LIBRARY OF THK UNIVERSITY OF CALIFORNIA. OF" Cl&SS CHEMICAL PRIMER: AN ELEMENTARY WORK FOR USE IN HIGH SCHOOLS, ACADEMIES, AND MEDICAL COLLEGES. BY S. P. MEADS W. B. HARDY, E I2x .A. JL, 961 BROADWAY, OAKLAND, CAL. J-fiV ENTERED ACCORDING TO ACT OF CONGRESS IN THE YEAR 1884, BY S. P. MEADS, IN THE OFFICE OF THE LIBRARIAN OF CONGRESS, AT WASHINGTON, D. C. FACIKIC PRESS, m Preface to Second Edition. iHIS Primer has been prepared for use especially in those schools that can give to chemistry only one term's work. It has grown out of the needs of the class-room, as I have felt them. Its statements are necessarily somewhat narrow, confining the pupil to gen- eral rules. Refined accuracy means a treatise, not a primer. I have given in the following pages as much as I think the average class can digest in a single term, and I hope my fellow- teachers will carefully examine the plan throughout before passing judgment. I have freely consulted whatever chemical works were within my reach, especially Attfield, Barker, Roscoe and Schorlemmer, Eliot and Storer, Appleton, and Jones. For criticisms and valuable suggestions in preparing this Second Edi- tion, I am indebted to Prof. Joseph LeConte and Prof. W. B. Rising, of the University of California. I wish to acknowledge my obligation to many teachers who are using my humble work in their classes, es- pecially to Prof. Geo. R. Kleeberger, of the State Normal School, San Jose, and to Mr. Volney Rattan, of the Girls' High School, San Fran- cisco. Nor should I forget my indebtedness to Mr. C. B. Bradley in the preparation of my First Edition. An experience of three years in teaching chemistry to medical stu- dents has enabled me, I hope, to anticipate their wants in several direc- tions. It has shown me how greatly they need an elementary book before opening the excellent but voluminous works which should be their life companions. Natural Science Dept., S. P. MEADS. Oakland Hiyh School, Jan. 2, 1884. Preface to Third Edition. unexpected exhaustion of the Second Edition of this work in the space of six months, for use in the schools of California alone, has made it necessary for me, in order to meet the demand, to send this Third Edition hastily to the press. I have taken the opportun- ity to make a few needed corrections in the plates, and to put the book into a more attractive dress. I wish to express my hearty thanks to my fellow-teachers for their kindly appreciation of my efforts to present plainly and tangibly to beginners, the A, B, C, of chemistry. Oakland, California, S. P. MEADS. A wj. 1, 1884. 119224 BRIEF SUGGESTIONS-MIXED. DO not allow pupils lazily to pronounce the symbol or the formula instead of the name, i. e., wherever "H" occurs, see that it is called hydrogen Have the pupils copy the two Reference Tables (pp. 16, 29) upon cardboard, and allow them the free use of these for the entire term. Never compel them to memorize formulas, atomic weights, strength, etc. It is as important to know what not to remem- ber, as to know what should be remembered, since the former comprises by far the larger portion of any text-book Let the pupils perform all experiments (except, perhaps, a few difficult ones, or for the sake of taking your turn with the class) in presence of the class, explaining each experiment as it proceeds. It takes time, but it is the only way to teach chemistry where a table for each student cannot be provided. If you haven't time, omit half the experiments to accomplish this result. Assign to separate pupils one experiment each a few days beforehand. The experiments may be performed upon a plank table (see FRONTIS- PIECE), costing not over four dollars Every experiment teaches something, and the sooner you can impress this fact the better. While you should make every experiment as impressive as it can be made, get the pupils through the babyhood which craves noisy or showy experi- ments, as early in the term as possible See that a number of larger works upon chemistry are at your desk for reference After you have passed the "Reactions," encourage any pupils who may show a special liking for the science to work out after school hours a number of solutions (not too complex, and mixed by you) by the Analytical Charts. Teach pupils to use small flasks (test-tubes answer well) and small quantities of chemicals. It isn't necessary to burn a forest to prove that hydrocarbons are combustible, nor to blow up a continent to prove a substance explosive Don't be afraid to teach anything contrary to the text, if you have good authority for it; but let disputed points alone. Teach any simple principles beyond the text, instead of others more complex omitted; but don't teach intricate matter outside of text, else the result will be pupils will know neither the text nor the "intri- cate matter." Remember that one of the chief ends of a small text book in science is to teach the pupil to read intelligently larger works. Spend at least half the time in reaching carbon, page 63. Use the METRIC SYSTEM throughout; it is the system Use either thermometer. The CENTIGRADE (C) is used in this book, though the corresponding Fahrenheit (F) degrees are given in a few places. INDEX. PAGE. ACID, ACETIC 121, 132 " Benzole 133 ' ' Boracic 85 " Carbolic 121, 137 " Carbonic 66,159 " Citric 124 " Gallic 124 " Hydrochloric 75 " Lactic 160 " Malic 124 " Muriatic 75 " Nitric 59,60 " Oleic 16, 130 " Oxalic 124 " Palmitic 16 " Picric ....147 " Prussic 58,78 " Salts 140 " Stearic 16, 130 " Sulphuric ....." 81 " Tannic 124, 125 " Tartaric 124 Acids ..25, 135 Aconite 127, 136, 158 Air 34,47, 58, 67 Albumen 122, 134, 156 Alcohol 119, 120 Alkalies 25,136 Alkaloids 125, 127, 136, 157 Alloys 91, 143 Alum , 148, 154 Aluminum 105, 106, 154 Amalgam 91 Amber 133 , Ammonium 61, 62, 114 Ammonia 60, 61, 62 " Type 125, 126 Anesthetic 59, 120, 121 Analytical Charts 162, 163 Aniline 126, 147 Antidotes 133 Antimony 91, 152 Antiseptic 81, 97, 111, 112, 121 Aqua-f ortis 60 Aqua-regia 60, 75, 152 Arsenicum 88, 135, 152 Atomic Theory 10, etc. Atmosphere 34, 47, 58, 67 Atoms 10-13, etc. Atropia 127, 158 BALSAMS 133 Barium 109, 155 Bases 25, 136 Basic Salts 141 Beer 119 Belladonna 127, 158 Benzol 70, 121 Bessemer's Process 102 Binary Compounds 11, 17 Bismuth 104 Bleaching 74, 81 Powder 74 Blowpipe 53, 71, 94, 162 Borax 85 Boron 85 Brass 143 Bread-making 122 INDEX. PAGE, j PAGK. Brimstone See Sulphur. I Corrosive Sublimate 97 Bromine 76 Cotton 116 Bronze 143 Cream of Tartar 124 Bunsen's Burner 70 | Creosote 121 CALCIUM . .107 I Crystallization .",<>, 145, 146 154 ! Cupellation 95 Light 108, Calomel 97 | Cyanogen, 78 DAVY'S SAFETY LAMP 71 Deliquesence 56 Dextrin 116 Dextrose 117 ! 17 j Dialysis 158 ' Diamond 63 Diastase 118 Diffusion of Gases 52, 58 Disinfectant 50, 64, 73, 121 Distillation 57, 119, 120 ..147 Camphor 133 Candles 69, 130 Caoutchouc 133 Carat 93 Caramel Carbon 63 Carbon Dioxide 66, 159 Carmine 143 Cast-iron 101 Cellulose 110 Chalk 108, 135 Charcoal 63 j EFFLORESENCE Chemistry of Candle 69 j Elements " Cooking 122 j Essences 120, " Cleaning 131 j Etchings 60, 77 Chlorine 72, 150 j Ether 120 Chloroform 120 Ethyl Hydrate 119 Chloral 121 " Hydrate 121 Choke-damp 68 Chromium 92 Cinnabar 96 Clay 87, 106 Coal Gas 70 Cobalt 104 Cochineal.. ..148 56 16 132 Oxide. ..120 FATS 128 Fermentation 1 18, 130 Fireworks. .111, 155 Flame ... 69 Fluorine 77 Formula, Empirical 115 Rational 115 Fusil Oil 120 Fusible Metal. . ..104 GALENA. Coin 143 Coke 63, 70 Collodion 116 Compound Ethers ; 120 Radical 18 i Gas, Illuminating 70 Combustion 34, 48, 49 i Gelatin 122, 125 Copper 100, 134, 154 German Silver 143 Galvanized Iron. . 98 .103 INDEX. Glass 86,87 Okie 122 Gluten , 122 Glycerin 130 Gold 92, 153 Graphite 63 Gum Arabic 116 Gum Resin 133 Gun Cotton 116 Gunpowder Ill Gutta-percha 133 Gypsum 108 HALOGENS 27, 72 Hard Solder 143 " Water 54 Hematite 23, 101 Hydrocarbons 48 Hydrogen 50, 149 Hydrogen Sulphide 82, 162 INDIA-RUBBER 133 Indigo 147 Ink 73,125,132 " Printers' 73 Iodine 76 Iron 101 Isomerism 115 LAKE 148 Laudanum 127, 136 Laughing-gas 59 Lead 98, 103 Leather 125 Lime 107 Lime-light 154 Linen 116 Litmus 25 Litharge 65 Logwood 148 Lunar Caustic 95 Lye 129, 136 PAGE. MADDER 148 | Magnesium 34, 106 Malt 119 Manganese 105 Marble 108 Marsh-gas 70 Matches 83 Mercury 96, 153 Metals 92 Methyl Alcohol 120 Metric System 160 Milk 122, 134 Miscellaneous Questions, 45, 78, 138 Molasses 117 Mordant 148 Morphine 127, 136, 157 Mortar 108 NAPTHA 110, 112 Nascent State 63 Nickel , 104 Nicotine 127 Nitre Ill Nitrous Oxide 59 Nitrogen 57 Nomenclature 17, 24 OILS 128 Oleiii 128 Opium 127, 136, 157 Organic Acids 124 Bases 127,157 " Chemistry 114 Oxides 34 Oxygen 46, 149 Ozone 50 PAPER 116 i Paregoric 127 | Pearlash Ill | Pencils 63 | Petrifaction 86 ! Pewter . . . . 143 INDEX. Phosphoresence 84 Phosphorus 83, 137, 151, 152 Photography 95, 96, 153 Plants, Office of 67 Plaster of Paris 108 Platinum 94, 149 Plumbago. 63 Porcelain 87 Potash 110 Potassium 110 QUARTZ 86,93 Quicksilver 96 Quinine 127, 157 REACTIONS 33 Reference Table 1 16 Table II 29 Table IL (con.)... 160 Resin 133 RochelleSalt 141 Rosin 133 SAGO 116 Sal-ammoniac 60, 114 Saleratus Ill Salt, Common 112 Salts 25 Salts, acid, etc 140 Salts, Epsom 106, 135 Salts, Glauber's 113 Salts, Rochelle 141 Saltpetre Ill Sand 86 Selen-salts 142 Shellac 133, 155, 158 Shot 143 Silicon 85 Silver 94, 153 Soap ...128, 131 Sodium 112 Solder.. ..143 PAGE. Solution 37 Spectrum Analysis 143, 144 Stalactites 108 Starch 115, 122 Stearin 128 Steel ..102 Strontium 109 Strychnine 127, 136, 157 Sublimation 80 Subnitrate of Bismuth 142 Sugar, Cane 116 " Grape 117, 15,5 " of Lead 99 Sulphur 79 Sulph-Salts 142 TAPIOCA 116 Tar 70 Tartar Emetic 91, 124 Tin 103 Turpentine 133 Type-metal 143 VERDIGRIS 100 Vermilion ... 96 Ventilation 68 Vinegar 121, 136 Vitriol, Blue 100 " Green 102 " Oil of ...:.... 81 Volatile Oils 132 WATER 13, 14, 37, 53, 139 " of Crystallization 55 " type 26, 125 White-lead 99 Wines 119 Woody Fiber 116 YEAST . ZINC. . us, 123 . . 103 THEORETICAL CHEMISTRY. CHAPTER I. INTRODUCTION. MATTER exists in three states: 1. Solid: Ex., iron, lead, ice. 2. Liquid: Ex., mercury, bromine, water. 3. Gaseous: Ex., hydrogen, air, steam. Nearly all substances ordinarily in the solid state may, by applying heat (and removing pressure), be made first liquid and then gaseous. Nearly all gases, by cold and pressure, may be made first liquid and then solid A change which merely converts a solid to a liquid, or a liquid to a gas, or vice versa, however wonderful such change may be, is not a chemical, but a physical change. Ex., Ice may be heated and converted into water, a liquid, and then into steam, a gas. All such changes are studied in Phyiics, not in Chemistry. Chemistry deals with such changes "only incidentally. The molecules (small, invisible particles) of a solid move with diffi- culty upon each other The molecules of a liquid move readily upon each other, so that the liquid assumes the shape of the vessel holding it. The molecules of gas have an apparent repulsion for each other, so that a gas, regardless of its specific gravity (t. e. whether light or heavy), escapes from an open vessel and diffuses itself throughout the surround- ing space. We learn many things incidentally about solids and liquids before studying either Physics or Chemistry. We know comparatively little about gases, except about the gaseous ocean of air at the bottom of which we live. To the chemist, however, the gas is in many respects the simplest state of matter and the most convenient for him to exam- ine critically. 10 CHEMICAL PRIMER. CHAPTER II. The Atomic Theory divides matter into: 1. Mass. Any portion of matter appreciable by the senses. 2. Molecule. The smallest particle of matter that can take part in a mere physical change. It may exist alone. 3. Atom. The smallest particle of matter that can take part in a chemical change. An atom does not exist alone. Atoms compose molecules ; i.e., two or more atoms make a molecule. Chemistry treats of the atomic condition of matter and especially of atomic changes. It will be inferred from the definitions that a mass may be very large or exceedingly small, also, that the molecule and the atom are not visi- ble even with the aid of the most powerful microscope, otherwise they would be "appreciable by the senses." Chemistry treats of more subtle changes than physics. If the mol- ecule is not broken up and the atoms set free to form new combinations, it matters not how violent, or how wonderful the change may be, it is purely physical and in no sense chemical. Of course, atoms "exist alone" during the instant of chemical change. One atom may rarely make a molecule. At this stage, however, the pupil should not trouble himself with exceptions. NOTE. We know that there are masses and molecules, but we do not know that there is any such thing as an atom. More than this we do not care whether there is or not. The atom is to chemistry what the .r, 01 unknown quantity, is to algebra. It enables us to accomplish results which otherwise would be impossible. The Atomic Theory is as useful in the study of chemistry as th/*. 3. In 100 kgs. of potassium arsenate how much arsenicum? 4. In 150 gms. of mercuric (Hg = dyad) nitrate, how much mercury? 5. In 75 gms. of mercunw* (Hg. 2 = dyad) nitrate, how much mer- cury? 6. How much lead carbonate (white lead) could be made from 50 kgs. of lead? REACTIONS. 33 CHAPTER XIV. We have seen that chemical changes are called reactions. There are various classes of reactions, of which the sim- pler should be thoroughly mastered by beginners, and the more complex let severely alone. CLASS 1. Reaction by Direct Union (or Separation). EXPERIMENT. L Heat a small quantity of sulphur well mixed with fine copper fillings on a broken test-tube or other piece of glass; a reaction takes place and copper sulphz'efe is formed. Reaction (atomic): Cu -f- S = copper sulphur (red) (yellow) CuS copper sulphide (black) - EXP. 2. In a test-tube of hard glass place a small quan- tity of mercuric oxide (red) and close by rubber cork through which passes a fine glass tube connected to rubber tubing (Fig. 3). Place mouth of tube below the surface of water and heat test-tube to dull redness. The oxygen sepa- rates from the mercury and escapes bubbling through the water, while the mercury condenses in a ring upon the colder part of the test-tube. Reaction: Hg - Hg + red solid liquid invisi sible gas 34 CHEMICAL PRIMER. EXP, 3. Bum a small piece of magnesium ribbon in the air; the oxy- gen of the air unites with the magnesium, forming magnesium oxide. Reaction: Mg + = Mg O magnesium oxygen magnesium oxide 1. How much Mg O could be made by burning 30 gins, of Mg? 2. If you make 80 gins, of Mg O, how much Mg must you take ? Air is composed of one part by volume of the gas oxy- gen and about four parts by volume of the gas nitrogen (with traces of carbonic oxide and vapor of water, etc.). Burning, or combustion, is, in general, the rapid union of a substance with ox}'gen. The temperature at which the substance takes fire, i. e., unites rapidly with the oxy- gen of the air, is called the igniting point (/. ., kindling point). Of course, the product of the burning will be an oxide. EXP. 4. Burn some sulphur in a bottle containing a small quantity of water. (See Fig. 13 and Exp. 23. S. in burning always acts as a tetrad.) Reaction (a): S + O 2 SO., (a gas) Close the mouth of the bottle and shake; Reaction (b): SO 2 + H-^O H-jS0 3 (an acid) Test for the acid by litmus paper. EXP. 5. Scrape some fine powder from a piece of quicklime into a test-tube of water; Reaction: Ca O -J- H.,0 = Ca 2 HO (a base) quicklime water-slaked lime, a soft solid, part of which dissolves Test for the base by litmus paper. The last two reactions reveal the fact that there are different kinds of oxides, The two principal classes of oxides are: 1. Acid-forming oxides. 2. Basic oxides. REACTIONS. 35 The first are oxides of negative elements and they unite directly with water to form acids, as in reaction (b) of EXP. 4. The second are oxides of positive elements (metals) and unite directly with water to form bases, as in reaction of EXP. 5. Acid-forming oxides are often called anhydrides (with- out water), since they may be considered as acids deprived of water. EXAMPLE. SO 2 = = sulphurous anhydride. (The older chemists c lied the anhydride the acid, as S0 2 = sulphur- ous acid, but this is not now correct usage.) Basic oxides are often called bases. (It is important to know that this is still correct usage. Indeed, some authors give as the definition, "A base is a metallic oxide," and these authors call the true base a "hydrated oxide" or "hydrated base.'') Basic oxides unite with acids to form salts, just as the true bases do, and by a reaction very similar. It will be seen that the term "base" is used by chemists somewhat indefinitely. In a wide sense it is used of any substance that will unite with an acid to form a salt (or a salt and water, or a salt with free hy- drogen, etc.). In this wide sense it would include: 1. Positive elements (oi* groupings). 2. Basic oxides. 3. Positive hydrates. The word "base has thus far been used in this last and restricted sense. The word "alkali' is also used in a comprehensive sense. The sense of the words, however, may easily be told from the connection. 36 CHEMICAL PRIMER. CHAPTER XV. CLASS 2. Reaction by Change of Partners. EXP. 6. Dissolve one gram of sodium chloride (common salt) in nine grams of (distilled) water (a ten per cent, solution). Dissolve one gram of silver nitrate (lunar caustic) in nineteen grams of water (a five per cent, solution). Pour a little of the first solution into a small test-tube, and into it let fall a few drops taken from the second, by means of a glass tube pipette dipped beneath the solution and closed at the opposite end by the finger. A beautiful, white, curdy solid (silver chloride) is formed by the reaction, and slowly settles to the bottom of the test-tube. Fig. 4. (a) lead post, (b) rubber band. Taking this reaction as the type of its class, we may learn much from it. REACTIONS. 37 Just as by change of partners, George ") Lucy j NaCl f Charles \ v ~ f George ] n _ ( Emma j ( Emma j SO As NO 3 = Na NO, sodium chloride sudiiuu nitrate Soluble solid and therefore not precipi- tated, but re- maining in solution. Charles Lucy AgCl silver chloride Insoluble solid, called a precipi- NOTE. This is a very simple and frequent method of reaction. Fil- ter, wash, and preserve all precipitates for future use in experiments, or as samples of the various compounds. (See EXP. 7.) Carefully label the vials in which precipitates are preserved. It will be noticed that Ag Cl turn* dark when exposed to the light. (See SILVER.) Water favors chemical change. (There are exceptions. Water does not favor ordinary combustion.) Thus, two substances in solution will react with each other, which would not if they were mixed dry. Iron rusts (unites slowly with the oxygen of the air, forming ferric oxide Fe 2 3 ) if exposed to the air wet. Knives and forks must be wiped dry, else they rust. Solution divides a substance more minutely and evenly than can be done by any other method of mechanical division. Solution separates the molecules. For instance, if a teaspoonful of common salt be thrown into a ban-el of water and dissolved, molecules of salt may be found in every drop of the entire barrel. They seem to move among the molecules of water freely, the water giving them an atmosphere in which they easily per- form reactions with other substances. The water is not written in the reaction, unless it really takes some part in the atomic changes. When a substance dissolves in water, and unites chemically with the water to form another compound (as in reactions of EXP. 4 and 5), this is not a mere solution, but something more. In a mere solution the sub- stance goes into the water (somewhat as grains of sand might be poured into a measure of peas) without uniting with the molecules of water at all. A gas, as we have already learned, may be dissolved in water as well as a solid. 38 CHEMICAL PRIMER. A liquid may also be dissolved in water, but we speak of the liquid not as dissolved in water, but as diluted with water (or mixed)' and we do not speak of the resulting liquid as a solution. (See VOLATILE OILS.) When as much as possible of the substance is dissolved in a certain amount of water, the solution is said to be a saturated Solution. Many solids and gases are insoluble in water. (Some liquids will not mix with water and therefore cannot be diluted with water. ) Often these may be dissolved in other liquids, as alcohol (ethyl hydrate), hy- drochloric acid, etc. The liquid dissolving the substance is called a solvent. Whenever two substances, one at least being in solution, react, forming a solid insoluble in the liquid, the resulting solid, as it usually quickly falls to the bottom, is appropriately called a precipitate. If soluble solids are formed at the same time, they of course remain in solution. If gases are formed in the reaction, they come off from the liquids in bubbles. Substances which react with each other as in the above reac- tion, especially those that are much used in the chemical laboratory, are called reagents. EXP. 7. Into a test-tube containing silver nitrate solution let fall a few drops of dilute hydrochloric acid. The chemicals react by change of partners, as in EXP. 6, thus: Reaction: H Cl + AgN0 3 H NO 3 hydrosjei chlor " hydrogen nitrate + Ag Cl silver chloride (precipitate) Precipitates may be separated from the liquid by filtration. and fold some filter paper, thus: Cut Fig. 5. and place it on a funnel (tunnel), pouring the contents of tlie test-tube upon it. REACTIONS. Fig. 6. Section of Filter Stand. The precipitate remains upon the filter, while the liquid called fil- trato passes through. Wash the precipitate, to free it entirely from the filtrate, by forcing with the breath water in fine spray from wash bottles upon it. Remove the precipitate and dry upon glass, or dry before removing, a* is sometimes more convenient. Fig. 7. Bottle for cold water. Flask for hot water. 40 CHEMICAL PRIMER. CHAFTKR XVI. CLASS 2. (continued.) EXP. 8. Place a very little ferrous sulphide in a small bottle, and pour upon it dilute sulphuric acid. [In some cases the reaction is v. * prompt, i nis depenu^ upon pi eparation of Fe S used. Heat acid and Fe S in test-tube, Fig. 3 and Fig. 18.] / Reaction: Fe S + H. 2 S0 4 Fe SO 4 -f H 2 S As H^S is a gas, it comes off in bubbles. Close the mouth of the flask by a rubber cork, through which a fine glass tube passes. By means of a rubber tube and another glass tube, allow the gas to pass into water. As the gas is soluble (three volumes in one of water), we have a solu- tion of the gas. Set this aside carefully corked, as a reayent. (It decomposes in about four weeks and becomes worthless. ) Fig. 8. -Making solution of hydrogen sulphide. Caution. H^S is a poisonous gas, and EXP. S should be performed under a gas chimney, or near a window with an outward draft. (To breathe a small quantity mixed with air will, however, do no harm. ) This gas is largely used in the laboratory, and chemists are often more careless with it than is consistent with health. Learn to be caution* and careful in performing all experiments, followiny direction* minutely. EXP. 9. To a solution of lead acetate in test-tube add drop by drop solution of H>,S. (Reagents are hereafter presumed to be in solution. ) Reaction: Pb 2 C.H 3 2 lead acetate H,S =. PbS + 2HCAO, hydrogen lead hydrogen sulphide sulphide acetate (black precipitate) It will be noticed that when the hydrogen changes partners with the lead atom and takes the acetate grouping, the hydrogen and acetate grouping being univalent, they are matched one to one, giving us two REACTIONS. 41 molecules of acetic acid. It would be incorrect to write H 2 2 C 2 H 3 2 . Never put two monads with ttco monads in reactions^ but always one monad with one monad, and if there be two of each, double the mol- ecule. Just as we must take t^uo monads to match one dyad in a binary, so we must take two molecules containing monad partners to react with one molecule containing dyad partners. EXP. 10. To mercuric chloride (corro- sive sublimate) add drop by drop potas- sium iodide. (Fig. 9 represents a conven- ient test-tube stand. ) Reaction: Hg C1 2 mercuric chloride Hgl, + mercuric iodide (red precipitate) + 2KI = potassium iodide 2KC1 potassium chloride If too little is added, the precipitate dis- solves; if too much is added, the precipi- Fig. 9. (A) rubber band. tate dissolves, i. e., the precipitate dissolves in CXCCSS of either re- agent. Notice that the molecule of mercuric chloride contains dyad partners (Hg a dyad, and C1 2 two monads = a dyad,) while potas- sium iodide contains monad partners; therefore, we must take two mol- ecules of the latter to react with one of the former. EXP. 11. Into a solution of arseno-s oxide (dissolve in hot water and filter) let fall a few drops of dilute hydrochloric acid. Reaction (a): As 2 3 + 6 H Cl = 2 As C1 3 + 3 H 2 As 2 3 , a molecule containing hexad partners, requires six molecules of H Cl to react with it. As C1 3 , arsenous chloride, being soluble in water, does not appear as a precipitate. Into the test-tube drop solu- tion of H 2 S. Reaction (b): 2 As C1 3 + 3 H 2 S = As,S 3 + 6 H Cl (lemon yellow precipitate) In reaction (b) we must take two molecules containing triad partners (As C1 3 ) to react with three molecules containing dyad partners (H 2 S), just as we take two triad elements to match three dyad elements in forming binaries. In the second member of the equation we must be 42 CHEMICAL PRIMER. careful to match the atoms according to their "strength" and to mul- tiply the molecules affcnrard, so that the number of atoms of any ele- ment shall be the same in both members. EXP. 12. To lead acetate (sugar of lead) add magne- sium sulphate. Reaction: Pb 2C.HA + Mg SO, ** Pb SO 4 + Mg 2C.HA a poisou its antidote insoluble and soluble, but harm- therefore harmless l^ss salt (white xirecipitate) Inspection of this last reaction will reveal the exact nature of a chemical antidote. Let the test-tube repre- sent the stomach. A chemical antidote is a substance which will unite with the poison, forming insoluble or harmless compounds, or both. (See ANTIDOTES.) EXP. 13. To calcium hydrate (lime water) add ammonium carbonate. Reaction: Ca 2 HO -f (H 4 N) 2 C0 3 = Ca CO 8 + 2 H 4 N HO white precipitate (chalk) Inspection of the following questions and the method of solving them will open to the attentive student a wide field for careful and accurate work. To such a student the problems are not difficult. 1. From 542 mgs. of mercuric chloride, how much mercuric iodide could be made by adding potassium iodide? Reaction: Hg C1 2 + 2 K I = Hg I, -f- 2 K CI 200 200 71 254 271 mol. wt. 454 mol. wt. (will make) 271 mgs. Hg C1 2 = 454 mgs. Hg I 2 1 " = ^ of 454 Hg I a 542 " - f if of 454 mgs. Hg I 2 = 908 mgs. Ana. 2. How much mercuric chloride will be required to make 150 gms. of mercuric iodide (adding K I)? REACTIONS. 