by moist heat may be treated in this way. The goods may be heated in an oven, but should not be folded or piled close together. This method has been used for dis- infecting by boards of health in large cities, but it is inferior to steam at the same temperature, and does not penetrate as well. Sulfur dioxid, made by the burning of sulfur, is one of the oldest agents used for disinfection. A convenient way in which to use this is to put several pounds of sulfur in an iron kettle, and to place that on bricks in a pan of water. Then light the sulfur by means of burning coals, or alcohol, and close the room very tightly. Five pounds is considered a sufficient quantity for a room containing 1000 cu. ft. of space. Sometimes a solution of sulfur DISINFECTANTS, ANTISEPTICS, AND DEODORANTS 111 dioxid is simply exposed to the air of the room. Ten pounds of the liquid would be necessary for 1000 cu. ft. of space. The presence of moisture in the room or on the goods greatly assists the operation. The more tightly the room is closed, by pasting strips of paper over the cracks beside the doors and windows, the better the disinfection will be accomplished, and this precaution should not be neglected. Clothing and bedding should be opened out as much as possible, so as to bring it in contact with the S0 2 gas, and the room should remain closed at least 24 hours. This gas is liable to bleach certain colors, so it should not be used with colored fabrics. Liquid sulfur dioxid, con- tained in strong steel cylinders, can now be obtained in the market. It is extremely convenient to use for disinfection as it is only necessary to open the valve and allow the gas to fill the room. Sulfur dioxid is, after all, only a surface disinfectant, and is said to be effective only against a limited number of pathogenic bacteria. Carbolic acid, C 6 H 5 OH, is an agent that has often been overrated, on account of its penetrating odor, and because a small quantity will overcome most other odors. This acid of a strength of 1 to 15,000 will prevent decomposition, but 1 to 1000 will be needed to destroy spores. 1 It is an excellent substance to use for washing floors, walls, etc., and for disinfecting soiled clothing and discharges, as its antiseptic power is great. Although not very soluble in water, a con- venient solution can be made by adding it to water till the latter becomes saturated, about 1 to 20, or the solubility can be increased by the addition of glycerin. The cresols, which are found in commercial carbolic acid, and are powerful germicides, are constituents of many of the disinfecting solutions now on the market, and they are believed by some to be superior to carbolic acid. 1 Price, "Handbook of Sanitation," p. 252. 112 SANITARY AND APPLIED CHEMISTRY Copper sulfate, CuS0 4 5H 2 0, or "blue vitriol," of about 10 % strength, is to be recommended, on account of its comparative cheapness, especially as a deodorant. It forms a blue solution, with water, and is very soluble in that agent. Iron sulfate, FeS0 4 7H 2 0, or the "copperas" of com- merce, is very efficient for certain purposes. In the propor- tion of 2 Ib. to a gallon of water, it may be used with great convenience and success to purify sink drains and cesspools. It may also be sprinkled in places where there are foul odors from the decay of organic matter, and they will be completely overcome. Zinc chloride, ZnCl 2 , is very largely used as a disinfectant and a deodorant. As its solution, as well as that of zinc sulfate, is colorless, it will not stain the most delicate fab- rics, so it can be used on any clothing that is not injured by washing. A 5 % or 10 % solution may be used for this purpose or for destroying foul odors. Potassium permanganate, KMn0 4 , since it is a strong oxi- dizing agent, may be used as a germicide in some cases, but is rather expensive. The use of this material in the purification of cistern waters has already been suggested (p. 73). Hydrogen peroxid, H 2 2 , is now a commercial article, and its aqueous solution is sold at a reasonable price. There are some cases where this mild disinfectant may be applied with success, as it will destroy the bacillus of ty- phoid fever, cholera, and diphtheria quite readily. There are, however, more efficient agents in disinfection than those that have been mentioned, because under the proper conditions they are of sufficient power to destroy the spores of disease. Fire, it is well known, is effective to wipe out the disease germs. Old clothing and bedding would better be burned than that an attempt should be made to disinfect it. The DISINFECTANTS, ANTISEPTICS, AND DEODORANTS 113 great fire of London, that followed the plague, no doubt was a blessing, in that it actually destroyed the last traces of the disease. That was more important in those days than it would be now, for they did not know the first principles of the science of disinfection. Steam heat is one of the most valuable physical agents for the destruction of germs, as it kills bacteria at once, and spores after a short time. It is especially valuable for the disinfection of clothing, textile fabrics, carpets, etc., as it is very penetrating. Municipal authorities are making use of this method of disinfection on a large scale with great suc- cess. If it seems desirable, the material can be subjected to quite a high temperature by the use of superheated steam. In some communities machines mounted on wheels are used. A large apparatus has been introduced which is so constructed that the mattresses, bedding, etc., may be intro- duced into a chamber, from which the air is exhausted by means of a steam jet. Dry steam is then allowed to enter, and a temperature of 230 to 240 F. is maintained for 15 m., after which the steam exhauster again produces a practical vacuum, and finally air is drawn through the chamber, and the dried materials may be removed. An apparatus of this character is used at the New York Quar- antine Station. Boiling water is one of the most satisfactory materials to use for disinfecting purposes. There are very few germs that can withstand a boiling temperature for half an hour. A temperature of 70 G. will be sufficient to kill the germs of cholera, tuberculosis, diphtheria, etc. Hot water is spe- cially applicable to textile fabrics. Calcium hypochlorite, CaOCl 2 , chlorid of lime, or "bleach- ing powder," is a convenient disinfectant to use in some cases. The chlorid of lime holds the chlorin in combination very feebly, so that the smell of chlorin is always apparent in 114 SANITARY AND APPLIED CHEMISTRY a good sample. The fresh sample should contain from 30 to 36 % of available chlorin, but if it is exposed to the air for a time it loses all its chlorin, so it must be kept in a sealed package till used. Calcium hypochlorite, the efficient substance in the bleaching powder, is soluble in water, but the solution loses its strength if not closely corked. It is decomposed when brought in contact with organic matter, and very effectually kills the germs of disease. Experiments with chlorid of lime as a disinfect- ant were begun as early as 1881, by Koch. They have been continued by Sternberg, Jaeger, Nissen, Klein, Duggan, and others, and all showed the very efficient character of this substance as a true germicide. Chlorid of lime is convenient to sprinkle about in the vicinity of bad odors, but the odor of the chlorin gas given off is disagreeable and in considerable quantities poisonous, and furthermore it has a very destructive action on metals, so it must be used with discretion. Formaldehyde gas, HCHO, or "formalin," which is a 40 / solution of the gas, is one of the recent disinfectants of great merit. It first came into general use in 1892. As it is a good germicide, has no injurious effect on fabrics and colors, and can be readily applied, it is taking the place of sulfur dioxid gas. There are several ways of applying the gas : A polym- erized formaldehyde, known as "paraform," is sold in pastilles, which when heated give off formaldehyde gas ; 2 oz. of paraform for 1000 cu. ft. of space, with an ex- posure of 12 hr., is recommended. A large number of lamps have been devised for vaporizing the liquid formalin or the paraform. Another method of generating the gas is to use " baignetti, " which contain a core consisting of 50 grams of paraform. As the baignette burns slowly the paraform is volatilized to formaldehyde. The objects to be disinfected DISINFECTANTS, ANTISEPTICS, AND DEODOBANTS 115 may be sprinkled with formalin, and inclosed in a tight box, so that they may be subjected to the vapor for several hours. Another method is to wet sheets with the solution and hang them in the room, which is tightly closed, for some time. Still another method, which may be used on a large scale, is to vaporize the formaldehyde gas in a retort outside the room, and force it through an opening into the tightly closed space. Mercuric chlorid, HgCl 2 , or "corrosive sublimate," which stands probably at the head of all substances used as disinfectants and antiseptics, is a deadly poison. In solutions of 1 : 15,000 it stops decomposition, and a 1 : 2000 solution will kill most bacteria in two hours. If of 1 : 500 strength, it will act very quickly on bacteria and spores. It was said by Koch to exercise a restraining in- fluence on the development of the spores of anthrax bacillus, even when present in the proportion of 1 : 300,000, but recent experiments show that its germicidal power was overrated. It is of importance to note, however, that mercuric chlorid is not very efficient where there is much albuminous material, because it so readily forms with the latter an insoluble substance. If a wound is produced by a rusty nail or by any blunt instrument, so that the flesh is lacerated, it should be opened as well as possible, and cleansed with warm water and then filled completely with a solution of corrosive sublimate (1 to 1000), or a solution of carbolic acid of 5% strength should be injected to destroy any dangerous bac- teria that may be present. Dr. Sternberg recommends the following as a convenient solution of corrosive sublimate for general use: Mercury bichlorid 1 oz. Copper sulfate 1 lb. Water 1 gal. 116 SANITARY AND APPLIED CHEMISTRY The advantage of this solution is that we not only mix with the chlorid of mercury a valuable disinfectant, but the solution is colored blue, and so it is less liable to be used accidentally. It should be marked " Poison." PAET II CHEMISTRY OF FOOD CHAPTER X USE OF FOODS IN the consideration of so broad a subject as food, there is difficulty at the outset in giving it a satisfactory defini- tion. The growth and repair of the body, as well as the potential energy by virtue of which the body is able to do actual work, need to be taken into account. Food has been defined as, "Anything which, when taken into the body, is capable either of repairing its waste or of furnishing it with material from which to produce heat or nervous and muscular work." l It is important to distinguish between food and medicine, and to notice that the latter may revive some vital action but will not supply the material which sustains that action. There are, however, many articles of diet, such as tea and coffee, and the food accessories, such as spices and condiments, which, although they do not strictly come within the above definition, are often useful to stimulate the appetite or to make the food more agreeable. It is by no means essential that a single food should con- tain all the nutrients needed by the body, and in fact it is desirable that there should be a variety of food to stimulate the appetite and vary the character of the work which the organs of digestion are called upon to perform. Food may contain substances which must be broken up or decom- 1 Hutchison, " Food and Dietetics," p. 1. 117 118 SANITARY AND APPLIED CHEMISTRY posed by the body before it is of value, or it may contain substances which can immediately be taken into the circu- lation and utilized. Some food is of use because it furnishes nearly all the nutritious substances needed by the body, while other foods furnish some special material in an economical or agreeable form. Some act readily in sustaining the body, or are easily digested ; others are economical and offer a maximum amount of nourishment at a minimum cost. Not only does food sustain the body, but there is a pro- vision of nature that animals should derive great pleasure and satisfaction from eating, and this pleasure is due to both the sense of smell and that of taste; it is difficult to consider the function of one without that of the other. Since these senses have not been cultivated as highly as the others, there is much room for further development; but there are some trades, such as that of the tea taster, the wine sampler, and the perfumer, where they are cultivated and utilized. The student of physiology finds it difficult to classify the sense of taste and smell, but it is possible to test the relative delicacy of these senses for various sub- stances in different individuals. Some experiments 1 made by the author for the delicacy of the sense of taste, with a number of persons of both sexes, showed that it was possible to detect BY MALES (1 part in) BY FEMALKS (1 part in) 1 Bitter substance (quinine) 392,000 456 000 2 Acid substance (sulfuric acid) .... 2080 3280 3 Salt substance (sodium chlorid) . . . 2240 1980 4 Sweet substance (cane sugar) .... 199 204 6 Alkali substance (baking soda) . . . 98 126 1 Science, Vol. XI, p. 145. USE OF FOODS 119 This showed that the sense of taste for bitter substances was far more delicate than for other classes, and that, ex- cept in the case of salt, the females could detect smaller quantities than the males. A separate set of tests made upon the pupils in a large Indian school l showed the same order of delicacy. The knowledge that man has obtained as to which foods are wholesome and which are poisonous is largely the result of experience, and this experience was transmitted and grew from one generation to the next. Much is due, then, to our ancestors, who have had the courage to explore in the realm of untasted food. Even now, fatal mistakes in the selection of food are sometimes made, and children must in every generation be warned against brilliantly colored berries. In the early ages the variety of food was not as great as now, for the people not only had less skill in preparing and less experience in selecting food, but they were obliged to depend on the chase, or to use only that food which was ob- tained in the immediate vicinity of their dwellings. They were not able to draw on all climates as we do, nor could they preserve the fruits of one season to consume in another. Grain was stored, fruits were dried, and meats were salted or dried, but beyond this little was done to preserve food. A mixed diet, then, may be considered as evidence of ad- vancing civilization. The palate becomes surfeited with too much of one kind of food, and so a change is welcome to stimulate the appetite. A monotonous diet is often a matter of necessity, but as soon as man has the oppor- tunity to indulge in a mixed diet he is not slow to take ad- vantage of it. With increased civilization the diet becomes more mixed in character, and on this account it does not interfere with the health to move from one locality or cli- mate to another. 1 Rons. Univ. Quarterly, Vol. II, p. 96. 120 SANITARY AND APPLIED CHEMISTRY There is no doubt that man, as well as the lower animals, is benefited by a variety in food. It has been stated that "digestion experiments made with one kind of food material do not give on the whole as valuable results as those in which two or more food materials are used. In other words, it appears that with a mixed diet the same person will digest a larger proportion of nutriment than with a diet composed of a single food material." It is, of course, admitted that a mixed diet may present greater temptations to overindulgence in food. It stands to reason that as some foods are too rich in proteids and others contain too large a proportion of carbo- hydrates, we should mix these in the proper quantities. This we do when we eat "bread and cheese," potatoes and beef, or rice, eggs, and milk in puddings. As the system adapts itself to a certain kind of food and the stomach secretes gastric juice sufficient in kind and quantity for that food, it is not advisable after being ac- customed to one kind of diet for a long time to change too suddenly to one that is entirely different, for indigestion may result. The food selected should be suited to the habits, age, and employment of a person. A sedentary man will not thrive on a diet that is too stimulating, nor one engaged in active manual labor upon starchy foods alone. The food that is readily digested by an adult will be not at all adapted to the use of a young child. There seems to be an instinctive selection of particular classes of foods for special climates the Eskimo eats large quantities of whale blubber or fats; the Congo natives live mostly upon the plantain; the Polynesians subsist almost wholly on bread fruit. Even in the temperate zone we find that less meat is eaten in warm weather. Food, in order to be agreeable and wholesome, is usually cooked. This is necessary, USE OP FOODS 121 First, to improve its appearance and to make it more agreeable to the eye and thus more appetizing. Second, because warm food is often more agreeable than cold. Third, to improve the flavor and develop the odor, par- ticularly in the case of meats. Fourth, in order to destroy any parasites or micro- organisms that may be contained in the food. Fifth, to bring about certain chemical changes in the food, that the better adapt it to digestion. Sixth, to soften the material so that it may more readily be acted upon by the digestive fluids. When proteids, such as meat or eggs, are acted upon by heat, even if the temperature is not above 170 F., they are coagulated and made more solid, but they are not so tough, and the bundles of fibers may more easily be torn apart. When starchy food, as grains or potatoes, is cooked, the granules swell up, the outer cellulose envelope bursts, and thus after mastication the digestive ferments have an oppor- tunity to come more intimately in contact with the starch. According to Sykes, moist heat, even below 185 F., causes most starch grains to burst, so that the starch is said to be gelatinized. 1 Food must be of such a character that it will build up the tissue of the body and supply it with energy for doing work. Incidentally the heat of the body is kept up by cell action, or, as one author puts it, ."is a by-product" of functional activity. It is not necessary nor advisable, however, that all the food taken into the body should be positively nutritious. It will be a long time before the dreams of those who propose that we carry concentrated, or perhaps "synthetic," foods for several days' rations in the vest pocket will be realized. Not only would such 1 Hutchison, "Food and Dietetics," p. 378. 122 SANITAEY AND APPLIED CHEMISTRY food soon become positively insipid and disagreeable, but there is an absolute necessity for a certain amount of inert matter to distend the walls of the alimentary canal and distribute the nutrient material so that it may the more readily be absorbed. Too large an amount of indigestible material in the food is, on the other hand, not satisfactory, for not only does it require of the different organs an undue amount of work in handling it, but the indigestible material may act as a positive irritant in the stomach and bowels. Too coarsely ground cereals sometimes overstimulate and irritate the mucous surfaces and thus become a source of impaired digestion. Not only should the food contain the nourishing material, but this should be of such a character that it is just adapted to the wants of the body. In order to find out what the human body needs for its sustenance we may notice either the composition of the body, or we may study milk, which is the food provided by nature to nourish the young. The body contains the following chemical elements : oxygen, carbon, hydrogen, nitrogen, phosphorus, sulfur, chlorin, fluorin, silicon, cal- cium, potassium, sodium, magnesium, iron, manganese, and copper sixteen in all. The fact that these elements are found, however, means very little, if we have no information as to how they are combined, what proximate substances or compounds they form, for these elements might be combined to form innu- merable substances. According to a recent authority, 1 the body of a man weighing 154 pounds is made up of the following com- pounds, in approximately the quantities noted: i A. H. Church, " Food," p. 6. USB OF FOODS 123 POUNDS OUNCES Water, found in all the tissues Albumen, myosin, etc., found in muscular flesh, chyle, lymph, and blood Calcium phosphate, found in tissues and liquids, but chiefly in the bones and teeth .... Fat, distributed through the body .... Ossein, or collagen, found in the bones and connective tissues Creatin, etc., in the skin, nails, and hair . . Cartilagan, found in the cartilages .... Haemoglobin, a substance containing iron, found in the blood Calcium carbonate, in the bones Neurin with lecithin, cerebrin, and similar com- pounds, found in the brain, nerves, etc. . . Calcium fluorid, found in the bones and teeth Magnesium phosphate, chiefly in bones and teeth Sodium chlorid, throughout the body . . . Cholesterin, inosite, and glycogen, which are found in brain, muscle, and liver .... Sodium sulfate, phosphate, carbonate, &c., found in all liquids and tissues Potassium sulfate, phosphate, and chlorid, found in all liquids and tissues Silica, found in hair, skin, and bone . . . 109 16 8 4 4 4 1 1 1 8.0 12.0 8.0 7.8 2.0 8.0 8.0 0.8 13.0 7.4 7.0 7.0 3.0 2.2 1.7 0.1 Besides the above there are other complex compounds which occur in small quantities, but which are none the less of importance. Each of the proximate principles is made up of two, three, four, or possibly more, elements, and the compounds thus formed are some of them very com- plex in their structure. No classification of food is very satisfactory, for although we may adopt the classification of Liebig and divide the 124 SANITARY AND APPLIED CHEMISTRY foods into the carbonaceous, or those which furnish heat, and nitrogenous, or those whose function it is to build up the body and furnish muscular energy, we are met at the outset by the fact that a large number of foods partially fulfill both functions. The cells of the body may draw their sup- ply of energy from proteids, albuminoids, carbohydrates, or fats ; but material for the manufacture and repair of tissues must come from the proteids. Heat is produced as a result of cell action. 1 The proximate substances that go to make up foods include (1) water, (2) fat, (3) carbohydrates, (4) protein and related nitrogenous bodies, (5) organic acids, and (6) the mineral salts. Water, although absolutely essential as a con- stituent of the food material, need not be considered in the light of a nutrient. The fats which occur both in vegetable and animal foods are glycerids of the fatty and other acids. They contain only carbon, oxygen, and hydrogen. The oxygen is not present in sufficient quantity so that with the hydrogen it would form water. Fats are more fully dis- cussed under Soap, p. 96, also on p. 49 and in Chapter XVIII. CARBOHYDRATE FOODS The carbohydrates include, with a few exceptions, only those compounds of carbon, hydrogen, and oxygen in which the hydrogen and oxygen are in the proportion to form water ; that is, two parts of hydrogen to one of oxygen. This group includes such common foods as starch (C 6 H 10 5 ) n and cane sugar (CtfH.gjOn). These foods may be divided into: 1. The cellulose group (QJlJd^u including cellulose, starch, inulin, dextrins, gum, etc. 2. The cane-sugar group (C^H^On), including cane sugar, milk sugar, maltose, etc. 1 Hutchison, "Food and Dietetics," p. 3. USE OF FOODS 125 3. The glucose group (CgH^Og), including dextrose, levu- lose, grape sugar, starch sugar, and galactose. In addition to the above, inosite, C 6 H 12 6 ,H 2 0, which oc- curs in muscular tissues, and pectose, the jelly-producing substance of vegetables, should according to some authors be classified as carbohydrates. The ordinary analysis of a food stuff includes a determina- tion of the amount of water, fat, nitrogenous matter, carbo- hydrates, and ash. A study of these analyses is of value in the comparison of different foods. CHAPTER XI CELLULOSE, STARCH, DEXTRIN, ETC. CELLULOSE (C 6 H 10 5 ) n is the main product of vegetable life, and forms the principal part of wood, cotton, filter paper, etc. In fact, cotton fiber, linen rags, and " washed " filter paper are nearly pure cellulose. It is insoluble in most chemical reagents, but may be dissolved in cuprammonia, and from the solution the cellulose may be precipitated as a gelatinous mass which is similar to aluminum hydroxid in appearance and dries to a hard mass. When cotton or paper is treated with a mixture of nitric and sulfuric acids, a substance called nitrocellulose is formed. One variety of this substance is gun cotton. When the nitrocellulose is dissolved in ether it yields collodion. Another product known as celluloid is made by dissolving certain varieties of nitrocellulose in ether and camphor, and afterwards evaporating off the solvent. There are some special properties of cellulose, which are illustrated in the experiments which follow this section. Although some of the lower animals, as the rodents, can digest cellulose and make it available for nutrition, the stomach of man has this power only to a limited extent. According to Atwater some of the cellulose of the food is absorbed, but much of it passes through the system un- changed and is of value only as it helps distend the alimen- tary canal. Whatever digestion takes place in the intestines is due to the action of certain microorganisms, by which fatty acids are produced, which upon absorption yield nutriment. 