43 Reaction: Hg C1 2 + 2 K I = Hg I 2 + 2 K Cl 200 200 71 254 271 454 would require 454 Hg I 2 = 271 Hg Cl, 1 T i T of 271 Hg C1 2 150gms. " = IfJ of 271 gins. Hg C1 2 = 89lff- gms. 4/w. 3. How much potassium iodide would be required to make 227 gms. ofHgI 2 ? Ans. 166 gms. 4. How much potassium chloride could be made by using 996 gms. of potassium iodide ? Ans. 447 gms. CHARTER XVII. CLASS 3. Reaction of Acid and Base. When an acid and "base are united, the result is a salt and water. The acid is said to neutralize the base (or vice versa). EXP. 14. To barium hydrate add drop by drop sulphuric acid. Reaction: Ba 2 HO + H 2 SO 4 Ba SO 4 -f 2 H 2 O base acid salt water (white precipitate) EXP. 15. To oxalic acid add calcium hydrate. Reaction: H 2 C 2 4 + Ca 2 HO = Ca C 2 4 + "2 H 2 O acid base salt water (white precipitate) EXP. 16. To sodium hydrate add drop by drop acetic acid, till solu- tion is neutral to litmus paper. Reaction: Na HO + H C 2 H,O 2 = Na C 2 H 3 O 2 + H 2 O base acid salt water 44 CHEMICAL PRIMER. There is no precipitate, be- cause sodium acetate is soluble in water. Filter to remove any slight solid impurities and evaporate to dryness in evaporating dish (or beaker) over a water bath, /. e. , steam bath. (See Fig. 10. ) Sodium acetate, a solid, remains. NOTE. Whenever a water 1 ath is recommended, the simple meaning is that the evaporation be carefully done, so as not to Fig. 10. -Water Bath. ge()rch Qr sublime the res idue. The water bath prevents the heat from rising above 100 C. It may be dispensed with in most cases if sufficient care be used. CLASS 3 is only another form of CLASS 2. In reactions of CLASS 3 the same law holds good, viz. : "That two molecules containing monad part- ners must be taken to react with one molecule containing dyad partners, etc. " CLASS 4. Reactions of Acids and Carbonates. In these reactions, the carbonate grouping breaks up. When an acid unites with a carbonate, the result is a salt, water, and carbonic oxide (a gas). The law in re- gard to molecules containing partners of different strengths holds good, as in the last two cases. This reaction is fre- quently used by the druggist and pharmacist. EXP. 17. To acetic acid add sodium carbonate (solid or in solution) till effervescence ceases. (Effervescence is the bubbling caused by the rapid separation of a gas from a liquid. ) Reaction: Na,C0 3 + 2 H C 2 H 3 O 2 2 Na C,H 3 O., -f- H 2 O carbonate acid salt water (soluble) C O 2 carbonic oxide Filter, evaporate filtrate, and preserve. The salt is obtained as in EXP. 1 0. The heat of evaporation entirely expels any C O 2 that may be held in solution after the reaction. REACTIONS. 45 EXP. 18. -Into dilute citric acid let fall an excess of finely pulverized calcium carbonate (marble). When effervescence ceases, boil (to pre- cipitate any dissolved carbonate), filter, evaporate, and preserve as before. / Reaction: 3 Ca C0 3 + 2 H 3 C6H 5 7 = Ca 3 2 C 6 H 5 7 + 3 H. 2 -f 3 CO, carbonate acid salt water carbonic oxide NOTE. Three molecules containing dyad partners (Ca"CO 3 ") must react with two molecules containing triad partners (HyCtfHsO/"), as before. (See also EXP. 33.) Notice, in evaporating, that this salt (calcium citrate) is less soluble in hot than in cold water; an exception to the general rule, that "for equal volumes, hot water dis- solves more of a solid than cold water. As a rule, "hot water dissolves less of a gas than an equal volume of cold water." Indeed, many gases not only will not dissolve at all in boiling water, but may be completely expelled from water, in which they may have been previously dissolved, by boiling it. Before leaving these chapters on reactions, the student should be able to write promptly any reaction belonging to either of the four classes, provided he. has the names of the two substances given and the two refer- ence tables before /dm. MISCELLANEOUS PROBLEMS. 1. Write formulas for five binary acids. 2. Write formulas for ten ternary salts. 3. Write formulas for two binary salts. 4. Write formulas for six ternary acids. 5. W T rite formulas for five bases. 6. In 150 gms. of arsenous oxide, how much As? 7. In 1000 gms. of silver chloride, how much silver? 8. How much mercuric sulphide could be made by using 50 kgs. of mercury (Hg")? 9. Reaction when phosphorus burns in air? 10. When carbon burns? Reactions when the following are united: 11. Stannous chloride (Sn") and hydrogen sulphide? 12. Copper sulphate and sodium hydrate? 46 CHEMICAL PRIMER. 13. Sodium carbonate and hydrochloric acid? 14. Ammonium carbonate and calcium hydrate? 15. Potassium hydrate and sulphuric acid? 16. Calcium hydrate and citric acid? 17. Potassium carbonate and tartaric acid? 18. Acetic acid and magnesium carbonate? 19. To make 190 gms. of magnesium chloride (by adding H Cl), how much magnesium carbonate must be taken ? 20. How much arseiious oxide, As.,0 3 (white arsenic) was contained in a vessel full of water, from which 15 mgs. of arseiious sulphide was precipitated (by adding H Cl and H a S)? CHAPTER XVIII. OXYGEN. EXP. 19. Carefully pulverize in a mortar a small quantity of potas- sium chlorate, and, having mixed it thoroughly with an equal bulk of pure manganese dioxide, introduce into a small copper retort. Heat by a strong alcohol flame, or flame from a Bunsen's burner. Collect in receivers over a pneumatic tub, as represented in Fig. 11. [A glass flask heated upon a sand bath (iron basin filled with sand, Fig. 21) may be used in place of the copper retort. ] Reaction: K Cl O 3 = K Cl + 3 Fi-. 11 (a) retoi t stand ; (b) letort; (c) receiver; (d) -pneumatic tub; (e receiver removed. OXYGEN. 47 NOTE. The presence of Mn 0. 2 causes the to come off more steadily and at a lower temperature, but as it takes no part in the reaction, (?) it is not written. The first bubbles that come off are composed principally of air from the retort and should be allowed to escape. The often looks cloudy, because small particles of the salt and oxide are carried over by the draft. These gradually dissolve or settle into the water. Three or four receivers should be inverted, and as fast as filled removed by means of a small, shoal tin cover, holding a little water, to prevent the escape of the gas. Small quantities of may be conven- iently made by using test-tubes as retorts, test-tubes, or bottles, as receivers, and a beaker or basin as a pneumatic tub. (See Fig. 3.) Avoid heating too rapidly in one place, by carrying lamp or burner back and forth slowly, so that test-tube shall pass through the bottom of the flame, nearly touching the wick or burner. Caution. K Cl 3 must not be heated alone. Commercial Mn 2 is sometimes adulterated with carbon (pounded coal) and when mixed with K Cl O 3 and heated, the mixture explodes violently. Test by heating in test-tube a small quantity of the oxide and chlorate mixed, unless the former is warranted to be pure. The delivery tube must be removed from the water before the heat is taken from the retort, other- wise, as the gas in the retort cools and contracts, the water is forced back along the tube by atmospheric pressure. The first that falls into the highly heated retort is instantly converted into steam, causing an explosion. Ordinary care will prevent any serious accident. The chief danger in breaking glass retorts is to the eyes. Learn here that an explosion is (generally) caused by the sudden con- version of matter from the solid or liquid to the gaseous state. Oxygen is a colorless gas, without odor or taste. As we have inferred from the formulas thus far used, it is a very abundant element. It exists free (uncombined) in the air, forming one-fifth its volume. Chemically com- bined with other elements, it forms by weight eight-ninths of water, one-half of minerals, three-fourths of animal tissues, and four- fifths of vegetable tissues; in short, so far as we know, about two-thirds of the earth. EXP. 20. Into a receiver (bottle) of 0, plunge a taper having a live coal upon the end, it immediately bursts into a blaze. Quickly remove and blow out the flame. Repeat the relighting from twenty to forty 48 CHEMICAL PRIMER. times, as may easily be done before the gas is exhausted. Do not plunge deeper than is necessary to rekindle, as this uses up the rapidly. Wood, oil, tallow, etc. (things that we ordinarily burn), are composed principally of H and C, and are therefore called hydrocarbons. When hydrocarbons (as the taper in the experiment) burn, two reactions take place, viz. : H 2 + O = H 2 O (steam)) Gaseous prod- _ , \-ucts of the C + O 2 = CO 2 (a gas) J combustion. Immediately after the is exhausted, pour into the receiver a very small quantity of water, and closing its mouth, shake at intervals. The C O 2 gradually dissolves. Reaction: C 2 -f H 2 = H 2 C0 3 acid forming acid oxide Test by litmus paper, but as H 2 C0 3 is a very weak acid, litmus paper must remain a little time in it. O is a vigorous supporter of combustion. O is heav- ier than air, for we hold the mouth of the receiver upward to retain the gas. Water is the standard of specific gravity for solids and liquids, and air for gases (in physics). Sp. gr. of air is 1 , of O 1.1+. But in chemistry^ hydrogen (which see) is made the standard for gases. Exp.21. Straighten a narrow steel(Fe)watch-spring and file the end bright. Attach (Fig. 12) a very short piece (head) of a common match, as kindling for the steel. Ignite by flame and quickly plunge into a receiver of 0. The steel burns vividly Reaction: Fe^ -j~ 0, = Fe,0 4 (triferric tetroxide black or magnetic iron oxide) If a large receiver is used, and the head of the match is attached to the spring by winding a very fine iron wire closely about both, the experiment is a very brilliant one. As this oxide of iron does not unite with water, the water shaken up in the receiver has no effect upon litmus paper. Though a positive oxide, it is not a basic oxide. This reaction is an irregular one, that is, the strength of iron is apparently not according to the Table. OXYGEN. 49 If the air were pure O undiluted with N, our iron stoves would take fire, and a general conflagration would spread over the earth. We could not, for any length of time, breathe pure O, as it would so stimulate the vital processes as to produce speedy death. A small animal placed in a jar of constantly renewed O, dies in a few hours. EXP. 22. Charcoal baric, a small part of which has been heated to a live coal, plunged into (by means of a Cu wire twisted about it), bursts into a vivid combustion. EXP. 23. Repeat EXP. 4 in jar of 0. (Place S on chalk in a combustion spoon. Copper wire twisted about a piece of chalk makes a good com- bustion spoon.) EXP. 24. Cut under water, quickly and care- fully dry between pieces of blotting-paper, a small piece of phosphorus (not larger than a grain of wheat). Place in a combustion spoon, ignite by hot wire, while lowering into a large jar of O, containing at the bottom a little water. A blinding light is caused by the combustion. Reaction: P 2 -f 5 = P 2 5 dense white . 1Q fumes *m* i6 - In a short time these fumes are dissolved in the water, and the follow- ing reaction slowly takes place: PA + 3H 2 = 2H 3 P0 4 acid furniiiii.' oxide Test by litmus paper. Caution. Handle P with great care, on no account touching it.' The heat of the hand may inflame it, and its burns are dangerous. Its va. A or is highly poisonous and nui. 3 t not be inhaled. The dense, w*nuj fumes should be immediately shut in by stopple attached to combustion spoon. (See Fig. 13.) O is an exceedingly active gas. It alone supports all ordinary burning that takes place in the air. To bring this gas in contact with the blood is the object of respiration 50 CHEMICAL PRIMER. in animals. The blood absorbs and carries O to all the tissues, the most prominent chemical change taking place in the body being that of oxidation. (See carbonic oxide. ) There is a peculiar form of condensed O, called Ozone. It is O in an aUotropic state. It may be made in various ways, especially by the action of electricity on common O. It occurs in minute quantities in the air. It is even more active than O and is a powerful disinfectant. In ozone tainted meat rapidly loses its putrescent odor, because the foul material is oxidized, forming relatively wholesome compounds. The molecule of ozone may be represented thus ^ j with three atoms, that of oxygen being ! OO_, composed of two atoms, that is, three vol- umes of oxygen if it could all be changed to ozone would make but two volumes of ozone. CHAPTER XIX. HYDROGEN. EXP. 25. Place in a small flask, or large test-tube (hydrogen gener- ator), some granulated Zn. Upon it pour dilute (10 per cent. ) sulphuric acid. Close mouth of flask with perforated rubber cork, through which passes a fine glass tube. Collect H over pneumatic tub, as in Fig. 14. Zn + H,S 4 = Zn S 4 + H, NOTE. Collect several re- ceivers of the gas, and, after the reaction has ceased, filter the liquid remaining in the flask; evaporate filtrate, and the white salt, zinc sulphate, is obtained. If a drop of the fil- trate is placed on a piece of glass and set aside, away front the dust, beautiful crystals of Fig. U.-Making Hydrogen. the salt are left upon the glags HYDROGEN. 51 Hydrogen i* a colorless gas, without odor or taste (when pure). It is the essential constituent, as we have seen, in acids. Indeed, acids have sometimes been defined as "salts of hydrogen." H does not occur free. It has been condensed by cold and pressure, first, to a liquid and then to a white solid. H is not poisonous, but destroys life, just as water does, by shutting out the O. The lungs may be inflated with the pure gas without harm. Caution. Gases made by beginners must never be breathed. As a rule, a gas is obtained absolutely pure with great difficulty. For methods of obtaining gases pure, see larger text-books or some treatise. EXP. 26. Remove a jar of H, holding the mouth downward, and into it plunge slender lighted taper. The H takes fire and burns at the mouth of jar, but the taper is extinguished in the gas above. It may be relighted by the burning H as it is being removed. H is lighter than air, for we hold the gas by keeping the mouth of the receiver downward. H is very inflam- mable, i. e., its igniting point is low. It does not sup- port combustion (of hydrocarbons). NOTE. Combustible bodies and supporters of combustion are relative terms. A jet of O would burn in a jar of H just as well as a jet of H in a jar of 0. One as well as the other could be called the supporter of the combustion. EXP. 27. Collect H from generator in test-tube by displacement of air. Pour upward into another test-tube, displacing the air. Test by igniting. EXP. 28. Attach by rubber tube a clay pipe to generator and blow- soap bubbles with H. They ascend and may be ignited in the air. Hydrogen is the lightest substance known, being about 14| times lighter than air. Chemists take hydrogen as the standard of specific gravity for gases. With this stand- ard, "one-half its molecular weight is the specific gravity of any gas." (See Miscellaneous Questions, Chap. XXII, NOTE.) 52 CHEMICAL PRIMER. EXP. 29. Fit a perforated cork, through which passes a glass tube, deeply into a new, dry porous cup (such as is used in Bunsen's battery). Melt over the surface of the cork sufficient paraffine (or tallow) to make it air- tight. Place the end of tube just beneath water in a beaker (Fig. 15), and cover the porous cup with receiver of H. The H passes by diffusion in through the pores of the cup much more rapidly than the air passes out, therefore bubbles of air are forced out through the water. Remove receiver and soon the water rises in the tube because of the diffusion of the H outward. All gases possess power of diffu- sion, but the power is possessed by H in an extreme de- gree. The diftusibility of gases is "inversely as the square roots of tleir densities" the density (or sp. gr.) of any gas being, as given above, half its molecular weight. EXAMPLE. density of H , diffusibility of H (Uffusibility of O That is, H has four times the diffusive power of O, or dif- fuses four times as rapidly. H may leak through vessels that would retain O permanently. EXP. 30. Close generating flask by a rub- ber stopple, through which passes a hard glass tube, with fine opening. After the air has been expelled by the H, ignite the jet. The appa- ratus is the "Philosopher's Lamp." Over the flame invert a cold, dry test-tube. It is be- dewed with moisture. H 2 -f = H 2 When H burns, the product is Fig. IB. Philosopher's lamp, water (steam). The H flame gives little light, but great heat.. The alcohol (ethyl hydrate) HYDROGEN. 53 flame gives little light and great heat, because alcohol contains much H. The flame of the oxy-liydrogen blowpipe melts many substances (as platinum), infusible in ordinary fire, the alcohol flame, or the flame from a Bunseii's burner. Fly. 17. Section of oxy -hydrogen blowpipe. The H from the gasholder is first turned on and ignited, and after- ward the is turned on. EXP. 31. Fill over a pneumatic tub a stout quart fruit jar one-third with O, and the remainder with H. Wrap alwtt it a cloth; remove, and, holding the mouth downward, quickly ignite by means of a taper. A sharp explosion ensues. There are two reports heard as one, the second so closely follows the first. The first is caused by the sudden (but not greater than a few volumes) expansion of the gases heated by their union; the second is caused by (the steam suddenly condensing) the rush of the air from all sides to fill the partial vacuum. Caution. Of course, H explodes when mixed with air. Care must be taken to expel all air from appa- ratus before igniting jets of H. Never ignite large quantities of the gas. EXP. 32. Repeat the experiment of decomposing water as explained in connection with Fig. 1. This proves by Analysis the composition of water. If we explode two volumes of H with one of and find we have nothing but water left, we prove the composition of water by Synthesis. Water H,O The wonderful power of chemical affinity is shown in 54 CHEMICAL PRIMER. this compound. A union of the most inflammable sub- stance known with the most vigorous supporter of com- bustion, forms another substance which will extinguish fires. We have called this substance by its pet name, because it is so common a substance and so generally dis- tributed. Its systematic name (hydrogen oxide) is seldom used. We have already learned that water is the general solvent in nature, dissolving most gases and solids and diluting most liquids. Hard water contains minerals in solution ; soft water does not. NOTE. In a narrower, but very common usage, only such water is called hard as contains in solution minerals that either react with soap, or hinder its solution (see SOAP). Water containing such minerals as borax and potassium carbonate would be called in the laundry soft water. Water or soil containing potassium carbonate, sodium carbonate, etc., is often said to be " alkaline,'' 1 because these salts have an alkaline reac- tion Tipon litmus, and because the old chemists called the strongly posi tive carbonates "mild alkalies." (They called the strongly positive hydrates "caustic alkalies," and these hydrates are still frequently thus called.) ' EXJ>. 33. In a test-tube place small pieces of marble and cover with dilute hydrochloric acid (ten per cent). Reaction (Class 4th): Fig. 18. By means of a delivery tube (Fig. 18) pass the gas through clear lime water (solution of Ca 2 HO, see EXP. 5) in a second test-tube. The lime water at first becomes milky because of white precipitate of Ca C0 3 . Reaction: Ca 2 HO + CO, = CaC0 3 + H,O aci forming oxide HYDROGEN. 55 Allow the gas to continue bubbling through the lime water. After all the Ca is tiuu vva down as a carbonate, the CO^ dissolves in the water. Carbonates dissolve in water containing C0 2 in solution, but not in pure water. ) The water becomes clear again because the calcium carbonate is dissolved. This clear water is now water of " temporary hardness. " Boil. The C0 2 in solution is driven off, and the calcium carbonate is again precipitated, being insoluble in pure water. Hardness produced by earthy (Ca. Mg. Sr. Ba., etc.) carbonates is called "temporary hardness," because the carbonate may be precipitated by boiling, leaving the water soft. The "fur" upon the tea-kettle is a precipi- tated carbonate. Hardness produced by earthy sulphates is called " per- manent hardness," because the water cannot be made soft by boiling. (See SOAP.) The vapor of water in the atmosphere is essen- tial, not only to plant life, but to animal life as well. The earth would be a vast desert were it not that tons of water are constantly being carried up from the ocean by evaporation, so that the air currents may distribute it, not alone to fall as rain, but also to keep the atmosphere everywhere moist. Many substances, when they crystallize (assume a sym- metrical shape in solidifying), take up a definite amount of water, called water of crystallization. This may be expelled by heat, but the essential properties of the sub- stance are not changed. EXP. 34. Heat in a narrow, deep test-tube of hard glass, small crys- tals of pure copper sulphate previously carefully weighed; the water of crystallization is expelled and part of it condenses in small drops on the cooler part of the test-tube. The blue color disappears. Wipe with dry cloth the water from the test-tube. Remove and weigh the sulphate. It has lost over one-third its weight, as the formula of c?v/. t'tlhzed copper sulphate is Cu S 4 , 5 H^O. Touch with a drop of water, the color slowly returns. Dissolve in a small quantity of water, evap- 56 CHEMICAL PRIMER. orate slightly, and set aside to cool. Beautiful crystals of copper sul- phate form as the solution cools. Fine crystals of various siibstances may be formed in this way, viz., by making saturated solution of the substance (slightly evaporating), and setting aside for a few days. Making a collection of crystals will be found a very profitable exercise. Water of crystallization is not written in ordinary reactions of substances in solution, but must be taken into account in dealing with the dry solids. Of course a larger quantity of the crystallized solid must be taken to equal a smaller quantity of the uncrystallized, // tin' solid takes up water of crystallization. Some substances, such as sodium acetate (Na C S H 3 O 2 3 H. 2 O), sodium carbonate (Na, C O 3 , 10 H 2 O),etc., when exposed to the air lose their water of crystallization, and crumble to powder. These are said to be efflorescent. Some substances, as potassium carbonate (K 2 CO 3 ), when exposed to the air, absorb moisture and dissolve (or partially dissolve). These are said to be deliquescent. The law of physics, that "heat expands and cold con- tracts," does not hold with water in cooling from about 4 (C) to 0, through which space it steadily expands, until it freezes (crystallizes) at 0. At the moment of freezing there is a sudden and great expansion. (See Plot b, Fig. 19.) The importance of this exception cannot be overestimated, for it makes ice lighter than water, and so prevents lakes and rivers from freezing solid. Water containing impurities in solution may be puri- fied by distillation. The water is placed in a retort, or u still," is heated, rises as steam (at 100), which, passing through the condenser (supplied with cold water in direction of arrows, Fig. 19), condenses, and is collected in a receiver. Steam ("dry steam") is an invisible gas. That which is seen and often miscalled steam is steam condensed (or partially condensed) into minute globules NITROGEN. 57 of water and held in suspension (like dust) by the air (or by the invisible steam, in which case the steam is called "wet steam.' 1 ) Fig. 19. Retort, or " still," and condenser. Plot b Effect of "cold" upon water. CHAPTER XX. NITROGEN. Exr. 35. Place a piece of chalk on a tripod wire-holder, standing in a deep plate of water. Upon the chalk place a small piece of P. Ignite by hot wire and quickly invert a receiver over it. (Caution, EXP. 24.) P, + 0, = PA soluble white fumes The P unites with the in the jar. The phosphoric oxide dissolves and the water rises by atmospheric pressure and fills one-fifth of the receiver, the space before occupied by the 0. N remains in the receiver above the water, neither burning nor supporting the combustion of the remaining phosphorus. (See Phosphorus. ) Fig. 20. .58 CHEMICAL PRIMER. Nitrogen is a colorless gas, without odor or taste. It forms by volume i of the atmosphere. N is not poison- ous, and destroys life only by shutting out O. It is not inflammable and it does not support combustion. It is a very inert element. It dilutes the active O of the air, and the mechanical mixture is thus fitted for respiration. Some of its compounds are by no means inert. For ex- ample, "nitro-glycerine," the violent explosive, is glyc- eryl nitrate, and the deadly poison, prussic acid, is hy- drogen cyanide. No one can predict with certainty the character of a chemical compound from the nature of its constituents. It might be supposed that, N being lighter than O, the air would separate into two layers, the heavier, O, sinking. The two gases, however, are kept thoroughly mixed by the law of diffusion of gases. N forms with five oxides, viz. : N 2 0, hyponitrous oxide (acid-forming). N 2 2 nitrogen dioxide. N 2 O 3 nitrous oxide (acid-forming), N 2 4 nitrogen tetroxide (or peroxide). N 2 O 5 nitric oxide (acid-forming). These oxides illustrate well the great law of multiple proportions. When one substance unites chemically with another, it is in some definite proportion, or multiple of that proportion. Whenever substances are united phys- ically (mechanically, as in alloys of metals, etc.) they may be united (mixed) in any proportion. NOTE. We see from the above that there is a third class of indiffer- ent oxides (as N 2 2 , N 2 O 4 ), neither acid-forming nor basic. The pupil need not give much attention, however, to this class. All the positive indifferent oxides, as Mn O 2 , Ba O 2 , K 2 O 4 , Pb 2 , having more O than the basic, are called peroxides. For preparation of N 2 O 3 and N 2 O 5 see larger text-books. NITROGEN, 59 KXP. 3(>. Heat in flask ammonium nitrate and collect gas over pneu- matic tub of warm water. / H 4 N N0 3 = 2 H,0 + N 2 Hyponitrous oxide ("nitrous oxide" "laughing gas"), inhaled with a small proportion of O, produces a peculiar intoxication, hence its name of "laughing gas." If the pure gas is inhaled, it soon produces insensibility. It is much used as an anaesthetic by dentists and by surgeons in minor operations. It is kept condensed in liquid state in iron cylinders. (See Caution, under Hydrogen, Exp. 25.) EXP. 37. To small pieces of copper add dilute (50 per cent.) nitric acid, red fumes appear in generator (see EXP. 38), but a colorless gas collects over the tub. Reaction (irregular, don't attempt to remember it) : / Cu 3 -f- 8 H N O 3 = 3 Cu 2 N O 3 + 4 H. 2 + N 2 O 2 nitrogen dioxide After the action has ceased, filter water in flask, evaporate, and obtain blue crystals of Cu 2 N O 3 . EXP. 38. Admit to test-tube containing N 2 O 2 a bubble of O (or air). Red fumes of N 2 4 appear. N 2 2 + 2 =' NA nitrogen tetroxide These fumes are very soluble in water, and the water slowly rises to take the place of the dissolved gas. If air is admitted, of course the water will not entirely fill the test-tube, as the N will remain undis- solved above the water. EXP. 39. Into a test-tube put a small quantity (4 gms. ) of sodium nitrate (or K N0 3 ) and 2 gms. of sulphuric acid. Carefully heat. Col- lect nitric acid in a narrow, deep test-tube, well cooled by sinking to its mouth in cold water. [Sink test-tube by tying stone to the bottom. Don't breathe the fumes.] 2NaN0 3 + H 2 S0 4 = Na 2 S O 4 + 2 H N O 3 60 CHEMICAL PRIMER. Nitric acid (old name aqua fortis) is prepared by heat- ing sulphuric acid with sodium nitrate (but see acid-^alts). It is a colorless (if pure), fuming, corrosive liquid. EXP. 40. Place a quill in H N O 3 and heat. The quill turns yellow. EXP. 41. To dilute H :X0 3 add a crystal of Fe S0 4 ; then add a few drops of H. 2 S 4 . A brown compound (Fe S0 + , N 2 0. 2 ) slowly forms about the crystal. This is a good test for H N 3 and other nitrates. EXP. 42. Throw a small crystal of potassium nitrate upon a red-hot coal. The coal burns rapidly (almost explosively). Nitric acid stains organic matter, as the skin, nails, etc., a dingy yellow. It is a powerful oxidizing agent, as are all the other nitrates. EXP. 43. Spread upon a piece of clean copper (also upon a piece of iron) a thin layer of paraffine. Write upon each, taking care not to scratch the metal. Upon the writing put nitric acid (50 per cent.). It etches the words by oxidizing the metals, dissolving and uniting with the metallic oxides. Nitric acid is used in etching upon copper and iron (copperplate, swords, razors). EXP. 44. Into a test-tube containing nitric acid, drop a piece of gold- leaf and heat. It does not dissolve. Add a few drops of hydrochloric acid. The gold rapidly dissolves, forming An C1 3 in solution. Nitric acid (about 3 parts) and hydrochloric acid (5 parts) form aqua regia, the solvent of gold (and plati- num). EXP. 45. Place in a flask a little ammonium chloride (sal ammoniac) with an equal weight of calcium oxide (quicklime), each finely pulver- ized. Add a little water and, quickly closing flask, heat upon sand bath. Dry gas by passing through bottle containing Ca 0. Collect by dis- placement of air in receiver. (See Fig. 21.) ["Drying tube" may be dispensed with and gas passed directly from flask into receiver. Don't breathe too much of the gas. ] 2H.XC1 + CaO =: CaCl, + H,0 -f 2 H,N NITROGEN. 61 Fig. 21. A sand bath; B drying tube; C receiver. EXP. 46 (45 concluded). Quickly close mouth of bottle of ammonia by perforated rubber cork, through which passes a glass tube drawn to a fine point and connected with water colored red by slightly acidulated litmus solution. Hasten the action by forcing air into lower flask (through tube A B, Fig. 22, till a few drops of water reach the receiver (C) of ammonia. The gas dissolves so rapidly in the water that a par- tial vacuum is formed, and the outside atmospheric pressure acting through A B produces the "ammonia fountain." The water turns blue as it enters the receiver! Ammonia is a colorless gas, with pungent odor. It is much lighter than air. It is Yery soluble in water, 700 gals, dissolving in a single gallon of water at 15 (1000 vols. at 0, see coal gas). It not only dissolves, but unites with water Reaction : H 3 N + H 2 - H 4 N HO forming ammonium hydrate ("ammonia water," harts- horn, etc.). Fig. 22. Ammonia fountain. 62 CHEMICAL PRIMER. The ammonium grouping can be passed from compound to compound like an clement, and hence is a compound radical. (See AMMONIUM.) In concentrated "ammonia water" there is probably a large excess of the gas dissolved (more than unites with the water). Ammonium hydrate (or ammonia in the presence of moisture) has a strong alkaline reaction. It has been called the "volatile alkali," .because its effect upon vegetable colors is only temporary. Prove this by dipping red litmus paper into dilute ammonia water and noticing that the red color returns again after a few hours. When the color of cloth, stained by an acid, has been restored by "ammonia water," the ammonium salt should be thoroughly washed out with water, or the red spot returns. (See CHEMISTRY OF CLEANING.) " Evaporation cools." This means that when a substance evapo- rates it absorbs heat from what is near by. (See sulphur dioxide, AP- PENDIX.) Wet one hand and pass both hands rapidly through the air. The wet hand is sensibly colder from the evaporation of the water. Pour a little ether upon the thermometer bulb. The ether quickly evaporates and the mercury falls. A pressure of about 4| atmospheres (at 0) converts gaseous into liquid ammonia. The evaporation of liquid ammonia produces intense cold ( 40). Advantage is taken in the arts of this fact to produce ice artificially. In a strong generator, A, is placed ice water saturated with ammonia gas (1,000 vols. in one). This is con- nected with an equally strong receiver D, by the tube B. Receiver D is placed in cold water. Heat is applied to A and the great pressure of escaping gas converts the gas into a liquid in D. Water is now placed in vessel C. Generator A is cooled and the liquid ammonia in D evaporates and is reabsorbed by water in A. The evaporation produces sufficient cold (takes away or absorbs sufficient heat) to freeze water in C. Other sub- stances than ammonia may be used Fig. 23. Ice Machine, for this purpose, all, however, involving the principle of evaporation. CARBON. 63 Nitrogen and hydrogen do not unite directly to form ammonia, but when decomposition is taking place in organic substances, and these two elements are leaving their old compounds, they unite. Elements just leaving their old compounds are said to be in the nascent state, and they have a much greater tendency to form new compounds. CHARTER XXI. CARBON. Carbon is a very abundant element. It forms a large proportion of vegetable and animal tissues, and is a prom- inent constituent of limestone, marble, etc. (carbonates). We know it in three allotropic states: 1. Diamond. 2. Graphite (plumbago, black lead). 3. Amorphous Carbon (uncrystallized). Graphite, mixed with a little Sb and S, is used to make common "lead pencils." Mixed with clay, it makes cru- cibles, the most refractory (difficult to melt, or of ores, difficult to reduce) known. Amorphous Carbon (more or less impure) includes charcoal, mineral coal (the remains of vegetation of the carboniferous age), coke, peat, animal charcoal (bone black), soot, lamp-black, and gas-carbon. NOTE. For fuller description of the above and of all such substances briefly mentioned in this primary work, see the dictionary and cyclopae- dia. Every High School should have an unabridged dictionary and a cyclopaedia placed where scholars can readily refer to them. 64 CHEMICAL PRIMER. Fig. 24. Mercuric Tub. Carbon for a long time resists decay. Fence posts are charred to preserve them. Neither acids (except nitric) nor alkalies affect it. EXP. 47. Collect in test-tube over mercury (or by displacement of air) H 3 N. Introduce into the gas a piece of fresh burned, dry char- coal, mounted on wire attached to perforated cork, and quickly dip the mouth of test-tube beneath mercury. The Hg rises in test-tube, be- cause C absorbs the H 3 N in its pores. NOTE. Chisel out of hard wood a trough o inches long, 1 inch wide, and 1 inch deep. Nail a lead post to one or both ends to support small test-tube. This makes a very good mercuric pneumatic tub, but the mercury must not come in contact with the lead. To avoid this the supports may be made of wood. Use narrow test-tubes and keep them from the side of the tub, else the air creeps in. Carbon absorbs many times its bulk of gases, condens- ing them in its pores. Fresh burned charcoal is a good " disinfectant " for foul gases. They are destroyed within its pores by the absorbed O ; i. e., by oxidation (so that C is not a disinfectant in a strict chemical sense, but its action is mechanical). O is the real disinfectant. EXP. 48. Finely pulverize charcoal by rubbing two sticks together, or, if animal charcoal is used, by grinding in mortar, and place upon filter. Slowly moisten with distilled water. Let diluted ink (or indigo solution, vinegar, etc.) fall drop by drop upon the charcoal from an ordinary paper filter above it. The filtrate from charcoal is colorless. Charcoal is a good decolorizing agent. Animal char- coal is largely used in sugar refineries to remove soluble impurities and color. CARBON. 65 Ex P. 49. Heat upon platinum foil a piece of sugar (or other organic matter, as tartaric acid, flesh or vegetable). It chars (turns black, as the more volatile constituents are driven off, leaving the carbon free). Charring is a good test for carbon (or for organic mat- ter) EXP. 50. Upon charcoal put a little litharge (Pb O). Heat in the blow-pipe flame. The O is taken by the C leaving the Pb free (uncom- bined). / 2PbO + C = Pb, + C0 2 etaliio lead Carbon is a good deoxidizing or reducing agent. Heated with the oxides of most metals it deoxidizes them, and is thus of special use in reducing ores that are oxides (or carbonates, since great heat breaks up the carbonate grouping, setting C O 2 free, and leaving an oxide behind). EXP. 51. Upon pieces of marble (Ca C0 3 ) in a flask, pour dilute (20 per cent. ) H Cl. Collect gas by displacement of air. Reaction (class 4): Ca C0 3 + 2 H Cl = Ca'd^ -f H 2 + C O 2 carbonate acid salt water carbonic oxide Fig. 25. 66 CHEMICAL PRIMER. Carbon dioxide (carbonic oxide, carbonic anhydride, old name carbonic acid) is a colorless gas, with slightly acid taste. It is much heavier than the air (sp. gr. 1.5, with H as standard 22) in which it exists free, forming about ^(^575-0 by volume. EXP. 52. Into a jar of C 2 introduce a lighted taper. It is extin- guished. EXP. 53. Arrange short lighted candles along an inclined (not too steep, else draft is produced) trough (piece of gutter). Pour a large receiver of C O. 2 into the top of the trough. The candles go out in order as C 2 reaches them. EXP. 54. Put a mouse into a receiver of C O 2 . The animal dies. Carbon dioxide does not support combustion and is not inflammable. Though not poisonous in a strict sense of the word, yet animals die from suffocation in air containing about five per cent, of the gas. It hinders the elimination of the same gas, C O 2 from the lungs (but see C O, in APPENDIX). EXP. 55. Burn Mg ribbon in a jar of C 2 . Black particles of carbon appear mixed with the white oxide. CO, + Mg 2 = 2MgO + C white black Dissolve oxide in dilute H N O 3 and C is made more distinct. C 2 supports the combustion of magnesium^ but by a supporter of combus- tion in general we mean a substance that supports the combustion of hydrocarbons. EXP. 56. Repeat EXP. 33. Lime-water is the test for C O 2 . No other gas will (1) extinguish flame and (2) render lime-water milky. EXP. 57. Hold the breath a short time and then expel the air into a receiver. Test. It extinguishes the flame of taper and turns lime-water, shaken up in the receiver, milky. CARBON. 67 Animals exhale C O 2 from the lungs as a waste product. They use up O from the air and replace it by C O 2 . EXP. 58. Place a small branch having numerous and fresh leaves in a tall receiver (prepared as in Fig. 26) of spring or brook water (/'. e. , water that has been sufficiently exposed to carry much air dissolved) and place apparatus a few hours in direct sun- shine. O is evolved and, together with a little N and traces of C O. 2 driven off by the sun's heat (of course a little is also driven .off by sun's heat), collects in top of receiver. Test by very slender and glowing taper. The gas is found to be principally oxygen. Plants in sunshine exhale through their leaves O (except certain low orders), using up C O 2 of the air and building the C into their tissues. The leaves of plants are often compared to the lungs of animals, except we must remember that the process is reverse. They receive the air through little stomata (mouths) on the under side (prin- cipally). But in some important respects the leaves cor- respond to the digestive organs of animals (including glands preparing chyle for the general circulation, viz., " mesenteric glands" and the liver). The plant gets vastly more food (by weight) from the air than from the richest soil. The smaller portion which it gets from the soil is, however, an essential portion, and it will not nourish in poor soil. Plants purify the air for animals, and animals by a reverse process supply from their own waste the needed elements of plant food. Carbon dioxide is also formed in large quantities by the decay of organic matter. The proportion, however, of C O., in the air remains practi- cally the same from year to year. 68 CHEMICAL PRIMER. C 2 tends to collect in old wells and in unventilated portions of mines. It is called by miners choke-damp. Wherever a light is ex- tinguished by C 2 , it is unsafe to go. EXP. 59. Place a short lighted candle on a rubber cork and intro- duce it into the bottom of a vertical glass tube, which the cork tits. The candle goes out. In the tube suspend a smaller tube and introduce the lighted candle as before. It burns steadily. The heated air (and C 2 ) rises in the small tube (upward draft) and the fresh air containing O falls between it and the larger tube. Two openings, at least, are necessary for proper ventilation. In mines where it is possible, two shafts, one at each end, with a fire at the base of either, answers the purpose. Very complex arrangements, however, have to be made in many cases to force air into the various parts of large mines. Plenty of fresh air is the only preventive to keep fire-damp (marsh gas C HJ and C 0. 2 from accumulating in dangerous quantities. EXP. 60. Hold the breath a short time and then expel it into a jar and close by rubber cork. Set aside in a warm place for a day or two and then open. A very offensive, putrescent odor greets the sweetest- breathed experimenter. (C 2 has no odor.) [This experiment may, perhaps, best be performed at home. ] Churches, school-rooms, bedrooms, etc., should be very thoroughly ventilated, not so much to free them from the injurious C O 2 as to remove the poisonous "animal vapor 1 ' (moisture in suspension) thrown off from the lungs. This " vapor " holds all manner of organic impurities in solution. EXP. 61. Fill a narrow, deep test-tube with C 2 . Close with the thumb and open under cold water (but previously boiled), pressing the mouth a few inches below the surface. Close the test-tube, remove and shake. Part of the C 0. 2 dissolves. Open under water and repeat shak- ing. In this way the test-tube of C O 2 may be dissolved in a test-tube of water. Water at 15 dissolves one vol. of C 2 , but if the gas is under press- ure, it dissolves much more (by weight). CARBON. 69 "Soda Water" is nothing but a oolution of O, under pressure in water. It probably receives ics inappropriate name because of its effervescence when relieved of pressure (like sodium carbonate, "soda," when mixed with an acid). C O 2 has b^eii condensed to a liquid, and by rapid evaporation of a part, the rest is solidified (frozen), forming a snow-white solid. This solid is so cold that when touched it produces the same effect as red- hot iron (see similar condensation of S O 2 , APPENDIX). As we have seen, C O 2 and H 2 O are the two great products Ox ordi- nary combustion, The chemistry of a burning candle is in a general sense very simple. The wick is first raised to the igniting point, the heat melts the tallow (composed chiefly of H and C combined), and the liquid is then drawn up by cap- illary attraction into the wick. Here the great heat changes the liquid tallow into the gaseous state (with decomposition into various hydro- carbons). Flame is burning gas. The flame is hollow, as no O can penetrate to its center, and the hol- low is filled with the unburnt gases. (These may be drawn away by a Fig-. 27. fine glass tube and burned at its end, if the candle is a large one.) In floating outward, the C from the decom- posed hydrocarbons becomes white hot and gives out light, but soon meets the O of the air and becomes C O 2 at the instant it ceases to give light. Outside is a faintly blue cone, cup-shaped at the bottom and composed of burning H (and C O). If a cold piece of glass or porcelain is in- 70 CHEMICAL PRIMER. troduced into the flame, the C is lowered below the ignit- ing point and i:s deposited as smut. The H. 2 O (steam) is condensed and deposited also. We notice this condensed steam upon the cold chimney when the lamp is first lighted, but it evaporates as the chimney becomes hot. Illuminating gas is made from bituminous coal by heating in retorts and collecting volatile hydrocarbons in a holder. It contains various gases, H, C O, C H 4 (marsh gas, "fire damp" of miners), C 2 H 4 (olefi- ant gas, ethylene), C 6 H S (vapor of benzol), etc., and (before purifica- tion) others that must be removed, as H 3 N, C 2 , H.jS (and other sul- phur compounds), besides vapor of "tar." Tar is a very complex sub stance, from which the aniline dyes, carbolic acid, etc., are obtained. H 3 N may be removed by passing through water (or H Cl, old method), C O 2 by passing through "pans" of lime (Ca O), and the sulphur com- pounds by passing over ferric hydrate. The last reaction may be rep- resented thus: Fe., 6 H fcnic hydrate hydrogen sulphide = 2 Fe 2 H O ferrous hydrate 2H 2 free sulphur >f Gas Meter. On exposure to the air, ferrous hydrate becomes ferric hydrate, and the material may be repeatedly used till the free sulphur forms from 40 to 50 per cent. The tar vapor condenses and runs into the "tar well." The refuse (coke) is left behind in the retorts. The purified gas is measured by the meter and passes into the holder, from which it is distributed to con- sumers. Illuminating gas is also made from crude petroleum, more big. 23. Secti m The three arrows represent the rota- tion of the chambers; the solitary arrow the escape of the gas from chamber, complex machinery being used. Gas enters through the U-shaped center. Blinsen's Burner is represented in Fig. 21 and is used when heat, not light, is wanted. The gas is mixed with the air, drawn in through openings at the side. The flame is condensed, is much hotter, and does not smut cold glass. CARBON. 71 EXP. 62. Heat in ex- treme tip of blowpipe flame the end of a clean copper wire. It turns black, i. c., is oxidized, forming Cu 0. Heat in the midst of flame nearer the blowpipe. The Cu is reduced (deoxi- dized) and the bright me- tallic copper appears. By means of the blowpipe we may do two things, oxidize most metals (a very small portion is sufficient for tests) and reduce their oxides. At A (Fig. 29) a substance may be oxidized, because here we have an excess of thrown forward from the blowpipe and highly heated. The flame in the center at B is reducing, for here there is an excess of highly heated carbon. The reducing flame is best produced by holding the noz- zle of blowpipe a very short distance from the flame instead of in it. The blowpipe is a very valuable instrument in the analysis of oreSj EXP. 63. Two inches above a gas burner hold a fine wire gauze and ignite jet of gas above the gauze, It burns above, but not below. The wire being a good conductor of heat reduces the gas below the igniting point, and the flame cannot pass through the gauze Davy's Safety Lamp used by miners is essentially a lamp surrounded by a wire gauze. The flame cannot pass through this to ignite the "fire-damp" (C H 4 marsh gas). This dangerous gas explodes vio- lently when mixed with air and ignited, EXP. 64- Into a flask put a small quan tity of oxalic acid crystals and cover with strong sulphuric acid. Heat gently and pass gases through wash bottle containing strong solution of K H 0. Collect over water. / S H 2 C A = H 2 + C O 2 -f- C O Fig. 30. Wash Bottle, 72 CHEMICAL PRIMER. The sulphuric acid absorbs H^O from the oxalic acid, breaking up the molecule. The K H O solution absorbs the C 0. 2 , becoming K 2 C 3 (and H 2 O), and the C is collected in receiver. Test by lighted taper. It burns with bluish flame, Carbon monoxide C O (carbonoits oxide, old name car- bonic oxide) is a colorless poisonous gas formed by burn- ing C in a close atmosphere. Escaping from hot stoves through the pores of the iron into ill-ventilated rooms, it causes headache. In large quantities it speedily produces coma and death. Its pale, lambent flame is frequently seen when fresh hard coal is placed upon the grate, NOTE. Organic chemistry may be considered as carbon continual The previous rules for writing formulas and names, which hold so gen erally in inorganic chemistry, fail in numberless instances to meet the requirements of organic chemistry, as we shall see. Notice that the order of C H and is usually used in organic chemistry instead of H C and 0. (See marsh gas, vapor of benzol, etc., above, and also ORGANIC CHEMISTRY. ) CHAPTER XXII. BINARY ACID- AND SALT-FORMERS FLUORINE, CHLORINE, BROMINE, IODINE, AND CYANOGEN. EXP. 65. Into a small flask on a sand-bath, put equal weights of common salt and manganese dioxide, well mixed. Add sufficient water to make thin paste. Pour in through funnel a small quantity of sul phuric acid (commercial) and collect gas in large test-tube over hot water, or by displacement of air in deep receivers. Heat should ^e applied to flask to di'ive off the last (and greater portion) of the gas. A double reaction takes place: (1) H. 2 SO 4 + 2NaCl = Na,S 4 + 2 H Cl / (2) Mn0 2 + 4HC1 = Mn Cl a + 2 H,0 -f- Cl, BINARY ACID- AND SALT- FORMERS. 73 The gas may be freed from H Cl by passing through wash bottle (see Fig. 30) of cold water. It may be dried, if desired, by passing through strong H 2 S 4 in the same manner, and then collected by displacement of air. Caution. Care should be taken not to breathe (except in minute beautiful reddish-purple flame. (Caution. EXP. 65.) (l)-Hg2CN Hg + (CN) 2 (2) C N + 2 C 2 + N Cyanogen (C N or Cy) is a colorless, pungent, inflam- mable gas with strong ^^each-blossom odor. As the mol- ecule of hydrogen has been represented thus | H H | , so the molecule of free cyanogen may be represented thus | ON (JN | or C 2 N 2 . It is interesting as being the first "compound radical" isolated. It forms binary salts, several of which are very important. The intensely poisonous "prussic" acid (hydro-cyanic acid, H C N) may be formed by the action of sulphuric acid on potassium cyanide. (Do not perform the experiment.) 2KCN + H 2 S0 4 K 2 S0 4 + 2HCN Prussic acid is used in medicine. Many patent medicines claiming to be preparations from cherry bark are essentially nothing but very dilute solutions of hydro-cyanic acid. Potassium cyanide is one of the most important of the cyanides. It is very poisonous. MISCELLANEOUS QUESTIONS. 1. Reactions in making 0? 2. How many litres of can be made from 150 grams of K Cl 3 ? [NOTE. A litre of H weighs .0896 grams (at and barometer 760 mm), and a litre of weighs 16 times as nmch, a litre of N 14 times as much, etc., according to the atomic weight of the gas. To find the weight of compound gases, multiply the weight of H ly one-half the molecular wight of the gas. Ex. A litre of C 2 weighs 22 times .0896 gins.] 3. Tell what you know about O (ten lines). 4. Give experiments proving the character (properties) of O. 5. Reaction in making H? 6. How many litres of H could be made by using 5 grams of Zn? 7. How many grams of Zn must be used to make 15 litres of H? f UNIVERSITY or SULPHUR AND PHOSPHORUS. 79 8. Give properties of H and prove by detailing experiments. 9. What is a deliquescent salt? An efflorescent salt? 10. How was N obtained? 11. Give the composition of air, 12. What was proved by the "ammonia fountain"? 13. What is "aqua regia"? and why so called? 14. What is meant by "nascent" hydrogen? 15,, Give experiment proving that C is a good decolorizing agent. 16. Give experiment showing that fresh burned C is good "disinfect- ant '' 17. How may C O 2 be made? 18. Fifty litres of C 2 could be made by using what quantity (grams) of MgCO 3 ? 19. Detail three experiments under carbonic oxide. 20. Animals and the higher orders of plants differ with respect to use of C 2 and 0. How? 21. Write 5 lines about chlorine, saying the most possible. 22. How is glass etched ? Copper and iron ? 23. What is cyanogen? Why is it treated in the chapter on chlorine, bromine, etc., rather than under nitrogen or carbon? CHAPTER XXIII. SULPHUR AND PHOSPHORUS. Sulphur is found free (native) in volcanic regions. It is found combined in cinnabar (Hg S), iron pyrites (Fe S. iron disulphide), galena (Pb S), blende (Zn S), etc. It is contained in most animal tissues and especially in the perspiration and hair, also in many vegetables, especially in those that are strong-smelling. CHEMICAL PRIMER, EXP. 88. Drop a well-cleaned silver coin upon yolk of egg and leave over night. It is blackened. Eggs contain sulphur and so tarnish silver spoons, black silver sulphide (Ag 2 S) being formed, EXP. 89. Into a strong solution of lead acetate introduce white horse-hairs, and heat to hasten reaction. They turn dark. Many "hair dyes" contain salts of lead. The metal unites with S of the hair, forming black Pb S. Such hair dyes are highly injurious, Sulphur exists in several allotropic (physically different) states, among which are (1) the crystallized, (2) the common uncrystallized ("amor- phous"), and (3) the plastic (viscid, also uncrystallized). EXP. 90. Heat a small quantity of sulphur for about five minutes, 01 till the thin, light-colored melted mass, after becoming dark and thick, becomes thin again. Pour by thin stream into cold water. Plastic S results. This form is unstable and becomes brittle in a day or two, as may be proved by examining specimen the next morning, EXP. 91. In a small glass tube closed at one end (by fusing tip in flame of Bunsen's burner) place small piece of iron pyrites (Fe S 2 ) and heat slowly so as not to crack the fused end of tube. Part of the sulphur sublimes and condenses on cold part of the tube. = Fe 3 S 4 + S 2 Fig. 32. 3FeS, NOTE. A substance sublimes when, on applying heat, it rises as a vapor and condenses as a solid. A substance distills when it rises as a vapor and condenses as a liquid. S may be obtained from iron pyrites by "roasting" the ore and condensing the S. The principal supply, how- ever, comes from the volcanic regions of Italy. (See EXP. 93.) EXP. 92. Repeat EXP. 4, placing in the bottle a red rose, is slowly bleached. The rose SULPHUR AND PHOSPHORUS. 81 Sulphur dioxide is used in bleaching silk, straw, and woolen goods, which would be injured (turned yellow) by chlorine. Colorless compounds are formed by the union of the S O 2 with the coloring matter, but the reaction is too complex to be written out. 8 O 2 is also an antiseptic. S burned in a vessel pre- vents the fermentation of the liquid (as new cider) after- wards put in. Like all strong antiseptics it is poisonous. EXP. 93. Burn S in a large, clean flask and pass into it H 2 S. (See EXP. 8. ) Let stand a few hours the bottom and sides of the flask are covered with a thin white coat of sulphur. [S looks white when in thin deposit. ] S0 2 -f 2H 2 S = S 3 + 2H 2 This illustrates the formation of native sulphur in vol- canic regions, as volcanic gases contain S O 2 and H 2 S. EXP. 94. Burn S as in EXP. 4, and quickly stir with glass rod, upon the end of which is twine wet with strong H X O 3 . (Nitrates are good oxidizing ctgents, we have learned.) The S O 2 takes O from the nitric acid, becoming S 3 sulphuric oxide (anhydride). Shake up with water. SO, -f- H 2 = H,S 4 (dilute) Test water with barium chloride, the test of sulphuric acid (and solu- ble sulphates). H 2 S 4 -f Ba Cl, = Ba S 4 + 2 H Cl white precipitate Sulphuric acid ("oil of vitriol") is a colorless (if pure) oily liquid (sp. gr. 1.84). It is the most important of the acids, and is used in preparing numberless other sub- stances, especially acids. The experiment illustrates its preparation. 82 CHEMICAL PRIMER. S O 2 from burning sulphur is carried into large leaden chambers, whose floors are covered with water. Into these air and nitric acid fumes are admitted. The N.,0 2 from the nitric acid acts as a carrier of O from the air to the S 2 . (See EXP. 38.) 2S0 2 + NA = 2SO a + N 2 2 / the air The dilute acid is evaporated in leaden pans, till it begins to attack the lead. (Commercial H 2 S 4 contains Pb S O 4 , which falls as white precipitate when the acid is diluted.) It is then removed and concen trated in glans or platinum stills. EXP. 95. Into a beaker containing water pour twice its volume of strong H 2 S 4 . Great heat is developed. EXP. 96. Upon white sugar (C 12 H 22 O n ) (starch or wood C 6 H 10 O 5 ) pour strong sulphuric acid. It chars by removing the elements of water, leaving the black carbon free. Evaporate dilute H 2 S 4 upon white paper. As the acid increases in strength, the paper chars. Concentrated sulphuric acid has a great affinity for water. It is used for drying gases with which it does not react. Care must be taken in diluting the acid, to mix in a vessel that will stand the heat. (In dilating heavy liquids, pour the liquid into the water, not water into the liquid.) "Fuming sulphuric acid" is a solution of S O, H in H 2 S 4 . EXP. 97. Into a solution (slightly acidulated with H Cl) of salts of lead, copper, bismuth, mercury (ic). arsenicum, antimony, and tin respectively in test-tubes, put solution of H 2 S. Reaction by change of partners throws down sulphides. Pb S black, Cu S black, Bi 2 S 3 black, Hg S white, yellow, reddish-brown, and finally black, As 2 S 3 lemon yellow, Sb 2 S 3 orange, Sn S brownish-black, Sn S 2 yellow. Hydrogen sulphide (H 2 S "sulphuretted hydrogen") is much used in the laboratory to precipitate metals, as sul- phides. (See ANALYTICAL CHARTS.) H 2 S is readily in- flammable, as may be shown by igniting in test-tube. SULPHUR AND PHOSPHORUS. 