126 CELLULOSE, STABCH, DEXTRIN, ETC. 127 Herbivorous animals eat food that contains large amounts of cellulose associated with smaller quantities of starch, fat, and nitrogenous substances. Experiment 64. To 3 volumes of water add 1 volume con- centrated sulfuric acid and cool the mixture. Pour this into an evaporating dish, and immerse in it strips of unsized paper, and allow to soak for about 15 seconds. Wash thor- oughly, first with water, then with dilute ammonia solution, and again with water. Dry the parchment paper or amyloid thus obtained, and notice its peculiar properties. Although it has undergone a physical change, it still has the composi- tion of paper. Unsized cloth may be treated in the same way. Experiment 65. Another sample of unsized paper is treated with strong sulfuric acid, and allowed to stand for 5 minutes. It dissolves into a pulpy mass, which is then washed thoroughly, and tested with tincture of iodin. If a purple color is produced, it is an indication that the cellulose has been changed to dextrin. Experiment 66. To show the action of alkalies on cellu- lose, treat a piece of cotton cloth for 20 minutes with a solu- tion of sodium hydroxid of a specific gravity of 1.25. Wash and dry, and notice the change in the structure of the fiber. This is practically the process used to make " mercerized " goods. In this process the linear contraction is about 25%, and the increase of strength is 50%. Experiment 67. Make cuprammonia (Schweitzer's re- agent), Cu (NH 3 ) 4 S0 4 , as follows: Add to a cold solution of copper sulfate, Cu SO^ a cold solution of sodium hydroxid, filter, wash, and dissolve in concentrated ammonium hy- droxid and add a little dilute sulfuric acid. Schweitzer's reagent should be freshly prepared, and "should be capable 128 SANITARY AND APPLIED CHEMISTRY of immediately dissolving cotton or fine grades of filter paper. It may be used to dissolve cellulose from pectose, in working with the microscope. Experiment 68. Dissolve cotton or filter paper in Schweitzer's reagent, and add to the solution an excess of hydrochloric acid. This will precipitate the cellulose, which may be washed on a filter so that its properties can be examined. STARCH (C a H 10 5 ) x The starches are regarded as the most important of the foods of this group; indeed, they form the principal part of most vegetable foods. Starch is stored up in seeds, roots, fruits, and vegetables, and is adapted for food purposes; and so it is utilized by man and the lower animals. As the bee stores honey for future use, so the plants store starch for the use of the germinating seed, and man takes advantage of both kingdoms of nature. The carbohydrates circulate through the plant in the form of sugar, but they are stored up in the form of starch, and this store can be drawn from by the plant in time of need. Sources of Starch. The most important source of starch is the cereals. The amount of starch contained in some grains is as follows : PER CENT PM Cwrr Wheat flour 76.6 Rice 79.4 Graham flour 71.8 Buckwheat flour .... 77.6 Corn meal 71.0 Barley 62.0 Oatmeal 68.1 Sorghum seed 64.6 Rye flour 78.7 Millet 60.0 Various roots, tubers, and stems are also sources of starch, as follows : l 1 For complete composition, see " Foods, " by A. H. Church. CELLULOSE, STARCH, DEXTRIN, ETC. 129 PER CENT PEE CENT Potato 18.0 Artichokes (gum and inulin) 10. 2 Yam 16.3 Sweet cassava (tapioca) . 30.98 Sweet potato .... 16.0 Arrowroot ( Maranta arundi- Carrots (pectose) ... 2.5 nacece) 22.93 Parsnips 3.6 Onions (pectose, etc.) . . 4.8 Turnips (pectose) ... 3.0 Radishes (carbohydrates) . 4.6 Beets (pectose) .... 2.4 Some less familiar sources of starch are the Bitter cassava (tapioca), Salep (orchids), Tous les mois (Canna edulis), the sago palm, and celery roots. The leguminous plants also furnish starch, thus : PER CENT PER CENT Beans 67.4 Peanuts 11.7 Peas 51.0 Soy beans 12.5 Lentils 56.1 There is some starch in all fruits, but those mentioned are of special value on account of the amount which they contain: PEB CENT PER CENT Bananas 22.0 Breadfruit 14.0 Plantain 15 to 20 Some nuts contain considerable starch, thus : PER CENT PER CENT Acorns 43.35 Horse chestnuts . . . .68.25 Chestnuts 42.1 Of the above, the most important commercial sources of starch are wheat, corn, rice, potatoes, acorns, and chestnuts. A special variety of starch is also put on the market under the name of tapioca, arrowroot, and sago. The other starch-bearing vegetable products, as well as those specially noted, are used in some countries as food. TVHBAT The examination of the wheat grains by the microscope shows that upon the outside there are bran cells ; next to 130 SANITARY AND APPLIED CHEMISTRY these are cells of a thin cuticle ; within these are the gluten cells, and finally, nearer the center of the grain, are the starch cells. If a longitudinal section be made of a wheat grain, and it is examined by a microscope of low power, it will be found to be made up of the " germ," which is near one end, the "kernel," and the " bran," or outer envelope. 1 Wheat is a typical bread-making cereal. Its proteids differ from those of other cereals, and are composed chiefly of a globulin, an albumin, a proteose, and the two bodies, gliadin and glutenin. 2 The two latter form the gluten, and give the characteristic properties to wheat flour. The prod- ucts of wheat are used as human food in many forms. There are nearly a hundred different grades of food materials made from wheat by the patent-roller process of milling. 3 Wheat sown in the fall is called winter wheat, and that sown in the spring is spring wheat. The kernels of winter wheat are usually larger and softer than the spring variety. Spring wheat usually contains more gluten than winter wheat. In comparing the milling and the food value of wheat, it should be remembered that this depends largely on the amount of nitrogenous matter present. A high percentage of proteids is not always a sure indication of the milling value of the wheat. It is the gluten content of the flour on which the bread-making qualities chiefly depend. The per- centage of dry gluten is considered the safest index to use in the comparison of different samples of flour. A comparison of the analysis of different samples of wheat is of interest : 4 1 For full description, see Jago, "The Science and Art of Bread Making," p. 265. 2 Osborn and Voorhees, Am. Chem. Jour, Vol. XV, p. 392. Bui. 13, Pt. 9, U. S. Dept. Agric., Div. Chem. * Wiley, Bui. 45, U. S. Dept. Agric., Div. Chem. CELLULOSE, STARCH, DEXTRIN, ETC. 131 MOISTURE ALBUMI- NOIDS ETHER EXT. 3RUDE FlBEE ASH CARBO- HYDRATES Domestic .... 10.62 12.23 1.77 2.36 1.82 71.18 Foreign .... World's Fair, 1893 . Mean, given by Jen- kins & Winton 11.47 10.85 12.08 12.20 1.78 1.74 2.28 2.35 1.73 1.81 70.66 71.09 Spring . . . Winter . . . 10.40 10.50 12.50 11.80 2.20 2.10 1.80 1.80 1.90 1.80 21.20 72.00 Mean, by Konig Miscellaneous . 13.37 12.51 1.70 2.56 1.79 68.01 Spring Wheat . 13.80 19 KR 14.95 17 fiK 1.56 1 K 2.19 i ftft 67.93 fift 7 A. There are, however, some special varieties of wheat, including a Russian wheat, that contain more protein. Twenty-four analyses of this variety show an average of 21.56% of nitrogenous substances. 1 The ash of wheat contains about 30 % of potash, 3 % of lime, 12 lUO.O^ Mynstic,palmitic,and steanc acids 49.46 These results, and many others that might be quoted, show that butter fat is practically a mixture of various esters, those of butyric, palmitic, and oleic acids being the most abundant. The amount of stearic acid contained in butter is probably very small. The first four constituents are those which distinguish butter fat from ordinary fats like lard or tallow. It is by the determination of the amount of these that the chemist is able to distinguish between genuine butter and its imitations. The amount of fat varies from 3 % to 6.5 %, or even 7 %, in normal milk. In some countries any milk having less than 4 % of fat is considered adulterated, but the minimum 1 James Bell, from Allen's " Commercial Organic Analysis," Vol. II, p. 181. 244 SANITARY AND APPLIED CHEMISTRY amount allowed in many cities in the United States is 3 %. The Secretary of Agriculture in consultation with the Asso- ciation of Official Agricultural Chemists has adopted as a "standard" for milk, that it shall contain not less than 12% of total solids, and not less than 8.5 % f solids not fat, nor less than 3.25 % of milk fat. The fat in milk can be separated for laboratory purposes by shaking it out with ether, and then allowing the ethereal solution to evapo- rate. A practical method for the determination of fat is the one used in large dairies; that is, by the use of the Babcock tester. This instrument, invented by Professor Babcock of the University of Wisconsin, has proven of im- mense value to the dairy interests, as it is possible for the producer, as well as the" manufacturer, to know exactly the value of the milk. The first milk, called the " fore milk," which is drawn from the udder of the cow, is poor in fat, because the fat globules have risen to the top ; but for the same reason, the " strippings," or last of the milk drawn, is rich in fat. The cream may be raised upon the milk by allowing it to stand in shallow pans for a long time, by putting it in deep vessels and keeping it at a comparatively low temperature, or more recently, and more practically, by the use of the " separator." This is nothing but a centrifugal machine so arranged that the lighter cream shall, when the milk is whirled with great rapidity, come to the center and be car- ried off by a pipe, and the heavier milk shall be thrown to the outside by the same motion, and carried off to a sepa- rate receptacle. There is a fermented beverage known as "koumiss,* made from milk, which should be mentioned. It was originally prepared from mare's milk. It is made by mix- ing milk with yeast and some sugar, putting it in a bottle, and closely corking it. Fermentation takes place after MILK 245 two or three days, and the beverage is fit for use. It is used as a nourishing tonic for invalids and seldom contains as much as 2% of alcohol. Experiment 132. Shake a few cubic centimeters of milk with ether, allow the ethereal layer to separate out, draw it off with a pipette, and allow it to evaporate on a watch glass. This gives quite a pure grade of butter fat. Experiment 133. Determine the amount of butter fat in several samples of whole milk by the use of the Babcock tester. By the action of oil of vitriol on a measured quan- tity of milk, a great amount of heat is evolved, and the mixture turns dark brown upon the addition of hot water ; when the bottle is put into a "centrifuge" and whirled rapidly, the fat, which is lighter, collects in the narrow stem of the bottle. The graduations of this stem have such a relation to the quantity of milk used that the per cent of butter fat can be read directly upon it. The total solid matter in milk is also of use to the chemist in forming an opinion as to whether a sample has been diluted with water or not. The lowest amount of solids usually permitted in normal milk is 12 %, but most milk contains from 1 to 3 % more. Experiment 134. Test the sample of milk, the specific gravity of which has been already determined (Experiment 131) for " total solids," by weighing a small glass or porcelain evaporating dish on the horn-pan balance. Weigh into this about 5 cc. of the sample, and evaporate for about 2 hr., or till perfectly dry, on a water bath. Weigh the residue, and from this and the known weight of the milk, calculate the per cent of total solids. Reserve the residue for Experi- ment 136. The casein of milk exists apparently in the fresh sample as a soluble compound of albumin and calcium phosphate, 246 SANITARY AND APPLIED CHEMISTRY which by the action of " rennet," a ferment from the calf's stomach, is converted into an insoluble compound known as casein. The casein precipitate of rennet contains from 1 to 1.5% of ash, consisting almost entirely of calcium phos- phate. Lactic acid also precipitates the casein, but the pre- cipitate contains less ash than that separated by rennet. Mineral acids also precipitate a casein containing less ash. The proportion of albumin in milk is always, according to Blyth, about one fifth of the casein. The proteids of milk contain about 80 % of casein, which is not coagulated by heat but is coagulated by acids, about 15 % of lactalbumin, which is soluble and coagulates by heat and forms the skin on boiled milk, and a few minor ingredients. In the souring of milk, which is caused by certain acid- forming bacteria, part of the inilk sugar is changed into dextrose and galactose, and the latter sugar changes to lac- tic acid: Ci2H 22 11 ,H 2 = CgH^Oa + CeH^Og. C 6 H 12 6 = 2 C 8 H 6 3 . Lactose Dextrose Galactose Galactose Lactic acid This coagulates the casein, but when a certain degree of acidity is reached the ferment is killed, and the action stops. This suggests the change that takes place in wines (Chap. XXIII), for there also, as the alcohol increases, the ferment is destroyed. Coagulated milk is frequently used to make a kind of cheese which undergoes what is known as " butyric fermentation," producing an odor that by some is considered very disagreeable. After the casein has been separated from the milk by means of rennet, the whey, which remains, may be util- ized for making milk sugar. It is evaporated in a vacuum pan, purified by animal charcoal, and set aside to crystallize on sticks or strings that are hung in the vessel. The crystals have the formula C^H^O^HjO, and undergo lactic fermenta- tion readily, but alcoholic fermentation with difficulty. MILK 247 Experiment 135. Treat a sample of skim milk in a test tube with just enough dilute HC1 to cause it to coagulate, keep warm for some time, and filter. Burn a little of the " curd " which remains on the filter, and notice, from the odor, its nitrogenous character. Neutralize some of the filtrate (the whey) with sodium hydroxid, and test it by Fehling's solution (Experiment 82) for milk sugar. The ash of milk consists essentially of phosphates and chlorids of potassium, sodium, calcium, and magnesium salts that are especially needed for the growth of bone ma- terial in the young. A small quantity of citric acid is also found in milk in combination with lime. STERILIZED AND PASTEURIZED MILK Although milk which is drawn from a healthy, clean cow by clean hands into a bottle which has been sterilized is a sterile fluid, yet practically these conditions are not attained, and ordinary milk contains a variety of microorganisms. Some of these may produce souring and others may be bearers of disease. These organisms can be destroyed by a tempera- ture of 100 C., and a temperature of 75 C. will destroy most of the pathogenic bacteria. This process of heating is known as sterilizing, and although it is advocated for the treatment of milk for infants and invalids especially in large cities, yet the quality of the milk is decidedly altered. Some of the changes noticed in sterilized milk are : 1. A change of taste. 2. The amylolytic ferment is destroyed. 3. The fat is not so easily emulsified, and so cannot be so readily absorbed from the intestine. 4 The casein does not coagulate so quickly, and there- fore is not as digestible. 5. The lactalbumin is destroyed. On account of these changes produced by sterilization the 248 SANITARY AND APPLIED CHEMISTRY method of Pasteurization has come into vogue, except in those cases where the milk must be kept for several days. Pasteurization consists in keeping the milk at a temperature of 167 F., for 20 minutes, instead of raising the temperature to the boiling point, as in sterilizing. By this process most of the bacteria that are liable to be present in the milk, are destroyed, the taste of the milk is not so much altered, and its nutritive qualities are not seriously interfered with. This milk will keep only one or two days under ordinary conditions. CONDENSED AND EVAPORATED MILK It is extremely convenient under some circumstances to have at our disposal condensed, or evaporated, milk. This may be made from " whole " milk or from skimmed milk, and it may or may not be preserved with cane sugar. There is one product on the market which is obtained by boiling the milk first in open pans and then in vacuum pans. This product is served to customers fresh, and will only keep for a few days. Another product, one which is more commonly used in the United States, is canned milk. This is made by boiling down the milk in a vacuum pan and mixing with cane sugar and sealing in the cans while hot. This product will keep for a long time, but not indefinitely, as it is liable, after a time, to become ropy and unfit for use. The unsweetened variety is often called " evaporated milk " or " evaporated cream." The latter, however, is usually noth- ing better than whole milk evaporated in a vacuum pan. According to a report of the Massachusetts State Board of Health, the following is the analysis of a normal condensed milk : total solids, 74.29% ; milk solids, 32.37% ; cane sugar, 41.92% ; milk sugar, 11.37% ; proteids, 8.46% ; fat, 10.65% ; ash, 1.29% ; number of times condensed, 2.3. United States standard condensed milk should not contain MILK 249 less than 28 % of milk solids, of which not less than one fourth is milk fat. Although it must be admitted that in some cases condensed milk can be digested more readily than fresh milk, yet in general its chief defect is that it con- tains too little fat ; that is, the dilution that is necessary on account of the large amount of sugar present, reduces the per cent of fat much below that of normal milk. One of the newest milk products on the market is " dried milk. " This product, as well as " dried cream," is made by feeding continuously a thin sheet of milk between two steam-heated cylinders, revolving in opposite directions, and having a surface temperature above 100 C. The cyl- inders are slightly separated, and the milk is dried in 30 seconds, and scraped from the rolls by a knife edge. The product is mixed with warm water for use. MODIFIED MILK From an inspection of the table given on p. 242, it will be seen that human milk differs from cow's milk in several important particulars. The latter contains a little less fat, considerably less sugar, more proteids, and more ash. On this account a great demand has arisen for cow's milk so modified that it shall approximate human milk in composition. The general method adopted to render common milk better adapted to the feeding of infants is to bring the proteids and ash to the right proportions by dilution with water, then to increase the per cent of sugar by the addition of lactose, and finally to add cream and usually some limewater. ADULTERATION OP MILK The most common adulteration of milk is by the addition of water, but the acid of milk is sometimes neutralized by the use of baking soda, or various preservatives may be added to it, especially in warm weather. 250 SANITARY AND APPLIED CHEMISTRY Experiment 136. To detect sodium bicarbonate and borax in milk, the residue obtained in Experiment 134 is ignited to obtain the ash. After cooling, add a drop or two of HC1, and notice if there is any effervescence, which would denote the presence of carbonates. Test this acidified solution for borax by soaking in it, for a short time, a strip of turmeric paper, and allowing it to dry on the side of the dish above the solution. If the paper becomes of a dark cherry-red color when dry, and turns dark olive when treated with dilute sodium hydroxid solution, boric acid or borax has been added as a preservative. Experiment 137. To test milk for formaldehyde, use " For- maldehyde Reagent, " which is made by adding to a liter of commercial hydrochloric acid (1.2 specific gravity) 2 cc. of a 10 % ferric chlorid solution. Ten cubic centimeters of this reagent is added to 10 cc. of milk in a small porcelain casserole, and the solution is heated, slowly, nearly to boil- ing, and at the same time a rotary motion is given to the vessel to break up the curd. When formaldehyde is present there will appear a violet coloration, especially when it is partially cooled. The color of this solution will vary with the amount of formaldehyde present. If this preservative is absent, the solution slowly turns brown. This test is said to be delicate to . * . n if the milk has not soured. With L o U % -- sour milk the limit of delicacy is 50 * 00 . This test cannot be used when the milk is flavored with vanilla. CHEESE The general method of making cheese is by the addition of rennet to milk warmed to about 41 C. Rennet is the name given to an infusion in brine of the middle stomach of the calf. The rennet produces a coagulation of the milk by the action of an enzyme, which acts only in an acid or neutral solution. The coagulated milk, after having been broken MILK 251 up several times in vats and heated to a moderate degree, is inclosed in cloth, and the whey is pressed out. After the cheese has become solid, the molds are removed and the cheese is placed in well-aired rooms to cure. The flavor improves with age, from the development of fatty acids and ethers, and by the action of certain bacteria. A peptonizing enzyme has been recently discovered in milk, and to this is probably due the flavors that are induced in cheese during the process of ripening. As this process goes on, the cheese is turned daily and rubbed with oil. This improvement with age suggests what takes place in wines and liquors in the process of aging. Some yellow coloring matter, such as "annatto" or a coal tar dye, is frequently added to the cheese in the process of manufac- ture. Cheeses are generally classified as cream cheese, whole cheese, and skim-milk cheeses. Soft cheeses, like Brie, Neufchatel, and Cammembert, are made in a short time, and by coagulating with rennet at a low temperature ; i.e. below 30 C. Medium cheeses are allowed to drain for some time without pressure. The English "Stilton" and the Swiss "Gruyere" belong to this class. Hard cheeses, like "Cheddar," and the common cheese of the United States, is made by coagulating at a higher temperature 30 to 35 and then thoroughly pressing. The names applied to cheeses are frequently those of the locality from which they originally came. Limburger is. a soft, fat cheese. Roquefort is made from the milk of the ewe. Parmesan is a dry Italian cheese, with a very large amount of casein, and a moderate percentage of fat. Edam is a Dutch cheese, quite dry, and having a red coloring on the outside. The following compilation by Woll 1 shows the average composition of some common varieties of cheese. 1 Dairy Calendar, p. 223. 252 SANITARY AND APPLIED CHEMISTRY WATER CASEIN FAT SUGAR ASH Cheddar 34.38 26.38 32.71 2.95 3.68 Cheshire 32.59 32.51 26.06 4.53 431 Stilton 30.35 28.85 35.39 1.59 3.83 Brie 50.35 17.18 25.12 1.94 5.41 Neufchatel 44.47 14.60 33.70 4.24 2.99 Roquefort ... . 31.20 27.63 33.16 2 00 6.01 Edam 36.28 24.06 30.26 4 60 4.90 Swiss 35.80 24.44 37.40 2.36 Full cream ( average ) ... 38.60 25.35 30.25 2.03 4.07 It is evident that cheese is made up of about one third water, one third nitrogenous matter, and one fourth fat. The mineral matter is also of considerable importance. Cheese is so rich in nitrogenous matter, and also in fat, that it might properly form a valuable food for the poorer classes, while it is used by the more wealthy as a relish. A comparison with other animal foods shows very distinctly its theoretical value as food. It is rather difficult to digest in the stomach, unless finely grated or dissolved, as the fat protects the casein from the action of the digestive fluids. Protein and fat are often much cheaper in cheese than in meat. Kich cheese is very liable to decay, for it furnishes an excellent medium for the growth of living organisms. In 1884 Dr. V. C. Vaughan isolated from cheese the poison, which he called tyrotoxicon. This poison, which produces gastro- intestinal irritation and nausea, is developed in milk, ice cream, and cheese when the material is stored in dark, damp, filthy rooms or cellars, or where vessels used for holding the milk are not thoroughly cleaned for use. With proper care of the milk there is no danger of the development of this poison. MILK 253 About the only falsification of cheese, aside from the fraudulent sale of skim-milk cheese for fall-cream cheese, is the so-called " filled cheese," which is made by working into the material in the process of manufacture some foreign fat, as oleo or lard. BUTTER AND BUTTER SUBSTITUTES Commercial butter is somewhat granular in appearance, and this is considered a very valuable quality of butter. It has a fragrant odor and an agreeable taste. It contains more or less casein, which causes it to undergo decompo- sition, if the butter has not been thoroughly washed. Butter must be salted in order to preserve it for any length of time. The composition of butter fat has been noted under the discussion of milk. The proportion of these different fats varies within slight limits only, and on this account it is not difficult to distinguish between natural butter and oleomargarin, or a butter that has been adulterated with other fats. Cream which is obtained by the use of the separator should be allowed to ripen for some time before it is churned into butter. In this process of ripening, certain bacteria take an active part, and to such a degree is this the case that the variety of bacteria in the dairy affect very materially the quality of the butter. Indeed it has become the custom in some dairies to import bacteria, or some material containing bacteria of a specially high grade, so as to make a fine quality of " June butter." On the continent of Europe the people purchase butter every day for that day's supply only, as the butter is never salted, and as it usually contains considerable buttermilk it will not keep. Butter has the average composition: water, 13.59%; fat, 84.39%; casein, .74%; milk, .50%; lactic acid, .12 %; and salts, .66 %. 254 SANITARY AND APPLIED CHEMISTRY "Renovated," or "Process," butter is, in general, made as follows: Old, rancid, and unsalable butter is melted in a large tank, surrounded by a hot-water jacket, at a temper- ature of about 45 C. The curd and brine are then drawn off at the bottom and the scum is taken off from the top. Air is blown through the mass, to remove the disagreeable odor, and, after mixing with some milk, the mass is churned, and then run into ice-cold water so as to make it granular in structure. The butter is then ripened, worked to free it from buttermilk, and salted. Some states require that this should be marked " Renovated Butter " when exposed for sale, while others allow dealers to handle this product with- out restriction. The manufacture of artificial butter, butterine, or oleo- margarin has received encouragement, both in the United States and abroad, on account of the low cost, and also because the imitations are frequently better and more pala- table than low grades of cheap butter. The materials used in the manufacture of artificial butter are : " neutral " or leaf lard, from 25 to 60% ; oleo oil, from 20 to 50% : some vegetable oil, like cottonseed oil, from 5 to 25% ; milk or cream, from 10 to 20%; butter, from 2 to 10 or 12% ; salt and annatto or aniline coloring matter. For different grades of oleomargarin different quanties of these substances are used. " Neutral " is made by melting leaf lard, and allowing it to " grain " by letting it stand at a temperature favorable for the separation of the stearin in coarse grains. Oleo oil is made in immense quantities, both for use in the manu- facture of butterine in the United States, and for shipment abroad. The process of manufacture is to cut the beef fat into small pieces and " render" it in water-jacketed kettles at the lowest possible temperature that is practical. The scum which separates at the top is drawn off and the scraps settle MILK 255 to the bottom. The liquid fat is then run into vats, where it becomes partially cool. The semiliquid mass is wrapped up in cloths and pressed to remove the liquid oil from the solid fat. The solid fat, known as oleo-stearin, is used in the tanning and leather trades, by candle makers, for the manufacture of soap and of " compound " lard. The oleo oil is used in the manufacture of oleomargarin. For the manufacture of oleomargarin certain proportions of the ingredients, mentioned above, are churned and run into ice water to cool the mass rapidly, and then worked like ordinary butter. The particular variety made depends upon the market. The manufacturers exercise great care that the process shall be a clean one, and most authorities agree that a good quality of butterine is better than a bad quality of butter. At the instance of the dairy interests of the United States, however, a tax probably intended to be prohibitory has been levied upon butterine. This tax is very small, 1 cent per pound in case the butterine is not colored. If it is colored in imitation of butter, the tax is 10 cents. Until this law was passed at a recent session of Congress, the manufacture of butterine constantly increased, even though the industry was obliged to bear a small tax. In 1903 the total product of oleomargarin was but 71,237,438 Ibs., while the previous year it was 123,133,852 Ibs. Experiment 138. Place about 5 grams of butter in a small flask, add to it 30 cc. of a solution of potassium hydroxid in alcohol, and warm on a water bath. After the soap has had time to form, and while some alcohol still remains, add about 30 cc. of dilute sulfuric acid, and warm, the solution. Notice the peculiar odor of butyric ether, especially if the solution is allowed to stand. Experiment 139. Foam test for purity of butter. Heat about 3 grams of the sample in a large iron spoon over a low 256 SANITARY AND APPLIED CHEMISTRY Bunsen flame, stirring constantly. Genuine butter will boil quietly, with the production of considerable froth or foain, which may, on removal from the flame, boil up over the side of the spoon. Renovated butter or oleomargarin will sputter and act like hot fat containing water, but will not foam. Examine also the curdy particles when the sample is removed from the flame; in the case of genuine butter these particles are small and finely divided, but in the case of oleomargarin the curd will gather in large masses. Experiment 139 a. To make the " milk " test for butter, place about 60 cc. of sweet milk in a wide-mouthed bottle, which is set in a vessel of boiling water. When the milk is thoroughly heated, a spoonful of the butter is added and the mixture is stirred until the fat is melted. The bottle is then placed in a dish of ice water, and the stirring con- tinued until the fat solidifies. If the sample is butter, either fresh or renovated, it will be solidified in a granular con- dition and distributed through the milk in small particles. If, on the other hand, the sample consi&fe of oleomargarin, it solidifies practically in one piece, so that it may be lifted by the stirrer from the milk. By the two tests just described, the first of which distinguishes fresh butter from process or renovated butter and oleomargarin, and the second of which distinguishes oleomargarin from either fresh butter or renovated butter, the nature of the sample examined may be determined. 1 Experiment 140. To test for coal tar colors in butter, a small sample is mixed on a porcelain plate with Fuller's earth, and if they are present, there will be a red mass, while if absent the color will be only light yellow or brown. i Bigelow and Howard, U. S. Dept. Agric., Bu. Chem., Bui. 100, p. 51. CHAPTER XXII BEVERAGES THE ordinary beverages, not including milk, may be classified as nonalcoholic and alcoholic. NONALCOHOLIC BEVERAGES From the earliest time there has been a demand for some slightly stimulating beverage that is nonintoxicating in character. The simple herb drinks, such as catnip tea, sage tea, sassafras tea, etc., have been used and are more agreeable than hot water alone, which in itself is slightly stimulating. It is interesting to observe that in the very early history of the world, people, in different countries and under different conditions, selected certain plants which seemed to be stimulating in their effects, and made bever- ages from them. It was later found out that the plants so selected contain certain active principles which were stimulating in character. The most important of the beverages at present in use are tea, coffee, and cocoa. There is a growing demand for tea in the United States. The imports of tea for 1905 were 96,779,145 Ibs., valued at $15,003,588. The importation of coffee in 1905 amounted to 893,889,352 Ibs., valued at $75,307,536. The importation of cocoa (crude) for 1905 amounted to 79,722,791 Ibs., valued at $8,965,387, besides 923,127 Ibs. of manufactured cocoa products. 1 The per capita consumption of these beverages in 1903 is reported, 1 Bui. Dept. Com. and Labor. Dec. 1905. 8 257 258 SANITARY AND APPLIED CHEMISTRY for tea 1.30 Ibs., for coffee 10.79 Ibs. In Great Britain the per capita consumption of tea is four times that of the United States, while the per capita consumption of coffee is only one tenth that of the United States. TEA About 51% of our tea comes from China and 42% from Japan. The history of the discovery of tea is lost in antiq- uity. The first authentic account was as late as 350 A.D., while in European literature the earliest record appears in 1550. The first consignment of tea into England took place in 1657, and it came into the United States in 1711. Genu- ine tea is prepared from the leaf of the Thea sinensis, a plant which grows to the height of 4 to 5 ft. The leaves are ready for picking at the end of the third year, and the average life of the plant is about 10 yr. The leaves are picked at least three times per year, in April, May, and the middle of July. The first pickings are the best and tenderest, and make the best grade of tea. PREPARATION OF THE TEA After sorting, the natural moisture is partially removed by pressing and rolling, then the leaves are dried by gently roasting in an iron pan for a few moments. They are then rolled on bamboo tables and again roasted, and finally sepa- rated into the various grades by passing through sieves. The difference between green and black tea is mainly due to the fact that the green is steamed thoroughly and then rolled and carefully fired, whereas black tea is first made up into heaps which are exposed to the air and al- lowed to ferment, and thus the olive-green is changed into a black color. In the preparation of Japan tea, the leaves are steamed in a tray over boiling water. They are then heated on a tough paper membrane over an oven and at the same time BEVERAGES 259 stirred with the hand. The tea after being thus fired is dried for some hours and sorted by passing through sieves. Then it is sent to the warehouse, where sometimes the " facing process " is carried on, by heating the tea in large bowls and adding various pigments to it. There are but few spurious teas on the market, but the range in quality is very great. On account of the strict enforcement in the United States of the adulteration act, no adulterated tea is permitted to be imported, and the con- sumer is reasonably well protected. He usually secures genuine leaves though he may get very inferior grades of tea. Tea, as prepared for the foreign market, is exposed to a large number of sophistications and adulterations, mainly for giving it an increased weight. These adulterations include adding foreign leaves, spent tea leaves, metallic iron, sand, brick dust, etc. Again, substances, such as catechu or similar materials that contain tannin, are added to produce an artificial appearance of strength. Another sophistication, which is practiced especially on green tea, consists in imparting a bright appearance to inferior tea by means of coloring mat- ter or facing ; for this purpose they use soapstone, gypsum, Prussian blue, indigo, turmeric, and graphite. Another form of sophistication is practiced on exhausted tea leaves by a similar process of facing. It is even said to be possi- ble, by careful manipulation, to change black tea to green and vice versa. The Indian teas are very much stronger than those from China and Japan, so that they produce a beverage that seems too strong to those accustomed to Chinese and Japanese teas. The Indian teas only come in contact with the hands of the workmen at the time of picking. The Chinese teas are manufactured almost entirely by hand, although sometimes the feet are used in rolling the cheaper grades. 260 SANITARY AND APPLIED CHEMISTRY A substance called " lye tea " is frequently put upon the foreign market. This consists of fragments of genuine leaves, foreign leaves, and mineral matter held together by a starch solution and colored with various preparations. It is prob- able that the addition of foreign leaves is but little practiced at the present time in the United States. In England black teas are used much more than the green. This is due to the supposition that black teas con- tain less astringent matter and also act less upon the nerves. By comparison of analysis of black and green tea it is evi- dent that there is less material soluble in hot water in the former. 1 GREEN TEA BLACK TEA Crude protein .... Fiber 37.43 10.06 38.90 10.07 Ash 4.92 4.93 Thein 3.20 3.30 Tannin 10.64 4.89 Total nitrogen .... 6.99 6.22 The important constituents are the extract, a certain amount of tannin and thein, and the volatile oil. On account of the presence of a large amount of tannin in tea, which is extracted by heating with water, it is important, in making the beverage, that the water should not stand for any length of time upon the leaves. On this account a much more wholesome beverage may be made by the use of the tea-ball with the hot water. It is a great mistake to allow the tea to draw, as the saying is, for hours at a time. Freshly boiled water should be used in making tea, and it should be thoroughly boiling when poured upon the leaves, and allowed to digest about three minutes, not 1 Analysis by Kozai : W. G. Thompson, "Practical Dietetics," p. 211. BEVERAGES 261 longer. Longer infusion will make the tea appear stronger but will spoil its delicate flavor, and extract too much tannin, which will have an injurious effect on the system. The water used should not be too soft, as that will extract more soluble material, nor should it be extremely hard. The thein is practically all extracted from tea within the first five minutes, while the amount of tannin continues to increase for 40 minutes or more. The infusion should be poured off from the grounds as soon as made. According to Hutchison an ordinary cup of tea will con- tain nearly a grain of thein, and from 1 to 4 grains of tannin, dependent on the kind of tea used. There is no direct relation between the quality or price of the tea and the proportion of thein. This substance, thein, which has the formula C 8 H 10 N 4 2 , is an ureide belonging to the same general class as guaranin, xanthin, uric acid, etc. The vola- tile oil which is present gives to the tea its agreeable flavor and aroma. Experiment 141. Make a decoction of tea in a test tube, pour it off from the grounds, and test a part for tannic acid. First, by ferric chlorid ; Second, ferrous sulf ate ; Third, by a mixture of the two reagents. A black or bluish black color (ink) will be produced. PARAGUAY TEA There is another variety of tea known as Paraguay tea, or Yerba Mate, which was selected by the people of South America to use as a beverage. This tree grows wild, and is known to the botanist as Ilex paraguayensis. The tea is prepared in Paraguay by cutting off the small twigs and leaves and placing them on a clean plot of earth surrounded by fire. In this way the leaves are wilted and cured, and they are afterward dried on a grating over a fire, and then 262 SANITARY AND APPLIED CHEMISTRY reduced to a coarse powder. The infusion, which is pre- pared in a kind of gourd, is conveyed to the mouth by means of a reed or a silver tube called a "bombilla," with a strainer at the end. Mate' contains 1.3% of thein and 16% of tannic acid, also an aromatic oil and gluten. The tannic acid has entirely different properties from that contained in tea or coffee. COFFEE LEAF TEA In some coffee-growing countries the natives use the leaves of the coffee tree to make an infusion which has about the same constituents and properties as ordinary tea. COFFEE Coffee is the seed of the Coffea arabica, indigenous in Abyssinia and Arabia, and this plant, at the present time, is grown in Java, the West Indies, in Ceylon, Mexico, and Central and South America. It was used in the remotest time in Arabia. It was introduced into Constantinople in 1574; in 1660 it was carried from Mocha to Java, and thence specimens of the tree were taken to Holland and France. Coffeehouses were opened in London about the middle of the seventeenth century. In 1809 the first cargo was shipped to the United States. There is a great difference in the quality and flavor of coffee from different localities. The coffee tree is productive for about thirty years. The trees are usually planted every twenty years and grow best on the uplands. The trees are raised from seeds in nurseries and transferred to the plantations. In Java the picking of the berry begins in January, and lasts three or four months ; in Brazil, the picking begins in April and May, and continues throughout the season. After the berries are harvested, the first operation by which they are treated is called pulping. Sometimes the berries are BEVERAGES 263 pulped in the soft state, sometimes they are first dried, and then the dried skins are removed by a machine called a huller. The West India and Brazilian method is to macer- ate the berries in a large vat, where they are treated by what is known as a pulping machine, which is an iron cylinder set with teeth, which removes the outer covering. The loosened pulp is carried out at one side and the berries sink to the bottom of the vat. The berries are afterward dried, cleaned, and sorted. The next process is the roasting of the bean. This may be carried on directly over a fire or in an oven. The average loss of weight in the process of roasting is about 16%. This process develops an essential oil and brings out the aroma of the coffee. If the operation is carried too far, the best properties and ingredients are lost. The following analysis by Konig shows the difference be- tween raw and roasted coffee : RAW COFFEE BOASTED COFFEE Water . . 11.23 1.15 Caffein 1.21 1.24 Fat 12.27 14.48 Sugar 855 66 Cellulose 18.17 10.89 Nitrogenous substance 12.07 13.98 Other non-nitrogenous matter 32.58 45.09 Ash 3.92 4.76 The effect of roasting is to drive off a large part of the water, and to caramelize most of the sugar. The bean becomes more brittle, and the caffeol 1 (C 8 H 10 2 ), to which coffee largely owes its odor and flavor, is, at the same time, 1 Hutchison, "Food and Dietetics," p. 310. 264 SANITARY AND APPLIED CHEMISTRY developed. The active principle, called thein, or caffein ( CgHj^Oa), is believed to be identical with that of tea. The infusion of coffee also contains some nitrogenous material. Ground coffee is especially liable to be adulterated. Some of the chief substances added to the commercial ground coffee are chicory, caramel, peas, and roasted grains, such as corn, wheat, and rye. There has also been found upon the market an artificial coffee bean which contains absolutely no coffee, and is made by compression of harmless, starchy ingre- dients into the form of the coffee bean. This is mixed with the genuine beans. The raw coffee bean is sometimes sub- jected to the process of sweating, by which it is increased in size and improved in color and flavor ; it is sometimes moistened with water containing a little gum and colored with various pigments, such as Prussian blue and turmeric, so as to improve its appearance. In this way, for instance, Mexican coffee is made to resemble Java coffee. In regard to making the beverage coffee, there are two methods, either of which may be used. The first is to put ground coffee into cold water and bring the decoction to the boiling point. The second, and probably better, method is to have the water boiling tumultuously and add to it the required amount of finely ground coffee, boil not more than three minutes, and then serve immediately. If the coffee is allowed to boil for any length of time, not only is the tannin extracted from the berry, but the agreeable aroma and flavor is lost, as it is carried off with the volatile oil. The coffee is then not as wholesome, and it certainly is not as agreeable in flavor. Many persons find that black coffee produces less ill-effects upon the system than does coffee served with cream. This may be due to the compound produced by the action of the tannin of the coffee upon the proteid substances of the milk. Ga.fi au lait, which is a mixture of three parts of hot milk BEVERAGES 265 with one part of coffee, is a popular beverage in many countries. It will be noticed that coffee contains less of the alkaloid than tea. There are many varieties of coffee upon the market, but the Mocha and Java coffees usually command the highest price. The low grades of coffee have decreased very much in price during the last few years. This is probably due to the competition, and, also, to the fact that immense quan- tities of the cheaper grades are raised in South and Central America. The latest official report (1905) shows that three fourths of the coffee imported into the United States comes from Brazil. The coffees range in price from 8 cents to 45 cents per pound at retail. Some persons have become accus- tomed to the strong black coffee made from the Bio brand, and to meet their demand, in " blending," some Bio is often added to other grades. There is no great objection to the substitutes for coffee that are upon the market, if they are not bought as coffee. Many of these are no doubt wholesome enough, and if coffee has been found to disagree with the system, it is probably better to use some beverage of this kind, which is simply an extract of a roasted cereal. COCOA AND CHOCOLATE The raw material from which cocoa, and chocolate is made, is the seed of the TJieobroma cacao. It grows most readily from Mexico to Peru on the west coast of the American continent, in Mexico and Brazil on the east coast, and in the West India Islands. It was introduced into Europe by the Spaniards in 1519. Chocolate was first prepared in the United States in 1771, at Danvers, Mass. 1 The tree is about 18 or 20 ft. high, blooms continuously, and yields two crops a year. The lemon-yellow fleshy fruit is about 7 in. long, 1 Harrington, " Practical Hygiene," p. 174. 1200 SANITARY AND APPLIED CHEMISTRY something like a short cucumber in appearance, and has ten longitudinal ridges. The seeds are arranged in five rows in the pulpy flesh. There are two processes for preparing the seed for the market. For unfermented cocoa the seeds are separated from the pulp and dried in the sun ; for the fermented cocoa the seeds are placed in piles and allowed to ferment, before being dried. Much of the acridity and bitterness disappears in this process of fermentation. The principal operations in the process of manufacture are, first, the sifting of the raw cocoa to remove the sand and dust ; second, the separation by hand of the larger stones and empty pods, etc. ; third, roasting the cleaned seeds. The following table l shows the composition of some cocoa products : PURE PLAIN CHOCOLATE, AVERAGE or 6 ANALYSES PURE SWEET CHOOOLATE, AVERAGE or 12 ANALYSES PURE COCOA, AVERAGE or 26 ANALYSES COCOA SHELLS (HANDSHELLBD), AVERAGE or 17 ANALYSES Water 3.78 2.17 6.23 4.87 Ash 3.15 1.40 6.49 10.43 Theobromiu .78 .35 1.15 .49 Caffein .13 .08 .16 .16 Other nitrogenous substances (protein) 12.36 4.58 18.34 14.46 Crude fiber 2.86 .95 4.48 16.66 Sugar 56.44 Pure starch 18.11 2.88 11.14 4.13 Other nitrogen-free substances Fat 16.64 62.19 7.64 23.51 26.32 26.69 46.16 2.76 Cocoa is not only used to make a pleasant and exhilarat- ing beverage; it is a valuable food material. The most 1 Rep. Conn. Agric. Exp. Station, 1903, Pt. IT, p. 125. BEVERAGES 267 important constituents are fat, theobromin, which is the alkaloid or, properly speaking, the ureide of cocoa, a little starch, and some albumin and fibrin. The fat usually forms about 50 % of the husk and bean. It is a mixture of the glycerides of stearic, palmitic, lauric, and arachidic acids, and is extensively used in pharmacy under the name of " cocoa butter " Theobromin, which was discovered in 1841 by Woskresensky, is very closely related to xanthine, being dimethyl xanthine, C 5 H 2 (CH 3 ) 2 N 4 Oy Caffein is trimethyl xanthine, C 5 H(CH 3 ) 3 N 4 2 . The commercial preparations of cocoa are quite numerous. Plain chocolate is prepared by grinding roasted and husked seeds to a paste and pressing in the form of cakes. When this is combined with sugar, vanilla, etc., sweet chocolate is the product. Since there is so much fat in the cacao, this is frequently partially removed, and the residue is put on the market under the name of cocoa. Cocoa shells or husks are sometimes used for making an exceedingly weak beverage of this class, which contains little fat, but considerable nitrog- enous matter and extractives. Cocoa "nibbs" are the bruised, roasted seeds freed from the hardened grains, and contain all the fat. The names that are applied to the differ- ent preparations of cocoa and chocolate vary in different countries. Cocoa and chocolate preparations are very readily adulterated, but, after all, the general adulterants, if such they may be called, are sugar and starch, which are not injurious, but only decrease the cost for the benefit of the manufacturer. The genuine chocolate should contain all the original fat. An inferior vanilla chocolate is flavored with the artificial vanillin and coumarin in place of the finer flavored vanilla bean. It is said that the term " soluble cocoa " is erroneous, as very little of the albuminous substances or the fat are solu- ble. In order to grind the bean to a very fine powder it 268 SANITARY AND APPLIED CHEMISTRY must be mixed with sugar or starch, and this, in fact, is the method used in the preparation of some of the powders rec- ommended for invalid diet. Sometimes, in order to make a cocoa that shall be more digestible, a part of the fat is sa- ponified by the use of sodium hydrate and magnesia, a pro- cess that may in some cases produce a food that is less digestible than the material that is not so treated. Sweet chocolate, especially by reason of the sugar that is added, has a high food value. Chocolate does not, like tea and coffee, produce wakefulness, though, on account of the large amount of sugar and fat which it contains, it may pro- duce indigestion. As chocolate is a concentrated food, it may be conveniently used when the weight of food to be carried must be considered, as on the march, or on camping expeditions. Experiment 142. Shake a few grams of powdered chocolate in a test tube with ether, filter, and allow the filtrate to evap- orate spontaneously in a glass evaporating dish. Notice