83 NOTE. Hydrogen sulphide has a slight acid reaction and was called by the old chemists hydrosuipfutrie acid. It unites with many of the bases to form sulphides, and these sulphides might be classed as binary salts. For reasons which need not be explained here, chemists do not novv class sulphides in this way, but consider them as analogous to oxides. Carbon disulphide (0 S,), a volatile, colorless, inflam- mable liquid, may be produced by passing sulphur over red-hot coals. It is an excellent soh'ent, dissolving readily S, P, I, and many organic substances. It refracts light powerfully, and hence is often used in filling prisms. The impure disulphide (its heavy vapor) is used to poison squirrels, insects, etc. The rare element, selenium, in many respects resembles sulphur. We have the compounds H 2 Se, Se 2 , H. 2 Se 4 , etc. (See SULPH- AND SELEN-SALTS.) Phosphorus is a semi-transparent, nearly colorless, wax-like solid. It is kept under water in "sticks," as it slowly oxidizes in the air and takes fire at a very low temperature. It is highly po'sonous. Its vapor breathed (in more than minuto quantities) produces ulceration of the jaw, cured with difficulty. (See CAUTION, EXP. 24.) Another variety, red or amorphous, is known. This differs widely from ordinary P. It does not emit the "jaw-poisoning fumes" and can be safely handled. P in this "allotropic" stats maybe prepared by heating ordinary phosphorus in a closed vessel. Part of the P used in making N (Exp. 35) is changed into the red variety. Phosphorus, because of its low igniting point, is largely used in the manufacture of matches. The wood of the match is first dipped in melted sulphur, then into paste of P, potassium nitrate (or chlorate) for an oxidizing 84 CHEMICAL PRIMER. agent and glue (varnish). The P is kindling for the S, the S for the wood (hydrocarbon), while the nitrate fur- nishes the O for rapid combustion. The reactions in burning a match are: P. + 5 =: P,0 5 ; S + O, .: S0 2 ; H 2 + O : H 2 O; C + O 2 ^ CO.. "Safety Matches" contain no P, and ignite readily only when the chemicals of the match are rubbed on a surface of red phosphorus (and powdered glass to increase friction). Phosphorus glows in the dark (its best test). (See APPENDIX.) Such glowing without heat is called phosphorescence, but not by any means is all so-called "phosphorescence" produced by phosphorus. EXP. 98. Into a test-tube half full of water drop several very small pieces of P. Cover P with fine crystals of K Cl 3 (oxidizing agent). By means of a pipette (glass tube) take up a little strong H 2 S 4 , and, introducing the tube into the water as deep as the K Cl 3 (Fig. 33), open, letting the strong acid upon the chlorate. The P burns be- neath the water. A combustible element burns if raised to the igniting point in presence of free oxygen, or of uti oxidizing agent. (In this case C1 2 4 from the reaction. ) Fig. 33. Calcium phosphate (Ca 3 2 P 4 ) forms fully one-half by weight of bones, and is the source of P. "Superphosphate of lime" is a peculiar acid phosphate of calcium (Ca H 4 2 P 4 ), BORON AND SILICON. 85 CHAPTBR XXIV. BORON AND SILICON. Boron may be obtained from boron oxide B. 2 S as a brown powder, and also in yellowish- brown crystals. Boracif acid, or boric acid (H 3 B O 3 ), is found in the lagoons of the volcanic regions of Tuscany. Jets of steam containing the acid issue from the earth and are absorbed by the water. This is afterward ^vaporated by heat from the jets, leaving the crystallized acid. Boracic acid is also made from borax. EXP. 99. Upon copper (or iron) wire covered with a coating of the black oxide, melt a borax bead. The melted borax dissolves the oxide, leaving the bright "metallic" copper (or iron). Borax (sodium tetraborate, Na, B 4 O 7 , 10H 2 O) is used in welding and soldering, because when melted it dissolves the oxide of the metal, leaving the surfaces bright. (See HARD WATER.) EXP. 100. Dissolve boracic acid (or borax previously moistened by drop of dilute sulphuric acid, to liberate boracic acid] in a little alcohol (C 2 H 5 H 0) and ignite. The flame has a peculiar green tint. This is a good test for the presence of a borate. EXP. 101. Dissolve copper oxide in borax bead in oxidizing flame of the blowpipe. Color yreen when hot, Uue when cold. Change to reduc- ing flame, color, reddish-yellow. Dissolve Mn 2 , intense reddish-violet in oxidizing flame, in reducing flame almost colorless. (See BLOWPIPE, APPENDIX.) Borax is largely used in blowpipe analysis as a "flux." Silicon is, next to O, the most abundant element, though, unlike O, it is always found combined (not free or native). The larger part of the earth's crust is silicon 86 CHEMICAL PRIMER. oxide (Si O 2 silica, white sand, quartz), or silicates. Many precious stones (amethyst, agate, etc.) are quartz col- ored with some metallic oxide. Sili- cates of K and Na, absorbed by roots, give by deposit of silica thj stiffness and shining- surface to corn-stocks and the edge of ' sword grass" Quartz veins often "carr" more or less free Fig. 34.-Quartz Crystal. Petrifaction is the replacement of wood by stone (sil- ica). Silica and certain silicates are soluble in water con- taining alkaline (K, Na, H 4 N) carbonates. As fast as the wood placed in the water decays, the silica is depos- ited, and copies very precisely the lines of the wood (knots, grain, etc.). Glass is a mixture of several silicates (as is also porce- lain). Crown or plate glass (common window glass) is chiefly calcium and sodium silicates. Ca hardens and gives luster. Na makes fusible, but gives greenish tint. Bohemian glass is chiefly calcium and potassium sili- cates. Potassium gives no color. Flint glass is chiefly K and Pb silicates. This can be ground into imitation gems, prisms, etc. When very rich in lead it is known as "paste." EXP. 102. Into a piece of soft glass fuse cobalt oxide (CoO), the piece is colored a deep blue. Glass is colored any desired tint by fusing with a small quantity of some metallic oxide. "Purple of Cassius" (which see) is used for the finer ruby red; cuprous oxide slso colors red; cupric, chromium, and ferrous oxides give cjreen; cobalt oxide gives blue, arsenous oxide the white, soft enamel of lamp shades; manganese oxide violet, etc. Glass is annealed by being cooled very gradually for days. When cooled quickly, it is very brittle. Lamp BORON AND SILICON. 87 chimneys break from sudden change of temperature, Because not properly annealed. Glass is etched by hydrofluoric acid as we have seen in EXP. 86. Pure clay (kaolin, china clay, H a A1 2 Si 2 O 8 + H 2 O) under the influence of heat forms a hard, porous solid. Pure feldspar (K 2 Na 2 A1 2 Si 6 O 16 ) when heated fuses to a colorless glass. ]f china clay and ground feldspar are heated together, the fused feldspar penetrates the porous, infusible clay, producing a hard, translucent, lustrous mass porcelain. Besides the many well-known uses of porcelain, it is employed in the laboratory, as it resists the action of acids and is quite refractory. Stoneware differs from porcelain in opacity, due to the fact that the fused, feldspathic glass does not penetrate the entire porous mass of clay. In common earthenware a poorer clay is used. The glaz- ing is done by throwing common salt (Na 01) into the kiln when the burning is nearly complete. The salt volatilizes and chemical reactions produce sodium aluminum silicate, giving a glassy surface. Common pottery ware ("brown earthen") is made of the most impure forms of clay, usually colored reddish- brown with ferric and other oxides. It is often glazed with "lead" by mixing lead oxide or galena (Pb S) with the clay. Silicates (or silica) are most excellent substances to ''make hills of," because of their insolubility and hard- ness. Evidently the earth's crust could not l>e made of sol- uble matter, nor could there be firm continents if the crust were made of soft material. 88 CHEMICAL PRIMER. XXV. ARSENICUM, ANTIMONY, AND CHROMIUM. Arseuicum (sp. gr. 5.7) is a brittle, steel-gray solid (semi-metal), generally found in combination. Two sul- phides, yellow, As.,S 3 (arsenous sulphide, orpiment) and red As 2 S 2 (realgar), occur native. Caution. Care must be taken in experimenting with arsenicum, as itself and its compounds are violently poisonous. Use very small quan- tities in all experiments; especially avoid breathing H 3 As. (See ANTI- DOTES. ) EXP. 103. Place in a small glass tube, closed at one end "white arse- nic" (As 2 O 3 arsenous oxide " ratsbane") of the bulk of a pin's head. Hold inclined and heat very gradually (more perfect crystals are formed than by rapid heating). The "arsenic" sublimes and condenses in minute, octahedral crystals in the upper and colder part of the tube. (Examine crystals with a lens.) EXP. 104. Perform EXP. 103 in a closed, drawn-out tube (Fig. 35), plac- ing above the arsenous oxide (anhy- dride) powdered charcoal, and first raising the charcoal to low red heat. A dark mirror-like ring of arsenicum condenses upon the tube above, and a garlic odor is distinctly perceived. 35> [If heating is too rapid the carbon is thrown up by draft. Though not so sharply defined, the arsenicum minor, in case of this accident, is readily distinguished from the char- coal.] ARSENICUM, ANTIMONY, AND CHROMIUM. 89 X 2AsA + C 3 - 3C0 2 + As 4 EXP. 105. Boil a few decigrams of "white arsenic'' in water. AsA + 3 H,0 = 2 H 3 As 3 avid-forming water hydrogen oxide <>r arsenite .anhydride (acid) Filter and preserve filtrate as a sample of an arsenite. (Of course this may be considered a solution of arsenous oxide in water. (See EXP. 11.) EXP. 106. Place a little of As A of the bulk of a pin's head in ten drops of strong H N 3 , and, having raised to the boiling point, evapo- rate over water-bath nearly to dryness." Dilute with water, filter and preserve as an example of an arsenate. 1. As A + 2 As A arsenous from nitrif arsenic oxide acid, an oxide oxidizing a-ent 2. As 2 5 + 3 H,0 = 2 H 3 As 4 acid-forming water acid oxide EXP. 107. To copper sulphate solution (5 per cent.) add H 4 N H O till the precipitate formed is partially but not wholly dissolved. Filter, divide filtrate into two portions. To the first add drop by drop an arsen/te, a yrwii precipitate of acid copper arsenite (H Cu As 3 , "Scheele's Green," Paris green, etc., used as a pigment) falls. To the second portion add a few drops of an arsen^te, an acid copper arsenate (H Cu As 4 ) bluish-green, falls. (See ACID-SALTS.) EXP. 108.- To silver nitrate solution (2| per cent.) add H 4 N H till precipitate is partially but not wholly dissolved. Filter, divide filtrate into two portions and proceed as in Exp. 107; from first portion yellow silver arsenite (Ag 3 As0 3 ) falls; from the second portion a beautiful rhocolate silver arsenate (Ag 3 As OJ falls. Add ammonium hydrate (or other moderately strong alkaline solution), each of the precipitates dis- solve. By the last experiment an arsenite may be readily dis- tinguished from an arsenate. The pupil may learn here that the chemist in analysis depends largely upon the color of precipitates and solubility (or insolubility) in various reagents. (See EXPS. 109 and 111.) Arsenic acid is used in preparing aniline red (for dyeing), and other arsenates (especially Na a As 4 ) are used in calico printing. 90 CHEMICAL PRIMER, EXP. 109. Into a small flask prepared with safety-funnel as in Fig. 30, ; ml containing Zn, pour dilute H.jS 0^ and cfter air is expel'cd ignite as with philosopher's lamp. P ur through the fun- nel a few drops of arsenical solution (nte or ite). The color of the flame changes and the cold dish is smutted with arsenicum. (Just as a candle-flame smuts a cold dish with C. The arsenicum of the H 3 As is lowered below the igniting point, while the hydrogen is not. ) Upon the mirror-like spot um chloride solution (or of hot Fig. 36. place a drop of strong nitric acid), it dissolves, unlike the antimo- nialspot. (See EXP. 111.) (1) Zn -f H. 2 S O, = Zn S 4 -f H 2 )-H + As "nascent'' hydrogen = H 3 As inflanunablt g-as (3) 2 H 3 As 6 = 3H 2 from air As 2 3 If a cold test-tube be placed over without touching the arsenical flame, octahedral and characteristic crystals of As 2 3 and moisture condense upon its sides. NOTE. Don't breathe the gas H 3 As. The experiment should lie per- formed under a gas chimney or near a window with outward draft. If a small test-tube (without safety-funnel) is taken instead of the flask, if but two or three drops of As 2 3 solution is used and the apparatus held at arm's length, the experiment is a perfectly safe one even in a closed room. This is stated so explicitly because a few teachers are overcautious and omit many experiments, while on the other hand a few are culpably careless. This last experiment is Marsh's test for " arsenic " (any compound of arsenicum). Of course in all tests the chemist must first make sure that his materials are pure, or at least free from the substance he is searching for in the unknown liquid or material. (See MAGNESIUM.) Arsenicum (and its compounds) is a powerful antisep- tic. Bodies of those poisoned with it are sometimes pre- ARSENICUM, ANTIMONY, AND CHROMIUM. 91 served from putrefaction for years. In small doses it stimulates and causes persons to grow fat. It is said to beautify the complexion, but its use is a very dangerous practice. All the symptoms of arsenical poisoning- appear, if one ceases the practice. It is a singular fact that in a certain district of Hungary the peasants habit- ually eat "arsenic." Antimony (sp. gr. 6.7) is a brittle, highly crystalline solid (semi-metal), with brilliant luster. Upon the surface of its bluish-white masses are usually fern-like crystalli- zations. EXP. 110. Into an acidulated (H Cl) dilute solution of antimony (tirtar emetic, K Sb C 4 H 4 6 , potassium "antimonyl" tartrate) pass H 2 S gas (or its solution). Sb. 2 S 3 , antimonous sulphide, orange-yellow, falls. Filter, dry, and heat carefully; it turns grayish-black. Native unt imoiioiis sulphide (gray antimony, or antimony glance) is the source of the Sb of commerce. EXP. 111. Perform EXP. 109, using antimonial solution instead of arsenical. Dark antimony spots are obtained. Upon one place solu- tion of calcium chloride, it is unaffected: upon another place a drop of hot nitric acid, it is oxidized (turned white, Sb-jOs), but not dissolved. (See Remarks, EXP. 108.) Antimony is a constituent of several important alloys, as type metal, etc. (See ALLOYS.) An alloy is a mechanical mixture of two or more metals (including semi-metals). If one of the metals is mercury, the alloy is called an amalgam. A mechanical mixture differs from a chemical compound in that it may contain its constituents in any proportions, but a chemi- cal compound must contain each constituent in some one proportion, or multiple of that proportion. 92 CHEMICAL PRIMER. Chromium (sp. gr. 4.8) is a silver-white metal (considered a metal, though ordinarily negative to H). (Let the student learn right here that the order of elements in Table No. 1 is the usual order. Rarely an element takes a different position when obtained by electrolysis under different circumstances, or from different compounds. ) Chromium makes both acid-forming (Cr 3 ) and basic (Cr 2 O 3 ) oxides with corresponding acid (H 2 Cr 4 chromic acid) and base (Cr 2 6 H 0) respectively. The principal ore of chromium is "chromic iron ore" (Fe Cr 2 4 ). A few of its compounds are extensively used in the arts, viz. : potassium chromate (K 2 Cr0 4 ), potassium bichromate (di-) (K 2 Cr 2 7 ),and lead chro- mate (Pb Cr OJ "chrome yellow." (See ANA. CHARTS.) CHAPTKR XXVI. GOLD AND PLATINUM. NOTE. With this chapter we begin the study of the metals proper. In general, a metal is an elementary substance (1) with a peculiar luster, called metallic, (2) insoluble in water, (3) a good conductor of heat and electricity, (4) positive, with reference to hydrogen, and (5) uniting with H and to form bases. Chemists are not, however, agreed as to any precise definition, and the line between metals and non-metals cannot be sharply drawn. This is the case with terms used in all sciences (except in the exact sciences, included in the general term mathematics). No line can be drawn between soluble and insoluble substances, for one kind fades gradually into the other. For ex inple, Pb is considered insoluble, but traces of the metal may be found in dis- tilled water that has been in a leaden dish for a day or two. It oxid- izes and dissolves. No line can be definitely drawn between "hot" substances and "cold" ones, but the terms are relative. The same is true of poisonous and non-poisonous substances. In the arts an alloy of two or more metals is often spoken of as "the metal," but this is a technical and loose use of the term. GOLD AND PLATINUM. 93 For uses of the metals, reduction of their ores, etc., see fuller accounts in the cyclopaedia and in larger works on chemistry. See also APPENDIX. Gold (sp. gr. 19.3, fusing point 1,100) is found native (free), frequently alloyed with silver, in quartz veins, allu- vial deposits ("placers"), etc. It is obtained by (1) quartz mining, (2) placer mining, and (3) hydraulic mining. EXP. 112. Dissolve a piece of gold-leaf in globule of Hg. Place the amalgam on hard glass and in window with outward draft; keep at dull red heat for a little time. Hg distills leaving the gold. Mercury is used to extract gold from the sands or from pulverized quartz. The amalgam of Au and Hg is then submitted to pressure in "bags," which squeezes out much of the Hg. The remainder is driven off by distillation, but the Hg is saved, not thrown away as in. the experi- ment. Gold is a very brilliant orange-yellow solid, the most ductile and malleable of the metals (280,000 sheets of the finest gold-leaf make only one inch in thickness). It was known as the "king of metals," and together with plati- num and silver (also rare meta's of platinum group) is called a noble metal. The others in contrast are called base metals. It is insoluble in any of the common acids, but dissolves in "aqua regia," chlorine-water, or bro- mine-water. Pure gold is too soft for jewelry, coin, etc., and is hardened by cop- per. A carat is ~^. An alloy containing i~ pure gold is said to be gold of 16 carats tine. Aurous cyanide (Au C N) dissolved in solution of K C N is used in electro-gilding. The clean substance to be plated is hung upon the neg- ative pole of the battery and gold upon the positive pole. 94 CHEMICAL PRIMER. Platinum (sp. gr. 21.5, fus. pt. 2,000) is found native, usually alloyed ("platinum ore") with iron, copper, or some of the rare metals (palladium used to color "salmon" bronze, rhodium, iridium used to tip gold pens, ruthe- nium and osmium) of the platinum group. Like gold, it is insoluble in any one of the common acids, but dis- solves in chlorine- water, and slowly in aqua regia (H Cl -{- H N O 3 ). Its "ore" is worked by means of the oxy-hydrogen blowpipe, coal gas being usually used in place of H. Platinum because of its high fusing point and its insolubility in most liquids is to the chemist an exceedingly useful metal. From it he makes crucibles, stills (see ELS 4 ), wire, blowpipe tips, etc. CHAPTER XXVII. SILVER, MERCURY, AND LEAD. Silver (sp.gr. 10.5, fu;i. pt. 1,040) is found native, often alloyed with copper, mercury, and gold. Ag 2 S (mixed with other sulphides, as galena, Pb S) and Ag Cl ("horn silver") are among its chief ores. EXP. 113. Repeat Exr. 6 and place the resulting Ag Cl, mixed with a little K 2 C O 3 (or Na. 2 C 3 ) upon charcoal and heat in reducing flame of the blowpipe. A silver globule ("button") is obtained. (1)-K,C0 3 + 2AgCl = Ag,C0 3 + 2KC1 / (2)-Ag. 2 C0 3 = Ag,0 + CO. (3)-2Ag,0 + C = Ag 4 + C0 2 deoxidizing agent SILVER, MERCURY, AND LEAD. 95 The melted globule absorbs oxygen from the air, and if cooled quickly the escaping breaks the hardening surface, and the melted ("molten") silver runs out ("spitting" or "sprouting"). Silver is a brilliant white metal. For jewelry, coin, etc., it is hardened with Cu. It is used for silvering mir- rors because it takfs a high polish. It is not acted upon by fused caustic alkalies (K H O, Na H O, etc.), as glass and platinum are, and hence certain chemical vessels are made from the metal. It expands at the moment of solid- ification and hence can be cast (copies fine lines of the mould). Silver is obtained from the sulphide by (1) roasting the pulverized ore with salt, Ag a .S + 2 Na Cl 2 Ag Cl -f Na 2 S, and (2) by placing the Ag Cl in a cylinder with H 2 0, Hg and Fe scraps, 2 Ag Cl + Fe = Fe C1 2 -f- Ag. 2 . The Hg forms an amalgam with silver from which the Ag is obtained, as gold is obtained from gold amalgam. The process of EXP. 113 is too expensive for the practical miner, though used by the assayer. Silver may be freed from lead by fusing the alloy, and as Pb crys- tallizes first it may be skimmed out. This leaves a portion of the Pb, which may be completely extracted by cupellation. (A cupel is a shallow dish made of bone ashes. ) The Ag containing Pb and other impurities is placed in the cupel and raised to the red heat. A hot cur- rent of air plays upon the fused mass. The Pb is oxidized and the Pb O is absorbed by the cupel. After a while the refiner sees the mirror-like globule of pure silver and quickly removes it, lest it also oxidize and waste. Silver nitrate (Ag N O 3 , lunar caustic) is the most important salt of silver. It forms with organic compounds by the action of light a very stable, dark compound, and hence is used in indelible inks* Hair dyes sometimes contain it, but these are highly injurious. The changes which the salts of silver undergo when exposed to light, especially in presence of organic matter, is the basis of photogra- phy. (See EXP. 6, NOTE.) EXP. 114. Borrow an old "negative" from a photographer, and upon a sheet of prepared paper (moistened with silver salt and dried in the 96 CHEMICAL PRIMER. dark) furnished by him, print by means of a few moments' exposure to direct sunlight, a photograph. After removal and a few hours' exposure (even to reflected light), the picture fades out, because the entire paper turns black. The photographer applies reagents to dissolve from the unblackened portion the silver salt, and thus preserves the picture. In preparing the negative he first covers the glass with an organic film (collodion) to receive the silver salts. (Hold a lens up between the window and a sheet of paper. The lens converges the rays of light and forms an in- verted image of the window upon the paper. This explains the forma- tion of the "negative" in the dark "camera.") After the formation of the image, he treats the slide (glass) with reagents whose action upon the part previously influenced by the light is different from their action upon the part uninfluenced by the light. The silver salts upon the un- blackened portion are dissolved and the blackened portion is "fixed" so that his picture does not fade out like ours. But the simple princi- ple of photography should be learned here, not the art. (See APPENDIX. ) A solution of Ag C N in solution of K C N is used in electroplating. The clean substance to be plated is hung upon the negative pole, and silver upon the positive. Mercury or "quicksilver" (sp. gr. 13.5, fus. pt., i. e., freezing point 39.4) is found native in small quantities, but its chief source is the ore cinnabar (Hg S mercuric sulphide) from which the liquid metal is obtained by mix- ing with iron turnings (or lime) and distilling. HgS + Fe = FeS + Hg When Hg S is prepared artificially (by "subliming" together S and Hg) it is called vermilion and is used as a pigment. Mercury is largely used in making thermometers, ba- rometers, etc., for collecting gases soluble in water (see FIG. 24), for extracting go'd and silver from their ores, for silvering mirrors (tin amalgam), and formerly was much more used in medicine than now. SILVER, MERCURY, AND LEAD. 97 "Blue pill" is Hg "rubbed up" with confection of roses till the globules are not visible to the naked eye. Blue ointment is mercury "rubbed up" with lard. EXP. 115. Pour a little dilute nitric acid upon a considerable quan- tity of Hg, and, bringing to boiling point, leave over night; pour off from the excess of Hg and preserve as solution of mercuroMS nitrate (Hg, 2 X O 3 ). Dissolve a small globule of Hg completely in an excess of hot, strong nitric acid. Evaporate nearly to dryness, dilute and pre- serve ; s solution of mercuric nitrate (Hg 2 N O 3 ). (Of course these salts may be obtained dry by evaporation over a water- bath. ) EXP. 116. To a solution of mercurous nitrate add H Cl. Hg./2N0 3 -f- 2HC1 = Hg. 2 Cl, -f 2 H N 3 white precipitate Mercurous chloride (calomel, Hg 2 Cl 2 ) is an insoluble (in water) white powder. It acts powerfully upon the glandular system (liver, etc.), and in large or long contin- ued doses produces salivation (excessive action of the sal- ivary glands) and other serious results. It was formerly used in medicine much more than now, by some almost as a "cure all." EXP. 117. To a solution of mercuric nitrate add H Cl. Hg 2 N 3 + 2 H Cl = Hg Cl, + 2 H N 3 There is no precipitate because Hg C1 2 is soluble. Place one drop of the solution on clean glass and evaporate at lo>r heat. White crystals of Hg C1 2 are obtained. Mercuric chloride (Hg Cl a corrosive sublimate) is a powerful poison and a strong antiseptic. It is used to prevent the decay of wood, and its dilute solution in alco- hol brushed over specimens in Natural History preserves them. (See ANTIDOTES.) 98 CHEMICAL PRIMER. Lead (sp. gr. 11.4, fus. pt. 334) is rarely found free. Its chief ore is lead sulphide (Pb S, galena), often carrying Ag. 2 S. The roasting ("smelting") of this ore and separa- tion of the metal is a very simple process. Pb is soft and malleable, and when fresh cut has a lustrous bluish -gray color, quickly dulled by oxidation. Its common uses are well known to every school-boy. It contracts in solidify- ing, and hence will not make accurate castings (i. e., will not copy the fine lines of the mould). EXP. 118. Make two moulds by boring conical cavities into plaster of Paris (Ca S O 4 , 2 H^ 0) and making fine, clean-cut grooves on the sides. Into one pour pure melted lead. Into the other pour melted lead, in which a little Sb and Sn has been previously dissolved (type metal). The first casting is blunt and does not copy the grooves; the second is sharp, pointed, and copies the grooves accurately. This is caused by expansion of the crystalline Sb and Sn in solidifying. [Sb alone may be used as well.] Water used for drinking purposes should not be brought great distances in lead pipes (unless the water contains considerable quantities of phosphates, carbonates, or sul- phates, which coat the lead with white coat), and water that has stood over night in the short lead pipe connect- ing with faucet should be allowed to run out before drink- ing. Water containing even minute quantities (and otherwise practically harmless) of ammoniacal salts (from decomposition of organic matter) dissolves lead and keeps the surface bright. Chronic lead poisoning is produced by drinking such water. Lead is an ''accumulative" poison, i. e., it remains in the system and is thrown off with difficulty. Painters are often attacked by "colic" produced by lead poisoning. Fruit cans should not be soldered with an alloy of Pb. (See Ex P. \'2() and connection.) Metallic Pb is not poisonous because of its insolubil- ity. (Plumbers are not attacked by "lead colic.") SILVER, MERCURY, AND LEAD. 99 Litharge (Pb 0) (see KXP. 50) "red lead" (Pb s 4 ) " sugar of lead" (lead acetate Ph2C 2 H ;1 O i ). and "white lead " chiefly (PbC0 3 but containing a little Pb 2 H 0) used in painting, are important com- pounds. All are poisonous, especially the very soluok acetate. (See ANTIDOTES, also EXP. 12.) White lead is made as represented in Fig. 37. A roll of lead (B) is placed in an earthen vessel, and below, weak vinegar (A). Above (and around) is packed decaying tan- bark (C) and refuse. These vessels are arranged in immense piles; the heat of the decomposition assists the evaporation of the vinegar, and in five or six weeks the lead is all converted into Pb C O 3 . Fife'. 