the taste and odor of the fat or " cocoa butter " that remains. Notice also that cocoa butter gives a clear solution with ether, while wax or tallow gives a turbid solution. Experiment 143. Boil a few grams of powdered chocolate with water, filter off 10 cc., and treat the cold solution with iodine reagent for starch. COLA The cola nut grows on a small tree in several tropical countries especially Jamaica, Africa, East India, and Ceylon. It contains caffein, theobromin, tannin, and the other con- stituents of tea and coffee. As a beverage it is made into an infusion like coffee, and is served with milk and sugar. BEVERAGES 269 COMPARISON OF THE COMMON STIMULATING BEVERAGES These beverages possess qualities in common for which they are universally esteemed by mankind. First, they re- tard the retrograde metamorphosis of the body tissues, and thus enable the work of the individual to be done upon a smaller supply of food material and with less fatigue. Second. When used in moderation, they are all more or less stimulating to the mental powers. Third. They act as sedative to the nervous system. The similarity of the action of these beverages is due to the pos- session of common constituents. While there are diver- gences from each other, in their finer shades of action their value depends upon the aromatic and volatile oil which modi- fies the action of the alkaloid. It is an interesting fact that similar properties are developed in each of them by roast- ing and drying. Coffee is more stimulating than cocoa. It is apt to cause irregularity and palpitation of the heart and may disorder digestion if boiled too long. Tea is the most refreshing and stimulating of these bev- erages. Used in excess, however, it powerfully affects sta- bility of the motor and vasomotor nerves, the action of the heart and the digestive functions, producing dyspepsia, tremulousness, irregular cardiac action, headache, etc. Mate is supposed to be intermediate in its effects between tea and coffee. Chocolate is more nutritious than tea or coffee on account of the amount of fat which it contains; although much of this fat is removed in making cocoa. Since but little of the solid is used in making the beverage cocoa or chocolate, the food value is not very great. Cocoa and chocolate are only slightly stimulating in their effects. Cola probably has a restraining influence on tissue waste 270 SANITARY AND APPLIED CHEMISTRY and is mildly stimulating to the heart and nervous system. As it will increase the endurance, it may be used when severe muscular exercise is to be undertaken. When we consider the whole subject of beverages of this class, it is extremely interesting to notice that uncivilized people and civilized people in different ages of the world, in different climates, and under entirely different circumstances, have chosen plants to use in the manufacture of beverages that contain these alkaloid principles; caffein in the case of tea, coffee, and cola, and theobromin in the case of choco- late. Most of them also contain the astringent principle tannin. The use of these beverages has increased from year to year in all civilized countries. CHAPTER XXIII ALCOHOLIC BEVERAGES IT is probably true that alcohol, as such, is not found in sound fruit, yet alcohol is so readily formed by the process of fermentation of sugar, that it was not strange that it was accidentally discovered, and that beverages having intoxi- cating qualities should have been used very early in the history of the world. Alcohol, C 2 H 5 OH, is a colorless liquid, having an agreeable odor, burning with a blue flame, and having a specific gravity of .792. Ordinary alcohol is about 95 % strength, and the remaining 5 % is water. Proof spirit, as it is called, contains 42.50 % of alcohol by weight or 50 % by volume. This was originally named from being the most dilute spirit which when lighted would fire gunpowder. The annual consumption of alcoholic beverages, per cap- ita, in the United States, and in several other countries, in 1900, was : GALLONS Beer Wine Spirits 30.31 .39 1.02 6.10 21.80 1.84 Germany 25.50 1.34 1.84 Japan, all liquors (mostly sake') . . . United States 12.30 .44 6.25 .84 271 272 SANITARY AND APPLIED CHEMISTRY The Statistical Abstract of the United States for 1903 reports the per capita consumption of distilled spirits to be 1.46 proof gal. ; that of wine, 0.48 gal. ; and that of malt liquors, 18.04 gal. There is a notable increase in the con- sumption of malt liquors from year to year. Alcoholic beverages may be made from any vegetable product that contains starch or sugar. There are four general classes, viz. : 1. Fermented liquors : as wine, cider, perry ; wine from fruits, berries, etc. ; palm wine, called " toddy " in India ; bouza, made in Tartary and the East from millet seed; honey wine, used in Abyssinia ; koumiss, made from mare's milk in Tartary ; fig wine, made in the vicinity of the Medi- terranean Sea ; and pulque, made by the Mexicans from the juice of the century plant. 2. Malt liquors : as lager beer, ale, porter, stout ; kvass, made in Eussia from rye ; chica, made in South America from corn, rice, etc.; sake, made in Japan from rice; and pombe, made in Africa from rice. 3. Distilled liquors : as alcohol, whisky, brandy, gin, and rum, and vodka made from grains in Russia, arrack made from rice and palm juice in India, mescal or pulque brandy, and cherry brandy, or " Kirsch-wasser," as it is termed, in Germany. 4. Liqueurs and cordials : as absinthe and vermuth. The fermented liquors are made from the juices of fruits, which contain sugar, and they require no yeast to start the fermentation, but depend on the germs which are present in the natural juices. Most of the sugar present in fruits is in the form of invert sugar. As the quantity of alcohol that can be obtained from any fruit juice is dependent on the amount of sugar contained, a consideration of the sugar content is important. ALCOHOLIC BEVERAGES 273 The following analyses, by Fresenius, show the amount of sugar and acid in the common fruits : PER CENT SUGAR PER CENT FREK MALIC ACID Grapes 16.15 Sweet cherries 16.30 Sour cherries 10.44 Mulberries 10.00 Apples 9.14 Pears 8.43 Gooseberries 8.00 German prunes 7.56 Currants 7.30 Strawberries 6.89 Blackberries 5.32 Raspberries 4.84 Green grapes 4.18 Plums 2.80 Apricots 2.13 Peaches . 1.99 .80 .88 1.52 2.02 .82 .09 1.63 1.08 2.43 1.57 1.42 1.80 .67 1.72 1.25 .85 WINE The most important of the fermented beverages is wine. The cultivation of grapes, for the purpose of making wine, began in the East in the earliest times, and extended along the shores of the Mediterranean Sea. Germany, Austria, France, Italy, Spain, and Portugal are the continental wine- growing countries, while in the United States the industry is of great importance in Ohio, New York, Virginia, and California. The quality of the wine depends on the variety of grapes, the soil, climate, and even on the weather. In order to make genuine wine, the grapes are allowed to ripen, so that they contain as much sugar as possible. The grapes are carefully crushed and pressed, and the first juice that runs off produces the best quality of wine. The 274 SANITARY AND APPLIED CHEMISTRY " marc," as the pulp is called, is sometimes pressed several times after being soaked with water, and this affords cheaper qualities of wine. The " must," as the pressed juice is called, is allowed to ferment from 10 to 30 days. Fermentation be- gins at from 10 to 15 C., and is brought about by the germs which grow at the expense of the saccharin and albuminous substances present, and change the sugar to carbon dioxid and alcohol. Thus : 06^06 = 20^0 + 200,. Sugar Alcohol Carbon dioxid After the first fermentation, the wine is drawn off from the "lees" and put in casks, where the after fermentation takes place. The " lees " consist of the fungus growth, some calcium salts, coloring matter and "argols," potassium bitartrate, or " cream of tartar," which is insoluble in dilute alcohol. This is the only practical source of cream of tartar ; consequently this chemical commands a good price. From 60 Ib. to 70 Ib. of "must" can be obtained from 100 Ib. of grapes. The quantity of sugar in the juice va- ries from 12 to 30%. It is of importance that the ferment be of a certain kind to produce a good wine ; and, indeed, the bacteriologist has begun to propagate special cultures of a pure yeast to produce wine of a desired flavor. The wine is stored in casks for some months, for the process of aging. Before being placed in the cask, the wine is treated with isinglass, or egg albumen, and " racked off " from the depos- ited impurities. It must not be too freely exposed to the air, as there is danger that the alcohol, by the aid of the acetic ferment, shall be changed to acetic acid, according to the reaction, C 2 H 5 OH + 2 2 = C 2 H 3 O.OH + 2 H 2 0. During the aging process a variety of fragrant ethers, as acetic ether, malic ether, etc., are formed, which produce an agreeable odor or bouquet. Wines are sometimes aged ALCOHOLIC BEVERAGES 275 and at the same time preserved, by pasteurization, which consists in heating them for some time at 60 C., with a limited supply of air. In regard to the changes that take place in the cask, Leach observes that the alcoholic strength of the wine rises. This is due to the fact that the water of the wine soaks into the wood more than the alcohol does, and is lost by evapo- ration, so that the wine becomes more concentrated. As the water so lost is replaced by the addition of more wine, the increase in the proportion of alcohol is rendered all the greater. In the cask, too, a partial oxidation of the tannic acid takes place. This causes the white wines to become darker in color, but has just the reverse effect upon the red wines ; for the oxidized tannic acid unites with and precipi- tates some of the pigment. The alcoholic strength of the wine is somewhat increased by a further fermentation of the sugar. By the oxidation of some of the alcohol to acetic acid, compound ethers are formed. There is an impression that wine continues to im- prove with age, and " old wine " is highly prized. Some of the stronger wines improve for a few years, but not for an indefinite time, and wines often begin to deteriorate after a short time. The " extract," as the term is used below, is what remains upon evaporation. The following table gives the composition of a few wines : COMPOSITION op WINES ALCOHOL EXTRACT FKBE ACID TABTAKIO SUGAR ASH French red 7.80 2.97 .58 .46 .26 French white 10.84 1.26 .44 .88 .20 Spanish red 12.34 3.84 .57 .25 .75 Calif, red 10.03 2.11 .64 .25 .34 Calif, white 11.16 11.80 .63 .20 .17 276 SANITARY AND APPLIED CHEMISTRY SWEET WINES ALCOHOL. EXTRACT FREK Aon> TABTABIC BUOAB Asa Champagne . 9.60 14.34 .58 .75 .16 Port .... 16.29 8.30 .38 6.26 .25 Sherry . . . 15.93 5.00 .48 2.76 .56 Madeira . . 15.49 5.61 .41 3.18 .33 CLASSIFICATION OF WINES Wines are either natural or "fortified." Natural wine contains no added alcohol or sugar. When the pure juice of the grape is allowed to ferment, if it contains sufficient sugar, the amount of alcohol will continue to increase till the wine contains about 15%, and this amount of alcohol prevents any further fermentation. Hock and claret are usually of this class. When alcohol is added to the wine it is said to be "fortified." Port and Madeira are often treated in this way. Wines are divided into red and white wines, from the color ; also into dry wines, or those in which all the sugar has been changed to alcohol ; and sweet wines, or those in which some sugar still remains, although these are often reinforced by the addition of grape sugar. Dry wines are consequently slightly sour. Wines are also divided into "still" wines, or those in which the carbon dioxid gas has been allowed to escape ; and effervescent wines, in which the carbon dioxid has been retained in the liquid under pressure. Grapes make better wine than other fruit because the potassium bitartrate (KHC 4 H 4 6 ) is precipitated as the alcohol becomes stronger in the process of fermentation. Other fruits and berries, on the other hand, contain citric, malic, or succinic acids, and the salts of these are not pre- ALCOHOLIC BEVERAGES 277 cipitated during fermentation, and so this wine has not the agreeable taste that characterizes grape wine. ADULTERATION OP WINES The adulterations of wine are very numerous. Plaster of Paris is often used abroad for the adulteration of wines, but native wines and those imported into the United States are usually free from this material. This is done, it is said, to clarify it, to improve the color, to make the fermentation more complete, and to improve the keeping qualities. On the other hand, this process is supposed to leave some injurious compounds in the wine. The reaction due to "plastering" is as follows : 2 KHC 4 H 4 6 + CaS0 4 = CaC 4 H 4 6 + H 2 C 4 H 4 6 + K 2 S0 4 . Pot. bitartrate Cal. sulfate Cal. tartrate Tartaric acid Pot. sulfate In France there is a law against the addition of more than a limited quantity of plaster of Paris to wines intended for home consumption. Not over .2% of potassium sulfate is allowed to be present. The wine manufacturers also burn sulfur in the casks so that the sulfur dioxid shall artifi- cially age the wine. This tends to decrease the number of germs that would be injurious in fermentation. The addi- tion of cane sugar, called " chaptalising " in France, is prac- ticed, under certain very carefully guarded conditions, to in- crease the yield of alcohol, and commercial glucose is used in the same way. In Germ any the addition of sugar to " musts " deficient in this material, is permitted. A cheap wine is sometimes put upon the market which contains no juice of the grape whatever, but is made from cider as a basis, to which is added alcohol, tannin, glycerin, glucose, cream of tartar, orris root, ethereal oils, and frequently osnanthic ether. An extract is frequently made from raisins, which is colored and flavored to imitate wine. 278 SANITARY AND APPLIED CHEMISTRY Wine is subject to numerous diseases, such as souring, ropiness, bitterness, and molding. Poor wines or those that have deteriorated are sometimes distilled to make brandy. Experiment 144. Test a small portion of wine in a test tube for grape sugar, by the Fehling test. Experiment 145. Evaporate 10 cc. of wine to one half its volume on a water bath, and to the solution add 50 cc. of a mixture of alcohol and ether. Put this solution in a flask and allow to stand tightly corked for some time, and notice the acid potassium tartrate which crystallizes out. Experiment 146. Acidify a sample of wine with hydro- chloric acid, heat to boiling, and add a few drops of barium chlorid. If there is more than a trace of barium sulfate, " plastering " of the wine is indicated. Normal wine does not contain over .06 % of sulf uric acid calculated as potas- sium sulfate. CIDER The fresh juice of the apple, known as sweet cider, is a very convenient solution for growth of the yeast Saccha- romyces apiculatus, which starts fermentation, and so cider does not long remain sweet. The crushed apples are pressed in a cider press, and the juice is then run off into barrels and allowed to ferment. The refuse left after the juice has been expressed is called " pomace," and is utilized in some other industries. (See p. 219.) In some countries more care is used in the preparation of this beverage, and it is clarified by the use of gelatin and racked off or filtered from the de- posited matter. This process tends to improve the quality of the cider. Cider contains from 3 to 7% of alcohol by volume, besides malic acid, sugar, extractives, and mineral salts. ALCOHOLIC BEVERAGES 279 ADULTERATION AND FALSIFICATION OF CIDER There are found on the market samples of cider made by adding water to the pomace, and repressing ; but this cider is more frequently used as a basis for the manufacture of other beverages. The most important sophistications of cider are water, sugar, and especially the use of preserva- tives. The preservatives most commonly used are benzoic acid, salicylic acid, sulfurous acid or sodium sulfite, and betanaphthol. Mustard seeds, borax, and horse radish are also used. From some experiments by the author : it was shown that the effect of those substances is to retard the fermentation, and not to ultimately prevent it. It is prob- ably true that substances that will retard fermentation will also have a tendency to produce indigestion. 2 (See Chapter XXV.) Substances which have a proper place when used as medicines should not be taken in small doses with the food from day to day. 3 Perry, or pear cider, is made and consumed more exten- sively abroad than in the United States. It does not differ essentially except in flavor from cider. Experiment 147. To test for salicylic acid in cider or beer, acidulate a sample with sulf uric acid and shake with a mixture of equal parts of ether and petroleum naphtha. Eemove the ethereal layer with a pipette and allow to evapo- rate to small volume on a watch glass. Add a little water and a few drops of ferric chlorid solution, when the pres- ence of salicylic acid will be indicated by a violet color. 1 Kas. Univ. Quar., VI, A, p. 111. 2 Shepard, Keport, Ohio Food Commis., 1904. 8 Harrington, " Practical Hygiene," p. 211. 280 SANITARY AND APPLIED CHEMISTRY BEER This beverage is a representative of malt liquors. Accord- ing to the best authorities, genuine beer should be made from malt, starchy material, hops, yeast, and water, and noth- ing else. Malt is made by soaking barley in water for several days, then piling it up on the floor or " couching " till it sprouts and the little radical starts to grow ; then the process of germination is retarded by " flooring," as it is called ; i.e. spreading in progressively thinner and thinner layers upon the floor, and germination is finally stopped by drying the grain. The color of the malt depends upon the temperature at which this drying is conducted. If dried be- tween 32 and 37 C., it forms a "pale malt"; if from 38 to 50, a brown malt. In the process of malting the albu- minous substances of the grain are changed in part to diastase, an active ferment, which has the peculiar property of chang- ing starch to dextrin and then to sugar (maltose). One part of diastase under favorable conditions will convert 2000 parts of starch to sugar. The next process is known as " mashing. " This consists in grinding the malt and soaking it in water at a tempera- ture of 75 C. The change from starch to sugar is still more completely effected here. The clear infusion, called the " wort," is boiled with hops, and the solution is cooled very rapidly to 18 C. Yeast is added, in the proportion of about 1 gal. to 100 gal. of wort, and the liquid is allowed to fer- ment about 8 days. It is then drawn off into settling tanks and finally into casks, and stored in a cool place to ripen. The yeast changes the sugar into alcohol and carbon dioxid, in accordance with the reaction, CeHjA = 2 C0 2 + 2 C 2 H 5 OH. The sugar is not completely eliminated, as that would inter- fere with the agreeable taste. ALCOHOLIC BEVERAGES 281 The following analyses of malt liquors, taken from various sources, will give an idea of their composition : SP. GKAVITI WATBE ALCOHOL BY WEIGHT EXTKAOT SUGAR (MALTOBE) Gnu AND DEXTKIN ACID AS LAOTIO s Milwaukee lager, bottled . . 1.0100 1.0178 4.28 4.40 4.18 615 1.10 2.14 1.57 2.54 .06 .07 .20 .81 Philadelphia ale, bottled . . . Pilseu lager 1.0059 6.24 8.29 3.46 422 .59 .69 .90 2.65 .28 .40 85.85 4.60 940 1.0114 91.11 8.86 5.84 .95 8.11 16 .20 Lager ( beer ) 1.0162 90.08 8.93 5.79 .88 8.73 15 .23 1.0176 89.01 4.40 6.88 1.20 3.47 16 .25 1.0213 87.87 4.69 721 1.81 3.97 .17 .26 1.0137 91 63 2.78 543 1.62 242 89 15 Dublin stout, XXX .... Porter 1.0191 88.49 6.78 4.70 9.52 6.59 5.85 2.62 2.09 3 08 .25 .36 Ale 1.0141 89.42 4.74 5 65 1 07 1.81 .28- .31 Burton bitter ale 544 542 1 62 2.60 17 The quality of the beer depends upon the manner of brewing, the temperature, qualities of ingredients, method of storing, kind of water used, quality of the yeast, whether "top yeast" or "bottom yeast," and the temperature at which it is stored. The lager beer proper, or store beer, should be kept in a cool place for several months before being used. Very much of the beer in use in the United States is what is known as " present use " beer. Bock beer is a strong variety of beer made for use in the spring only, and Weiss beer is a very weak beverage used in Germany. Ale, porter, and stout are richer in alcohol than lager beer. In the manufacture of beer the tendency is to use as little of expensive ingredients as possible, so in cheap beers, part, or all, of the barley malt is replaced by some other grain, as corn or rye, and even a special kind of glucose is added to 282 SANITARY AND APPLIED CHEMISTRY furnish a material that will readily ferment. It is asserted that sometimes the bitter principle in cheap beer is also replaced by quassia and other bitter substances. Most of the beer on the market contains from 2 to 4 % of alcohol by weight. There are comparatively few adulterations in beer except those mentioned. Salicylic acid is, however, frequently used as a preservative. A kind of so-called beer has been put upon the market in some prohibition localities. This often contains less than 2% of alcohol, and is sold under a variety of special names. Sakd, the favorite beverage of the Japanese, is prepared from rice fermented by the use of a peculiar fungus grown for that purpose. It contains about 12.5 % of alcohol. 1 Experiment 148. To show the presence of alcohol in a sample of wine, beer, or cider, heat about 100 cc. in a 500 cc. flask, into the neck of which is fitted the large end of a cal- cium chlorid tube. As soon as the liquid begins to boil slowly, light the vapor that escapes at the top, and observe that it burns with a characteristic alcohol flame. Experiment 149. Collect some of the distillate from a sample of malt or fermented liquor, by boiling it very gently in a 500 cc. flask, to which is fitted, by a perforated cork, a glass tube about 60 cm. long, bent at an acute angle above the cork. At the other end of the glass tube place a small flask or test tube surrounded by cold water. The alcohol will condense in the cooled flask. Experiment 150. Test some of the alcohol, first by taste, second, by burning, third, by adding to a sample about 1 g. solid NaOH and a few crystals of iodine. The formation of a yellowish crystalline precipitate of iodoform, CHI 3 , which has a characteristic odor, indicates the presence of alcohol in the distillate. 1 Church, "Food," p. 195. ALCOHOLIC BEVERAGES 283 DISTILLED LIQUORS Distilled liquors, such as rum, gin, brandy, and whisky, are made from some saccharine substance like molasses, or some starchy substance like corn, rye, barley, or rice. The chemical action in the case of starch is first to change the starch by the addition of ground malt to sugar, which is then decomposed in the process of fermentation with yeast, into alcohol and carbon dioxid. Diastase, which is present in the malt, is the active agent in transforming the starch to sugar. This sugar is principally maltose, mixed with one of the dextrins. 1 After fermentation the alcohol is distilled off, and with it some other volatile substance, especially ethers, which give the characteristic odor and taste to the liquor. (See also Bread, p. 160.) Originally the liquid actually distilled over was used directly as a beverage. This was about of proof strength, and had the characteristic flavor of the substance from which it was distilled. Practically, at the present time, a large proportion of the liquor on the market is made by the rectifiers, using as a basis pure alcohol and " high wines," which are diluted, colored, and flavored to imitate the required beverage. The method used in making alcohol is to prepare what is called the mash by crushing the grain and other starchy material into a fine pulp, and soaking it with water, cooling it quickly, and allowing it to ferment with yeast. Some- times the mash is made by the use of sulfuric acid, thus converting the starch directly into dextrin. The mash, after fermentation, is distilled in an apparatus so arranged that the alcohol, as it is volatilized, shall be quickly cooled and condensed in a coiled pipe. Theoretically, 1 Jago, "The Science and Art of Bread Making," p. 126. 284 SANITAKY AND APPLIED CHEMISTRY 100 parts of starch yield 56.78 parts of alcohol, 100 parts of cane sugar yield 53.08 parts of alcohol, 100 parts of dextrin yield 51.01 parts of alcohol, but practically this output is not reached. The last part of the distillate usually contains more of the higher alcohols of the series, especially amyl alcohol, which is one of the constituents of "fusel oil." This is considered one of the most injurious ingredients in ordinary liquors. Brandy should be made by the distillation of wine, and should obtain its odor and flavor from the fermented juice of the grape. Practically in the hands of the rectifier, it can be made from alcohol diluted, colored with caramel, flavored with oil of cognac, which is distilled from the marc or refuse, from the manufacture of wine. The flavor of brandy is much improved by age, but many processes of artificial aging have been devised. Whisky, as originally made from corn, barley, or potatoes, had a brownish color, and a peaty or smoky flavor that was imparted to it by the smoke of the peat fires used in its manufacture in Scotland and Ireland. This flavor is now imparted to the commercial article by the use of creosote or some similar compound. Rum was originally made in the West Indies from residue left after the manufacture of cane sugar or from molasses, and the peculiar flavor it possessed was produced by the volatile oils that are developed in the manufacture of sugar from cane juice. Much of it is now manufactured by the " rectifier " in a manner already described. Gin was originally made by the distillation of an alcoholic liquid with juniper berries, but at present the rectifier adds to the diluted alcohol, oil of juniper or turpentine, or both, some aromatic seeds and fruits, and redistills the mixture. Many roots and drugs are frequently added to improve the flavor of gin. ALCOHOLIC BEVERAGES 285 Experiment 151. Alcohol may be made from the fer- mentation of a saccharine liquid, as follows: In a 2-liter flask mix 60 cc. of molasses with 700 cc. of water, and add a small amount of yeast, and set aside in a warm place for a day or two. When the mass foams and carbon dioxid is freely given off, distill slowly by attaching a condenser, or a cork, through which passes a long tube bent to an acute angle, as in Experiment 149. Examine the distillate by taste and smell, and by the test mentioned in Experi- ment 150. Dr. Battershall l says : " The most prevalent form of sophistication with brandy, rum, and gin is the artificial imi- tations, and the direct addition of substances injurious to health is of unf requent occurrence. " He believes that the most dangerous ingredient in the fictitious product is the fusel oil, which is a mixture of the higher alcohols, but other authorities have made experiments with this substance, and find no injurious effect, even when considerable quanti- ties mixed with whisky are taken for quite a length of time. It is -suggested that perhaps the compounds which make some spirits, especially those which are recently distilled, or " raw, " more injurious than those which are " aged," may be other by-products of fermentation, such as furfurol. LIQUEURS OR CORDIALS These beverages consist of very strong alcohol, flavored with aromatic substances, and often highly colored, with a coal tar or a vegetable coloring matter. Absinthe, the most important of these, is yellowish green in color, and contains oil of wormwood, a substance that has a very injurious effect on the nervous system, with anise, sweet flag, cloves, angelica, and peppermint. This liquor usually contains over 5Q% of alcohol. 1 " Food Adulteration and its Detection," p. 192. 286 SANITARY AND APPLIED CHEMISTBY Other beverages of this class are maraschino, distilled originally from the sour Italian cherry; chartreuse and benedictine, named from the monasteries where they were originally made ; kummel ; curaqoa, made from the rind of bitter oranges ; ratafia, made in France from fruits ; angus- tura and vermuth. Nearly all these contain a large amount of sugar and a high per cent of alcohol, and are flavored with various essential oils, herbs, and spices. PHYSIOLOGICAL ACTION OF ALCOHOL The question as to whether alcohol is, properly speaking, a food, or whether it simply acts as a stimulating beverage, is one that has occasioned a vast amount of discussion. The best authorities seem to agree that there are cases of disease in which it is the most useful material that can be administered. Professor Atwater, who has investigated the action of alcohol in his respiration calorimeter, speak- ign of its use in disease says: "What is wanted is a material which will not have to be digested and can be easily absorbed, is readily oxidized, and will supply the req- uisite energy. I know of no other material which would seem to meet these requirements so naturally and so fully as alcohol. It does not require digestion, is absorbed by the stomach and presumably by the intestines, with great ease. Outside the body it is oxidized very readily, within the body it appears to be quickly burned, and it supplies a large amount of energy." From one fifth to one seventh of the total calories of the diet may be replaced by alcohol. The same author says of the results of his experiments, that he found that " the alcohol was almost completely oxidized. The kinetic energy resulting from that oxida- tion agrees very closely with the potential energy of the same amount of alcohol as measured by its heat of combus- tion as determined by the bomb calorimeter, and the alco- ALCOHOLIC BEVERAGES 287 hol served to protect body protein and fat from oxidation." Alcohol is inferior to carbohydrates, however, to protect pro- tein of the body from oxidation. 1 As a stimulant, alcohol acts primarily upon the nervous system and the circulation, and quickens the transmission and enhances the effect of nerve currents. Although alcohol tends to remove muscu- lar fatigue and to increase the force of muscular action, yet its use is absolutely forbidden to athletes in training, and soldiers in the army continue in better health if they entirely abstain from the use of this substance. It will be seen that although alcohol has some right to be regarded as food, yet it is not a food of any practical im- portance, for it can merely replace a certain amount of the fat, and perhaps of the carbohydrates, in the body, while its secondary effects on the nervous and vascular systems coun- teract, to a large extent, the benefits derived from the pro- duction of heat and energy by its oxidation. 2 1 Thompson, "Practical Dietetics," p. 229. 2 Hutchison, " Food and Dietetics." CHAPTER XXIV FOOD ACCESSORIES A LARGE number of aromatic substances, which have no direct food value are prized for the agreeable flavor which they impart to food. Condiments are by some writers de- nned as the substances eaten with meat and used with salt, while the term spices is restricted to those substances which are used with sugar. It is however impossible to draw a definite line between the two classes of substances. The spices, since they are used only in small quantities and are quite expensive, readily lend themselves to all kinds of falsification and adulteration. The adulterants are usually of a harmless character, and consist of English walnut shells, Brazil nut shells, almond shells, cocoanut shells, date stones, sawdust, linseed meal, cocoa shells, red sandal wood, Egyptian corn, rice flour, ground crackers, or " hard tack," bran and many other by- products from milling, plaster, corn meal, turmeric, cotton- seed meal, olive stones, and pea meal. 1 Various mixtures of some of the above are prepared and colored to imitate each of the ground spices and put on the market, at a very low price, for use in spice mills. In most cases these fraudu- lent mixtures can be detected only by the skilled chemist or microscopist, so the only safeguard of the housekeeper is to buy of reliable dealers, get the goods in sealed pack- ages, and to pay a fair price. In most cases it is safer to buy the unground spice. A brief account only of the source and properties of the most important products will be given. 1 Rep. Conn. Agric. Exp. Station, 1898-1904. 288 FOOD ACCESSORIES 289 Cloves are the dried flower buds of a plant belonging to the Myrtle family, growing in Ceylon, Brazil, India, the East Indies, and Zanzibar. The tree, which is an evergreen, is usually less than 40 ft. high. After the buds are picked they are laid in the sun to dry. The volatile oil of cloves, which may be distilled off with water, contains about 70% of eugenol, C 10 H 12 2 . In addition to the use of the clove " stock " above mentioned, " exhausted " cloves, both whole and powdered, that is, those which have been deprived of a portion of their volatile oil, are put upon the market and mixed with fresh cloves, so that the fraud shall be less apparent. Experiment 152. Grind about 15 grams of cloves in a porcelain mortar and introduce into a liter retort with water and boil for some time, condensing the steam in a flask floating in a pan of water. Pour the distillate into a tall tube and allow it to stand, and the oil of cloves will rise to the surface. Cinnamon is the inner bark of a tree of the Laurel family, which is cultivated in Ceylon, Java, Sumatra, and surrounding countries. A cheaper and more common cassia which is also commercially known as cinnamon, comes from another tree of the Laurel family, which grows in China and India. Cassia buds, the dried flower of the China cas- sia, are also upon the market. The odor of cinnamon is due to the presence of a volatile oil, which consists princi- pally of cinnamic aldehyde, C 6 H 5 CH : CH.CHO. A " stock " colored with red sandalwood is commonly used as an adul- terant; this stock frequently consists largely of foreign barks, such as that of the elm. Pepper is the dried berry of the Piper nigrum, a climbing plant which grows in tropical countries. For preparing black pepper the unripe fruit is dried in the sun, but to pre- pare the white pepper the ripe fruit is soaked in water and 290 SANITARY AND APPLIED CHEMISTRY the skins are removed by friction. The taste and odor of pepper is due to the presence of an essential oil, a hydro- carbon, having the formula C 10 H 18 , and another important substance called piperin, C 17 H 19 N0 8 . In addition to the or- dinary adulterants in ground pepper, Egyptian corn and " long pepper " are used, while cayenne pepper is often added to raise the pungency nearer to that of the pure product. Ginger is the rhizome of the Zingiber officinale, an annual herb which is a native of India and China, and is cultivated in the West Indies, Africa, and Australia. Black ginger is prepared by scalding the freshly dug root, and drying immediately. White, or " scraped," ginger is the same material that has been scraped and sometimes further whitened by treatment with some bleaching agent. Pre- served ginger is prepared by boiling the root and curing with sugar. A volatile oil and a pungent resin give to gin- ger its characteristic odor and taste. Ginger is often adul- terated by mixing with it ginger roots that have been ex- hausted with alcohol. The alcoholic extract or water extract is used for the manufacture of ginger ale. Nutmeg and mace occur in the fruit of trees of the Myris- tica family, which grow especially in the Malay Peninsula. The tree grows from 20 to 30 ft. high, and produces flowers after about the eighth year. The fruit is surrounded by a fleshy crimson covering, which when dried furnishes the mace of commerce, and the hard seed the nutmeg. This is further prepared by washing with milk of lime. Nutmegs contain from 3 to 5% of a volatile oil. As the whole nut- meg is used by the cook, rather than a ground product, there is not much opportunity for adulteration. Mace has the usual adulterants, and frequently a wild mace, known as Bombay mace, which is practically without taste is added. White mustard is the seed of the Sinapis alba, and black mustard that of the Sinapis nigra. The plant, which is FOOD ACCESSORIES 291 an herb, having yellow flowers, grows both in the United States and in Europe. Both varieties contain about 35% of a fixed oil, which can be separated by heat and pressure, a soluble ferment called myrosin, and sulfocyanate of sina- pin, C 16 H23N0 5 . The black mustard contains potassium my- ronate, which, when moistened with water, forms the volatile oil of black mustard, known to the chemist as allyl isothyocy- anate, C S H 6 CSN". This has a strong mustard-like odor, and the vapor excites tears. This oil produces blisters on the skin, and hence the use of the so-called " mustard plaster." The chief adulterants of ground mustard are wheat, flour, or starch, mustard hulls, and turmeric to restore the yellow color lost by the adulteration with a starch powder. Some- times cayenne pepper is also added to restore the pungency. VINEGAR Since most of the vinegar of commerce is used in connection with spices and in the preparation of pickles, etc., its prop- erties may be studied in this connection. Vinegar is dilute acetic acid, C 2 H 4 2 , flavored with the fruit ethers, and can be made from any dilute alcoholic liquor. The whole pro- cess of the conversion of cane sugar to vinegar would be rep- resented by the equations, C^H^OU + H 2 = 2 C 6 H 12 6 ; Cane sugar Invert sugar CH U 6 = 2 C 2 H 5 OH + 2 C0 2 ; Alcohol C 2 H 6 OH + = C 2 H 4 + H 2 ; Aldehyde C 2 H 4 + = C 2 H 4 2 . Acetic acid 292 SANITARY AND APPLIED CHEMISTRY The change from alcohol to vinegar is brought about by the ferment mycoderma aceti, found in the " mother." The conditions for this fermentation are an alcoholic liquid con- taining not over 12% of alcohol, an abundance of air, a tem- perature of from 20 to 35 C., and the presence of the ferment. The materials used are (1) wine ; (2) other fermented fruit juices; (3) spirits like diluted whisky, or residues from the manufacture of sugar; (4) malt wort, or beer; (5) sugar beets. There are several processes used for the manu- facture of vinegar on a large scale, in addition to the usual process of allowing the cider to ferment in an ordinary barrel in a warm cellar with the bunghole left open for two or three years. In France and Germany vinegar is made from wine by pouring it from time to time into an oaken vessel which has been soaked with boiling vinegar, and then siphoning off into storage tanks. The " mother casks " are used for a long time, till they contain a large amount of argols, ferment, etc. Another method is by the " quick vinegar process, " which was introduced by Schutzenbach in 1823, and is quite exten- sively used for spirit vinegar in Germany and the United States, and for malt vinegar in England. In this process, an upright cask about 10 ft. high, and provided with a perforated false bottom about a foot above the true bottom, is filled with beech or oak shavings. Just under the false bottom a series of holes slanting downward is bored entirely around the cask. The shavings are soaked in warm vinegar, and covered by a wooden disk perforated with numerous holes, through which cords are loosely drawn. There are also several glass tubes extending through this disk to assist in the circulation of the air. After covering the cask with a wooden cover having a hole in the center, the dilute alcoholic liquor is poured into the upper compart- ment and slowly trickles over the shavings. FOOD ACCESSORIES 293 As the process of oxidation proceeds, considerable heat is developed, and this causes an upward current of air which enters the cask below the false bottom, and escapes to the upper part through the glass tubes. By a siphon the par- tially acetified liquid is drawn off into a second cask. With 4 f of alcohol in the original liquid, good vinegar will be drawn from the second vat. If " vinegar eels " appear, the convert- ing cask is treated with vinegar so hot that when drawn out it has a temperature of 50 C., which kills the eels. When spirit is used in this process, a little infusion of malt is added to furnish organic matter sufficient for the growth of the ferment. Wine vinegar may be red or yellowish in color, and con- tains from 6 to 9% of absolute acetic acid. Beer and malt vinegars are higher in specific gravity than wine vinegar, and contain considerable extractive matter, and from 3 to 6% of acetic acid. Cider vinegar has the odor of apples, and when evaporated yields an extract that smells and tastes like baked apples. It contains malic acid and from 3^ to 6% of acetic acid. The acidity should never be below 3% and the spe- cific gravity should never be less than 1.015. Imitation vinegars are sometimes made by the use of acetic acid distilled from wood, or from some mineral acid, and flavored with acetic ether and colored with caramel. The extract from this imitation vinegar differs from malt vinegar in not containing phosphate, and from wine vinegar in the absence of tartaric acid, and from cider vinegar in the absence of malic acid. The acidity of vinegar assists in the softening of some foods, such as beets, cabbage, cucumbers, hard-boiled eggs, corned beef, and lobsters, but it should not be used in excess on account of its tendency to cause anemia and emaciation. Experiment 153. The approximate acidity of a sample of vinegar may be ascertained by the use of saturated lime- 294 SANITARY AND APPLIED CHEMISTRY water. This is made by allowing water to stand for some time with frequent shaking over slaked lime. The strength of this is very nearly th normal. To test the vinegar, 2.75 cc. are placed in a small Erlenmeyer flask with some water, and a few drops of phenolphthalein as an indicator, and titrated with limewater contained in a burette. When the pinkish color shows that the free acid has been neutralized, read the number of cubic centimeters of limewater used, and divide this by 10. This gives the percentage of acid in the vinegar. Experiment 154. To detect a free mineral acid in vinegar, add to 5 cc. of vinegar 5 or 10 cc. of water ; after mixing well, add 4 or 5 drops of an aqueous solution of methyl-violet (one part of methyl-violet 2 B in 10,000 parts of water). The occurrence of a blue or green color indicates a mineral acid. 1 Experiment 155. Caramel is often used to color imitation vinegars. To detect this, place about 25 cc. of the sample in a large test tube or in a bottle, and add to it about 10 grams of fullers' earth, shake the sample vigorously for several minutes, and filter. The first portion of the liquid which passes through the filter should be filtered again. Return the filtered sample to original tube, and compare the color of this solution in a similar tube with that of an equal quantity of vinegar that has not been treated. If the treated sample is considerably lighter in color than that which has not been treated, the vinegar is probably colored with cara- mel. Caramel occurs naturally in malt vinegar. 2 Experiment 156. To obtain the acid, except sulfuric, of vinegar free from extractive matter, pour 250 cc. of vinegar into a flask, add to it 25 cc. of dilute sulfuric acid, and distill by the use of the simple apparatus described in Ex- 1 Bul. 66, U. S. Dept. Agric., Bu. Chem., p. 64. 2 Bui. 100, U. S. Dept. Agric., Bu. Chem., p. 48. FOOD ACCESSORIES 295 periment 149. Collect the distillate in a flask and examine its odor, taste, etc. SALT Common salt, Nad, has been used for thousands of years as an essential ingredient of foods, and as a preservative. Fortunately, it is found in numerous localities all over the world. In the United States, the chief salt-producing local- ities are Michigan, New York, Kansas, and Ohio, which to- gether furnish about 90 % of the total output, 1 and smaller quantities are obtained from California, Utah, West Virginia, Louisiana, Oklahoma Territory, Texas, and Pennsylvania. Salt is obtained either as rock salt, which is mined in sev- eral localities, by the evaporation of sea water or that of salt lakes, or by the evaporation of brine, which is obtained from salt wells or borings into the salt bed. Most of the table salt of commerce is made by the latter process. In some localities solar evaporation is relied upon for concentration of the brine, but usually the brine is heated in an open pan by direct heat or in a "Grainer" by steam heat. Many producers are introducing cement evaporating pans, automatic self-acting rakers, and vacuum pans. The brine when pumped from the wells contains some impurities, and these, especially the calcium sulfate, are deposited when the brine is first concentrated, so that in this way the brine can be partially purified in the first pan, before it is run into the evaporating pans proper. The com- position of a good brand of salt is as follows : PIB CENT Sodium chlorid 97.75 Insoluble residue .03 Calcium sulfate 1.84 Magnesium chlorid .38 Total 100.00 1 Bailey, International Congress of Applied Chemistry, Berlin, 1903. 296 SANITARY AND APPLIED CHEMISTRY Most of the salts on the market contain from 97 to 99 % of pure salt. When salt absorbs moisture it becomes hard and inconvenient for domestic use. This is sometimes remedied by the addition of a small quantity of starch or some such material. Experiment 156 a. To test table salt for starch, boil a sample with water, allow to cool, and test by tincture of iodine. The production of a blue color indicates starch. CHAPTER XXV PRESERVATION OF FOOD IT is only within the last hundred years that any adequate methods for the preservation of food have been devised ; in fact, within the last fifty years the greatest advances have been made in this art. Formerly, fruits, vegetables, and meats must be consumed in the locality where they were produced, and fruits especially must be used as soon as ripe. In 1804 M. Appert of Paris found that meat and other organic substances would keep indefinitely if sealed and then heated in boiling water. In 1810 he suggested the method of introducing steam and heating, and then sealing, so that when the vessel cooled a vacuum was formed. Canned meats and fruits have been kept for quite a number of years, and were found to be in good condition. By the use of modern methods of preservation the season for the use of each fruit has been extended ; and the product of one climate can be transported to another climate for consump- tion. Meats and vegetables can be preserved for months, and so the variety of food for man has been greatly increased. Since the fermentative changes that take place when food is kept for some time are due to the growth of various micro- organisms, any process which will prevent this growth or keep these organisms out of the food will assist in its pres- ervation.- Warmth, moisture, and access of germ-laden air are conditions favorable for the decomposition of food. Some of the methods adopted for the preservation of food are : (1) maintaining a low temperature ; (2) drying so as to 297 298 SANITARY AND APPLIED CHEMISTRY remove as much moisture as possible ; (3) addition of sugar or glucose ; (4) the use of saltpeter or brine ; (5) pickling with vinegar ; (6) canning or placing in a sterilized atmosphere ; (7) the use of chemical preservatives. Fermentation and decay take place best at a moderately high temperature, so cold storage is introduced not only to transport fruits and meats from one section of the country to another, but also to keep the food from the season when it is abundant until the season when it is scarce. Preservation by the use of salt, smoke, sugar, saltpeter, or vinegar fur- nish conditions unfavorable to the growth of microorgan- isms, and so decay is prevented. Dried or "jerked" meat will keep a long time for the same reason, especially in a dry climate. In smoking the meat, which is usually previously salted, it is dried and penetrated by acetic acid, creosote, and other preservatives of the smoke. In "quick smoking" processes the meat is dipped several times in a solution of pyroligneous acid (which is made by the distillation of wood) and dried in the air. Other chemicals are frequently used. The process of food preservation by canning or protecting from air and sterilizing has developed to an enormous extent in the United States. When we consider the annual output of 100,000,000 cans of corn, 1 the same quantity of peas, and 150,000,000 cans of tomatoes, besides millions of cans of other vegetables and fruits, some idea of the value of this process to the human race is obtained. Fortunately, too, most of this food is prepared in such a way as not to be injurious to the system. The object to be attained in canning is to destroy the microorganisms of various kinds, so it makes no special difference whether a little air remains in the can or not, as long as the contents is i Leach, " Food Inspection and Analysis, " p. 689. PRESERVATION OF FOOD 299 perfectly sterilized, although formerly it was held that all the air must be excluded. In domestic practice, fruit may be preserved by packing in glass cans, filling nearly full of water, adding some sugar if desired, and then immersing the cans nearly to the neck in a vessel of cold water. The water is heated to boiling, and allowed to boil from 15 to 30 m., dependent on the size of the fruit, and then the cans are removed from the water and immediately sealed. This process has the advantage of preserving the fruit whole and unbroken. Another method much in vogue is to cook the fruit or vegetables, then put it, while still hot, in glass or tin cans that have just been taken out of boiling water, and to seal immediately with the ordinary glass cover and rubber washer or with cork and sealing wax. The method used at canning factories is, in general, to pack the material in tin cans, with the required amount of water, and after sealing to cook with hot water or steam. The cans are then punctured to allow the excess of air to escape, again sealed with a drop of solder, and again heated for some time to destroy all microorganisms. A more modern method of canning is to cook the fruit at a temperature of 82 to 88 C. before transferring to the cans, and afterward heat in the cans, when sealed, to a temperature of about 125 C. in dry air retorts, so that it shall be completely sterilized. 1 This process can be fin- ished in a shorter time than the former, and on account of the higher temperature employed is very effective. Experiment 157. To show the effect of exclusion of ordi- nary air from fruit, prepare two samples thus : Place some hot apple sauce in two 250 cc. bottles that have just been heated with boiling water. In the mouth of one bottle 1 Ibid. p. 690. 