37. Pb -f- O H C a HA = from vinegar Pb H C 2 H,0, luisic salt C O. 2 + Pb H O C. 2 H 3 O, = Pb C 3 from decomposing basic lead "white refuse acetate lead" (see basic salts) unites with another portion of Pb White lead is often largely adulterated with gypsum (CaS 4 2 H 2 0) heavy spar (Ba S 4 ), etc. Pure Pb C O 3 dissolves completely in hot dilute H N O 3 , and the adulteration is easily detected. EXP. 119. Add a little mucilage to lead acetate solution (sympathetic ink) and write with line hand a few words. Dry; they are invisible. Moisten the paper and allow H 2 8 gas to come in contact with it. The letters become black. (See EXP. 9.) H 2 S is a test for lead, and, vice versa, lead acetate (paper moistened with it) is a test for H 2 8. "A fjody acted upon characteristically by a reagent is (is yood a text for tlo' ri'ayent < the reofjent is for it.'' Attfield. (See test in ANA. CHARTS.) 100 CHEMICAL PRIMER. CHAPTER XXVIII. Cu, Fe, Zn, and Sn. Copper (sp. gr. 8.9, fus. pt. 1,200) is found free in large masses (Lake Superior mines). Its most common ore is copper pyrites (Fe Cu S 2 ), from which it is obtained by roasting with a silicate, or with silica (Si O.J, to remove the iron as iron silicate, and again roasting the Cu S. It is a reddish metal, highly malleable and ductile. With the exception of Ag it is the best conductor of heat and electricity. Brass, bronze, and bell -metal contain Cu. (See ALLOYS.) The salts of copper are poisonous. (See ANTIDOTES.) Substances containing acids (fruits, jellies, pickles, etc.) should never be put in copper (or brass) utensils. Fats dissolve copper oxide, and therefore should be put into copper dishes only when the vessels are bright. Copper sulphate ("blue vitriol," "blue stone'' Cu S O t 5 H 2 O) is used in calico printing and in galvanic batteries. (See EXP. 34.) The native malachite (Cu C O 3 + Cu 2 H O) takes a high polish and is used for jewelry and other ornamental articles. Verdigris is copper acetate (Cu 2 (\H S O 2 ) though the name is often applied to the artificial carbonate. CM, Fe, Zn, and Sn. 101 Iron (sp. gr. 7.8, fus. pt. 1,000 to 1,800) is the most important of all the metals. It is rarely found free (always found free in aerolites) but in combination it is widely distributed, traces being found in the blood of ani- mals and in the juices of plants. It is a soft, silver- white metal (if pure). Among the most important of its numerous ores are Fe., O 3 ("specular iron" hematite) Fe. 2 6 H O + Fe, O 3 (brown hematite, limonite) Fe 3 O 4 ("magnetic iron"), and Fe C O 3 (spathic iron, ferrous car- bonate). The value of the ore depends as much upon the nature of its impurities as upon the percentage of iron. The old process of reduction ("Direct Process") was to roast the ore with charcoal in an open "forge" fire. The pasty mass of reduced iron, called "bloom" separates from the fused silicates (or fused glass), called "slag." The modern process ("Indirect") consists of two parts, (1) obtaining the reduced iron from the ore, not pure, but containing a large percent- age if C. (This is cast iron, or "pig iron.") (2) The production of iron nearly free from C ("wrought iron") from the cast iron. 1. The ore is placed in a "blast furnace" with layers of coal, coke, and "flux" [the last, limestone Ca C O 3 , if impurities are silicates (clayey), and silicates, if the impurities are calcareous. Of course, the object is to form a "slag" of calcium glass]. Hot air is driven in below. The heat of the furnace is intense and its action continuous. The "life" of the furnace fire is often twenty years, fresh material being ceaselessly supplied from above. The melted iron and "slag" (floating on iron) is drawn off below. [The hot C 2 and unburnt gases passing from chimney are utilized for heating the air driven in below.] The iron runs into a large main, called "sow," and thence into lateral moulds called "pigs" (hence "pig iron"). 2. Pig iron (2 to "> per cent, of C) is changed to wrought iron (less than i per cent, of C) by burning out the C (also 8, Si, and P) in a reverberatory furnace, "puddling furnace" (Fig. 38). Fuel burns upon the grate A; pig iron is placed upon the floor B, and is frequently stirred by means of openings in the side. 102 CHEMICAL PRIMER. Steel contains more C than wrought iron and less than cast iron. It may be made by heating bars of wrought iron to redness in contact with powdered charcoal for eight or ten days. This is called the cementatl n process. Bessemer steel is made by decarbonizing the best pig iron (free from phosphorus and sulphur) at a fearful heat in an egg-shaped vessel (' converter") lined with infusible material. Hot air is driven in below through numerous openings by means of a powerful engine. Si is also re- moved. "Looking-glass" iron containing a known quan- tity of C and a little Mn is then added. Bessemer 's proc- ess is a rapid one. Bessemer steel is largely used in constructing railroads, bridges, etc. Steel expands at the moment of solidification and there- fore can be cast. Few metals besides iron can be welded. (To be welded a metal must soften before melting.) Cast iron cannot be welded. Iron (or its salts) is largely used in medicine as a tonic. readily distinguished from gold by heating and ol>serving the odor of S O^ and also the change in color. (See Exi'. !)1.) Cu, Fe, Zn, and Sn. 103 Zinc (sp. gr. 6.9, fus. pt. 410) very rarely occurs native. Its chief ores are Zn O 3 (smithsonite), Zn S (zinc blende), and Zn O ("red zinc ore" colored red by an oxide of Mn). It is a bluish-white crystalline metal. Fe dipped in melted Zn is coated with the metal and forms what is termed galvanized iron. Water that has stood a long time in zinc-lined vessels (tanks) is unfit to drink. Zn () (zinc white) is used as paint. (See ALLOYS.) Tin (sp. gr. 7.3, fus. pt. 230) is obtained from its prin- cipal ore Sn O., (tin dioxide, stannic oxide, "tin stone") by roasting with carbon in reverberatory furnace. It is a lustrous, white, highly crystalline metal, malleable and ductile. When a bar of tin is bent, a crackling sound ("tin cry"), caused by the friction among the crystals, is heard. "Tinware" is really iron ware coated with Sn (by dipping the iron into melted tin). When the tin wears off', the iron rust (Fe/J 3 , or hydrated Fe. 2 6 H O) is seen. Tin is often adulterated with (the cheaper) lead. Fruit con- tained in cans coated wi;h such "tin" is unfit to eat, for it contains poisonous lead salts. Solder for such cans should contain no lead. Pb is easily detected by EXP. 120. Upon a piece of "tin" (tinned iron) place a drop of H N O 3 and evaporate to dryness. Add a drop of K I solution, yellow Pb I 2 is formed if lead is present. [Try the experiment with a piece of "tin"' upon which a minute piece of lead has been melted, forming alloy.] Pb 2 N 3 + 2 K I = 2 K N 3 + Pb I 2 yellow Pins made of brass wire, copper utensils, iron tacks, etc., are often covered witli a thin coat of tin to give bright surface. Tin is largely used in making alloys (which see). Tin disulphide (.Sn S. 2 ), a bright golden-yellow, is known as mosaic gold, and is used in decorative painting. Sn C1 2 (stannous chloride) and Sn C1 4 (ic) are largely used in dyeing. 104 CHEMICAL PRIMER. CHAPTBR XXIX. Bi, Co, Ni, Mn, Al, and Mg. Bismuth (sp. gr. 9.8, fus. pt. 264) is a brittle, purplish- white, crystalline metal. It forms alloys with other met- als, expanding much in solidifying and remarkable for their low melting point. EXP. 121. Fuse Bi (5 dcg.), Pb (3 dcg.), and Sn (2 dcg.) togetiier. The alloy is fusible metal (one variety). Place the cold globule in water and raise to the boiling point. Notice that the alloy melts (at 91.6) before the water boils. Fusible metal is used for taking casts of wood cuts, etc. Fusible metal (of different composition and melting at some definite point above 100) is used for "safety plugs" in steam engines. When the tempera- ture approaches a point that would be dangerous, the plugs melt and let the steam escape. Cobalt (sp. gr. 8.6) is a silver- white metal. Its salts (acetate, sul phate, nitrate, chloride) are used for sympathetic ink. (See cyclopaedia". ) EXP. 122. Thicken a solution of cobalt chloride with a little pure mucilage. Write with a fine pen upon paper. The writing is invisible. Heat upon metallic support. The writing is distinctly blue. [Dry Co C1 2 is distinctly blue, but moist Co Cl., has a pale pink color and is invisible when thin spread The salt is deliquescent.] The ink becomes invisible again when the paper cools. Nickel (sp. gr. 8.9) is a lustrous white metal, taking a high polish. It is used for plating iron to protect from rusting. It is largely used in alloys. Bi\ Co, Ni, Mn, Al, and Mg. 105 EXP. 123. Repeat EXP. 122, using cobalt solution, to which nickel chloride has been added. The writing is yreen. [Nickel salts are used to make yreen sympathetic ink.] Manganese (sp. gr. 8, fus. pt. about 1,800) is a hard, brittle metal. It easily oxidizes in the air and hence is not found free. It is best kept under petroleum. Manganese dioxide (Mn 2 , see preparation of O and Cl) is its most important ore. Ma urinates (dyad grouping Mn O 4 ) and permanga- nates (dyad grouping Mn 2 O fc ) are largely used as disinfectants. EXP. 124. Place a small piece of fresh meat in a test-tube of water and leave till putrefaction begins. Filter (through paper) and let fall into it a single drop of dilute potassium permanganate (K.,Mn.,0 8 ). Place beside it a second test-tube of distilled water in which the same amount of permanganate has been put. Leave both over night. The permanganate in the first test-tube is decolorized, having given i;p a part of its O to the decomposed organic matter. In the second the color remains. [The presence of ferrous salts, or other easily oxidizable substances, must be avoided. Water through which the breath has been blown by means of a glass tube answers for the test.] Potassium permanganate is a powerful oxidizing agent and is a very delicate test for the presence of decomposing organic matter. [In such tests be careful not to add too much K 2 Mn. 2 O g , as of course the excess would not be decolorized.] Aluminum (or aluminium, sp. gr. 2.6, fus. pt. 700) is a bluish-white metal, taking a bright polish. Next to sili- con and oxygen it is the most abundant element in the earth's crust. It does not readily oxidize in the air. Delicate, light weights, and. in general, instruments need- ing lightness and moderate strength are made from alum- inum. 106 CHEMICAL PRIMER. Aluminum bronze (Cu 00 per cent., Al 10 per cent.) is a very hard alloy, malleable, has the color of gold, and takes a fine polish. Aluminum oxide (AL,0 ;i ) occurs in corundum, ruby, sapphire, and emery (impure). Common clay is chiefly aluminum silicate, Al 2 Si 2 7 (there are numerous silicate "groupings"), but no rh<'>:p method of obtaining the metal has yet been discovered. Al would be extensively used were it not for its high price. (See GLASS and PORCELAIX.) Common alum is a double sulphate (A1. 2 K 2 4 S 4 , 24 H 2 0) contain- ing much water of crystallization. Ammonium alum [A1 2 (H 4 N) 2 4 S 4 , 24 H. 2 0] is also somewhat common. Alum is much used as a "mor- dant" in dyeing. (See DYEINU.) Cryolite is Al, F e + Na F. . Magnesium (sp. gr. 1.75, fus pt. about 2,000, but ignit- ing point is low, the flame of a candle being sufficient to set it on fire) is a silver- white metal not found native, but in combination is widely distributed. Mg burns in the air with a brilliant light (Exp. 3), forming Mg () ("mag- nesia"). [In general, the ending a means (1) the oxide, (2) the carbonate, or (3) the hydrate of the metal.] The light from burning Mg is rich in chemical (actinic) rays, and hence is used for photographing in dark caves, etc. Arsenicum is never found with r, and the metal is used instead of Zn in important tests for As. (See Marsh's test.) Mg C1. 2 is found in sea water. Mg S 4 , 7 H., (Epsom salt) is found in many mineral waters and in sea water. '"Magnesia alba" is an arti- ficial mixture of Mg C 3 and Mg 2 H 0, principally the former. (See magnesite, hornblende, meerschaum, soapstone, talc, serpentine, dolo- mite, etc. , in cyclopaedia. ) CALCIUM, STRONTIUM, AND BARIUM. 107 CHAPTER XXX. CALCIUM, STRONTIUM, AND BARIUM. Calcium (sp. gr. 1.58) is a light-yellow, ductile metal. It oxidizes in inoist air and consequently is not found native (free). Its compounds are widely diffused. Calcium oxide (Ca O, quicklime, a basic oxide, EXP. 5) is prepared by heating the native carbonate (Ca C O 3 ) in egg-shaped "kilns" till C O 2 is all expelled. A kiln in which the process is continuous is shown in Fig. 39. / Reaction: Ca C O 3 =-- Ca O + C O, Mixed with sand, hair, etc., according to the purpose for which it is intended, calcium oxide is used for making mortar, cements, etc. The principal reactions are: (1) Ca O + H 2 = = Ca 2 H O 'water-slacked I la When exposed to the air, this absorbs C O 2 and hardens. (2) Ca i> H O + C O, = Ca C O, + H 2 O from "air-slacked evaporates air lime" 108 CHEMICAL PRIMER. i.w. 39. Afire. C ash-pit. Calcium. car- bonate U put in at t' ; of furnace and calcium oxide removed at B. Hydraulic mortars possess the power of hardening under water. These are made from quicklime that has been prepared from cal- cium carbonate containing a large percentage of silicates. Roman cement is made from calcium oxide containing from 25 to 35 per cent, of clay arid hardens under water in a few hours. Chalk and clay thoroughly ground together with water, dried, and carefully burnt in kilns, produce an impure quick- lime from which a good hydraulic mortar, called Portland cement, is made. The hardening of these mortars, like those above, depends upon the formation of calcium carbonate. Ca falls to a ponder when gradually air-slacked by exposure. It first absorbs water and then C 2 as in above reactions. Ca O is used in the laboratory for drying gases (Exps. 45, 56, and illuminating gas) and in the "lime light" (see APPENDIX), the flame of the oxy-hydrogen blowpipe raising it to the white heat and causing it to emit an intense light. Calcium carbonate (Ca C O 8 ) is found as marble, lime- stone, shells (chalk is formed by beds of tiny shells), sta- lactites, etc., also with Ca s 2 P O 4 in bones. (See HARD WATER and EXP. 51.) Calcium sulphate (Ca S O 4 , anhydrite) and calcium sul- phate with W((ter of crystallization (Ca S O 4 , 2 H 2 O gypsum, plaster, alabaster) occur native. When heated to 120, gypsum parts with its water of crystallization, forming "plaster of Paris." This plaster soon hardens ("sets") when mixed with water and hence is used as cement, and for taking casts. (See WATER permanently hard.) CALCIUM, STRONTIUM, AND BARIUM. 109 Calcium chloride (Ca C1 2 ) has so strong an attraction for water that it is deliquescent. It is used for drying gases and is a constituent of bleaching powder (which see). Calcium fluoride (Ca F 2 , fluor spar) occurs native and is used as a flux in the reduction of metals. The peculiar glowing of this mineral when heated gave rise to the term fluorescence. Hydrofluoric acid is prepared from this salt by the action of sulphuric acid. (See EXP. 86.) Barium (sp. gr. 4) and Strontium (sp. gr. 2.5) resem- ble calcium. Fig. 40. EXP. 125. Dissolve a barium salt in a little dilute H Cl. Make a loop upon one end of a short plat- inum wire and fuse upon the other end a piece of glass tubing for a handle. Introduce into the lower and outer flame of Bunsen's burner (Fig. 40) by means of this loop a little of Ba salt solution. The flame is colored yrccn. [Ba CL dis- solved in water answers.] Barium salts (especially Ba 2 N O 3 ) are used to give the color in green fire (in pyrotechny) and this color is a very good test for soluble or volatilizable salts of Ba. Barium sulphate (Ba S 4 , heavy spar) is often used to adulterate white lead (Pb C O 3 ). Barium chloride (Ba C1 2 ) is test for soluble sul- phates. (Exp. 94.) EXP. 126. Repeat EXP. 125, using Sr salt instead of Ba salt, flame is colored rl. The Strontium salts are used to give the color in red fire, and this color is a very good test for soluble or volatiliza- ble salts of Sr. 110 CHEMICAL PRIMER. CHARTER POTASSIUM, SODIUM, AMMONIUM. Potassium (sp. gr. .87, f us. pt. 03) is a light, bluish- white metal, soft enough (at 15) to be spread with a knife. Ex P. 127. Cut a small slice of K upon blotting paper. Trim away the edges and. throw the cleaned piece upon water in a beaker. Cover with glass plate (impurities cause spattering). The K decomposes the water. / K + H 2 O = K H -f H The reaction is so violent that the liber- ated hydrogen takes fire, and in burning the heat volatilizes a little of the K. which in burning colors the flame purple. The affinity of potassium for (.) is so great that it must be kept under naptha (C 10 H ltJ containing no O). EXP. 1 '17 proves that it cannot bo found free or native. The compounds of K are widely distributed. They are constituents of all plants and of the bodies of animals. Potassium hydrate (K H O "caustic potash") is a white solid made from K, C O 3 by action of Ca2H (and heat). K 2 C0 3 + Ca2HO = 2KHO -f Ca C O 3 It is largely used in the manufacture of soap. It is one of the strong- est alkalies known. (See SOAP and ANTIDOTES. ) POTASSIUM, SODIUM, AMMONIUM. Ill Potassium carbonate (K 2 C 3 "pearlash") is prepared by leaching wood ashes, evaporating the "lye" in large pots (hence potash), and purifying by crystallization. It is a deliquescent salt, with a strong alkaline reaction. It (or Na 2 C O 3 ) is largely used in chemical analysis. [See ANA. CHARTS, silver, lead, etc.] It reacts with insoluble silicates by change of partners. The metallic . . the metallic .,. potassium potassium . silicate = r .,. 4- carbonate ,. i i i v carbonate silicate t~ \ -\& \ (insoluble) (soluble) "Saleratiis" (H K C 3 bicarbonate of potash, acid salt with alkaline reaction, see ACID-SALTS) may be prepared by passing C 2 through strong solution of the normal salt (K. 2 C O 3 ). H. 2 + C0 2 = H,C0 3 K, C0 3 + H 2 C0 3 = 2HKC0 3 Potassium nitrate (K N O 3 saltpetre, nitre) together with Ca 2 N O 3 and Na N O 3 , is formed by the decom- position of refuse organic matter. The white incrustation often seen about such matter is principally K N O 3 . It is a strong antiseptic, and is used with Na Cl (common salt) for preserving meat. It is largely used in the man- ufacture of gunpowder. When gunpowder burns, the reaction may be represented thus: 2 K N 3 + S + C, = K. 2 S + N 2 ' + 3 C O 2 solid solid solid gas at gas gas oxidizing combustible combustible temperature age t substance substance <>f explosion Fireworks are composed of gunpowder containing an excess of C and S with coloring matter. Potassium chlorate (K Cl O 3 ) is largely used for making oxygen and as an oxidizing agent. (Exp. 19, 79, 98, and MATCHES.) It is much used in medicine to allay inflammation of the throat (as gargle), etc. K. 2 Cr. 2 7 forms chrome yellow with lead salts. (ANA. CHARTS.) The intensely poisonous K C N (solution) dissolves gold and silver cyanides for electroplating. 112 CHEMICAL PRIMER. K Cl resembles Na Cl. Potassium salts are largely used in medicine. EXP. 128. Repeat EXP. 125, using potassium salt instead of barium salt. The flame is colored purplish. This is a fair test for potassium compounds. Careful flame tests are of great value t > the experienced chemist. (See SPECTROSCOPE.) -. 42. Decomposing Water by Sodium. Sodium (sp. gr. .97) is a light, silver- white, soft metal, resembling potassium. It is used as a reducing agent in preparing silicon, bo- ron, magnesium, and aluminum. EXP. 129. Place a small clean piece of Na on water and quickly press below mouth of inverted test-tube by means of wire gauze at- tached to wooden rod. The water is decomposed and the H, set free, collects in test-tube. (If Na is thrown on hot water the liberated H immediately takes fire.) Na + H 2 = NaHO + H The above experiment proves that sodium cannot be found free. Like potassium, it must be kept under naptha. EXP. 130. Repeat EXP. 12"), using sodium salt instead of barium salt. The flame is colored yellow. Sodium chloride (Na Cl, common salt) is the most abundant of the sodium compounds. It is the source from which most compounds and sodium itself are obtained. Its distribution in larger or smaller quantities is almost universal, traces which the spectroscope reveals being found in the atmosphere. It is obtained from immense POTASSIUM, SODIUM, AMMONIUM. 113 deposits or beds, from saline springs and sea-water (by evaporation). It crystallizes in cubes. (See CRYSTAL- LIZATION.) It is one of our most common antiseptics. Sodium sulphate (Na 2 S 4 10 H 2 0, Glauber's salts) is remarkably efflorescent. Sodium carbonate (Na 2 C O 3 10 H 2 O, sal soda) is ex- tensively used in the arts. It is made by Leblanc's process : (1) Common salt and sulphuric acid are heated. / 2 Na Cl + H 2 S O 4 Na ? S O 4 + 2 H Cl The hydrochloric acid is saved by being absorbed (see EXP. 75, and comments) in tower of coke wet with con- stantly falling water. (2) The Na, S O 4 is heated with Ca C O 3 (equal wt.) and C (half its wt.) in a reverberatory furnace. (a) Na 2 S 4 + C 2 = Na,S + 2 C O, reducing agent (b) Na 2 S + CaC0 3 Na 2 C O 3 + Ca S insoluble "black ash" The Na 2 C O 3 is then washed out (lixiviated) from the " black ash" and purified by crystallization (one of the most valuable known means of purifying crystallizable solids). Acid sodium Cat ftonate (H Na C 3 , bicarbonate of soda, "soda" of cook-room, see ACID-SALTS) has alkaline reaction, and is prepared by passing C 0_. into the normal salt (see H K C 3 ). Sodium hydrate (Na H 0, caustic soda) is made from sodium car- bonate (just as K H O from K 2 C O 3 ) and is used in the manufacture of hard soap. Sodium nitrate (Na N 3 , Chilian saltpeter) is a deliquescent salt. 8 114 CHEMICAL PRIMER. Ammonium (H 4 N, a hypothetical metal), as we have seen, is a compound radical, closely allied to K and Na. Though it has never been isolated, an alloy of ammonium and mercury (i. e., an amalgam) has been formed. Ammonium chloride (H 4 N Cl, sal ammoniac) is used in medicine, in dyeing, in soldering, and in the laboratory as a reagent and source of ammonia (H 3 N, see EXP. 45). Ammonium nitrate (Exp. 36) and ammonium carbonate (see ANTI- DOTES) are important salts. Microcosmic salt (H Na H 4 N P 4 -f- 4 H 2 0, see DOUBLE SALTS) is largely used in blowpipe analysis as a flux. Ammonia hydrate (H 4 N H O "ammonia water") is a very strong base and is extensively used (dilute) as a cleansing agent. (See CHEMISTRY OF CLEANING.) CHAPTER XXXII. ORGANIC CHEMISTRY. STARCH, SUGAR, ETC. Organic chemistry treats of those compounds (composed principally of C, H, N, and O, but all containing C and H) which are formed chiefly by animals or plants in their processes of growth or partial decay. No line can be sharply drawn between organic compounds and inorganic. Many compounds which formerly were supposed to be produced only by the "vital force" of the plant or animal, have been formed recently in the laboratory. STARCH. 115 NOTE. It is important to remember that we may make two great divisions of "organic substances": I. That which is the essential physical basis of life (bioplasm). II. That which is essential only in a secondary sense and is used by the first in accomplishing its work somewhat as an engine uses fuel, water, and the iron rails. To this second division belong crystalline substances, fats, gelatine, cellulose, etc. Between the inorganic and this first division of the organic, a distinct line can be drawn. This line bounds all possibilities of the laboratory. It is probably within the province of chemistry to produce, unaided by the "vital force," all substances in this second division. The organic cell proper, with its subtle bioplasm, chemists can never hope to form. For example, the chemist's kernel of wheat will never grow. (See SPONTANEOUS GENERATION*^ cyclopaedia.) As a rule, inorganic substances have few atoms in the molecule, while molecules of organic substances frequently contain a very large number of atoms. Often different organic substances contain the same elements in the same proportion. This peculiar relation is called isomerism* EXAMPLE. Butyric acid and ethyl acetate, tw r o well-known compounds, differing in essential properties, are isomeric, having the "empirical formula" (expressing only the proportions of the elements): C 4 H 8 O 2 , but the "rational formula" (which attempts to represents some way the arrange- ment oi the atoms in the molecule) of Butyric acid = H C 4 H 7 2 . (RfiF. TABLE No. 2, Continued.) Ethyl acetate = C,H 5 C 2 H 3 2 . (Rfir. TABLE No. 2.) Plants in general prepare food for animals from the mineral kingdom, and animals, after using it, return it to the mineral kingdom again. The organic by complete decay returns to the inorganic. The sun's light and heat (Exp. 58) is the motive power by which the plant is ena- bled to build up the organic out of the inorganic. Starch (C 6 H 10 O 5 ) is a substance found in all cereals, in many roots, stems, and fruits. It is composed of grains, which the microscope reveals differing in size and shape in different plants. These grains swell up and burst on 116 CHEMICAL PRIMER. heating with water. Its use for food, in the laundry, etc., is well known. Arrow-root and tapioca are varieties of starch from roots of tropical plants. Sago is starch from the pith of the sago-palm. The test of starch is iodine, with which it forms a blue compound. (Exr. 84.) EXP. 131. Scrape some potato into cold water and squeeze through a linen cloth several times. The insoluble starch remains suspended in the filtrate, while the woody fiber (cellulose) remains upon the filter. After subsidence, pour off the water, and dry. This illustrates the method of obtaining starch from the potato. When starch is heated to about 205, it changes into an isomeric com- pound, dextrin, much used instead of gum arabic in making adhesive stamps. Dextrin is also formed if starch is boiled with water slightly acidulated with sulphuric acid. If the boiling is continued longer, the dextrin is converted into starch-sugar (C 6 H 12 6 ). Dextrin gives no blue color with iodine. Gum arable (C 12 H 22 U ) exudes from a species of acacia. Pectose is a gummy substance found in many fruits and vegetables. Cellulose (C 18 H 30 Oi-,), or woody fiber, is the frame-work of the cells of plants, and is found in every part, even in the pulpy fruits. Linen, made from the inner bark of flax, and cotton the hollow white hairs around the seed of the cotton plant are nearly pure cellulose. (See cyclopaedia.) If paper is dipped in dilute sulphuric acid (2 vols. H 2 S 4 , 1 vol. H 2 O) for a few moments, tough parchment paper results. Gun-cotton is cellulose, in which part of the H has been replaced by the negative radical N 2 , by dipping in a mixture of H N 3 and H 2 S O 4 . It is very explosive. Gun-cotton, dissolved in ether (ethyl oxide) and alcohol (ethyl hydrate) forms collodion, much used by photographers. Celluloid is made chiefly from gun-cotton and camphor, by submitting to great pressure. It can be colored in imitation of coral, made into col- lars and cuffs, and substituted, in general, for ivory. Its manufacture is comparatively a new industry. Cane-sugar, sucrose (C, 2 H, 2 O U ), may be obtained from the sugar-cane, beet-root, maple, and certain kinds of STARCH. 