300 SANITARY AND APPLIED CHEMISTRY place a perforated cork, through the opening of which passes a calcium chlorid tube packed with cotton, that has been heated in an oven to 120C. In the mouth of the other bottle place a cork having a small opening in it. Allow these bottles to stand for a week or more in a warm place, and notice the almost entire absence of mold in the bottle which is protected from the microorganisms of the air by the cotton, and the abundant mold on the surface of the sauce in the other bottle. When canned food spoils if put up in tin cans, the can usually becomes convex on the ends, instead of con- cave, as it is found normally, on account of the genera- tion of gases by fermentation. It is not an uncommon practice for manufacturers to puncture these " swells " and reheat them to stop fermentation, and afterward solder them again, and put them on the market. Since tin cans are used in the preservation of food, and as the tin plate, as it is called, from which the cans are made, often contains considerable lead, it is not uncommon to find salts of tin, iron, and lead in the canned products. This is partly due to carelessness in soldering of the cans, and allowing the drops of the solder, which may contain 50% of lead, to remain inside the can, and partly because the acid fruits act on the tin plate of which the can is com- posed. Formerly very grave danger was apprehended from the metals that might be contained in canned goods, but the fact is that we have not experimentally proven whether the small quantities that are found have a poisonous effect or not. Experiment 158. To show the presence of iron in canned fruit, test some of the juice from a can of California grapes (better one that has been canned for some time) with a little of a strong infusion of tea. Since the tea contains PRESERVATION OP FOOD 301 tannic acid (Experiment 141) it will form a black coloration (ink) with the iron that has been dissolved from the tin plate by the acid of the fruit. CHEMICAL PRESERVATIVES In recent years the practice of adding preservatives to food has greatly increased. These preserve the foods by preventing the growth of bacteria. There may be a differ- ence of opinion in regard to the use of some of them, but it seems perfectly reasonable that antiseptic substances which will prevent the decay of food will be liable also to retard the disgestive processes. Food that has really begun to decay may, by the use of these preservatives, be put on the market and sold as wholesome. It is no defense of the practice to claim that food that has been thus treated is better than if it had not been treated, for such food, which has begun to decay or ferment, should be condemned without question. When preservatives are added to food intended for the use of invalids and young children, they are especially liable to interfere with the digestion and prove injurious to the system. Many tests have been made upon the lower animals, and some results have been obtained which indicate that some preservatives may be used with impu- nity, but the time has not come to admit the use of preserv- atives in foods without question. This position has been taken by the health authorities in many states ; and where the use of these substances is not actually prohibited, they require at least that each package so preserved shall be labeled to that effect.''! In a recent article l Dr. Vaughan says, " A true food preservative must keep the substance to which it is added in a wholesome condition so that it can be consumed by persons in every physical condition of life without impair- 1 Jour. Am. Med. Assoc., Vol. XLIV., p. 753. 302 SANITARY AND APPLIED CHEMISTRY merit of health or danger of life. It is not the function of a food preservative to impart to the food a deceptive appear- ance and to make it look better than it actually is. The law . . . forbids the use of all meat preservatives that restore the color and fresh appearance to partially decomposed meats. ... To prevent the development of those bacteria that produce odoriferous substances while the more toxic bacteria, that develop no telltale odor, continue to grow and multiply, does not comply with the requirements demanded by a food preservative that asks for legal sanction. ... To retard the multiplication of the lactic acid bacillus, and thus prevent the souring of milk, while colon bacilli continue to multiply uninterruptedly is not the function of a true food preservative. . . . The man who adds formaldehyde to his milk takes down the danger signal, but does not remove the danger." In regard to the action of preservatives on the digestive fluids, it should not be forgotten that preservatives if permitted in the food are liable to be taken by persons with every degree of digestive impairment. The free hydrochloric acid of the gastric juice will be neutralized by sodium sulfite, if this salt is used as a preservative, and this cannot fail to interfere seriously with the action of the digestive enzymes. It seems to be well established that formaldehyde also inter- feres with their action. In regard to some of the other preservatives, sufficient experiments have not been made to prove definitely that they interfere with the digestive func- tions. The author above quoted believes that a food preservative in order to receive legal sanction should keep the food in a wholesome condition and not simply retain this appearance while bacterial changes continue ; in the largest quantities used it should not impair any of the digestive processes ; and finally this substance must not be a cell poison, or if it PRESERVATION OF FOOD 303 is a cell poison, it must be added to foods only by persons who have special training, and not by a manufacturer who has no knowledge of the subject. Foods containing these preservative substances should also be plainly marked, so that the presence of the preservative can be known to each consumer. "If the use of any preservatives is to be permitted in food, boric acid and sodium benzoate are the least objec- tionable, since they appear to have less tendency to dis- turb the digestive functions than have the others." l At the conclusion of an exhaustive series of experiments upon the effect of boric acid and borax on the general health, Dr. H. W. Wiley says : " It appears, therefore, that both boric acid and borax when continuously given in small doses for a long period, or when given in large quantities for a short period, create disturbance of appetite, of digestion, and of health." 2 Some of the preservatives most used are borax (Na 2 B 4 7 , 10 H 2 0), boric acid (H 3 B0 3 ), salicylic acid (HC 7 H 5 3 ), ammonium fluorid (NH 4 F), benzoic acid (HC 7 H 5 2 ), so- dium benzoate (NaC 7 H 5 2 ), formaldehyde (HCHO), sodium sulfite (Na 2 S0 3 ) and sulfurous acid (H 2 S0 3 ), beta-naph- thol (Ci H 7 OH), abrastol Ca(C 10 H 6 S0 3 OH) 2 and saccharin (C 6 H 4 COS0 2 NH). The detection of small quantities of these substances in food usually requires the service of an experienced analyst. Borax and boric acid are often sold under various names, such as " Preservaline," and mixtures of borax with other preservatives are also on the market under various trade names. This preservative is used especially in milk and meat products. The method of detection given under Milk, Experiment 136, should be followed. !H. Leffman, Jour. Franklin Inst. 147 (2), 97-109. 2 Circ. 15 or Bui. 84, U. S. Dept. Agric., Bu. Chem. 804 SANITARY AND APPLIED CHEMISTRY Salicylic acid is a white crystalline powder, very soluble in alcohol, and soluble in 500 parts of water. It is used in preserving fruit products, beer, cider, milk, etc. Experiment 159. To test for salicylic acid, to 50 cc. of the substance to be tested, made feebly acid with a few drops of sulf uric acid, add an equal bulk of a mixture of equal parts of ether and petroleum spirit, and shake vigor- ously. Allow the liquids to separate, and draw off the solvent, or take it out with a pipette, filter it, and allow it to evaporate at a gentle heat. If salicylic acid is present, fine silky crystals will usually be seen. Add to the residue left on evaporation a few drops of water and a drop of very dilute ferric chlorid or of ammonium ferric alum solu- tion, and if there is any salicylic acid, a characteristic violet color is produced. Sodium benzoate, which is more frequently used as a preservative than benzoic acid, is a white granular powder, of a slightly aromatic odor, and disagreeable taste. It is readily soluble in water, and the solution is used as a preservative, especially for catsup, mince meat, jams, and jellies. Experiment 159 a. Benzoic acid or a benzoate may be detected in the absence of salicylic acid by Peter's method, 1 which depends on oxidation of the benzoic acid to salicylic acid by treatment with sulfuric acid and barium peroxid, and then applying the ferric chlorid test for salicylic acid noted in Experiment 159. Saccharin acts both as a preservative and a sweetening agent. It is a white crystalline powder, soluble in 1000 parts of cold water. It is four or five hundred times as sweet as cane sugar. Sodium sulfite is a white solid readily soluble in water. 65, p. 160, U. S. Dept. Agric., Bu. Chem. PEESERVATION OF FOOD 305 It has the characteristic taste of the smoke of a burning sulfur match. The sulfites are used especially to preserve meat and meat products, and give them a "natural" red color, and for alcoholic beverages, cider, fruit juices, and catsup. Experiment 160. As the test for the detection of sulf ur- ous acid depends on converting it into sulfuric acid, the following method may be used : Place 200 g. of the sus- pected food, which, if solid, should be ground with water in a mortar, in a flask, make acid with phosphoric acid, con- nect with a condenser, and distill slowly, till 20 cc. have come over. Boil this distillate in a large test tube or small flask with bromin water and add a few drops of barium chlorid. The formation of a white precipitate of barium sulfate indicates that a sulfite was present. Formaldehyde is a gas that readily dissolves in water. The 40% solution is usually sold under the name of "for- malin." The gas has a characteristic odor. It is used as a preservative for fish, broken eggs, meat products, milk, etc. The method of testing for formaldehyde is given under Milk, Experiment 137. Experiment 161. To some egg-white, in a porcelain evapo- rating dish, add a moderate quantity of formaldehyde. Place the dish over a water bath, and warm, not above 60 C. for some time. Notice the leathery character of the product. Experiment 162. Saccharin is said by some to have slightly preservative qualities, but it is added to food products, such as canned sweet corn, principally as a sweetening agent. For its detection in jelly, preserves, or canned vegetables, use about 20 grams of the sample. Grind this in a mortar with about 40 cc. of water, strain through muslin, acidify with 2 cc. of dilute sulfuric acid, and shake moderately with ether. Separate the ethereal layer and allow this to evaporate 306 SANITARY AND APPLIED CHEMISTRY spontaneously in a watch glass, and take up the residue with water. If saccharin is present, this solution will have a sweet taste. To confirm this test add one or two grams of sodium hydroxid, place the dish in an oil bath and heat to 250 C., for twenty minutes. This will convert the saccharin into salicylic acid. After cooling and acidifying with sulfuric acid, extract as usual and test for salicylic acid according to Experiment 159. 1 COLORING OP FOOD PRODUCTS This is another method of falsifying food, and making it appear better than it is, or of simulating wholesome foods with a combination of entirely foreign substances. The coal-tar colors, of which there is an endless variety, lend themselves very readily to the coloring of foods and bever- ages. The use of these dyestuffs is not only liable to lead to injury of the health of the consumer from the poi- sonous nature of the coloring material, but the consumer is deceived so that he buys the goods thinking they are of greater value than they actually are. There are some of the coal-tar or aniline colors, which are of themselves harm- less, but in the process of manufacture some poisonous sub- stance such as arsenic or mercury is used, and a little of this remains in the finished product, making it dangerous for consumption. It is true that so far as we know the coal-tar colors are mostly harmless, so the chief cause for objection to their use is on account of the fraud on the consumer. It is the custom with many manufacturers of confectionery to use only such colors as are accompanied by certificates cf the chemist as to their purity. In some cases vegetable colors, such as turmeric, logwood, annatto, Brazil wood, beets, and safflower are used. The only animal coloring matter in common use is that of the cochineal, called carmine red. 1 Bui. 66, p. 51, U. S. Dept. Agric., Bu. Chem. PRESERVATION OF FOOD 307 Experiment 163. Test a sample of tomato catsup for a coal-tar dye by the method described in Experiment 122. Salts of copper are sometimes used to impart an artificial green color to canned goods, particularly peas, beans, brus- sels sprouts, and pickles. An old-fashioned method for greening pickles was to put a copper cent in the vinegar in which they were boiled. The practice of coloring food material by the use of compounds of copper is more common on the Continent than in the United States. Imported goods frequently contain considerable copper. 1 Examinations of a large number of canned vegetables greened by copper, as bought in Massachusetts, showed them to contain from a trace to 2.75 g. per can, calculated as copper sulfate. The author has found in an ordinary pickled cucumber the equiva- lent of one seventh of a grain of copper sulfate. Experiment 164. Incinerate fruit or vegetables in a por- celain evaporating dish with sulfuric acid, adding a little nitric acid from time to time till the carbon is completely consumed. Add a few drops of hydrochloric acid to the ash, filter into a small test tube, and add to this solution an excess of ammonium hydroxid, when a blue color indicates the presence of copper. 1 Leach, " Food Inspection and Analysis," p. 70. CHAPTER XXVI ECONOMY IN PREPARATION OF FOOD; DIETARIES THE importance of cooking food has already been dis- cussed (p. 121). It is owing to the practice of cooking food that the dietary of civilized man has been greatly en- larged and improved. Many kinds of food which would be not only unpalatable, but indigestible in the raw state, are rendered wholesome and nourishing by some process of cook- ing. So the proper cooking of food may be regarded as an art ; indeed, one distinction of a civilized man is that he is one who prepares his food by cooking. Most foods, with the exception of fruits, require cooking ; animal foods espe- cially are cooked to make them palatable and wholesome. In addition to what has been said on previous pages about cooking in the case of individual foods, since all the different foods have now been studied, some general state- ments will be more readily understood. In the cooking of starchy foods it will be noticed that the starch grains, as " put up," so to speak, by nature, are very close and compact in most seeds, so that they will withstand any natural temperature, and a moist as well as a dry climate. When these seeds are to be used for food they must be soaked with water and allowed to swell. By this treatment the fine particles of starchy substances will be in a much better condition to be attacked in the process of digestion by the alimentary liquids. The starch grains are rendered much more digestible by being cooked ; there is less lia- bility that they shall pass through the body unchanged, for 308 ECONOMY IN PREPARATION OF FOOD 309 if they are not changed to sugar by the ptyalin (see Ex- periment 84) of the saliva, or the juices in the stomach and intestines, they do not nourish the body. Fats undergo slow combustion in the body and are changed to carbon dioxid and water, thus furnishing much of the heat needed by the body. If these are too expensive, their place may, to a considerable extent, be taken by the carbohydrates. In any case the excess, or that which remains over what is actually used up in doing the work required of the body, is stored up, and may be drawn upon as a reserve. The fats should be taken into the system as fats and not as products of the destruction of fats. In the process of digestion in the intestine, the fat is subjected to a double process of emulsification and saponification, which is brought about by the combined action of the bile and the pancreatic juice. This process is interfered with, and indigestion is produced when overheated fats are taken into the system. These volatile products which are produced by the decompo- sition of the fats cause the familiar irritation of the eyes, and a disagreeable odor, when food is fried. In cooking an albuminous food, as an egg, if frying is the method of cooking used, the temperature is necessarily so high that the egg albumin is rendered hard and partially in- soluble in the digestive fluids. Oysters, 1 when satisfactorily cooked, are heated only to boiling, or if fried, are sur- rounded by a batter, which protects the albuminous tissues from being overheated. A high temperature also greatly decreases the digestibility of the gluten of grains and of the casein of milk, so the latter liquid is less wholesome when boiled. Beans and peas, which contain both legumin and starch, 1 Richards and Elliot, " The Chemistry of Cooking and Cleaning," p. 61. 310 SANITARY AND APPLIED CHEMISTRY require considerable cooking, to soften the cellulose and make the starch digestible. If these vegetables are cooked in hard water, there is danger that an insoluble compound shall be formed, by the combination of the legumin with lime or magnesia in the water ; steaming, as previously sug- gested, will partly obviate this difficulty. Again, in seeking for economy of food, the question arises, What food furnishes the largest amount of nutriment at the most reasonable cost ? As we shall see a little later, the amount of energy in terms of "calories" that each food is capable of producing, has been carefully determined, and this will furnish a clew to the value of different foods. For instance, a certain sum invested in bread will yield much more energy than the same sum invested in milk or in meats. Both the latter foods are valuable, but they are not cheap. To build up the tissues, a cheap form of proteid is that contained in peas or beans, while eggs are eight times as expensive, and beef five times as expensive at ordinary prices. In general, vegetable food is cheaper than animal food, either as a source of energy or to build up the tissues. The reason for this is evident when we consider that the vegeta- ble foods are built up from the simple substances found in air, water, and soil, while the food of animals consists of highly organized vegetable or animal substances. One author states, as an illustration of the comparative cost of vegetable food, that 1\ acres devoted to raising mutton would support a man for a year, while the same amount devoted to the growing of wheat would support 16 men for the same time. It may be said that as the vegetable food is so much more bulky it would require much more heat to cook it, but with the best appliances, the cost of this additional fuel would not counterbalance the increased cost of animal food. While carbohydrates are cheap constituents of food, pro- ECONOMY IN PKEPARATION OF FOOD 311 teids and fats are expensive. If the fat is derived from animal sources this is particularly true, but foods contain- ing cotton-seed oil, and the oil of some varieties of nuts, furnish fats at a reasonable price. There is no necessary relation between the cost of a food and its nutritive value, for we pay for color, size, appear- ance, and flavor, in foods, not for their value in feeding the body. There is practically as much nourishment in the cut of beef costing 8 cents a pound as in that costing 16 cents ; a fine quality of starch in the form of arrowroot or sago is expensive, but the same amount of starch of a different fla- vor made from corn is very cheap ; a Roquefort cheese costs perhaps 50 cents a pound, while a cheese just as good for food, but made in New York State, costs only 15 cents. It is important that the right method of cooking should be selected for each food, a method that shall develop the agreeable flavors and make the food as digestible as possible. A cheap cut of beef may be made appetizing and wholesome by careful and skillful cooking, and it is equally true that an expensive cut may be made tough and tasteless by the ignorant cook. It is easy to spoil good food, and render it unwholesome by cooking it in fat, or by too slow heating. Potatoes maybe cooked till they are "mealy" and the sepa- rate starch grains glisten in the light, or they may be water- soaked and waxy, and consequently slow to digest. It is easy to prepare sour or heavy bread, overheated toast, tough beefsteak, or muddy coffee, but the raw material costs just as much as if the food product had been made wholesome and agreeable. Great economy of fuel can be secured by the use of the right kind of stove or range, and by utilizing such an appliance as a " steamer," so that half a dozen dishes can be cooked at one time over the same fire. This latter vessel is especially economical when gas, either natural or artificial, 312 SANITARY AND APPLIED CHEMISTRY or gasoline is used for fuel in cooking. When the water is once brought to a boiling temperature in the steamer, a very small flame will keep it boiling, and the contents of the vessel will not become appreciably hotter, nor will it cook much quicker, if it boils much more tumultuously. Boiling water means 100 C., and it does not get any hotter, except under pressure. This is a fact too often forgotten by the cook, who is anxious to "hurry the dinner." Another interesting application of science to the culinary art is the invention of the Aladdin oven, by Edward Atkin- son. 1 This oven consists of a metallic chamber surrounded by nonconducting material, and so arranged that it can be heated from below with a good kerosene lamp or Rochester burner. Almost any food may be cooked in this oven, and it is especially adapted to the preparation of soups and the cooking of vegetables. The process depends on the use of a moderate heat for a long time instead of a high temperature for a short time, as in ordinary cooking. As the oven is surrounded by a nonconducting wall, the heat that is pro- duced cannot readily escape. This oven has been utilized on a large scale in preparing cheap and nutritious food for workmen. DIETARIES We have already discussed the two general classes of nutrients (p. 123) and to some extent the properties of each class. Most of our knowledge of the composition and nutritive value of food has been accumulated, in the United States and Europe, within the past fifty years. Although the analysis of milk was reported by Boussiugault and Le Bel in 1831, 1 yet it was not till Liebig, Playfair, 1 " The Right Application of Heat to the Conversion of Food Mate- rial," Proc. Am. Aatoc. for Adv. Science, 1890. 8 Atwater. " Foods, Nutritive Value and Cost," Farmer's BuL 23, U. 8. Dept. Agric. ECONOMY IN PREPARATION OF FOOD 313 Boeckman, and others, about the middle of the last century, devised new methods for the analysis of foods and feeding stuffs, that we began to have a definite knowledge of this important subject. With the adoption of the so-called Weende method, pro- posed by Henneberg in 1864, new impetus was given to this branch of investigation, and numerous improvements have been made, till now chemists generally agree on the methods of analysis to be employed. American food products first began to be investigated in 1878-1881, by Professor Atwater, under the auspices of the United States Fish Commission, and these investigations have been carried on more recently by agricultural colleges, the experiment stations of the va- rious states, and the Department of Agriculture of the gen- eral government. The latter department, at an expense of from $ 10,000 to $20,000 per year, for the past 10 years, has extended these investigations on human nutrition, till at the present time we have very complete data upon this subject. 1 We have already learned that the analysis of a food shows the per cent of water, proteids, fats, carbohydrates, and min- eral salts, which it contains, and each of these, with perhaps the exception of water, has its food value. In order to com- pare the different foods, and calculate the relative amount of energy that can be obtained from them, the ordinary method is to determine the "heat units," or "calories," that can be produced by the combustion, under standard condi- tions of a given amount of food. Although the results are not exactly the same when food is oxidized in the body to produce energy, and when it is burned in a calorimeter to produce heat, yet this method is convenient for classification and computation of the relative value of foods. *At-water and Woods. "Chem. Comp. of Am. Food Materials," Bui. 28, U. S. Dept. Agric., Office of Exp. Stations. 814 SANITARY AND APPLIED CHEMISTRY A calorie l is the amount of heat that is required to raise the temperature of one kilogram of water from to 1 C., or approximately the amount of heat that would be required to raise one pound of water 4 F., and is equal to 3084 foot- pounds. The "fuel value" means the total calories obtained by the combustion of any food substance within the body. Considering the ordinary food materials, the following esti- mate has been made for the average amount of heat and energy or the "fuel value" of each of the classes of nutrients : One pound of protein gives .... 1860 calories. One pound of fats gives 4220 calories. One pound of carbohydrates gives . . . 1860 calories. From this it will be seen that a pound of protein of lean meat, for instance, is about equal to a pound of sugar or starch, in yielding heat and mechanical energy, and that fats have a fuel value about two and a quarter times that of the carbo- hydrates or protein. From the analyses of foods, to which reference has been made, it is possible to calculate the fuel value of a given amount of any food or of the rations supplied to a number of people. Experiments have also been carried on by W. 0. Atwater, at the Wesleyan University, in what is known as a " res- piration calorimeter." In this apparatus, which is a small closed room, the experimenter remains for several days, and all the food, air, and water used is weighed and passed in to him, and all the products given off from the body are also weighed and analyzed. A careful record is also taken of the temperature, and if the experimenter works to exer- 1 See "Foods, Nutritive Value and Cost, " Atwater, also "Practical Dietetics," Thompson, also ''Air, Water, and Food," Richards and Woodman. ECONOMY IN PREPARATION OF FOOD 315 else his muscles, a record is made of the mechanical work accomplished. " The main value of the experiments so far conducted in this calorimeter consists in the actual demon- stration that the law of conservation of energy operates within the body in precisely the same manner as it does outside." In man it was found that the measured energy of the food consumed by the subject within the calorimeter was within 1 % of the calculated or theoretical energy. Having a knowledge of the composition of food, and a method for finding its value as an energy producer, we are in a position to study the food of different individuals or classes of people, or to study dietaries. A dietary, then, would be a known amount of food of known composition, per day per person, and a standard dietary would be such a combina- tion of materials as furnishes a sufficient amount of each of the nutrient substances to fully sustain the body. Professor Voit of Munich was one of the first to pre- pare standard dietaries, and his work has been supplemented by a large amount of work in the United States, espe- cially within the last ten years. It has been recently pointed out that there are two meth- ods of estimating dietaries. One method is by studying the food consumption of classes of people or individuals, when they have a free choice of food, or when they procure such food as their circumstances allow them to buy. The other method contemplates the feeding to classes of individ- uals, or to selected persons, certain foods of known weight and composition, and studying the nitrogen balance, as it is called ; that is, the amount of nitrogen taken into the body, daily, in the food, and the amount excreted. If there is more nitrogen excreted from the body than taken in, the system is evidently not fully nourished. If there is a slight excess of nitrogen maintained, the food is sufficient for the amount of work done by the individual. An excess of 316 SANITARY AND APPLIED CHEMISTRY nitrogenous material, or of fat, may be stored in the body for use in emergencies. Returning to the ordinary method of studying dietaries, some examples may be given of the results observed by different chemists : l DIETARIES * PROTEIN FATS CARBO- HYDRATES FUBL VALU* NDTRITIV KATIO .Lbs. Lbs. Lbs. Calories Ito Well-fed tailors, Eng- land, Playfair . . .29 .09 1.16 3055 4.7 Blacksmiths, England, Playfair .39 .16 1.47 4115 4.7 Well-fed mechanics, Mu- nich, Voit .... .34 .12 1.06 3085 4.0 Brickmakers, Munich, diet mainly corn meal and cheese, Hanke . .37 .26 1.49 4540 5.6 Brickmakers, Massachu- setts, very severe work .40 .81 2.54 8850 11.0 Professional men, Mid- dletown, Ct., Atwater .27 .34 1.08 3925 6.6 University professors, Munich, light exercise, Kanke 22 .22 .53 2325 4.7 In the above table the nutritive ratio, mentioned in the last column, is the ratio of the protein to the sum of all the other nutritive ingredients. The fuel value of the fats, as pre- viously noted, is two and a quarter times that of the protein and carbohydrates, so in the calculation the quantity of fats is multiplied by two and one fourth, and the product is added 1 Chittenden, "Physiological Economy in Nutrition"; also At- water, Inc. cit. 8 Per man per day. ECONOMY IN PREPARATION OP FOOD 317 to the carbohydrates. This sum, divided by the weight of the protein, gives the nutritive ratio. Thus, in the first dietary quoted, the ratio of protein to fats and carbohy- drates is as 1 to 4.7. Some standard dietaries have been compiled by Atwater, and represent what is believed by the several authors to be the amount needed by persons with different degrees of labor. (The amounts are expressed in grams.) PROTEIN FATS CARBOHY- DRATES TOTAL FUEL VALITB, OK CALORIES Children, 6 to 15 . 75 43 325 443 2041 Women, at moderate work, Voit . . . 92 44 400 536 2426 Man, at moderate work, Voit . . . 118 56 500 674 3055 Man, at hard work, Voit 145 100 450 695 3370 Hard labor, Playfair 185 71 568 824 3748 Man, at moderate work, Atwater . 125 125 450 700 3520 Man, at hard work, Atwater . . . 150 150 500 800 4060 Experiment 165. Study the food used by a family or club for a period of several weeks. Note the actual weight of all food purchased, the cost, and the number of individual meals taken. Prom the tables given by Atwater, compute the total amount of protein, fats, and carbohydrates consumed, and the amount per day per capita. By the use of the same tables estimate the " fuel value " of the food, and the nutri- tive ratio. Tabulate the results as in the table quoted from Mrs. Richards on page 319. The daily amount of solid food consumed by the adult male is 50 oz. to 60 oz., and the water used is about the 318 SANITARY AND APPLIED CHEMISTRY same. In case of severe labor this amount of food would be increased to 75 oz., the addition being mostly in fats and car- bohydrates. 1 The standard ratio for health, of protein to fuel ingredients, has been placed at 1 to 5.8 by the Experiment Stations of the Department of Agriculture. According to the standard dietaries given above, and many others that might be quoted, an average man doing light work would consume 116 g. of protein, with suffi- cient fat and carbohydrates, to give 3050 calories; many authorities would decrease this as low as 100 g. of protein. This could be obtained from a great variety of diet, either largely vegetable, or with a moderate amount of animal food. From some recent experiments by Chittenden, 2 and oth- ers, upon several groups of persons, some of whom lived sedentary lives, and others of whom were athletes and sol- diers, it was shown that it was possible to maintain the nitrogen balance and remain in good health with consid- erably less food, especially of the proteid class, than the accepted dietary standards would indicate. On a diet containing only 42 to 55 g. of proteid matter, instead of 116 to 121, and enough carbohydrates and fats to make 1750 calories, instead of 3050, the men lived and carried on their daily work for several months. This would indicate that there is a tendency to eat more food than necessary, and thus to overburden the excretory organs. The following ideal ration of solid food is given by Mrs. E. H. Richards: 8 1 Thompson, "Practical Dietetics," p. 20. '"Physiological Economy in Nutrition"; "Economy in Food," Century Magazine, Vol. 70, p. 859. " Chem. Com. of Am. Food Material." Bui. 28, U. S. Dept. Agric., Office of Exp. Stations. Also see Farmer's Bui. 23, U. S. Dept Agric. ECONOMY IN PREPARATION OP FOOD 319 MATERIAL AMOUNT GRAMS PKOTBID FAT CARBO- HYDRATES CALORIES Bread .... 463.6 31.75 2.26 257.28 1206.82 Meat .... 226.8 34.02 11.34 243.72 Oysters .... 226.8 12.52 2.04 70.01 Breakfast Cocoa 28.3 6.60 7.50 9.60 135.42 Milk 113.4 3.63 4.42 4.88 75.55 Broth .... 453.6 18.14 18.14 90.72 316.21 Sugar .... 28.3 27.36 112.17 Butter .... 14.17 .14 12.27 118.62 Total . . . 106.80 57.97 389.84 2574.60 Here the amount of proteid is nearly 107 g. or about the average suggested by the best authorities. In studying dietaries, it is also a practical question to ascertain what the cost of food per day per man should be. The habits of people differ so widely, that while in some countries good and sufficient food can be obtained at 10 to 15 cents per day per capita, in other localities as much as 35 cents per day is needed to procure satisfactory food. The following summary x of cost of food in different locali- ties, and under varying conditions of life, and showing the amount of food wasted, is of interest: COST OF FOOD PURCHASED CALORIES CALORIES WASTED NUTRITIVE EATIO Cents Teacher's family, Illinois . 27 3975 700 1:6.9 Professional men, Connecticut 25 3530 100 1:6.8 Mechanics' Boarding Club, 23 3720 330 1:6.1 Mechanic's family, Indiana 26 3840 555 1:7.9 Mechanic's family, Tennessee 16 4435 345 1:8.1 Students' Club, Kansas 2 . 18 3437 1:7.6 1 Bui. 91, U. S. Dept. of Agric., Bu. Chem., 1900. 2 Trans. Kan. Acad. of Science, Vol. XIX. 820 SANITARY AND APPLIED CHEMISTRY As some of these figures were obtained several years ago, they would not indicate the cost of living at the present time, as similar experiments have shown that it has in- creased, within a few years, from 25 % to 30 %. The waste of food referred to covers the necessary loss from skins, seeds, bones, etc. ; and evidently, from the great difference in different cases, it also covers a large amount of unnecessary waste. From statistics collected in this country, especially in Massachusetts, and in Europe, an idea can be obtained of the proportion of income that is ordinarily used for the purchase of food by families in different circumstances : * INCOME PER CBHT EXPENDED FOR FOOD GERMANY Workingmen Dollars 225 - 300 62 450-600 55 Well-to-do 750-1100 50 GllKAT lilUTAIN Workingmen 600 51 MASSACHUSETTS Workingmen 350-400 64 450-600 63 Workingmen 600-760 60 Workingmen 760-1200 56 Workingmen Above 1200 61 When the income is small, considerably more than one half is expended for actual food. This surely leaves a very small amount for rent, clothing and the other necessaries of life. Since a sufficient quantity of wholesome food is of the utmost importance, the poor man is justified in expending 1 Farmer's Bui. 23, U. S. Dept. Agric. ECONOMY IN PREPARATION OF FOOD 321 more than half of his income to provide his family with that which they need to give them health and strength. It is unfortunately true, however, that even the most intelligent people know less of the source, uses, and actual value of their food for fulfilling its important purpose, than they do of almost any of the other daily necessities. It is estimated that at least 10 % of the income is squandered not only by the well-to-do, but frequently also by those who have a very small income and so can ill afford it, in expensive food material which affords little nutrition, in unsatisfactory methods of preparation, in selecting foods out of season, by throwing away much valuable food material, and by using badly constructed cooking appliances. Much careful investigation is needed along these economic lines, and painstaking instruction will ultimately improve these conditions which are at present so much deplored. BIBLIOGRAPHY THE following books and periodicals will be found con- venient for reference. A more complete bibliography on foods is found under the individual topics in " Leach on Food Inspection and Analysis." An excellent bibliog- raphy on the general subjects discussed in this book may be found in Richards and Woodman's "Air, "Water, and Food." AUTHORS BOOKS PUBLISHERS Abady. Gas Analysis Manual. Spon & Chamberlain, New York. Allen. Commercial Organic Anal- Blakiston's Sons & Co., ysis. Vol. 1, 2, 3, 4. Philadelphia. Bailey. Mineral Waters of Kansas. Kans. State Univ., Geolog. Vol. VII. Survey. Bailey and Cady. Laboratory Guide to Study Blakiston's Sons & Co., of Qualitative Analysis. Philadelphia. Barry. Hygiene of the School- Silver, Burdett & Co., room. Boston. Bartley. Medical Chemistry. Blakiston's Sons & Co., Philadelphia. Barwise. Bacterial Purification of C. Lockwood & Son, Lon- Sewage. don. Battershall. Food Adulteration and its E. & F. N. Spon, New Detection. York. Benedict. Chemical Lecture Experi- Macmillan Co., New York. ments. Benedikt and Chemistry of Coal Tar Geo. Bell & Sons, London, Kneeht. Colors. 1889. Bergey. Methods for Determination Smithsonian Inst., Wash- of Organic Matter in Air. ington. 323 324 BIBLIOGRAPHY AUTHORS BOOKS PUBLISHERS Billings. Ventilation and Heating. Engineering Record, New York. Bissell. Household Hygiene. Hodges, New York. Black. Forty Years in the Medical Lippincott Co., Philadel- Profession. phia. Blyth. Dictionary of Hygiene and Griffin & Co., London. Public Health. Blyth. Food, Composition and Griffin & Co., London. Analysis. Bowditch. Coal Gas, Analysis, Valua- E. & F. N. Spon, London. tion, Purification and Use of. Catlin. Baking Powders. Rnmford Chemical Works, Providence, R. I. Chittenden. Studies in Physiological Scribner's Sons, New York. Chemistry. Chittcnden. Physiological Economy in Stokes Co., New York. Nutrition. Church. Food. Chapman & Hall, London. Clarke. Elementary Chemistry. American Book Co., New York. Crook. Mineral Waters of United Lea Brothers & Co., Phila- States and their Thera- delphia. peutic Uses. Dammer. Handhnch der Chemischen Ferdinand Enke, Stuttgart. Technologic. Davis. Potable Waters. The Author, Des Monies. Davis. Chemistry for Schools. Scott, Foresman & Co., Chicago. Duckwall. Canning and Preserving. Pittsburg Printing Co., Pittsburg Pa. Eccles. Food Preservatives and Van Nostrand & Co., New their Proper Uses. York. Effront. Enzymes and their Appli- Wiley & Sons, New York. cation. Eliot. Elementary Manual of American Book Co., New Chemistry. York. Erdmann. Lehr Buch der Anorgan- Vieweg & Sohn, Braun- ischen Chemie. schweig. 325 AUTHORS BOOKS PUBLISHERS Fox. Sanitary Examinations of Churchill Co., London. Water, Air, and Food. Franke. Die Chemie der Kiiche. Van Voorst, London. Freer. Microorganisms in Water. Allyn & Bacon, Boston. Frankland, P. and Bacteria in Daily Life. Longmans & Co., London. G. C. Frankland, Mrs. Elements of Chemistry. Longmans & Co., London. Percy. Gill. Gas and Fuel Analysis for Wiley & Son, New York. Engineers. Green. Food Products of the Hotel World, Chicago. World. Groves and Thorp. Chemical Technology. Blakiston's Sons & Co., Vol. I. Fuels. Philadelphia. Groves and Thorp. Chemical Technology. Blakiston's Sons & Co., Vol. II. Lighting. Philadelphia. Groves and Thorp. Chemical Technology. Blakiston's Sons & Co., Vol. III. Gas Lighting. Philadelphia. Hardin. Liquefaction of Gases. Macmillan Co., New York. Harrington. Practical Hygiene. Lea Brothers & Co., Phila. Hartshorne. Our Homes. Blakiston's Sons & Co., Philadelphia. Harrop. Flavoring Extracts with Harrop & Co., Columbus, Essences, Sirups, and Ohio. Coloring. HassaH. Food Adulterations, and Longmans, Green & Co., Methods for Detection. London. Hassler. Essentials of Chemistry. Sanborn & Co., Boston. Hazen. Filtration of Public Water Wiley & Sons, New York. Supply. Holland. Medical Chemistry and W. B. Saunders & Co., Toxicology. Philadelphia. Hutchison. Food and Dietetics. Wm. Wood & Co., New York. Jago. Science and Art of Bread- Simpkin, Marshall, Hamil- making, Chemistry, and ton, Kent & Co., London. Analysis of Wheat Flour. Jones. Principles of Inorganic Macmillan Co., New York. Chemistry. 326 BIBLIOGRAPHY AUTHORS BOOKS PUBLISHERS Jones. Elements of Inorganic MacmillanCo., New York. Chemistry. Kent. Steam Boiler Economy. Wiley & Sons, New York- Kenwood. Public Health Laboratory H. K. Lewis, London. Work. Konig. Chemie der Menschlichen Julius Springer, Berlin. Nahrungs und Geniiss- mittel. Lankester. ^ectures on Food. Hard wicks Co., London. Lassar-Cohn. Chemistry in Daily Life. Lippincott Co., Philadel- phia. Leach. Tood Inspection and Analy- Wiley & Sons, New York. sis. Leeds. Treatise on Ventilation. Wiley & Sons, New York. Leff mann and Beam. Select Methods of Food Blakiston's Sons & Co., Analysis. Philadelphia. Leffmann. Sxamination of Water for Blakiston's Sons & Co., Sanitary and Technologi- Philadelphia. cal Purposes. Lekowitsch. Chemical Technology and Macmillan Co., New York. Analysis of Oils, Fats, and Waxes, 2 vols. Letherby. On Food. Bailliers, Tindall & Co., London. Lewes. Air and Water. Methueu & Co., London. -Mallet. Water Analysis. National Bd. of Health. Mason. Water Supply. Wiley & Sons, New York. Newth. Chemical Lecture Experi- Longmans Green & Co., ments. London. Nichols. Water Supply. Wiley & Sons, New York. Paasche. Zucker indnstrie und Zuck- Gustav Fischer, Jena. erhandel der Welt. Pasteur. Studies on Fermentation. Macmillan Co., London. Paul. Payen's Industrial Chem- Longmans, Green & Co., istry. London. Pavy. Food and Dietetics. Wood & Co., New York. Peters. Modern Chemistry. Maynard, Merrill & Co., New York. BIBLIOGRAPHY 327 AUTHORS BOOKS PUBLISHERS Pharmacopoeia of 8th Decennial Revision. Blakiston's Sons & Co., United States. Philadelphia. Price. Handbook on Sanitation. Wiley & Sons, New York. Rafter. Microscopical Examina- Van Nostrand Co., New tion of Potable Water. York. Rafter. Treatment of Septic Sew- Van Nostrand Co., New age. York. Rafter and Baker. Sewage Disposal in United Van Nostrand Co., New States. York. Ramsay. Gases of the Atmosphere. Macmillan Co., London. Redwood. Petroleum and its Prod- Griffin & Co., London. ucts, Vol. I and II. Remsen. Introduction to Study of Holt & Co., New York. Chemistry, 7th Ed. Richards. Pood and Diet. Whitcomb & Barrows, Bos- ton. Richards. Cost of Living. Wiley & Sons, New York. Richards and Elliott. The Chemistry of Cooking Whitcomb & Barrows, Bos- and Cleaning. ton. Richards and Wood- Air, Water, and Food. Wiley & Sons, New York. man. Rideal. Water and its Purification. Lippincott Co., Philadel- phia. Rolfe. The Polariscope. Macmillan Co., New York. Sadtler. Industrial Organic Chemis- Lippincott Co., Philadel- try. phia. Schulz. Die Mineral-Trinkquellen J. Abel. Greifswald. Deutschlands. Sedgwick. Principles of Sanitary Sci- Macmillan Co., New York. ence and Public Health. Simon. Manual of Chemistry. Lea Brothers & Co., Phila- delphia. Smith. Foods. Appleton & Co., New York. Snyder. Chemistry of Plant and Macmillan Co., New York. Animal Life. Spencer. Handbook for Sugar Manu- Wiley & Sons, New York. facturers and Chemists. Stevenson and Mur- Treatise on Hygiene and Blakiston's Sons & Co., phy. Public Health. Philadelphia. BIBLIOQKAPHT AUTHORS BOOKS PUBLISHERS Soli. Treatise on Beverages. Sulz & Co., New York. Packing House Industries, International Text Book Cottonseed Oil, Manufac- Co., Scranton, Pa. ture of Leather and Soap. -Thompson, W. G. Practical Dietetics. Apple ton & Co., New York. Thorp. Outlines of Industrial Macmillan Co., New York. Chemistry. Thresh. The Examination of Waters Blakist on's Sons & Co., and Water Supplies. Philadelphia. Thudicum. Cookery, its Art and Prac- F. Warne & Co., London. tice. Thurber. Coffee from Plantation to American Grocer Pub. As- Cup. sociation, New York. Tollens. Handbuch der Kohlenhy- E. Trewendt, Breslau. drates. Tucker. Manual of Sugar Analysis. Van Nostrand, New York. Vaughan and Novy. Cellular Toxins. Lea Bros. & Co., Phila. Venable. History of Chemistry. Heath Co., Boston. Wanklyn. Water Analysis. Triibner & Co., London. Wanklyn. Bread Analysis. Triibner & Co., London. Wanklyn. Milk Analysis. Triibner & Co., London. Watts. Dictionary of Chemistry, Longmans, Green & Co., 4Vols. London. Weichmann. Sugar Analysis. Wiley & Sons, New York. Whipple. Microscopy of Drinking Water. Wiley & Sons, New York. Wiley. Agric. Chem. Analysis, Chem. Pub. Co., Easton. 3 Vols. Williams. Chemistry of Cookery. Appleton & Co. , New York . Willoughby. Hygiene for Students. Macmillan Co., London. Winton and Moeller. The Microscopy of Vegeta- Wiley & Sons, New York. ble Foods. Wood. United States Dispensa- Lippincott Co., Philadel- tory. phia. Yeo. Food in Health and Disease. W. T Keener & Co., Chi- cago. Zipprer. Manufacture of Chocolate. Spon & Chamberlain, New York. BIBLIOGRAPHY 329 PERIODICALS AUTHORS SUBJECTS PUBLICATIONS Abel. Sugar as Food. U.S. Dept. Agri. Fanner's Bui. 13. Abel. Beans and Peas and Other U.S. Dept. Agri. Office Leguminous Food. Exp. Sta. Bui. M. Amer. Chem. Jour., Vols. 1-34. Atkinson. Cooking of Food. U.S. Dept. Agri. Atwater. Experiments in the Con- U.S. Dept. Agri. Exp. Sta. servation of Energy. Bui. 63. Atwater. Bread and Principles of U.S. Dept. Agri. Farmer's Bread Making. Bui. 112. Atwater. Foods, Nutritive Value U.S. Dept. Agri. Farmer's and Cost. Bui. 23. Atwater, Benedict. Exp. in Metabolism of U.S. Dept. Agri. Office Matter and Energy in Exp. Sta. Bui. 69. the Human Body. Atwater, Woods, Metabolism of Nitrogen U.S. Dept. Agri. Exp. Sta. Benedict. and Carbon in the Bui. 63. Human Organism. Atwood. A Study of Cider Making. U.S. Dept. Agri. Bu. of Chem. Bui. 71. Atwood. Chemical Composition of U.S. Dept. Agri. Bu. of Apples and Cider. Chem. Bui. 88. Bailey. Recent Progress in the Salt Internationales Kong, fuer Industry in the U.S. angewandte Chem. 1901. Bigelow. Composition of American U.S. Dept. Agri. Div. Wines. Chem. Bui. 59. Bigelow and Some Forms of Food Adult. U.S. Dept. Agric. Bu. Chem. Howard. Bui. 100. Bigelow. Food and Food Control. U.S. Dept. Agri. Bu. Chem. Bui. 69. Pt. 2 & 4. Bui. 83, Pt. 2. Bigelow. Analysis of Foods. U.S. Dept. Agri. Bu. of Chem. Bui. 65. Bigelow, Gore. Studies in Apples. U.S. Dept. Agri. Bu. of Chem. Bui. 94. 330 BIBLIOGRAPHY AUTHORS SUBJECTS PUBLICATIONS Bigelow, Gore, Studies on Peaches. U.S. Dept. Agri. Bu. of Howard. Chem. Bui. 97. Causse. Recherches sur la contami- Storck, Lyons. nation des Eaux. Chase, Tolman, Chemical Composition of U.S. Dept. Agri. Bu. of Munson. some Tropical Fruits and Chem. BuL 87. their Products. Corbett. Tomatoes. U.S. Dept. Agric. Farmer's Bui. 200. Duggan. Cultivation of Mushrooms. U.S. Dept. Agric. Farmer's Bui. 204. Gibson. Dietary Studies. Univ. of Mo. Exp. Sta. Bui. 31. Grindley Losses in cooking Meat, U.S. Dept. Agric. O. Ex. Sta. etc. Buls. 102, 141, 162. Jour. Amer. Chem. Soc. Vols. 1-27. Jour. Chem. Soc. Vols. 38-64. Jour, of Soc. of Chem. Industry, Vols. 1-24. Jordan. Dietary Studies in Maine U.S. Dept. Agri. Office State College. Exp. Sta. Bui. 37. Kebler. Adulterated Drugs and U.S. Dept. Agri. Bn. of Chemicals. Chem. Bui. 80. Langworthy. Eggs and their uses as U.S. Dept. Agri. Farmer's Food. Bui. 128. Leffman. Milk Inspections and Milk Medical News, Feb. 2, Standards. 1895. Logan. The Underground Waters. Miss. Agri. Exp. Sta. Bui. 89. Mallet. Creatin and Creatinin. Exp. Sta. Bui. 66. McFarlane. Flavoring Extracts. Int. Rev. Dept. Canada, Bnl. 89, etc. Miller. Baking Powders. Fla. As. Ex. Sta. Bui. 52. Muuroe. Chemicals and Allied Prod- 12th Census U.S. No. 210, ucts. Jun. 25, 1902. Mnnson, Col man, Fruits and Fruit Products. U.S. Dept. Agri. Bu. of Howard. Chem. Bui. 66. BIBLIOGRAPHY 331 AUTHORS SUBJECTS PUBLICATIONS Norton. Palmer. Food Adult, in Ark. Chemical Survey of Wa- ters of Illinois. Ark. Ag. Ex. Sta. Bui. 88. Univ. of 111. Parola. Canned Fruit, etc. U.S. Dept. Agric. Farmer's Bui. 203. Proceedings Int. Congress Appl. Chem. Berlin, 1903. Richardson. Foods and Food Adulter- ants. U.S. Dept. Agri. Bu. of Chem. Bui. 13, Prt. 2. Robinson. Breakfast Foods. Mich. Exp. Sta. Div. of Chem. Bui. 21. Short. Fat in Milk. Univ. of Wis. Agri. Exp. Sta. Bui. 16. Siosson, Composition of Prepared Cereal Foods. Wyom. Exp. Sta. Bui. 33. Smith. Sewage Disposal on the Farm and Protection of Farmer's Bui. 43. Snyder. Snyder. Snyder. Drinking Water. Studies in Bread and Bread Making. Milling Tests of Wheat Digestibility and Nutritive Value of Bread. Minn.Ag. Exp.Sta.Bul.101. Minn. Ag. Ex. Sta. Bui. 90. Minn. Ag. Ex. Sta. Bui. 126. Snyder, Frisky, Bryant. Snyder, Voorhees. Squibb. Stone. Taylor. Composition and Digesti- bility of Potatoes and Eggs. Bread and Bread Making. Alcohol. Dietary Studies. Food Products. Minn. Ag. Ex. Sta. Bui. 43. Minn. Ag. Ex. Sta. Bui. 67. U.S. Pharm. 1890. Purdue Univ. Bui. 32. U.S. Dept. Agri. Diy. Microsc., Vol. 1. Teller. Chemistry of Wheat Ark. Ag. Ex. Sta. Buls. 42, 53. Tolman, Munson. Wait. Olive Oil and its Substi- stute. Effects of Muscular Work upon Digestibility of Food and Metabolism U.S. Dept. Agri. Bu. of Chem. Bui. 77. Exp. Sta. Bui. 89 & 117. of Nitrogen. 332 BIBLIOGRAPHY AUTHORS SUBJECTS PUBLICATIONS Wdderburn. Food Adulteration. U.S. Dept. Agri. Dir. of Chem. Bui. 25. Wedderburn. Food and Drug Adultera- U.S. Dept. Agri. Div. of tion Laws. Chem. Bui. 41. We Ida. Analysis of Chocolate and Univ. of Kans. Cocoa. Wiley. American Wines at the U.S. Dept. Agri. Bu. of Paris Exposition, 1900. Chem. Bui. 72. Wiley. Foods and Food Adulter- U.S. Dept. Agri. Div. of ants. Chem., Bui. 13. Prts. 4, 5, 6, 7, 8, 9. Wiley. Sweet Cassava. U.S. Dept. Agri. Bu. of Chem. Bui. 44. Wiley. Mannfac. of Starch from U.S. Dept. Agric. Div. Potatoes and from Cas- Chem. Bui. 58. sava. Wiley. Zinc in Evaporated Apples. U.S. Dept. Agri. Div. of Chem. Bui. 48. Williams. Food Analysis. U.S. Dept. Agri. Bu. of Chem. Cir. 20. Woods, Merrill. Investigations on Digesti- U.S. Dept. Ag. Office Exp. bility and Nutritive Sta. Bui. 86. Value of Bread. Woods. Meats, Composition and U.S. Dept. Agri. Farmer's Cooking. Bui. 36. STATE REPORTS Conn. Agri. Exp. Sta. Reports for 1887, 1897, 1898, 1899; 1900, part* 244; 1901, 1902, parts 3 & 4 ; 1903, parts 2, 4, 6 ; 1904, parts 2 & 5. Illinois State Board of Health, Sanitary Investigations; 1901. Kansas State Board of Agriculture ; 1887 to 1904. Kansas Academy of Science, Vols. 1-20. Man. State Board of Health, 1883, 1890, 1891, 1892, 1893, 1904. Minn. Dairy and Food Commission, 1905. National Board of Health Report, 1882, &c. N.Y. State Bd. Health Reports. New Hampshire State Board of Agriculture, Vol. 13, Wisconsin Dairy and Food Commission, Nos. 6, 6, 7. INDEX Acid, acetic in vinegar, 304. benzoic in foods, 304. citric, 217, 247. lactic, 246. malic in fruits, 216, 223. salicylic in foods, 304. tartaric, 217. tartaric, manufacture of, 217. Acidity of fruits, 216. Adulteration of milk, 250. Adulteration of wine, 277. Aerated bread, 156. Air, ammonia in, 14. amount, necessary for respiration, 41. composition of, 4. contamination of, by combus- tion, 40. determination of carbon dioxid in, 11. dew-point, 7. dust in air, 16, 17. ground, 20. humidity of, 7. hydrogen sulfid in, 14. in the lungs, 6. in public buildings, 41, 42. infectious diseases propagated in, 19. mechanical mixture, 5. methods of analysis, 6. moist, weight of, 8. nitric acid in, 14. of crowded rooms, 39. ozone in, 15. substances in suspension, 16. vitiated, how, 5. weight of liter, 7, 8. Aladdin oven, 312. Albuminoid ammonia in water, 70. Albuminous foods, 309. cooking of, 309. Albuminous substances, 230. function of, 230. Albumins, 229. Alcohol, as food, 287. from bread, 170, 171. manufacture of, 283, 284. physiological action of, 286, 287. properties of, 271. Alcoholic beverages, 271. per capita consumption, 271. sources of, 272. Algse, 210. Almonds, 227. bitter, 227. Alum, action of, on system, 163. in bread, 177, 178. Alum baking powders, 163. composition of, 162. Amides, 230. Ammonia, in the air, 14. free in water, 70. Ammonium carbonate, 155. use of, in baking, 155. Amygdalen, 227. Analysis of coals, 29. Analysis 'of gases (table), 5, 6. Aniline, blue, 105. Animal food, per capita, use of, 232. Anthracite coal, 28. Apples, 213. flavor of, 213, 214. ripening of, 213. Argol, 217, 274. Argon, discovery of, 2, 3. Arrowroot, 141. Arsenic in wall paper, 19. Artesian well water, 63. Asparagus, 209. 