117 palm. In making it from the sugar-cane (1) the canes are crushed, (2) lime (Ca O) is added to the juice to neu- tralize any acid formed by fermentation, (3) the liquid is evaporated to thick syrup, (4) set aside to cool, (5) the sugar crystallizes, forming brown sugar, (6) it is put into perforated casks to drain. The drainings ("mother liq- uor") are molasses. In the process of refining, brown sugar is (I) dissolved, (2) pumped to upper story of the high building, (3) filtered through twilled cotton bags, kept in bath of steam, (4)filtered through animal charcoal (Exp. 48), (5) evapo- rated in "vacuum pans" (kettles from which air and steam are partially removed by pump, so that the syrup boils at a lower temperature and does not burn), and (6) set aside to crystallize. If in moulds, loaf -sugar results; if in cen- trifugal machines, granulated. The drainings are syrup or sugar-house molasses. Caramel is sugar carefully "burnt" so that it loses part, but not all, of its elements of water. It is used for coloring liquors, flavoring confec- tioneries, etc. Cane-sugar is not found in animal tissues or secretions, but is changed in the alimentary canal before absorption into grape sugar. I Medical students xhould master all the tests for grape sugar in the APPEN- DIX..] Grape-sugar (C 6 H r /) 6 ). glucose (dextrose, starch-sugar,fruit-sugar), is found in honey, figs, grapes, and many kinds of fruit. It has much less sweetening power than cane-sugar. EXP. 132.- To a solution of grape-sugar (made by boiling a few raisins in water and filtering) add three drops of copper sulphate (5 per cent, solution and slightly acidulated with acetic acid), then add strong solution of K H O (potash or Na H 0, soda) till the light blue color of liquid becomes darker. Raise to the boiling point, but do not boil beyond a few seconds. A yellowish-red precipitate of cuprows oxide (Cu 2 0) falls. This is a delicate test for sugar in animal secretions (grape-sugar, or milk-sugar isomeric with cane). (See ADD. EXP.) 118 CHEMICAL PRIMER. EXP. 133. Divide a solution of cane-sugar into two parts; apply test as in EXP. 132, no cuprous oxide falls. Slightly acidulate the second portion with H 2 S 4 , and boil to syrup. The cane-sugar changes to grape-sugar. Dilute and apply test. Yellowish-red Cu 2 falls.- Boil for some time a minute quantity of starch in dilute (2 percent.) sulphuric acid. The starch changes to grape-sugar. Divide into two portions and test the first by iodine; no starch is found. Test the second; grape- sugar is found. Boil cellulose (woody fiber free from pitch) in dilute H 2 S O 4 and grape-sugar is found in the solution. The insoluble starch laid up in the seeds of plants is converted into (soluble) sugar by the action of a nitroge- nous substance, called diastse, in the presence of warmth and moisture. The sugar is then absorbed by the grow- ing plantlet, and is built into its structure as woody fiber, etc. Fermentation is a species of decay. A necessary condition is the presence of *>ome nitrogenous ("albumi- nous") substance, called a ferment, and the growth therein of a fungus plant called ^east. This plant is of a low order, and spreads by the rapid multiplication of cells throughout the whole fermenting substance, if it has the needed ivarmth (about 30) and moisture. In the fer- mentation of substances containing grape-sugar (or cane- sugar, which changes to grape-sugar), there are two stages: 1. The Alcoholic Fermentation, in which the sugar breaks up into alcohol and carbon dioxide. CeH^Oe 2C,H 5 HO + 2 C O 2 alcohol ca bo diuxi 2. The Acetic Fermentation, in which, by exposure to the air, the alcohol is oxidized, forming acetic odd and water. C. 2 H 5 HO + O, HC a H 8 O a + H 2 ethyl hydrate from the acetate acid air ALCOHOL, ETC. 119 NOTE. The two reactions above explain thoroughly the principal results of fermentation. It is evident that the second stage can be pre- vented, if the air (oxygen) be excluded from the fermenting material. The first stage cannot be prevented "by bottling," provided there is in the substance sufficient nitrogenous material (fennent), and provided the -ijc.nxt spores have not been killed by boiling or by an antiseptic. The second stage follows the first very rapidly, if the temperature is raised (to about 38, or 100 F). This explains the rapid "souring" of sub- stances in hot weather. The fermentation ("working") in preserves may be checked by boiling and then excluding the air, thus shutting out the i/t'nst spores. Beer, ale, etc., are made from malt (grain that has germinated suf- ficiently to change nearly all the starch to sugar, and in which the fer- mentation has been checked by drying). The malt is crushed, water added, and heat applied to turn starch to sugar. It is then cooled, hops and yeast are added, when the alcoholic fermentation at once commences. Wine is made by the fermentation of grape juice. Jf all the sugar is converted into alcohol and C 2 , dry wine results. If the fermentation ceases (from an excess of sugar over the ferment) when only part of the sugar is changed, sweet wine results. Effervescing wine is sealed in strong bottles while the alcoholic fermentation is going on. In sour wine the acetic stage has somewhat progressed. When any fermented liquor is distilled, the alcohol (having a lower boiling point than water) first passes over through the condenser (Fig. 19), together with certain flavoring substances and a certain part of the water. Brandt/ is made by distillation from wine; rum from fer- mented c .ne-juice; whiiky from fermented corn, rye, or potatoes; gin from fermented barley and rye, and afterwards distilled with juniper- berries (flavoring). Alcohol (C. 2 H 5 H O ethyl hydrate) is the intoxicating principle of all varieties of (unadulterated) "liquors." It is a colorless, volatile, inflammable, poisonous liquid. Its flame, as we have noticed, is hot and smokeless. It is a valuable solvent. Many substances, as resins, etc., insol- uble in water, are soluble in alcohol. A solution of a sub- stance (medicinal) in alcohol is a tincture. (See VOLA- TILE OILS.) Strong alcohol contain > about 10 per cent. 120 CHEMICAL PRIMER. water, all of which cannot be removed by distillation. It may be removed by Ca O, or some other substance which has a great affinity for water, when anhydrous, or abso- lute alcohol, remains. Anhydrous (white) Cu S O 4 (Exp. 34) is test for absolute alcohol. If water is present, the sulphate turns blue. Common alcohol belongs to marsh gas series. Strong alcohol is an antiseptic. Common Ether (C. 2 H 5 ) 2 O, ethyl oxide, is made by dis- tilling alcohol in presence of sulphuric acid. It is a very volatile, inflammable liquid. It produces great "cold" by its evaporation. If blown in a fine spray (from atomizer) upon some part of the body, the rapid cooling produces local anaesthesia by "freezing" (chilling) the spot. It is inhaled as an anaesthetic, and is a valuable solvent. There is a large number of alcohols (hydrates of positive radicals) and corresponding ethers (oxides) arranged in series. Methyl alcohol (C H 3 H 0, wood spirit) is formed by the destructive distillation of wood, and resembles ethyl or common alcohol in many particulars. Amyl alcohol (C 5 H n HO, fusel oil) has a very fetid odor, and is much more poisonous than C. 2 H 5 H O. It is formed in small quantities in the fermentation of potatoes and grain. Its boiling point is 137, while that of ethyl alcohol is only 78. The common alcohol is sepa- rated from it by fractional distillation, a valuable method of separating liquids whose boiling points differ materially. The salts of the positive groupings of the ethers, or alcohols, are often termed "compound ethers" (Ex.: ethyl nitrate, C. 2 H 5 N O 3 , etc.). Many of these "compound ethers" are sold as "essences," and they very closely imi- tato the true essences. Ethyl butyrate (GJB^^HjO,) is sold as "essence of pine-apple." Chloroform (C H CL.) is made by distilling alcohol with "chloride of lime." It is a colorless, volatile liquid, used as an anaesthetic and as a solvent. ALCOHOL, ETC. 121 Chloral (C 2 H C1 3 O), a colorless, oily liquid, is made by passing dry chlorine into alcohol. It combines with water of crystallization, form- ing a white crystalline substance, the so-called chloral hydrate (C 2 H C1 3 O H 2 0). Chloral, when taken, reacts with the alkali of the blood, producing chloroform and inducing sleep. It is much used in medicine . Acetic acid (H C 2 H 3 2 , the acid of vinegar), as we have seen, is pro- duced by the fermentation, under the proper conditions, of substances containing sugar. It is produced in the second stcuje by the oxidation of alcohol. Strong acetic acid crystallizes at 17 and is called glacial. The "mother" of vinegar is a fungus plant; it assists the fermentation by absorbing O from the air and giving it up to oxidize the alcohol. When the alcohol is all gone, however, it works mischief. The vinegar itself is oxidized and destroyed (destructive fermentation). Sulphuric acid and pungent spices are often added to vinegar to increase its strength. One gallon of sulphuric acid in a thousand gallons of vinegar is used to prevent the destructive fermentation. A large quantity of H 2 S 4 , however such as is added by some unscrupulous dealers to make weak vinegar strong is exceedingly injurious. Carbolic acid (C 6 H 5 H O, phenyl hydrate), better classed with the alcohols (of phenyl series), is obtained from coal- tar. It is a very poisonous liquid (it may be obtained crystallized) and is a powerful antiseptic and disinfect- ant. Carbolic acid is sometimes confounded with creosote (C 8 H 1( ,O 2 ), the antiseptic principle of smoke (by which "bacon," etc., is "cured"); indeed, impure carbolic acid is commonly called creosote. (See ANTIDOTES.) Benzol (C 6 H 5 H> phenyl hydride see ILLUMINATING GAS) is a very volatile, inflammable liquid, is a valuable solvent, and is used to remove grease spots from silk and woolen articles. From it, by the action of nitric acid, nitrobenzol (C 6 H 5 N O 2 ), an oily liquid is prepared. By the action of reducing agents upon nitrobenzol the celebrated aniline (C 6 H 7 N), the source of the "coal-tar" dyes, is prepared. (See DYEING.) (For tar, coal-tar, naphtha, benzine, kerosene oil, dead-oil, petroleum, bitumen, etc., see cyclopaedia. ) 122 CHEMICAL PRIMER. There are three great classes of (organic) foods: 1. Starch, sugar, and allied bodies. 2. Oleaginous substances. (See CHAP, xxxiv.) 3. Albuminous substances ("nutritious matter," nitrog- enous matter). Albumen (formula very complex, composed of C, H, N, S, and 0) is found nearly pure in white of eggs. Albuminous matter possesses the power of (1) becoming a ferment, (2) of coagulation, and (3) of putrefac- tion. Casein is found in milk, and is coagulated by rennet (acid); gluten, in flour, meal, etc.; fibrin, in blood, and another variety of fibrin in muscular tissue. (Medical students see ADD. EXP. for teste. ) EXP. 134. Soak a small, clean bone over night in H Cl (30 per cent.). The mineral matters are dissolved, and the soft animal matter left. Wash thoroughly in water and leave in water over night again. Boil the animal matter for some time in a small quantity of water and set aside to cool. A gelatinous substance remains. Gelatin (formula complex; a nitrogenous substance not belonging to albuminous matter proper] is formed by the action of hot water upon animal membranes, tendons, and bones. Glue is very impure gelatin. Isinglass is a very pure gelatin from the air-bladders of fish. (The mineral, mica, used in the doors and sides of parlor stoves, is often im- properly called isinglass.} CHEMISTRY OF COOKING. Flour consists of gluten, starch, and a little dextrin and sugar. The oily and mineral substances are con- tained chiefly in the bran of grain, l^nce "coarse food," as corn meal, graham flour, oatmeal, cracked wheat, etc., are very necessary for the proper development of bone and sinew. In bread-making the flour, mixed with milk (or water) containing yeast, is set in a warm place, and immediately the alcoholic fermentation begins. The carbon dioxide set free is held by the gluten, causing the dough "to rise." This is kneaded, to distribute evenly the fermentation and to break up the large bubbles of C O,. CHEMISTRY OF COOKING. 123 In baking, the C O 2 and alcohol escape. If the oven is too hot, a crust forms too quickly, prevents the escape of the C O 2 , and large cavities are formed. If the fire is not hot enough, the C O 2 escapes before the cells are sufficiently hardened, and the bread falls. Sour bread is formed when, before (or while) baking, the second stage (acetic) of fermentation is reached. The acetic stage follows the alcoholic very rapidly if the temperature of fermentation is high. (See NOTES under FERMENTATION.) A very slow fire in baking may produce the same result. Saleratus (H K C O 3 , or soda H Na C O 3 , acid salts, but these have alkaline reaction), is added to neutralize any acid that may be formed by this second fermentation. In raising biscuit, "soda" and "cream of tartar" (H K C 4 H 4 O 6 ) are used to furnish the C O,, while the salt that remains is a harmless one. Common baking powder is merely "cream of tartar" and "soda," but it is often adulterated with alum, to make inferior nour look white. Bread containing alum is highly injurious, producing chronic constipation. (See test, ADD. EXP.) "Yeast cakes" are made by exposing moistened corn meal (or other similar substance) containing a ferment, to 'moderate temperature till the gluten is in the midst of the alcohol fermentation. The fermentation is then checked by drying. The yeast plant (fungus) throughout the cake may be likened to so much dry seed, which needs only to be sown in the right soil (in the dough). The chemical changes in the body (Physiological Chemistry) are too difficult for insertion in a primary work. 124 CHEMICAL PRIMER. CHAPTER XXXIII. VEGETABLE ACIDS AND BASES (ALKALOIDS). * Compounds of oxalic acid (H 2 C 2 O 4 2 H 2 O), especially K 2 C 2 O 4 , and Ca C. 2 O 4 are found in rhubarb, sorrel, etc. (also a very little of the free acid). The acid is a power- ful poison. It is sold as "salts of lemon" (a dangerous name), to remove ink stains. It used to be very expen- sive, but it is now made on a large scale by heating saw- dust and caustic potash (K H O). (See ANTIDOTES and CHEMISTRY OF CLEANING.) Salts of tartaric acid (H 2 C 4 H 4 O 6 ), also minute quanti- ties of the free acid, exist in many fruits, and especially in the (jrape (as acid potassium tartrate, H K C 4 H 4 O 6 , see ACID-SALTS). It settles during fermentation, forming a crust ("argol," "bitartrate of potash") which, when purified, is cream of tartar (H K C 4 H 4 O fl ). Tartar emetic is a double salt: potassium antimony! tartrate (K Sb~0 CjTTOe). Rochelle salt is K Na C 4 H 4 O 6 . Citric acid (H 3 C 6 H 5 O 7 H 2 O) is the acid of the lemon, lime, etc. Its salts are also present. Malic acid (H 3 C 4 H 3 O 5 ) occurs (together with potassium malate) in most unripe fruits, especially unripe apples. Tannic acid (H 3 C 27 H 19 17 tribasic ?), or tannin, is found in the leaf and bark of most trees and of many shrubs (oak especially, in nut galls, hemlock, etc.), together with a little gallic acid (H a C 7 H 3 O 5 , H 2 O). or THEORY OF TYPES. 125 EXP. 135. To a solution of tannic acid add a solution of gelatin (from EXP. 134); a yellowish-white precipitate of gelatin tannate falls. In the process of tanning, the tannic acid unites with the gelatin of the hide, forming a tough compound (leather). EXP. 136. To a solution of tannic acid add copperas solution. Ink is formed, becoming darker by exposure to the air. (Ous salts of Fe have a tendency to oxidize and form peculiar and, as a rule, less soluble "oxy -salts"). 3FeS0 4 + 2H 3 C 27 H 19 17 = Fe 3 2 C, 7 H 19 1T + 3 H 2 S O 4 copperas taniiic acid INK corrodes pen Leather is blackened by washing one side with solution of iron sulphate, thus covering it with ink. Carbolic acid or corrosive sublimate (Hg C1 2 ), antiseptics, are used to keep ink from moulding. The alkaloids are organic bases (see comments, EXPS. 4< and 5), and they form salts on the ammonia type. Many of them have a bitter taste, are powerful poisons, and valuable medicines. (See ANTIDOTES.) The liquid alkaloids (few) contain C, H, and N, while the solid (nearly all) contain C, H, N, and O. Their salts occur in the plants from which they are obtained. THEORY OF TYPES. The theory of types has done much to advance the science of chemis- try. The pupil, however, must distinguish between theory and fact. The formation of compounds on the water-type is strictly represented thus: I = water NO H < nitric acid in which the negative radical, nitryl (N 0. 2 ), replaces an atom of H in the molecule of water. So: *** I q two molecules of water, S ^ 0^ = sulphuric acid 126 CHEMICAL PRIMER. in which two atoms of H in the water have been replaced by the negative radical sulphury 1, S 2 . The reaction in EXP. 16, written strictly to represent the water- type, becomes: Na| + C 2 H 3 1 xl O = H = ^Ta O + H It is easily seen how the negative radical, usually considered by chemists as the replaceable and replacing quantity in reactions, is obtained from the negative "grouping," viz.: by subtracting one atom of from monad groupings, two from dyad groupings, etc. Negative radicals usually take the termination, yl. Again, binary acids and salts cannot in any strict sense be referred to the water- type as in this book, but must be referred to the hydrochloric acid type. The formation of compounds on the ammonia type is shown in the following formulas, the connecting element being the triad, nitrogen, The examples given are artificial compounds (alkaloids): H | C 6 H 5 H I N ammonia H H H phenyl- C 2 H 5 N amine H (aniline) H N ethyl-amine TT N diethyl-amiiie C 2 H 5 N triethyl-amine If the H of ammonia (one or more atoms) is replaced by a positive radical, an amine results; if by a negative radical, an amide; if a posi- tive and a negative both take part in the replacement, an alkalamide all giving rise to very hard names. The ammonia type should be considered only in this respect by beginners. Ammonia forms salts with the acids, without replacing the hydrogen of the acid. The alkaloids do the same thing. EXAMPLES. H 3 N + H Cl = H 4 N Cl or H 3 N H Cl = chloride of ammonia CeH 7 N + HC1 C 6 H 7 NHG1 chloride of aniline ( chloride or C 17 H 19 N 3 + H Cl = C 17 H 19 N O 3 H Cl, 3 H 2 = \ hydrochlorate water of I o f morphine crystallization v ALKALOIDS, 127 Morphia (C n H 19 N O 3 , H 2 O), or morphine, is the prin cipal alkaloid in opium, the dried juice of the poppy. In small doses it acts as a sedative; in large doses, as a nar- cotic poison. It is combined with meconic acid in the plant as meconate of morphia. A salt of morphia (sul- phate or chloride, usually) is sold at the drug stores as "morphia," and the same is true of many other alkaloids. Laudanum is tincture of opium; paregoric, a camphora- ted tincture, flavored with aromatic s. Many patent con- coctions for "soothing" children contain opium, and are very pernicious. Quinia, or quinine (C. 20 H 24 N,0, 3 H 2 O), is obtained from the bark of the cinchona, a tree found native in Peru. It is largely used in medicine, especially in feverSo It has a bitter taste. In large or long continued doses it is apt to impair the hearing. Aconitia, or aconite (C 54 H 4W N O 2 ), is obtained from aconite leaves and root. It is used in fevers to cause per- spiration (sudorific). It is one of the most violent poisons known. Strychnia, or strychnine (C 21 H 22 N 2 2 ), is the alkaloid in nux vomica (seeds) and the St. Ignatius bean. It is also one of the most poisonous of the alkaloids. It is largely used in medicine as a nervous toniCo It is in- tensely bitter. Atropia (C 17 H 2S N O 3 ) exists in belladonna, or Deadly Nightshade, as malate of atropia. Mcotia, or nicotine (C 10 H U N 2 ), is the volatile liquid alkaloid of the tobacco plant. It is intensely poisonous, but unfortunately, being so volatile, its smoke does not kill. The human system at length becomes tolerant of the presence of the poison, even in the stomach. 128 CHEMICAL PRIMER, As a rule, it stupefies and clouds the intellect, especially of persons not full grown. Those boys who are great smokers rarely take a high standing in their classes. The alkaloids are very numerous, as are also the vegetable acids. For fuller account of each see cyclopaedia, also see ANTIDOTES. [Med- ical students should master the tests in APPENDIX.] CHAPTER XXXIV. OILS, FATS, RESINS, ETC, There are two great classes of oils: Fixed and Volatile (or Essential). Fixed oils cannot be distilled without decomposition into various hydrocarbons, Volatile oils can be readily distilled. Fixed oils are salts (using the term in a wide sense). Hard fat is principally glyceryl stearate ("stearin"), soft fat, glyceryl palmitate ("palmitin"), and liquid fat, glyc- eryl oleate ("olein"). Fixed oils, when boiled with an alkali (K, Na, etc., hydrate), react with the alkali to form a "soap,' 9 and "glycerine." (TABLE No. 2.) EXP. 137. Mix a strong solution of "caustic soda" (Na H 0) with olive oil and boil for about twenty minutes. SNaHO + C 3 H 5 3C 18 H 33 2 = 3 Na C, 8 H 33 2 + C 3 H 5 3 H O sodium glyceryl oleate sodium oleate glyceryl hydrate hydrate (olive oil) (hard soap, because it is (glycerine) not a deli'2.] Coarse scouring agents are easily obtained, but for silver and arti- cles of value, the best polishing agent is, perhaps, precipitated chalk. Five cents' worth of quicklime and ten cents' worth of hydrochloric acid by the process of EXP. 33, will precipitate sufficient to last for a long time. The water used should be filtered, and after quicklime is slacked, the clear lime water should be carefully drawn off by siphon so as to exclude all gritty sediment. After precipitation carefully dry and preserve. Many polishing agents, for a tablespooiiful of which twenty- five cents is asked, are principally, if not entirely, precipitated chalk. Most "tooth powders" are simply precipitated chalk (colored and per- fumed). JP Volatile oils (or Essential oils) are of vegetable origin. They exist in the petals of flowers, in leaves (of mint), in seeds (of carraway), in rind of fruit (of orange, lemon) and in the root (of sassafras). They are usually obtained by distilling with water (passing steam over), from the part of the plant containing them. They do not make soaps. Their 'solution" in alcohol is called an essence. Adulteration with a fixed oil is easily discovered by evap- orating on white paper and noticing that a grease spot is left. ANTIDOTES. 133 Oil of Turpentine (C U ,,H 16 "spirits of turpentine") is obtained from the "pitch" of pines by distillation. It is an excellent solvent, dissolv- ing the resins to form varniahes. A large class of volatile oils are pure hy- dro-carbons, many having the same empirical formula with oil of turpen- tine, though widely different in properties. Of a second class Camphor (C 10 H 16 0) is a type, as oil of bitter almonds, cinnamon, spearmint, etc. These all contain 0. A third class of "strong smelling" volatile oils contain S. Ex: Oil of mustard, horse-radish, onion, etc. A resin is an essential oil oxidized. ("Rosin" is the resin of tur- pentine.) A balsam is an oleo-resin, i. e., a resin dissolved in a vola- tile oil, or a volatile oil partially oxidized. If a balsam is distilled, the essential oil passes over, leaving the lesin behind. Shellac is a resin obtained from lac, the juice of an East India tree. (See APPENDIX.) Amber is a fossil resin. 0m resins are milky exudations from many plants, which afterward solidify in the air. Gutta-percha is obtained from the juice of an East India tree, as is also gum-benzoin, the chief source of benzoic acid (H C 7 H 5 2 ). India-rubber (caoutchouc) is the solidified juice of cer- tain tropical trees. Vulcanized rubber is made by heating the rubber with sulphur (Goodyear's patent). XXXV. ANTIDOTES. When a person is taken suddenly and violently ill after eating some- thing, poisoning may be suspected. By careful attention to this chap- ter it is more than possible that some member of the class may be able to save a human life. A poison is a substance which, if introduced into the animal system, may produce morbid or deadly effects. We give antidotes, either (1) to get rid of t/te poison at once (by means of an emetic, or cathartic a mechanical 134 CHEMICAL PRIMER. antidote), or (2) to hinder it* absorption (as when we give a chemical antidote to form an insoluble compound with the poison see EXP. 12), or (3) to counteract its effect (as when we give stimulants for the poison of serpent bites, for narcotic poisons, etc.). EXP. 138. Shake up thoroughly the white of an egg in a bottle half filled with water and filter. The filtrate is a solution of albumen. Arrange test tubes containing very sliyhtly acid solution of soluble com- pounds of Hg (corrosive sublimate), Cu. Zn, Sn, Fe (copperas) , Ag( ni- trate), [Pb and Ba] respectively. Into each let fall two or three drops of albumen solution. Insoluble compounds of albumen and the metal (formula too complex to be written) are precipitated. [Notice that with Pb and Bi compounds the precipitate does not readily appear and anti- dotes below are to be relied upon.] Albumen (milk, flour and water, and especially raw eggs) is an excellent chemical antidote for most metallic salts. As precipitates are not absolutely insoluble in tfte stomach, they should be immediately removed by an emetic. The best emetic is the common one, "mustard" (a tea- spoonful in a cup of preferably warm water). When- ever poisons are to be removed by an emetic, warm water should be freely drank to rinse out the stomach thor- oughly. Oils (fats, butter, and lard) and mucilaginous drinks (as flaxseed tea) are always beneficial and should be freely given immediately, and for treatment afterward. In general, whatever would be good treatment for a burned, bruised, or injured skin, is good treatment for the mucous membrane of the alimentary canal, burned or irritated by some poison. If silver nitrate or corrosive sublimate are titrony, the antidote must be given within a few seconds, or the poison will have done its worst, and recovery, if it takes place at all, must depend upon after treatment. A ANTIDOTES. rather large dose of a mild cathartic (as castor oil) should be used instead of the emetic whenever solution of either sublimate or nitrate has been taken. The best antidote for silver nitrate is salt and water, as we have inferred from EXP. 6, though albumen is about as good. If the other metallic salts (except, see cyanides below) have been swallowed, especially in the solid state (powder), the antidote may be given later (from ten to twenty minutes) with hope of its doing good. But the danger rapidly increases ivith the lapse of time. Most salts of Zn and Sb (also Cu S 4 ) are fortunately emetics them- selves, but if vomiting does not occur, prompt action must be resorted to. The best antidote for zinc, copper, or iron sulphate is a careful dose of sodium carbonate, "washing soda" (followed by emetic). Zn S O 4 -f Na, C 3 - Na 2 S 4 -f Zii C O 3 insoluble The best antidote for "arsenic" (or Sb) is fresh, moist ferric hydrate, Fe 2 6 H O. It is best precipitated when needed by mixing ferric chlo- ride solution (liquor or tincture) with slight excess of dilute ammonia water. An insoluble ferric arsenate (Fe 2 2 As 4 ) is formed in the stom- ach. Chalk, oil, milk, or mucilaginous drinks may be given to envelop the particles of As 2 3 mechanically, if it has been taken in the solid form; but the thing to be depended upon ordinarily is the emetic, followed by purgative (castor oil). A careful dose of potassium ferrocyanide is a good antidote for copper compounds, as Cu 2 Fe (C N) 6 is insoluble (give emetic). Magnesium sulphate (Epsom salt, EXP. 12) is the best antidote for lead and barium compounds (with emetic'). A careful dose of ammonium carbonate is the best antidote for tin compounds (with emetic). Example: Sn C1 2 + (H 4 N), C O 3 + H 2 == 2 H 4 N Cl -f Sn 2 H O -f- C 2 precipitate The antidote for acids (sulphuric, nitric, hydrochloric, etc.) is magnesium carbonate (see REACTION, CLASS 4), chalk, lime-water, or soapsuds. The antidote must be given within a few seconds if the acids are strong. 