333 334 INDEX Atmosphere, 1. Galileo's experiments, 1. history of, 1. Lavoisier's experiments, 2. Priestley and Scheele's experi- ments, 2. Rayleigh's and Ramsay's ex- periments, 2. Atwater, experiments by, 314. B Babcock tester, the, 244. Baking bread, 171. Baking crackers, 171. Baking powders, 158-164. age of, 158. manufacture of, 164. use of, in baking, 158. Bananas, 144. composition of, 145. cultivation of, 144. digestibility of, 146. food value of, 145. industry, 145. Banana flour, 146. Barley, 137. composition of, 137. Beans, 142, 143. Beef, lean, 232. raw, 232. roasted, 232. Beef extracts, 234, 235. Beef juices, 234. Beer, 280. preservatives in, 2S2. varieties of, 281. Beet sugar, 191. diffusion process, 191. history of manufacture, 191. manufacture of, 191, 192. production of, 192. Beets, 208. Beverages, 257. alcoholic, 257. non-alcoholic, 257. Bibliography, 323. Bituminous coal, 28. Bluing, 92. Bluing, aniline, 105. indigo, 103. Prussian blue, 104. Boiling water for disinfection, 113 Boneblack niters, 195, 201. Borax, use in cleaning, 93. Brandy, 284. use of, in baking, 155. Bread, 154. adulteration, 177. aerated, 156. alum in, 177, 178. analysis of, 173. baking of, 169, 170. brown, 176. copper sulfate in, 177. fermentation of, 170. food value of, 174, 175. fresh, 172. loss in baking, 170. making without yeast, 155. not raised by fermentation, 154. raised by fermentation, 165. raising of, 169. stale, 172, 176. white, 175. why bad, 176, 177. Breakfast foods, 181. analysis of, 182. value of, 183. Burners and lamps, 58. Burners for gas, 31. Burning fluid, 50. Butter, composition of, 253. "Process, "254. "Renovated," 254. structure of, 253. Butter color, test for, 256. Butter fat, composition of, 243. Butterine, 224, 254. Cabbage, 208. Caft. au lait, 244. Caffein, 264. Calcium hypochlorite, 113. Calories, 310, 313, 314. Calorimeter, 313, 314. Camphene, 50. INDEX 335 Candle Same, 47. Candles, 48. dipped and molded, 49. Cane sugar, 187. properties of, 197. Cane sugar group, 124. Canned fruits, 297. iron in, 300. metals in, 300. methods adapted, 297. testing of, 300. Caramel in vinegar, 294. Carbohydrate, 124. Carbolic acid for disinfection, 111. Carbon, burning of, 24. Carbon dioxid, 9. amount in air, 9. cause of bad effects, 10. determination of, in air, 11. effect of, on system, 10. effect on a candle flame, 11. in closed rooms, 10. properties of, 9. source of, 9. Carbon monoxid, 13. presence in air, 14. Carrots, 217. Casein in milk, 245, 246. Cassava, 141. Catsup, 210. Cauliflower, 208. Celery, 209. Cellulose, 126. action of chemicals on, 126. basis of fuels, 24. digestibility of, 126. Cellulose group, 124. Centrifugal, 190, 195. use of, 190. Charcoal, 26. deodorizer, 109. methods of making, 26, 27. Cheese, 250. coloring of, 251. decay of, 252. falsification of, 253. food value of, 252. tyrotoxicori in, 252. Cheeses, 251. Cheeses, analyses of, 252. different varieties, 251. Chestnuts, 42, 226. Chevreul's researches, 101. Chittenden, experiments by, 318. Chlorid of lime for disinfection, 113. Chlorin in water, 71. Chocolate, 265, 267, 268. action on system, 267. analyses, 266. food value, 268. manufacture of, 267. sweet, 268. Cholera epidemic in Messina, 75. Chondrin, 230. Cider, 278. adulteration of, 279. manufacture of, 278. preservation of, 279. Cinnamon, 289. City water supplies, 73. Cleaning, 92. Cleaning agents, 92. action of, 92. Cleaning powders, 92. Cloves, 289. Coal, 28. analyses of, 29. anthracite, 28. bituminous, 28. cannel, 28. lignite, 28. semianthracite, 28. semibituminous, 28. Cocoa, 265. amount imported, 267. analyses of, 266. cultivation of, 265. fat, 267. nibbs, 267. preparation of, 266. shells, 267. soluble, 267. Cocoa butter, 267. Cocoanut, oil of, 224. Cocoanuts, 227. Coffee, 262. action on system, 269. adulteration of, 264. 336 INDEX Coffee, amount imported, 267. analyses of, 263. caffein, 264. cultivation of, 262. history of, 223. preparation, 263. preparation of beverage, 268. roasting, 263. source of, 266. substitutes, 265. Coke, 29. Cola, 268. action on the system, 268. Collagen, 230. Coloring food products, 306. Combustion, complete and incom- plete, 24. Compound flour, 178. Condensed milk, 248. composition of normal, 248. food value of, 249. manufacture of, 248. Condiments, 288. Consumption, prevalence of, 40. Cooking of eggs, 240. of food, 121. right methods of, 311. Copper in foods, 207. sulfate for disinfectant, 112. sulfate in bread, 177. tests for, 307. Corn, 134. canned, 298. composition of, 134. Corn meal, 135. comparative value of, 135. Corn sirup, 200. Cornstarch, 14G. Corrosive sublimate, 115. solution of, 115. Cost of food, 311. Cottolene, 224, 226. Cottonseed oil, 224. Cottosuet, 226. Cracker baking, 171. Crackers, 174. Cream, dried, 249. raising of, 244. ripening of, 253. Cream of tartar, 273, 274. use in baking, 257. Cream of tartar baking powders, 158, 159. composition of, 159. Creatin, 231. Cremation to destroy refuse, 90. Creosote for disinfection, 111. Crowd poisoning, 40. Crumb and crust, 174. analyses of, 174. Defecation of sugar, 195. Delicacy of sense of taste, 118. Dextrin, 148, 280. action of acids on, 199. made from starch, 199. properties of, 149. Dextrose, 199, 246. Diet, mixed, value of, 119, 120. Dietaries, 312, 315. estimation of, 315. history of investigation, 312, 313. in common use, 316. standard (Atwater), 317. Diffusion process, 199. Dilution, purification of water sup- plies by, 79. Disinfection, boiling water for, 113. calcium hypochlorite for, 113. chlorid of lime for, 113. copper sulfate for, 112. corrosive sublimate for, 115. creosote for, 111. formaldehyde for, 114. hydrogen peroxid for, 112. iron sulfate for, 112. mercuric chlorid for, 115. potassium permanganate for, 112. sulfur dioxid for, 100. tests for, 107. zinc chlorid for, 112. Distillates from petroleum, 57. Distilled liquors, adulteration of, 285. Drinking water and disease, 74. Dry air a purifier, 109. INDEX 337 Dry earth, a purifier, 109. heat for disinfection, 110. wood, 26. Dust in air, infectious diseases propagated, 19. methods of examination, 17, 18. number of colonies, 18. Dutch oven, 171. E Economy in preparation of food, 308. of fuel, 311. Egg substitutes, 240. Egg yolk, composition of, 239. Egg white, composition of, 238. Eggs, 238. compared with meat, 239. cooking of, 240. desiccated, 239. food value of, 239. preservation of, 239. use of, in baking, 155. Elastin, 230. Electric lights, 60. Electricity used for heating, 38. Elements contained in the body, 222. Emulsin, 227. Enzymes, 229. Ergot, 179. Evaporated milk, 248. Experience in selection of foods, 119. Extract of beef, 234, 235. Extracts, flavoring, 221. Fat, amount of, from animal sources, 234. amount in vegetables, 223. composition, 297. food value of, 224. Fats, cooking of, 233, 309. digestion of, 309. edible, 223. properties of, 223. Fats and oils, 49. composition of, 49. Fatty acid, separation of, 49. Fermentation, causes that affect, 169. lactic, 246. Fibrin, 230. Filters, household, 82. Pasteur-Chamberland, 83. Worms and Fisher, 82. Filtration, 80. iron process, 82. mechanical, 80. sand, efficiency of, 81. sand gallery, 81. Fire, use of, to destroy germs, 112. Fireplace, use of, 33, 34, Fish, 235, 236. analyses of, 236. cooking of, 236. preservation of, 236. Flash point of oils, 52. apparatus used, 52. . Flavoring extracts, Mil* 2,< t Flour, 133. adulteration of, 177. compound, 178. ergot in, 179. Food, accessories, 288. borax in, 303. breakfast, 181. chemistry of, 117. cooking of, 121. cost of, 311. cost per day, 319. definition of, 177. indigestible material in, 122. preservation of, 288, 297, 298. skill in preparing, 119. suited to habit, age, etc., 120. use of, 117. varieties of, 120. wasted, 319, 320. Food products, cooking of, 306. Foods, albuminous, 309. animal, 228, 310. classification of, 123, 124, 229. cooking of, 309. 338 INDEX Foods, leguminous, cooking of, 310. nitrogenous, 228. predigested, 380, 382. synthetic, 121. vegetable, 310. Formaldehyde as a disinfectant, 114. method of using, 114. Fruit sirups, 221. Fruits, 212. acidity of, 216. analysis of, 214. canning of, 299. cooking of, 218, 219. distribution of, 212. malic acid in, 273. ripening of, 212, 214, 215. starch in, 214. structure of, 212. sugar in, 215. sugar in (table), 273. Fuel, economy of, 311. value of, 314. wood as, 25. Fuels, 23. calorie, definition of, 23. calorific power of combustibles, 23. Fungi, 210. Furnaces, hot air, 35. precautions in use of, 36. Fusel oil, 284. G Galacto-araban, 215, 216. Galactose, 199, 246. Garbage, disposal of, 90. Garlic, 210. Gas, 30. acetylene, 55. advantages of, 31. air, 54. artificial, 30. bi-producers of manufacture, 54. burners, 31. carbon, 54. coal, 53. composition of, 56. Gas, drilling wells, 30. fuels, 31. illuminating, 53. lights, incandescent, 59. methods of making, 53. natural and artificial, 30. natural, composition of, 32. Pintsch, 55. pressure for burning, 55. purification of, 54. water, 54. Gas burners for light or heat, 48. Gas lights, Welsbach system, 59. Gases, poisonous, 21. Gasoline, 51. use of, 32. Germ flour, 175. Gin, 284. Ginger, 290. Globulin, 229. Glucose, 281. commercial, 200. composition of, 201. healthfulness of, 202. manufacture of, 200, 201. properties of, 202. sirups, 202. sweetness of, 202. use of, 202, 219. Glucose group, 225. Gluten, 148, 166. in flour, 173. Glycerin, 101. from soap, 98. Granulated sugar, 196. Grape sugar, 200, 201. composition of, 201. manufacture of, 201. Grapes, 273. cultivation of, 273. ripening of, 273. Grease, removal of, 93, 94. Greens, food value of, 208. Ground air, 20. compared with atmospheric air, 20. effects on the system, 21. germs in air, 21. INDEX 339 Hamburg, Germany, epidemic of cholera in, 76. Hard water, 67. permanently, 67. temporarily, 67. Heat, means of obtaining, 33. Helium, discovery of, 3. Honey, 204. adulteration of, 205. composition of, 205. food value of, 205. Household wastes, 89. disposal of, 89, 90. Human body, compounds found in, 123. composition of (table), 122. Hydrogen, 24. burning of, 24. peroxid, 15. sulfid in air, 14. Hydrogen peroxid as a disinfec- tant, 112. Iceland moss, 210. Incandescent gas lights, 59. Income necessary for subsistence, 320. Indigo used in bluing, 303. Infants' foods, 174, 181. composition of, 181. Injurious trades, 20. Ink spots, removal of, 95. Inosite, 125. Introduction, xix. Inulin, 149. Invert sugar, 215. Investigations needed, 321. Iron sulfate as disinfectant, 112. Jams, adulteration of, 219, 220. Jams and jellies, 219. Jellies and jams, 219. E Kerosene, 51. purification of, 52. Koumiss, 244. Lactalbumin, 246. Lactometer, 243. Lactose, 199. Lamps and burners, 58. Lard, compound, 226. kettle rendered, 225. leaf, 225. neutral, 225, 254. prime steamed, 225. refined, 225. scrap, 225. steam rendered, 224. stiffening of, 225. Lausen (Switzerland), typhoid fever in, 77. Leaven, 167. use of, 167. Leaves used as food, 208, 209. Lecithin, 230. Leeks, 210. Legumes, 142. composition of, 143. food value of, 143. Legumin, 143. Leguminous foods, cooking of, 310. digestibility of, 143. Lemon, extract of, 221, 222. Lentils, 142, 143. Lettuce, 149. Levulose, 204. Lichens,. 210. Light, 46. candle flame, 47. early sources of, 48. source of, 46. Light-producing substances, 46. Light, ideal, 60. Lighting, 46. common methods of, 46. Liqueurs and cordials, 272, 285, 286. Liquors, distilled, 272, 283. fermented, 272. malt, 272. 340 INDEX Macaroni, 183. composition of, 184. food value of, 184. Mace, 290. Maize, 134. Malt, manufacture of, 280. Malt liquors, 2S1. analyses of, 281. Maltose, 199, 280. hydrolysis of, 199. Mantles, composition of, 59. life of, 59. Maple sugar, 192. adulteration of, 193. Mashing, 280. Masse cuite, 190, 195. Mate, 261, 263. Meat, boiling, 233. cooking of, 232, 233, 237. diseases, 236. effect of cooking on, 232. food value of, 231, 235. lean, 231. roasting, 233. stewing, 234. structure of, 231. varieties of, 235. water in, 234. Mercuric chlorid as a disinfectant, 115. Messina, epidemic of cholera, 75. Metals, cleaning of, 96. Milk, 242. adulteration of, 249. albumin in, 246. ash of, 247. borax in, 250. casein in, 245, 246. changes produced, 247. condensed, 248. dried, 249. evaporated, 248. fat in, 243, 244. fore, 244. formaldehyde in, 250, 302. from different anim^la, 242. Milk, modified, 249. pasteurized, 248. proteids of, 246. souring of, 246. specific gravity of, 243. sterilized, 247. strippings, 244. total solids in, 244. Milk sugar, 199, 246. manufacture of, 246. properties of, 199. Milwaukee sewage system, 86. Mineral water, 64. Modified milk, 249. Molasses, 194. Moss, Carrageen, 210. Iceland, 210. Irish, 210. Mucin, 230. Muscovado sugar, 189. Mushrooms, 210. poisonous, 211. Must of wine, 274. Mustard, adulteration of, 291. black, 290. white, 290. Mutton, 235. Myosin, 229, 231, 291. N Natural gas, 32. Nitric acid in air, 14. Nitrites and nitrates, 71. significance of, 71. Nitrites in water, 70. Nitrogen, properties of, 6. Nitrogenous foods, 228. classification of, 229. use of, 228. Non-alcoholic beverages, compari- son of, 269. per capita consumption, 257. use of, 270. Nuclein, 230. Nutmegs, 290. Nuts, food value of, 226. analyses of, 226. INDEX 341 Oatmeal, analyses of, 135. food value of, 136. Oats, 135. Offensive gases, 121. Oil, cottonseed, 224. petroleum, 51. Oil of cocoanut, 224. Oils, edible, 223. fire test of, 52. flash point, 52. Oleomargarin, 254. manufacture of, 254. production of, 255. tax on, 255. tests for, 256. Oleo-oil, manufacture of, 254, 255. Onions, 210. Organic matter in water, 69. Oven, heat of, 171. Oxidation of water, 79. Oxygen, properties of, 6. Oysters, 236. Ozone, constitution of, 15. discovery of, 15. occurrence of, 15. test for, 15. Paint, solvents for, 93, 95. Paraffin, 50, 62. Paraguay tea, 261. Parasites in meat, 237. Parsnips, 207. Pasteurized milk, 248. Pea sausage, 144. Peanuts, 227. Peas, 142, 143. green, 144. Peat, 27. abundance of, 27. source of, 27. Pectin, 215. Pectose, 125, 215. Peotous bodies, 215. Pepper, 289. Pepsin, 231. Peptone, 229. Perry, 279. Petroleum distillates, 51. Phosphate powders, composition of, 158, 160, 161. Physiological action of alcohol, 286, 289. Pie plant, 209. Pintsch gas, 55. Plantain, 144. Plastering of wine, 277. Plymouth, Pennsylvania, epidemic of typhoid fever, 76. Polishing materials, 92, 93. Potassium permanganate, 112. Potatoes, 138. analysis of, 139. food value of, 139, 140. introduction of, 138, 139. structure of, 140. sweet, 140. Predigested foods, 180, 182. Preface, v. Preservation of food, 297, 298, 299. history of, 297. Preserved food, metals in, 300. Preservatives, 219. effects on the system, 301, 302, 303. Preservatives in foods, 301. in common use, 303. Process butter, detection of, 256. Proteids, 229. Proteoses, 229. Prussian blue, 104. Ptyalin,. action of, 199. Purification of water supplies, 79. Quicklime for disinfection, 110. R Radiation, direct, 33. Radiation, indirect, 35. use of steam, 36, Ramsay and Rayleigh, discoveries of, 2. 342 INDEX Ration, ideal (table), 319. Reduction to destroy refuse, 90, 91. Refining sugar, 194, 195. Rennet, 246. Respiration, 39. air needed for, 41. Rhubarb, 209. Rice, 137. composition of, 138. food value of, 138. preparation of, 137. Richard's ideal ration, 319. River water, 62. Roots used as food, 207. Rum, 284. Rye, 136. composition of, 137. Rye flour, 136. S Saccharin, 186, 219. in foods, 304. tests for, 305. Sago, 141. Sake, 282. Salep, 142. Salt, 295. composition of, 295. production of, 295. Salt-rising process, 168. Sanitary analysis of water, 69. Saponification, 97, 98. Sauerkraut, 209. Scurvy, 237. Separator, use of, 244. Septic tank, 88. Sewage, composition of, 84, 85. definition of, 83, 84. disposal of, by dilution, 95, 96. precipitation of, 88. purification of, 85. Sewage disposal, 84. by chemical precipitation, 88. by intermittent nitration, 87. by irrigation, 87. by septic tank, 88. Shale oil, 50. Silver, cleaning of, 96. Sirup, maple, adulteration of, 192. Sirups, fruit, 221. Snow, use of, in baking, 155. Soap, 92. castile, 99. Chevreul's researches, 101. cocoanut oil, 99. economy in use of, 101. glycerin from, 101. hard, 101. lye, 100. manufacture of, 98. mottled, 98. sand, 100. soft, 100. theory of action, 101. toilet, 100. transparent, 100. yellow, 99. Soap-making materials, 91. Soap solution, 68. Sodium bicarbonate, use of, in baking, 155, 157. Sodium sulfite in fruits, 304. Softening of water by Clarke's process, 82. Sorghum sugar, 193. Sour milk, 246. use of, in baking, 157. Soy beans, 142. Spaghetti, 183. Spices, 288. Stalks, used as food, 208, 209. Standard dietaries, 217, 218. Starch, 128. adulteration of, 142. chemical properties of, 150. detection of source of, 150. hydrolysis of, 152. in cereals, 128. in fruits, 129, 214. in legumes, 129. in nuts, 129. in roots, 129. in wheat, 129. making from wheat, 147. methods for making, 146, 147. physical properties, 149, 150. sources of, 128. INDEX 343 Starchy foods, cooking of, 308. Steam for heating, 36. Steam heat for disinfection, 113. Steamer, use of, 311. Sterilized milk, 247. Stoves, precautions in use of, 35. use of, 34. ventilation with, 34. Subsistence, income used, 320. Sucrose, 187. Sugar, maple, 192. adulteration of, 193. manufacture of, 193. sorghum, 193. Sugar, powdered, 196. production of, 190. properties of, 197. refining, 194, 195. spots, removal of, 95. sources of, 187. triple effect evaporators, 189. use of boneblack, 189. Sugar beets, 190. Sugar cane, cultivation of, 187, 188. making sugar from, 188. Sugar making, 188, 189. Sugars, analyses of, 198. adulteration of, 194, 197. boiling, 189. classification of, 185, 186. consumption of, 186. cut, 197. filtration of, 195. food value of, 198, 199. granulated, 196. history of, 185. in fruits, 215. in fruits (table), 293. inversion of, 190, 193, 204. Sunlight as a disinfectant, 109. Sweet potatoes, 140. composition of, 140. Synthetic foods, 121. Table of contents, vii. Tallow, 49. Tannin, in tea, 261. Tannin, in coffee, 264. Tapioca, 141. preparation of, 141. Tartrate baking powders, 159. Taste, delicacy of the sense, 118. Taste and smell, 118. use of, 118. Tea, 258. action on the system, 259. adulteration of, 259. amount imported, 257. analyses of, 260. black vs. green, 258. coffee leaf, 262. cultivation of, 258. green, 258. history of cultivation, 258. Indian, 259. Japan, 258. lye, 260. Paraguay, 261. preparation, 258. preparation of beverage, 260. spurious, 259. tannin, 261. thein, 261. Tees Valley, epidemic of typhoid fever in, 75. Theobromin, 267. Toadstools, 210, 211. Tomatoes, 210. canned, 298. Touf lea Mots, 142. Trades, injurious, 20. Truffles, 211. Turnips, 207. Typhoid fever epidemic in Tees Valley, 75. in Lausen, Switzerland, 77. Tyrotoxicon in cheese, 252. U Ultramarine, 104. use of, 196. V Vacuum pan, 189, 195, 201. Vanilla, extract of, 221. Veal, 235. INDEX Ventilation, 33, 38. by natural or forced draft, 42. conditions necessary, 42. exhaust fans, 43. importance of, 38, 39. open grates, 44. special devices, 44. Vermicelli, 183. Vinegar, 291. acid of, 293. caramel in, 294. cider, 293. fermentation in, 292. imitation, 293. materials used, 292. quick process, 292, 293. wine, 293. Voit, experiments by, 315. W Wall paper, arsenic in, 19. Washing soda, 101. use of, 102, 103. Waste of food, 320, 321. Water, 61. analyses of city supplies, 72. chlorin in, 71. cistern, 61. drinking and disease, 74. effect of freezing on, 73. filtration and softening, 80. filtration by sand, 80. free ammonia in, 70. Hamburg (Germany), analyses of, 77. hard, 67. in air, 6, 7. in meat, 234. lake, 62. mineral, 64. mineral substances in, 64. mechanical filtration, 81. natural, 61. nitrates in, 61. nitrites in, 70. organic matter in, 69. oxidation of, 79. polluted by sewage, 74. Water, rain, 62. sanitary analysis of, 69. softening, Clarke's process, 82. spring, 62. storage, 63. turbid, 74. well, 63. Water, hot, for heating, 37. advantage over steam, 37. Water supplies, 79. purification of, 79. purification by dilution, 79. Waters, hard, 67. disadvantages of, 68. Well water, 63. artesian, 63, 64. impurities in, 63. wells, domestic, dangers of, 63. Welsbach lights, 59. Wheat, 130. proteids of, 130. Russian, 131. starch in, 147. structure of grain, 130. varieties of, 130. Wheat flour, 131. analyses of, 131, 132, 133. patent, 134. value of, 132. Whey, 246. use of, 199. Whisky, 284. White bread, 175. Wine, 273. adulteration of, 277. aging of, 274. analyses of, 275, 276. chaptalising of, 277. classification of, 276. manufacture of, 274. old, 275. plastering, 277. still, 276. tannin in, 275. Wood, ash of, 26. drying of, 26. seasoning of, 26. water in, 25. Wood aa fuel, 20. INDEX 345 Wort, 280. Wounds, lacerated, care of, 115. Xanthin, 231. Xyloiden, 153. Yeast, 165, 280. cakes, 167. Yeast, compressed, 166. cultivation of, 166. domestic, 167. history of use, 166. in beer, 280, 281. use of, 165. Z Zinc chlorid for disinfection, 112. """THE following pages contain advertisements of a few of the Macmillan books on kindred subjects MUNICIPAL ENGINEERING AND SANITATION By V. N. BAKER, PIiB. Associate Editor of Engineering Newt umo. Half Leather. $1.25, net " It ii designed to be a review of the whole field of municipal engineering and sanitation rather than an exhaustive study of one or a few branches of the subject. The most vital points, however, under each class of activities and interests have been dwelt upon, the underlying principles stated, and in many instances details from actual practice given," says the author. Among the practical questions discussed are: Ways and means of communication, municipal supplies, collection and disposal of waste, recreation and art, ad- ministration, finance and public policy. It is a volume which must appeal to all classes interested in any degree in municipal affairs. "Full of significant facts and judicial comments. The subjects covered include the building, repairing, and cleaning of streets, the construction of subways, the elimination of grade crossings, the management of water-works, the purification of water supplies, ice supplies, and milk supplies, the disposal of sewage and garbage, the protection of property from fire, the protection of health by plumbing regulations, the protection of comfort by smoke abate- ment and the suppression of noises, and, finally, a series of problems con- nected with the administration of various public works having an engineering or sanitation side. That which most impresses the reader is the wide range of observation from which Mr. Baker speaks. . . . The reports of foreign engineers upon experiments abroad are also frequently used, but the work is better for American readers because American experience is kept constantly in the foreground." The Outlook. THE MACMILLAN COMPANY 64-66 FIFTH AVENUE, NEW YORK PRINCIPLES OF SANITARY SCIENCE AND THE PUBLIC HEALTH WITH SPECIAL REFERENCE TO THE CAUSATION AND PREVENTION OF INFECTIOUS DISEASES By WILLIAM T. SEDGWICK, Ph.D. Professor of Biology and Lecturer on Sanitary Science and the Public Health in the Massachusetts Institute of Technology Cloth 8vo $3.00, net "The book is a most excellent one. No one in this country is better fitted to write it, and Professor Sedgwick has succeeded exceptionally well in pre- senting the subject in a comprehensive and intelligible style. The book will be extremely useful, and a debt of obligation is due to you and Professor Sedgwick for the work." H. W. CONN, Professor of Biology, Wesleyan University. " I regard it as a valuable addition to the literature of Sanitary Science, and shall take great pleasure in recommending it to my class next year among the books for collateral reading." DR. CHARLES HARRINGTON, Harvard Medi- cal School. "The work is admirable, as might naturally be expected, and I am sure it will do much to advance the cause of Sanitary Science in this country." H. L. RUSSELL, Wisconsin State Board of Health. "The name of the author is a guarantee of the excellence of the book. I am much pleased with the arrangement and interesting presentation of the subject-matter." WILLIAM H. WELCH, M.D., President Rockefeller Insti- tute for Medical Research. THE MACMILLAN COMPANY 64-66 FIFTH AVENUE, NEW YORK UNIVERSITY OF CALIFORNIA LIBRARY Los Angeles This book is DUE on the last date stamped below. Form L9-10m-3,'48(A7920)444 THE LIBRARY TTNTVFTCSTTY OF TAUFORVTA UCLA-Chemistry Library RA 430 B15t 1912 RA 430 Bl5t 1912 Cfcwwtrr Library