136 CHEMICAL PRIMER. For oxalic acid, lime-water (Exp. 15, or chalk) is the best antidote. Prussic acid (K C N) and other cyanides require stimulants, as cold douche to the spine, dilute ammonia water inhaled and ammonium car- bonate given in small doses (see snake poison below). If prussic acid is strong there is no antidote. Give no emetics with acids (unless acid is very dilute), but administer oil (olive) freely. The antidote for alkalies (caustic potash, "lye," caus- tic soda, etc.) is a dilute acid, preferably the most common one vinegar (acetic). KHO -f HC 2 H 3 O 2 KC 2 H 3 2 + H 2 soluble but harmless salt Or tartaric acid, "cream of tartar," citric acid (lemon juice), etc. If these are not at hand and the mineral acids are given, the acid must be very dilute and given sparingly. An overdose would be substituting one poison for another. (For caustic baryta, Ba 2 H 0, or for lead hydrate, see above.) If the caustic alkalies are strong, the antidote must follow in <> ./// seconds, or it will be of no avail. Give no emetic with alkalies. For narcotic poisons (as opium, morphine, cholera medicines, "soothing syrups") and the alkaloids in gen- eral, the emetic is to be relied upon chiefly, though tan- nic acid (strong tea or coffee) may be given, as it forms an insoluble compound with many alkaloids. The narcotic poisons require in addition to the emetic, stimulants (strong coffee, brandy, careful dose of ammonium carbonate) and vigor- ous efforts to keep tJte patient awake. Strong coffee is especially useful in cases of opium poisoning, as it acts as a powerful stimulant to the nerve centers affected by opium. Aconite calls for stimulants. Strychnine re- quires above all the emetic, also the inhalation of chloroform or ether to check spasms. Patient must be kept as quiet as possible. The emetic should be promptly given in case of poisoning by un- healthy iish or meat. Oils should follow (and paregoric in severe I). ANTIDOTES. 137 Phosphorus poisoning requires the emetic and mucilaginous drinks with magnesium hydrate (best precipitated when needed by adding ammonium hydrate to slight excfm of magnesium sulphate solution), followed by large doses of. the cathartic (purgative) castor oil. It is not generally known that "carbolic acid" (re- member that this is not an acid proper, but an alcohol) is a more dangerous poison than strychnine. Strychnine kills "deliberately" and with a smaller dose, but carbolic acid does its work quick. Strychnine gives time (10 to even 30 minutes) to hunt up antidotes, or call a physician ; but if a teaspoonful of strong carbolic acid is taken, usually no remedy will save a life after twenty seconds have elapsed. As it is frequently used in sick rooms for bathing pur- poses (diluted), its well known odor is no protection in such cases. Olive oil (butter, lard, etc.) freely given, fol- lowed by castor oil (cathartic) is its best antidote. Give no emetic. For the bite of poisonous serpents (poison, a powerful sedative), stimulants, as alcoholic liquors, but best of all, ammonium carbonate (a teaspoonful of 10 per cent, solution, which may be carried in a small vial, tightly corked, in the vest pocket) should be taken within a few sec- o/v//.s. The dose of ammonium carbonate should be repeated twice at intervals of ten minutes. If possible, the wound should be immediately cauterized (by nitric acid, caustic potash, or hot wire), or ligature put about the limb above, and the poison sucked out from the wound (the poison is harmless in the stomach). NOTE. The pupil will notice that in most cases of poisoning the emetic is given. He should charge his memory with the few excep- tions, rnvV/x, alkalies (also silver nitrate, corrosive sublimate), and car- Itolic acid, and give emetics in all other cases. To receive poisons into an empty stomach is most dangerous. In a full stomach the poison is diluted and the absorption is slow, so that rapid filling of the stomach with almost any liquid food would be better than nothing. Especially would milk and mucilaginous drinks be useful dilutents, to say nothing of their soothing action. A physician should be called in all cases of serious poisoning to direct the after-treatment. 138 CHEMICAL PRIMER. The following statements about poisons should be care- fully studied and observed at your homes: 1. Poisons should never be left within the reach of children. 2. They should be kept by themselves, apart from non- poisonous medicines. 3. They should be kept plainly labeled, as poison. 4. Any substance in an un labeled bottle should be promptly destroyed. 5. Whenever a poison is bought, its antidote should be bought, placed beside it and plainly labeled (as to the proper dose, if antidote in excess would be injurious). 6. After this last is done it should be remembered that "an ounce of prevention is worth a hundred pounds of cure." MISCELLANEOUS QUESTIONS. 1. Matter exists in what three physical states? 2. The atomic theory divides matter how? 3. Atoms of different elements differ in what three essential respects? 4. Define compound radical, acid, base, salt, precipitate, reagent, filtrate, sand bath, water bath, alkali, sublimation. 5. What is "soda water"? Davy's safety lamp? a deliquescent sub- stance? a condenser? a pipette? oil of vitriol? aqua regia? 6. How much mercury in 150 grams of mercuric sulphide (use tables)? 7. How much lead will be required to make 250 kgs. of lead carbon- ate? How much to make 25 grams of Pb 0? 8. How much silver nitrate was in a solution from which 30 gins, of silver chloride was precipitated ? 9. Write formulas for ferric oxide, cuprous oxide, mercuric nitrate, ferrous sulphide, cupric chloride, aluminum oxide, mercurous iodide, stannic chloride, ferrous sulphate, and ferric sulphate? 10, Reaction when calcium carbonate and citric acid are united. 11. Reaction in making oxygen, hydrogen, carbon dioxide, hydrogen sulphide, hydrochloric acid, and sulphur dioxide. MISCELLANEOUS QUESTIONS. 139 12. How many litres of O can be made from 300 gms. of potassium chlorate? (A litre of H weighs .0896 gms.) 13. If we obtain 500 litres of C 0. 2 , how much calcium carbonate was used? How might the druggist make Cu C 4 H 4 O 6 ? 14. Tell what you know of S 2 (3 lines), of oxygen, of nitrogen. 15. Tell what you know of H 2 S, of H, of C 0,, of Cl, of C N. 16. What is glass? How annealed? How colored? How etched? 17. How might you tell whether or not a white powder was As 2 3 ? 18. Give Match's test for "arsenic." How told from antimony? 19. What is an alloy? an amalgam? metal? "paste" diamonds? 20. What three methods of "mining for gold?" and tell much more about each than you find in this Primer (10 lines). 21. For what is platinum used? phosphorus? borax? mercury? 22. What would you do if you had taken by mistake nitrate of Ag? 23. How would you test for decomposing organic matter? 24. Why can some metals be cast, while others cannot ? 25. What is "white lead," and how made? What is mosaic gold? 26. What is the antidote for lead acetate? barium hydrate? carbolic acid? corrosive sublimate? oxalic acid? phosphorous? 27. Give Bessemer's process for making steel. Leblanc's process for Na 2 C 3 . How would the druggist make calcium citrate? 28. What is "galvanized iron?" "tinware?" quicklime? plaster of Paris? quartz? a "base metal"? an oxidizing agent? 29. What is fusible metal? indelible ink ? gelatin? leather? 30. Difference between water-slacked and air-slacked lime? 31. Give reaction in making soft soap (use TABLE); hard soap. 32. How is brown sugar refined? Name^/zre prominent alkaloids. 33. Reactions in alcoholic and acetic fermentations (C 6 H U 6 sugar). 34. Why is soap wasted when hard water is used in washing? 35. What is a resin? rosin? a balsam? tincture? essence? soap? 36. What would you do if one had taken an overdose of morphine? 37. In what cases of poisoning should no emetic be given? 38. What makes the bread "rise?" Explain fully. 39. Name all the antiseptics mentioned in this book. 40. Name the disinfectants; the anaesthetics; the bleaching agents. HO CHEMICAL PRIMER. APPENDIX, SECTION A. NORMAL SALTS, ACID SALTS, ETC. A normal salt (old name neutral salt) is one which is formed by replacing all the replaceable hydrogen of the acid by a positive element or grouping. EXAMPLE. H 2 C 4 H 4 O 6 = hydrogen tartrate acid. K.; C 4 H 4 6 potassium tartrate = normal salt. NOTE. Hitherto by salts have been meant normal salts. An acid salt is one which is formed by replacing only part of the replaceable hydrogen of the acid by a positive element or grouping. EXAMPLE. H. 2 C 4 H 4 O 6 = hydrogen tartrate acid. Hxr r> u f\ f hydrogen potassium tartrate 1 . -, ,, KC 4 H 4 6 =: I ^ r aefd potassium tartrate / : Acid salts usually turn blue litmus red, but this is by no means universal. In EXP. 39, if one-half as much sodium nitrate be taken, with strong sulphuric acid, an acid salt, instead of a normal salt, results. NaN0 3 + H,S 4 = H Na S 4 + H N O, sodium sulphate APPENDIX. 141 In general, by adding an excess of the acid (which is the same as taking less of the other substance), an acid salt may be obtained. Acid salts, as a rule, react with carbonates like acids, that is, forming a salt (normal), water, and carbon dioxide, as: 2HKC 4 H 4 6 + K 2 C0 3 = 2 K,C 4 H 4 O (! + H,0 + CO, acid salt carbonate normal water carbon salt dioxide A double salt is one which is formed by replacing part or all of the replaceable hydrogen of the acid by two pos- itive elements or groupings. EXAMPLE. H 2 C 4 H 4 O 6 = tartaric acid. K Xa C 4 H 4 potassium sodium tartrate = double salt. ("Rochelle salt") H 3 P 4 = phosphoric acid. H Xa H 4 X P 4 "= hydrogen sodium ammonium phosphate = double salt (microcosmic salt). A double salt may be at the same time an acid salt, like the last. A double salt may be formed by an acid salt of one metal acting 011 the carbonate of the other, thus: / Na,C 0, + 2 H K C 4 H 4 6 - 2 K Na C 4 H 4 O 6 + H 2 + C 0, sodium acid double water carbon carbonate potassium salt dioxide tartrate Acids containing one, two, three, etc., atoms of replaceable hydrogen are said to be respectively monobasic, dibasic, tribasic, etc. H X 3 = monobasic acid. H. 2 S 4 dibasic acid. H 3 P O 4 tribasic acid. H 4 Si 4 -=~- tetrabasic acid. NOTE. A tribasic acid may form two acid salts, as: H 2 Xa P 4 = dihydrogen sodium phosphate = acid salt. H Xa. 2 P 4 = hydrogen disodium phosphate = acid salt. A basic salt is one which may be formed by replacing one or more hydrate groupings of the base by a negative grouping. [This definition is a narrow one, covering most 142 CHEMICAL PRIMER. but not all basic salts. It may be, however, that basic salts are molecular compounds of the hydrate (or oxide) of the metal with the metallic salt, the hydrate uniting after the analogy of water of crystallization.] EXAMPLE. Pb 2 H O = lead hydrate base. Pb H O N O 3 = lead hydro-nitrate = basic salt. A1 2 6 H aluminum hydrate base. A1 2 (H 0) 2 Si 4 aluminum hydro-silicate basic salt. Bi 3 H O = bismuth hydrate base. -D. /T r A > XT A /basic bismuth nitrate, "subnitrate of bismuth," ' \ used largely in medicine. Sulph- and selen-acids and salts. In all formulas for ternaries thus far explained, oxygen has been the last ele- ment. It is supposed to be principally a linking or connect- ing element. Now there are a few other dyad elements that can perform this office of linking, especially sulphur and selenium. To write the form ilia for a sulph- or a selen-acid or salt, the same reference table may be used, only sulphur or selenium, as the case may be, must be substituted atom for atom, in place of oxygen. EXAMPLE. K 2 C 3 = potassium carbonate salt. K 2 C S 3 potassium sulpho-carbonate sulph-salt. Ag 3 As 4 silver arsenate = salt. Ag 3 As S 4 silver sulph-arsenate = sulph-salt. K 3 Sb O 3 potassium antimonite = salt. K 3 SbS 3 potassium selen-antimonite = selen-salt. H 3 As 84 hydrogen sulph-arsenate ~ sulph-acid. NOTE. Instead of sulph-, thio- (Greek thion, sulphur) is used by some chemists, as K 2 C S 3 = potassixim thio-carbonate. The sulph- and seleu-acids and salts are few compared to those con- taining oxygen. APPENDIX. 143 SECTION B. THE ALLOY, SPECTRUM ANALYSIS, AND SYSTEMS OF CRYSTALLIZATION. The most important alloys (with their usual proportions) are: Aluminum Bronze .' Cu (9) Al (1) Bell-metal Cu (9) Sn (2) Brass Cu (2) Zn (1) Bronze Cu (95) Sn (4) Zn (1) Coin (gold) Au (90) Cu (9) Ag (1) Coin (silver) Ag (9) Cu (1> Fusible Metal Bi (see) Pb Sn German Silver Cu (5) Zn (2) M (2) v brass ' Hard Solder '. .' . . .Cu (1) Zn (1) Pewter Sii (4) Pb (1) Phosphor-bronze Cu (88) Sn (10) P (1.5) Pb (.5) Shot Pb (99.5) As (.5) Soft Solder Pb (1) Sn (1) Type-metal Pb (70) Sb (20) Sn (10) The spectroscope, next to the balance, is the most useful instrument for original chemical research. It consists of a prism, mounted upon a stand, carrying a tube with fine, adjustable slit, through which light (the rays being made parallel by a lens) falls upon the prism. The light, refracted by the prism, is received by a small telescope, which magnifies the spectrum ("rainbow," if solar spectrum, i. e., if light is- sunlight) before it reaches the eye. The spectrum of the sun has dark lines (Frannhofer's lines), crossing it at right angles all along from the red to the violet portion, but at irregular intervals. The relative position of these lines has been accurately determined. 144 CHEMICAL PRIMER. If, instead of sunlight, the light from the sodium flame (Exp. 130) enters the slit, no colored bands from red to violet, as iu the solar spec- trum, are seen. Instead, the spectrum is totally dark except a brilliant yellow line (double) crossing the spectrum where before (in solar spec- trum) was the dark line D (double). If the light of the potassium flame enter the slit, three lines appear on the dark spectrum: a bright pur- plish line at (what was before) the violet end, and at the other end two red lines one somewhat bright, the other very faint. SPECTRA OF R ed | Yelilow Gr'eeln Bl ue Indigo Vio let Sun with few dark lines shown. ABC E b Sodium. fellow line Potassium. plish line Strontium. Red All the other metals and non-metals have characteristic spectra, but some substances require more heat than the flame of the Bunsen's burner to volatilize them. For these the electric flame is used. With a small spectroscope, however, the student can easily obtain the spectra of Na, K, Ba, Sr, and Cat, whose chlorides are volatilized in Bunsen's or alcohol flame. [See Fig. 43. For some laboratory spectroscopes, spectra are reversed and Fig. 43 must be turned upside down to represent the view.] APPENDIX. 145 Many rare metals have been discovered by means of the spectroscope (caesium, rubidium, thallium, indium, etc. ). By it the light of the heav- enly bodies reveals the presence in these orbs of many elements com- mon upon the earth. (Celestial Chemistry. ) Most chemical substances, when they pass from the liquid to the solid state, assume some definite form and are said to crystallize. (See EXP. 34 and connection. ) It has been found possible to arrange all crystals in six systems, according to the arrangement of their sides and angles around certain imaginary axes, intersecting at the center of the crystals. These axes are shown on.y in Plates I and n of Fig. 44. 1. Regular System. Three axes all equal and all at riijht angles. Plates I, II, and in. Ex. : Common salt, alum, garnet. 2. Hexagonal System. Four axes, three equal and in one plane, making angles of 60, and one, longer or shorter, at right angles to the plane of the other three. Plates iv and v. p]x. : Sodium nitrate, quartz, and ice. 3. Quadratic System. Three axes all at right angles, and one shorter or longer than the other two. Plates vi and vn. Ex. : Potas- sium ferrocyanide and tin dioxide. 4. Rhombic System. Three axes all unequal and all at right angles. Plates vm and ix. Ex. : Potassium nitrate, barium sulphate, and sulphur, crystallized from solution in carbon bisulphide. n. Monoclillic System. Three axes all unequal. Two cut each other obliquely, and one is at right angles to the plane of the other two. Plate x. Ex. : Sodium carbonate, sodium phosphate, ferrous sulphate, borax, cane-sugar, and sulphur from ftmon. 6. Triclinic System. Three axes, all unequal and all oblique. Plates xi and xn. Ex. : Copper sulphate, manganese sulphate, boracic acid and potassium bichromate. Certain substances, like S, crystallize in two systems, and are said to be dmtorphoit*. A very few substances are trimorphous. Anything without crystalline form is amorphous (as plastic sulphur). Different substances that crystallize in the same form are itomorphous (as com- pounds of the halogens with the same metal). A crystalline body splits moi-e readily in a certain direction than others. This splitting is called cleffnayr. The powder of a crushed or scratched mineral is called its streak. 143 CHEMICAL PRIMER. APPENDIX. 147 SECTION C. DYEING. EXP. 1. Dissolve a little aniline blue (C.^H^ (C 6 H 5 ) 3 N 3 ) in alcohol, and dip clean, white silk thread into it. Expose the thread to the air, the alcohol evaporates and leaves the blue color adherent to every fiber of the silk. Aniline (C 6 H 5 H 2 N) is a volatile, oily liquid; colorless, when pure, but by oxidation, action of chemical ayotte, etc., aniline black, red (ma- genta), orange, yellow, green, blue, and violet (mauve) are produced. The reactions in the formation of the wonderful "aniline dyes" are by far too complex for introduction here. EXP. 2. Upon fine zinc filings in a beaker place a minute quantity of blue indigo, add a moderately strong solution of potassium hydrate (potash) and heat. (a) Zn + 2 K H = K Zii O, + H 2 (b)-H 2 + C 16 H 10 N 2 0, C 16 H 12 N 2 0, reducing blue indigo white indigo agent Dip a piece of clean, white woolen (or cotton) cloth in the solution of white indigo and expose to the air, blue indigo is formed in its fibers by oxidation and adheres, that is, is a "fa#t" color (does not wash out in warm soap-s CjeH^NA + = C lfi H 10 N,0, + H,0 white indigo blue indigo t'V;i]><>rates EXP. 3. Divide a dilute (1 per cent.) solution of picric acid (CgHjNsOio) into two portions. Into one dip a piece of woolen yai'ii, into the other dip cotton yarn. Remove each and wash. The first is dyed a brilliant yellow, the second is not colored. 148 CHEMICAL PRIMER. Substances that dye directly are called sulxtantive colors. Coloring substances may form colored compounds with the fibers of the cloth, or (usually) may merely adhere to the fibers. Cotton and linen often require different treatment from wool or silk to produce the same color, and, in general, are dyed with more difficulty. EXP. 4. Divide a solution of alum into two parts. To the first add H 4 N H 0, a flocculent precipitate of aluminum hydrate (A1 2 6 H O) falls. To the second add a few drops of solution of cochineal (carmine ink), and then H 4 N H 0. Al.,6 H O is precipitated as before, and sloivly settles, carrying the coloring matter down with it, forming a "lake." Some other metallic hydrates (or oxides), especially of tin and of iron, have the same great affinity for organic coloring matter. The com- pounds they form with coloring matters are called lake*. The hydrates also have "great affinity for" (adherence to) the fibers of cloth. Every one knows that, though "dirt" can be readily washed from a white apron, iron rust is removed with great difficiilty (only by chemical agents see CHEMISTRY OF CLEANING). Hydrates (or salts, from which the hydrates may be produced) that have a great affinity for coloring matter and also for the fiber of cloth, are called mordants, and a color that will not dye directly, but needs a mordant, is called an adjective color. Coloring by means of mordants is the usual method. The most common mordants are copperas, tin salts, and alum. The cloth is first dipped into a solution of the mordant and then into the dye. Of course different mordants produce different colors, when used with the same dye. The mordants may be applied by means of stamps (or rollers) and any pattern (as for calico) brought out in the various colors. EXP. 5. Boil a piece of Fe S 4 in nitric acid (90 per cent. ), till red fumes cease to appear; dilute and filter. Preserve filtrate (Fe 2 3 S O 4 , "persulphate of iron"). Dip clean silk into this ferric sulphate (mor- dant) and leave for a few minutes. Drain, and immerse in solution of potassium ferrocyanide (dye). It is colored a deep blue (Prussian blue). 2Fe 2 3SO 4 + 3K 4 Fe(CN) 6 = 6K 2 S0 4 + (Fe. 2 ),3 Fe (C N) 6 mordant dye ferric ferrocyanide Prussian blue The reactions of the organic dyes with their mordants are too complex to be written out. Indeed, many of them are unknown. The most common coloring substances are madder (coloring principle alizarin, now made artificially from coal-tar), cochineal (dried insects from cactus of Central America, coloring principle, carmine), logwood, indigo, litmus, etc. (See DYEING, in cyclopedia. ) APPENDIX. 149 SECTION D. ADDITIONAL EXPERIMENTS. HYDROGEN AND OXYGEN. EXP. 1. Repeat EXP. 30 with a test-tube of the right size and the H flame "sings." It sets the column of air in vibration within the test- tube. EXP. 2. Ignite a small jet of H by holding in it platinum sponge (previously heated to expel absorbed gases which hinder the action). EXP. 3. Place a sounding tuning-fork in a jar of H; the tone is raised to a shrill pitch. EXP. 4. Burn a minute jet of O [driven by reservoir (1) from holder (3) as in frontispiece] in a jar of H, quickly igniting the jet by passing through burning H at the mouth. (See NOTE EXP. 26. ) [Bore hole in receiver (1) with rat-tail file moistened frequently by turpentine.] EXP. 5. Connect H and O holders with oxy-hydrogen blowpipe (Fig. 17), and igniting the H first, turn on the O. Place small piece of fine Pt wire (fused into glass holder, Fig. 40) in the flame. It melts. [The rubber cork in the H holder should be well oiled and firmly bound clown by strong twine fastened to shoulder of the bottle. The H should be drawn into a test-tube over water and tested before it is burned in the blowpipe. If it burns quietly after taking fire it is safe to ignite jet. If it burns explosively, it is mixed with air and must not be ignited. The holder is first filled completely with water and the H (from genera- tor as FRONTISPIECE 2) or pressing backward expels the water, the reservoir being kept so that the water in it shall be only about a deci- meter above the water in the holder. Common illuminating gas may be used instead of hydrogen with practically the same results.] 150 CHEMICAL PRIMER. Exv. 0. Into a tube closed at one end (through which Pt wires are fused with the internal ends almost but not quite touching) filled and inverted over mercury, put 2 cu. cm. of O and 4 cu. cm. of H and ex- plode by electric current. The mercury rises and with the water above completely fills the tube (except perhaps a bubble of gas, which is the result of inaccurate measurement). Composition of water is proved by synthesis, as nothing is found dissolved in the water. CHLORINE. EXP. 7. Mix in the dark, dry Cl and dry H in a stout bottle, and with care explode by sudden exjjosimj to direct Mimshinr. H Cl fumes are formed. EXP. 8. Fill jar with H Cl gas and make hydrochloric acid fountain similar to ammonia fountain of Fig. 22. SULPHUR. EXP. 9. Repeat EXP. 92 and afterward immerse rose in dilute sul- phuric acid. The color is restored to nearly the original tint. EXP. 10. Place in a small flask (provided with safety tube as in Fig. 25, or as in H. 2 S generator in FRONTISPIECE 2) pieces of copper wire (or "drop copper") and add as much strong H.^S O 4 as will not quite cover the copper. Carefully heat until gas begins to be evolved and then regulate heat; else the liquid froths from too violent reaction. Cu + 2 H 2 S O 4 Cu S 4 + 2 H 2 + S O 2 Pass through small con- denser and connect conden- ser with apparatus (S 2 condenser) shown in Fig. 45, which is immersed in a tivc/ing mixture (ice and 8 salt). SO, is easily con- x "*" ^xxxxxx^xxxx^vvxxx^ densed by ' 'cold " to a liquid. Turn stop-cocks and pre- serve. Wire stop-cocks (Fig. 46) on rubber connectors (boiled in paraf- fine) may be used in place of glass stop-cocks. APPENDIX. 151 S O 2 may also be condensed in xirony glass tube (drawn to a point at bne end) by pressure of a plunger with close-fitting, greased rubber head. When pressure (at 15) reaches one and one-half atmospheres, irops appear on the side, and liquid 8 2 gathers in the lower part of the tube. If plunger is quickly withdrawn a part is frozen (by cold produced by sudden evap- oration ) into a snow-white solid. Place water in a small plati- num or other thin-walled dish and pour around it a little liquid 8 O. 2 . Blow with bel- lows to hasten evaporation of 8 2 . The rapid vaporization produces a cold ( 50) so great 46-Spring Stop-Cock. (absorbs so much heat) that the water is quickly frozen. Mercury may be frozen if used instead of water. (It must not be put in platinum dish why?) If 8 2 be evap- orated in the receiver of an air-pump, a part will be solidified (frozen) forming snow-like solid. PHOSPHORUS. EXP. 11. In a flask place a few minute pieces of P and cover with strong solution of caustic potash. Displace the air in the flask by pass- ing H through the stopple of flask until the bubbles caught over pneu- matic tube of water burn quietly. Close by wire spring (Fig. 46) the rubber tube through which H is admitted and heat flask. 3 K H P 4 + 3 H, O = 3 K H 2 P O 2 -f H. P The hydrogen phosphide (phosphiiie) takes fire because vapor of liquid P 2 H 4 is present and the beautiful white rings of smoke ascend. (Pure H 3 P is not spontaneously inflammable. ) Remove heat and pass H as before and throw away poisonous liquid. Caution. Perform in a well ventilated room and immediately open doors and windows after the experiment. 152 CHEMICAL PRIMER. Fig-. 47. A from flask. B condenser. C D cold water, a b c d rubber tubes to ex- dude light. EXP. 12. The best test for the element phosphorus (paste, rat poison) is that of distilla- tion. Place suspected sub- stance in flask, add dilute sul- phuric acid and pass vapor through a glass condenser (set in a perfectly dark box painted with black pigment on the in- side) and into water (Fig. 47). Look into the box by means of a small tube, while the head, like the photographer's in ad- justing his camera, is covered by dark cloth or shawl. The vapor is distinctly phosphorescent if even a minute quantity of free. P is present in substance. The test determines with absolute certainty whether free phos- phorus is present. In cases of poisoning this test must be applied without long exposure to the air, as P in presence of organic matter and air rapidly oxidizes. ARSENICUM AND ANTIMONY. EXP. 13. Place a small piece of clean copper wire in arsenical solu- tion acidulated with hydrochloric acid, and boil. (H N 3 must not be present. ) Arsenicum is deposited 011 the copper. Wash, carefully dry and heat slowly in closed glass tube; octahedral crystals of As. 2 O 3 are deposited. (Reinscli's test.) EXP. 14. Generate hydrogen by heating to near the boiling point a strong solution of Na H O and Zn. Zn 4- 2 Na H = Na. 2 Zn O, + H. 2 Add a few drops of a solution of "arsenic,'' and pass gas through wash-bottle of lead acetate solution to remove accidental traces of H 2 S; spread over mouth of wash-bottle filter paper moistened with AgN0 3 . H 3 4 As = H,A H b As 4 3 H./) 4- 6 Ag N 0, = H,As 0, + (J H N O, + Ag fi APPENDIX. 153 The free silver turns the paper purplish-black. (Fleitlliaim's test dis- tinguishes arsenicum in presence of antimony. ) GOLD. EXP. 15. To a solution of an auric salt (Au C1 3 ) add H 2 S. A brown precipitate of Au 2 S 3 falls, soluble in (H 4 N) 2 S 2 . 2AuCl 3 + 3H 2 8 = Au 2 S 3 + 6 H Cl EXP. 16. To solution of salt of gold (Au C1 3 ) add ferrotu sulphate, and set aside for awhile. 2 Au C1 3 + 6 Fe S O 4 = Au 2 + Fe 2 C1 6 + 2 Fe 2 3 S O 4 ferroun free ferric ferr/c sulphate (fold chloride sulphate Boil precipitate of free gold in H Cl, mix with equal bulk of borax and fuse in strony blowpipe flame. A "button" of pure gold is obtained. EXP. 17. Add a few drops of solution of staimous and stannic chlo- rides (Cl water put into Sn C1 2 gives Sn C1 4 ) to dilute solution of Au C1 3 , a pui-plish, finely-divided precipitate, "purple of Cassius" (composition doubtful), falls. The same precipitate is slowly obtained, if tin foil is placed in solution of Au Cl a . SILVER. EXP. 18. Sink a small piece of unsized paper into Na Cl solu- tion for five minutes. Dry. In a dark box dip it beneath Ag N O 3 solution for one minute. Lay this "prepared paper" upon a flattened leaf which lies upon glass. Cover with an old book cover and expose the glass to sunlight. A white "picture" of the leaf is formed. Remove paper, and in dark box "fix" by dipping into sodium hyposulphite (Xa 2 S O 2 or hot Na Cl solution) for five minutes. Wash by dipping alternately for three minutes at a time into sodium hyposulphite and then into clear water. If glass is used in place of paper to hold the Ag N 3 and Na Cl, a "negative" of the leaf is formed. MERCURY. KXP. 19. In a solution of salt of Hg place a clean (by H N O 3 and afterward H 2 O) copper wire. It is soon coated with a mirror of Hg, more apparent if dried by blotting-paper and gently burnished with soft 154 CHEMICAL PRIMER. cloth. An equivalent amount of copper passes into the solution to take the place of the displaced Hg. Cut off the mirrored end of the Mire, and, placing in closed glass tube, heat. Hg distills and globules of the metal gather upon the sides of the tube. In almost any solution containing soluble compound of Hg, it may be detected by this test. No test for Hg should be considered complete unless metallic globules are obtained. A lens will often reveal the globules, if the amount of mercury is exceedingly small. EXP. 20. To mercurowtf nitrate add K I, yreen merciuw/s iodide (Hg 2 I 2 ) falls. To mercuric nitrate add K I, red mercuric iodide (Hg I 2 ) falls (Exp. 10). Wash, dry, place in cold tube, and sublime. Hg I 2 condenses on the sides of the tube in yellow crystals; rub crystals with stick, they change to the original red. This change of color may be re- peated indefinitely. COPPER. EXP. 21. Into a solution of a copper salt (as Cu S 4 ) put a piece of clean iron. It is coated with copper, an equivalent amount of iron passing into solution. Cu 8 4 -f- Fe = Fe S 4 -f Cu (deposited on iron). EXP. 22. Add H 4 N H O to cupric solution, a characteristic blue precipitate soluble in excess of H 4 N H O is obtained. Cu2N0 3 + 2H 4 NHO 2 H 4 N N 3 + Cu 2 H O precipitate ALUMINIUM. EXP. 23. Thoroughly char on platinum foil, bread isontaining a In in. Pulverize and boil in dilute H Cl, filter, neutralize with ammonium hydrate; a fine precipitate of A1. 2 6 H (having very distinct wr/nf' as it settles) falls. Set aside; minute, distinct crystals appear. CALCIUM. EXP. 24. Heat in oxy-hydrogen blowpipe flame the sharpened end of a stick of quicklime, a dazzling light is emitted ("lime light"). (Do not look steadily at the light. ) APPENDIX. 155 BARIUM AND STRONTIUM. sepa- care EXP. 25. Pulverize rately with great Ba 2 N 3 (oxidizing and col- oring agent), K Cl 3 (oxidiz- ing agent), and gum shellac (C and H principally, com- bustible body). Add om d -op of strong H Cl to the barium chlorate powder and mix care- fully and thoroughly equal bulk of each upon piece of paper. Place on wire gauze in shoal pan and ignite, using the paper as a fuse. It gives trci'ii fire. Fiji'. 47. Green Fire. EXP 26. Repeat EXP. 25, using Sr 2 N 3 instead of Ba 2 N O 3 . tttd fire results. Fig. 48. ORGANIC CHEMISTRY. EXP. 27. Repeat sugar test, EXP. 132. Albumen, if present, must be removed by boiling and filtering. Earthy phosphates should be removed by adding caustic potash to alkaline reac- tion and filtering. The caustic potash used must have been kept in the best Bohemian glass bottles, and not in bottles containing lead: otherwise Pb falls and is mis- taken for Cu 2 O. Fig. 49. A mere yellow color is not suffi- cient, there must be an actual precipitate, without pro- longed boiliny. Perform the same experiment without heating, but set test-tube away for twelve hours instead. The Cu 2 is precipitated. EXP. 28. Fill a test-tube entirely full of clear animal secretion con- taining sugar; add a small quantity of yeast and close the mouth of the test-tube by a rubber cork, through which runs a fine glass tube nearly 156 CHEMICAL PRIMER. to the bottom of the test-tube (Fig. 48). Set in a warm place for ten or twelve hours. The C 2 , produced by the fermentation, collects in the top of the test-tube, and forces the liquid out of the fine glass tube. This Fermentation Test is an excellent one for sugar in animal secretions. EXP. 29. Take the sp. gr. of a liquid containing sugar before fermen- tation and after; every "degree" lost corresponds to the presence of 21 mgs. of sugar in 10 cu. cm. of the liquid ("1 grain of sugar per fluid ounce"). That is, if uriiiometer (Fig. 49) shows 1050 before and 1030 after fermentation, there are 420 mgs. of sugar in 10 cu. cm. of the liquid (or 20 grains per fluid ounce). This is Roberts' qnnnt'itnt'irt' text. EXP. 30. Add a small quantity of albumen (Exp. 138) to distilled water, or to animal secretion filtered. Upon pure, colorless, nitric acid, in test-tube of small diameter, slightly inclined, allow the liquid to trickle from a pipette. A sharp, white zone appears at the junction of the two liquids, not dissipated by heat. This is an excellent test for albumen. (Urates, if present in excess, produce a somewhat similar white zone, but the zone is dissipated by heat much less than the boil- ing point. Be careful not to mistake the mere mixing of the zone by boiling, for dissipation. If liquid is highly colored, of course albumen will be tinged with the color.) EXP. 31. Add to animal secretion containing albumen, a few drops of strong caustic potash, and filter. Add nitric acid to distinct acid reaction and boil. White coagula appear (greenish, if bile is present, brownish-red, if blood is present). A good test for albumen. (Rarely it is necessary to allow to cool, and then boil the second time.) EXP. 32. Precipitate a large amount of albumen from solution (P^xp. 138) in distilled water, by adding nitric acid and boiling. Filter, wash, and dry over water-bath. Arrange a dozen narrow, deep test- tubes nearly filled with the acid water. Carefully weigh out, by means of a fine pair of scales (any chemist will allow the use of his scales), 5, 10, 15.... 55, 60 mgs. of albumen powder, and placing in each test- tube respectively, allow about three times as long for settling because of dryness of albumen. By means of a very fine, sharp file, carefully mark the height of the precipitated albumen. Reserve test-tubes for quantitative testing for albumen. For example: If 5 cu. cm. of liquid to be tested were placed in first test-tube, and the precip- itated albumen reaches to the mark on the test-tube, 1 mg. of albumen is present in every cu. cm. of the liquid. This is a very convenient approximate quantitative test for albumen. APPENDIX. 157 TESTS FOR THE ALKALOIDS. EXP. 33. Upon small piece of a salt of morphia on glass slide, place a drop of water. Warm till salt is dissolved. Place beside it a minute drop of strong neutral solution of perchloride of iron (Fe. 2 C1 6 ). Bring together by glass rod, a dirty-blue color results. EXP. 34. To solution of a salt of morphia, add sodium carbonate solution A white precipitate falls, crystalline if solution is dilute. Test as in EXP. 33 above. EXP. 35. Moisten a salt of morphia with nitric acid; an orange-red color results. EXP. 36. To a few drops of an aqueous solution of opium, add drop by drop neutral solution of perchloride of iron. A red solution of mec- onate of iron is formed, not destroyed by addition of corrosive sublimate solution. EXP. 37. Heat morphia on platinum foil, it burns and leaves no res- idue. EXP. 38. To solution of quinine (or of its salts) slightly acidulated with H Cl, add fresh chlorine water, and then ammonia water; a green coloration is produced. EXP. 39. Repeat EXP. 38, but add potassium ferrocyanide before adding ammonia; an evanescent red coloration appears. EXP. 40. Upon quinine (or its salts) let fall a few drops of strong sulphuric acid. It dissolves, producing faint yellow color. EXP. 41. Repeat EXP. 40, with quinine that has been adulterated with the cheaper salicin, a deep red color appears. EXP. 42. Dissolve quinine in cold nitric acid; a colorless solution is formed. Heat, it turns yellowish. EXP. 43. Heat quinine on platinum foil, no residue is left. EXP. 44. Place a small particle of strychnia on a white dish and near it a small piece of potassium bichromate. Add a drop of strong sulphuric acid to each and after a few moments bring the bichromate upon the strychnine drop with a glass rod; a vivid purple color ap- pears, rapidly fading into yellowish red. 158 CHEMICAL PRIMER. EXP. 45. Upon a drop of dilute solution of strychnia on glass slide, place drop of potassium sulphocyanide; a white precipitate appears. Examine with microscope and tufts of auricular crystals are seen. EXP. 46. Add strong sulphuric acid to a crystal of strychnia and heat over water -bath; it is unaffected. EXP. 47. Add strong, cold nitric acid to a crystal of strychnia; it is unaffected. Heat, it turns yellow but does not dissolve. EXP. 48. Place a small frog in water containing traces of strychnia and in two or three hours (sooner if stronger solution is used) a slight jar throws him into the characteristic tetanic spasms. EXP. 49. Place a drop of tincture of aconite upon the skin, a tin- gling sensation is produced followed by prolonged numbness. EXP. 50. To a solution of atropia (belladonna) add a few drops of perchloride of gold; a yellow precipitate appears. One drop of very dilute aqueous solution, applied directly to interior of eyelid, powerfully dilates the pupil. NOTES. (1) Uncrystallizable substances (colloids) in solution diffuse slowly through a septum, as parchment paper; while crystallizable substances (crystalloids) diffuse rapidly. If a small hoop, covered with parchment paper and filled with mixed solution, be floated upon water the crys- talloids pass rapidly through while the colloids principally remain be- hind. This process of separation is called Dialysis* The so-called "dialyzed iron" is the colloid, the basic oxy-chloride of iron. (2) See larger works as to properties of C O 2 , as to condensation of H; and late scientific journals as to whether shellac may not be principally an ani- mal product. (3) The soap bubble experiment, page 51, sometimes fails because too strong acid is used, and acid moisture being carried over in the draft makes the bubble brittle. But inquiries as to "what's the matter?" is a fruitful source of chemical knowledge. QUANTITATIVE TEST FOE CARBON DIOXIDE IN SCHOOLROOMS (AS AN INDEX TO THE AMOUNT OF POISONOUS "ANIMAL VAPOE" PRESENT). The proportion of carbon dioxide is generally estimated by volume and on a scale of so many parts in 10,000 of air. In pure out-do. >r air there are about 4 parts of carbon dioxide in 10,000 of air. In the school-room the proportion should never rise above 8 parts. Examination of the following 1 reactions and explanations will reveal the sim- plicity of the test. 'Ba2HO + H,C,0 4 , 2H,0 = Ba C, 4 + 4H,0 barium crystallized barium water hydrate oxalic acid ox ilat 171 126 Ba 2 H O + CO, = Ba C 3 + H 2 171 44 In neutralizing power. 126 gms. of cr. oxalic acid 171 gms. of barium hydrate. 44gms. of CO, = 171 " therefore 44 gms. of C 0, =. 126 " of cr. oxalic acid. 1 gm. C O 2 = 2.863 + gms., or 2863 mgs. of cr. ox. acid. If we weigh carefully 2863 mgs. of cr. oxalic acid (not deliquesced) and dissolve in 1,000 cu. cm. (litre) of distilled water, then 1 cu. cm. of that "standard" solution will equal (in neutralizing power) 1 milligram of carbon dioxide. LKeep solution in dark bottle. Prepare new solution of aci every two or three weeks. The most important thin^; in the test is that the oxalic acid solution be fresh and made from i erfect crys- tals.] We then make a solution of barium hydrate dissolving about 5 gms. in a litre of water. Suppose a jug (bottle) with tight-fitting rubber c n rk holds 4,155 cu. cm. (carefully measured 1 , which jug we fill from the air of the schoolroom by means of a small bel- lows (blown a sufficient number of times, say 25), and take temperature of the room at the same time as 20. Into this we pour from a sp. gr. bottle (holding with the glass stopper in, 100 cu. cm.) 100 cu. cm. of the barium hydrate solution and shake thoroughly at intervals. We now fill the burette (FRONTISPIECE 5) with the "standard" solution of oxalic acid, to a point a little above and run it d.nvn carefully drop by drop to the point i te isely. Measuring from barium hydrate solution (by means of another sp. '^r. bottle holding 50 cu. cm.) 50 cu. cm. we pour it into a clean, wide- mouthed bottle, rinse with di>til.ed water and pour this in also. We now add a little blue litmus solution (or brown solution of turmeric). Open the buiette and allow the acid to run slowly (the last drop by drop) into the wide-mouthtd bottle containing the 50 cu. cm. of barium hydrate solution. It takes say 24.5 cu. cm. of acid to neutralize the alkali when the last drop needed is added the litmus suddenly turns red (tur- meric turns yellow). Now carefully fill the second sp. gr. bottle (holding 50 cu. cm.) with the solution taken from the jug containing the schoolroom air. Again fill the burette as before and see how many cu. cm. of the acid are required to neutralize the 50 cu. cm. taken from the jug We find in every case it requires less, because the carbon dioxide in the jug lias already neutralized part of it. It requires, say, 22 cu. cm. of the acid. 24.5 cu. cm. 22 cu. cm. = 2.5 cu. cm. But from equations above we know that 1 cu. cm. of the acid corresponds to 1 mg. of carbon dioxide; therefore as we poured out only one-half of the alkali to test there were 5 mgs. of carbon dioxide in the jug. From table we see that 1 mg. of carbon dioxide at 20 occupies .544470 cu. cm. of space, therefore 5 mgs. occupy 2.72235 cu. cm. The question then becomes, If in 4055 (4155-100) cu. cm. of air there are 2.72235 cu. cm. of carbon dioxide, how much carbon dioxide in 10,000 cu. cm. of air? We have the proportion 4,055: 10,000:: .73S: from whir-h we obtain 6.7 parts in 10,000 as the answer, that is, the room is fairly ventilated. Space occupied by J mg. o/C O 2 at different temperatures (barom. 760 mm.). Degree C o Degree 32 Cubic Cm. .507306 T Decree Cubic Cm. .546328 Degree i Degree 82.4 Cubic Cm. .559336 15 59 .? 351 78 22 7i!e .548186 29 84.2 .561194 16 60.8 .537037 23 73.4 .550044 30 86. .563052 17 626 .538895 24 75.2 .551903 31 87.8 .564910 18 64.4 .540753 25 77. .553761 32 89.6 .566-69 19 66.2 .542611 2o 78.8 .555619 33 91.4 .568627 20 68 .544470 27 80.6 .557477 34 93.2 .570485 S6 95. .572343 A factor can be work e I out for each jug used and for each temperature, so that by a simple multiplication of the difference shown by the burette the result is ob ained. [The factor of this jug for this temperature is 2.68+. Dif. by burette 2.5 x 2.68+ = 6.7 + . ] Any bright pupil can master the test in a tew hours and can apply it in a :ew minutes by using factors. The test can be made after school or before school the next day. Such tests regularly reported would do much to awaken an interest in having a proper system of ventilation. 160 CHEMICAL PRIMER. SECTION E. METRIC SYSTEM. LINEAR. 10 Millimetres (mm.) = 1 Centimetre (cm. )i 10 Centimetres = 1 Decimetre (dcm.) 10 Decimetres 1 Metre (m) 10 Metres = 1 Dekametre 10 Dekametres = 1 Hektometre 10 Hektometres = 1 Kilometre CAPACITY. 10 Millilitres = 1 Centilitre 10 Centilitres = 1 Decilitre 10 Decilitres = 1 Litre 10 Litres = 1 Dekalitre 10 Dekalitres = 1 Hektolitre 10 Hektolitres = 1 Kilolitre WEIGHTS. 1 Metre (meter) = 39.37 inches. 10 Milligrams (ing.) = 1 Centigram (cgm.) 10 Centigrams = 1 Decigram (dc/.) 1 Litie 1 Litre = 61 cubic inches. = 1 cubic decimetre. 10 Decigrams = 1 <. ram fern-) 1 Gram = 15.43 grains. 10 G rams Dekagra m 1 Gram = weight of ] cu. cm. c f 10 D ekagrams = 1 Hektogr am wate r 4') 10 Hektograms = 1 f Kilogram (kgm.) ; or Kilo 1 Kilogram 1 Kilogram = 2 1-5 Ibs. = weight of 1 cu. dcm.(litre) 1,000 Kilograms = 1 Metric Tr n (M. T.) of water (4) in Illl 111 1 sq. cm. 1 Decimetre = 10 Centimetres. REFERENCE TABLE No. 2 CONTINUED. NEGATIVE GROUPINGS. /P 3 = metaphosphate Co H 9 3 = valerianate C N cyanate C H O.; formate C 4 H 7 0. 2 butyrate (butter) C 7 H 5 2 = benzoate X N O 2 = nitrite C 3 H 4 3 - lactate C 5 H 2 N 4 3 - urate B 4 ? = tetraborate (borax) Mn 4 = manganate Mii 2 8 = permanganate Cr0 = bichromate C 4 H 3 O 5 = malate H r C 7 H 7 ' - meconate (opium) | | Fe < C N ) - ^rrocyanide C 7 H 3 5 = gallate C 27 H, 9 Oi 7 = tannate "s C POSITIVE GROUPING. Fe 2 (C N) 12 = ferricyanide R x == amidogen S I APPENDIX. 161 SUGGESTIONS FOR STUDENTS USING THE ANALYTI- CAL CHARTS. In most schools this should be a volunteer class and tiie work extra, put in after school hours or on Saturdays. Be sure you want to do the work before you undertake it. Don't talk to others while at work, ex- cept in rare instances so far as quietly to obtain information. Don't "fool" in the laboratory and report those who insist upon doing it, that they may be promptly removed from the class. Have 110 false honor about this, for the nonsense of one may vitiate all accurate work for a class. Reserve a portion of the original solution to begin upon again in case of accident, also for special tests. Common drinking water, boiled, cooled, and filtered, usually answers for all work with the first two Groups; but distilled water must be used for the other Groups, and is better for all reagents. Precipitate tJioroughly each Group, but on the other hand avoid much excess of the precipitating reagent. Evaporate filtrates if they become too dilute. A coal-oil stove makes a cheap source of heat for evaporation. Avoid breathing, to any great extent, fumes of hot H Cl, H 4 N H 0, H N 3 , aqua regia, etc. Hold dishes at arms' length while pouring such liquids. Under a gas chimney with flame at base to increase draft, is the proper place to generate noxious fumes; but such work may be easily done upon a shelf by open window with slight outward draft. Make (H 4 N) a S by passing H. 2 S into dilute H 4 N H (10%) till saturated and then add equal volume of H 4 N H 0. Digest this with a little S and filter to make (H 4 N). 2 S. 2 (yellow], or expose (H 4 N). 2 S to air for sufficient time. A convenient H. 2 S generator is shown in FRONTISPIECE (2). The middle bulb contains Fe S. A test- tube with small hole in bottom (containing a little broken glass upon which is Fe S), lowered into wide-mouthed bottle of dilute H. 2 S 4 and test-tube closed by perforated rubber stopple through which is glass tube connected with rubber tube held by spring, Fig. 46, makes a cheap H. 2 S apparatus. Fig. 50 shows a' convenient reagent bottle with pipetted stopple. Take test-tube to bottle to add reagent, not bottle to test- tube, and be careful not to stir up any sediment which may have fallen in case drinking water has been used. Fig. 51 represents a system of rapid filtration. The stream of water must be regulated. The longer the tube rr, the more rapid the filtering. Chamber b must be air-tight at top. Pt (foil) funnel-shaped tip must support filter paper at bottom, and the wet edges of filter paper must be pressed firmly against upper part of funnel. A p .rtial vacuum is formed in chamber ft and flask c. For color of precipitates, additional tests, etc., see EXP. 97 and INDEX, also have a work on Qualitative Analysis upon the desk for reference. 162 CHEMICAL PRIMER. I. Add H Cl (15 per cent.) drop by drop till upon settling no pre- cipitate falls. . . . .Filter. Precipitate Hg 2 Cl 2 , Ag Cl, Pb C1 2 , insolu- ble chlorides. Wash twice with cold water (Fig. 7), drain, and washing from paper with wash-bottle into beaker, boil for one minute, and . . . . Filter while hot. Filtrate . . soluble chlorides of other metals, Cu, Bi, Fe, Mg also traces of Pb C1. 2 . Filtrate.. ..PbCL Precipitate Hg 2 C1 2 , Ag Cl. Wash with hot water to remove all of the PbCl 2 , (Hot water dissolves Pb Cl if Pb has been found, drain, and add warm H 4 N H O (15%), pouring it through two gla or three times. The ammonia water dis- solves Ag Cl but reacts with Hg 2 C1 2 . Precipitate H 2 NHg 2 Cl = amido- mercurous chloride black. (If no black color ap- pears no mercury in ous form is present.) Dis- solve in beaker a portion in five or six drops of aqua regia and evaporate carefully nearly to dry- ness, dilute and test so- lution of HgCl 2 (1) by EXP. 19, APPENDIX, or (2) by adding a drop of Sn C1 2 and white Hg 2 CL Filtrate. ..AgCl AddHN0 3 (15%) to acid reaction. Ag Cl is reprecip- itated because its solvent is neu- tralized. Filter, .... wash .... and fuse on charcoal as in EXP. 113, obtaining silver globule with no incrustation o n coal. is precipitated. Add excess of Sn C1 2 and gray metallic Hg falls forming into globule if boiled with H CL ( 1 ) Place drop of filtrate on ss and slowly evaporate white needle-shaped crystals of Pb C1 2 are left, touch with drop of K I solution, yellow Pb I 2 appears. Divide fil- trate into three portions and to first portion (2) Add H 2 S O 4 (15%), white Pb S 4 falls. To second portion (3) Add K 2 Cr 2 7 (3%) yellow Pb Cr O 4 falls. To third and largest portion (4) Add (H 4 N),S, black Pb S falls. Fuse with little K 2 C 3 on charcoal in reducing (near) flame of the blowpipe. Lead globule is obtained with yellow incrustation on char- coal. Globule is malleable. (Bi and Sb are brittle. ) 19. Evaporate filtiate from first group to small bulk, add ten drops of strong H Cl &,nd evaporate carefully nearly to dryness. Dilute with hot H 2 O and pass 1B 2 S Ras through hot solution Kilter. Precipitate insoluble sulphides of I Sn, Sb, As (Au, Pt). Wash with hot water minutes in (H 4 N)..S'2 (yellow) Ig(ic), Cu, Pb, Bi, Fil trate tolubie chlo- s of other metals, Fe, Mn, M?, etc. Filter Co, Precipitate... Hg, Cu, Pb, Bi (sulphides). Wash with hot water, add strong, boiling hot H N Os, pouring it on several times. Filter Filtrate. . .Sn, Sb, As (Au, Pt) tulphides. Add dilute H Cl, sulphides are reprecipi- tated .... filter, drain well, boil in little strong H Cl Filter. Ppt Hg.l Filtrate Cu, Pb,Bi. Dissolve in Add five drops strong H 2 S 64 aqua regia and and boil down to small bulk, test as in First Pb gives white precipitate. Group. i Filter Precipitate . . .As, yel- low. Wash and confii m by digesting in (H 4 N) 2 C 03 and reprecipitat- ing in filtrate As 2 O 3 by H Cl, otherwise S from decomposition of (H 4 N) 2 S 2 may be mis- taken for As. Filtrate.. Sn.Sb. Dilute with water and place a small piece of clean Zn, and of clean Pt wire in the solu- tion. Sb forms a distinct black stain upon Pt. ve in hot dilute jvaporate to dry- Precipitate Pb | Fml* Ri, r,, AddH 4 NHO Filter. Ppt.. Bi white. Fuse F.ltrate. .Cu, deep with K 2 COa on char- blue solution. ..test coal. . . brittle globule, by EXP. 21, APP. Wash Pt wire. Dissol H N Os, remove wire, < ness, add few drops dilute H Cl and pass H 2 S. Orange-yellow precipitate, turns gray- ish-black by EXP. 110. After Zn has all dissolved, filter and add drop of Hg CI& white precipitate of Hg 2 Cl s indicates Sn. (Au and Pt rarely occur in solution ) ANALYTICAL CHARTS. 163 III. To filtrate from second group add H 4 N H O till alkaline (avoid excess), then add H 4 N Cl and (H 4 N) 2 S and warm gently for five min- utes Filter. Precipitate, .sulphides of Ni, Co, Fe, Mn, Zn, hydrates I Filtrate, of Cr and AL Wash with very dilute (H^N) 2 S and then j soluble com* with water. Add dilute H Cl breaking bottom of paper j p OUI1 (i s o f and washing through into beaker Filter, j me talsofrvandv Group. Precipitate . . .Ni, Co (sulphides). Fuse a por- tion in borax head blue indicates Co. Violet when hot and brown when cold indicates Ni alone. If both are pres- ent Co overpowers Ni colors. Dissolve the re- maining ppt. in few drops of aqua regia, evap- orate to dryness, dissolve in few drops of water, add a little Co C1 2 and evaporate on white pa- per. Green indicates Ni. Jbiitiate Fe, Mn, Lr, Zn, Al. Add few drops of H N Og evapoiate carefully neaily to dr}ness, dilute slightly, add K H O till strongly alkaline, boil carefully 3 minutes. Filter. rpt Fe, Mn, Cr. Wash Filtrate Al, Zn. Add with hot water. Fue a por (H 4 N>j8 in s ijrht excess . Filter. tion on Pt f>il with bmall pp^ quantity of K 2 CO S (20%) acetic acid, add K 2 Cr 2 O 7 Filter, bonates of Fifth Group. Ppt. yello'(\ . .. Ba CrO 4 . Moisten Filtrate . . tate in H Cl, Sr, Ca. Add (H 4 N) 2 (J Os, filter add dilute H,S O. t and set as : de D ssol for an h \e precipi- our Filter. wun a. ci aim apj-iy Ppt . Sr s u 4 {Filtrate Ca. Add H ;N H O to alkaline reac- Jlameteit EXP. 125.{ moisten w itl tion and (H 4 N) 2 C 2 O4. Moisten wnite rpt. with H - 1 and apply flame test , Exp. l-'O.JH ( 1 ini.l or" Ivflame test. Dvll rerfindirates Ca> V. To tiltrai e Horn Fourth Group concentrated by e^apoiati* n add H 4 N H O to alkaline reaction and then H 5fa-2 I* O 4 let stand for ten minutes (till cold). Precipitate . . crystalline. H 4 N Mg P O, Filtrate Na, K (and H 4 N). Con rentrate by boiling. Apply /L me test. Yellow indicates Na, purplish K. If both ate present the yellow obscures entirety the purplish color. Look through blue white shows Mg glass at fl ame) the Na color is not seen and the*K color appeals red- dish-violet. Either metal may thus be detected in the presence of the other. Tests for H 4 N compounds of course must be applied to the original solution. Heat a portion of this with Na H O. H 3 N is recognized by (1) odor, (2) turns moist litmus paper, suspended in mouth of (but not touching) test-tube, Mz*e,and (3; by fumes with glass rod dipped in dilute H Cl. Pt wire for flame tests must be clean, indeed, all utensils should be. To digest is to warm without scalding. C. P. stands for chemically pure, and C. P. acids, etc., must be used in analytical work. Groups IV and v are best tested with the spectroscope (which see). Na a C 3 may be used for K U C 3 . Vis. 50. Reagent Bottle. Glass tube should nearly closed at top fusion. Tube b should be slightly drawn at bottom and arranged so as to throw its stream straight down the tube a. Chamber b need not be drawn out as in cut, but may be closed by rubber cork. 113 L TCI DJCS 3D OR, in IF 1 STPtTCF/P, Between California and Sacramento Streets, SAN FRANCISCO. ASSAYING TAUGHT. fl-zTF'er&cm.al attention insures Correct BART MORGAH ^c CO. 5 MARKET STREET STATION, OAKLAND. CAL. Will furnish a set of Chemicals (securely bottled and carefully labelled) and Appara- tus on receipt of thirteen dollars and fifty cents ($13.50), or a smaller set for eleven dollars (.$11,00). The set is sufficient for the performance (on a small scale and with fuw exceptions) of all the experiments found in this Chemical Primer. Send postal card for full circular. THOMAS PRICK, Assay Office, Bullion Booms, and Ore Floors, 524 Sacramento St., San Francisco. Careful Analyses made of Ores, Metals, Soils, Waters, Industrial Products, Foods, Medicines and Poisons. CONSULTATIONS ON CHEMICAL, MINING, AND METALLURGICAL QUESTIONS. A Mingle Copy of this CHEMICAL PRIMER will be sent by Hail on receipt of One Dollar, by IV. B. Hardy, ll Broad- way, Oakland, Cal.