UC-NRLF 
 
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Edmund O'Neill 
 
Massachusetts Institute of Technology 
 
 LABORATORY EXPERIMENTS. 
 
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LABORATORY EXPERIMENTS 
 
 GENERAL CHEMISTRY, 
 
 COMPILED FROM ELIOT AND STOREYS MANUAL 
 AND OTHER SOURCES, 
 
 11. RIPLEY NICHOLS AND LEWIS II, NORTON 
 
 FOR THE USE OF STUDENTS OF THE MASSACHUSETTS 
 INSTITUTE OF TECHNOLOGY. 
 
 REVISED BY FRED L. SARD WELL. 
 
 BOSTON, MASS. 
 1891. 
 
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 COPYRIGHT, 1884, BY W. R. NICHOLS. 
 
INTRODUCTION. 
 
 As this pamphlet may fall into the hands of teachers and 
 others outside of the Institute, it may be proper to say a few 
 words by way of introduction. 
 
 The pamphlet is not intended to be used without a 
 teacher. 
 
 As far as possible the directions are given which will 
 enable the student to perform the experiments successfully, 
 but he is left to make his own observations, and then to 
 interpret the results, with such aid as may be necessary from 
 the instructors who are always present in the laboratory. 
 This system, which was introduced by Professor Caldwell in 
 his " Introductory Chemical Practice," requires a careful 
 inspection of the laboratory note-books. 
 
 At the Institute most of the experiments are performed on 
 the lecture table before they are attempted by the student, 
 and any text-book may be consulted outside the laboratory; 
 in the laboratory itself no other book than this is allowed. 
 In some cases a sketch of the necessary apparatus, or an 
 example of the apparatus itself, is placed in the laboratory, 
 where it can be seen by the students. 
 
 8897' 
 
TO THE STUDENT. 
 
 UNLESS special directions to the contrary are given, no 
 text-book will be allowed in the laboratory, except this 
 pamphlet. 
 
 The laboratory work should teach us : 
 
 (1) To observe and to distinguish essential from non- 
 essential phenomena ; 
 
 (2) To express in writing the results of observation ; 
 
 (3) To draw proper conclusions as to what facts are 
 taught by the experiments. 
 
 The student's standing is largely determined by the qual- 
 ity of his laboratory work and note-book. The quality is 
 more important than the quantity, and one experiment well 
 and intelligently performed is worth more than a dozen, or, 
 indeed, than any number of experiments performed mechani- 
 cally without intelligence. The notes must be written clearly 
 and distinctly, in the laboratory note-books. As a rule 
 answer concisely, but fully, the following questions: 
 
 (1) What materials did you use ? 
 
 (2) What apparatus did you use ? 
 
 (3) What did you do ? 
 
 (4) What did you observe ? 
 
 (5) What has the experiment taught you ? 
 
 Begin the' entry for each day with the date. Do not 
 crowd your notes. Leave room for remarks, additions, or 
 corrections. Allow a paragraph for each one of the above 
 headings. 
 
Make the record of an experiment as soon as the experi- 
 ment is performed, and present the notes to an instructor 
 for examination before doing other work. 
 
 It is not expected that all the experiments in a given set 
 will be performed at any one exercise by all the students, 
 but each student will do only as many of the experiments in 
 the set as he can do well. Leave the note-book on the out- 
 side of the desk at the close of each exercise. 
 
 At the last exercise in each term the desks should be left 
 in good order. No allowance is made for apparatus which is 
 not in proper condition to be served out to other students. 
 No allowance is made for files, iron pincers, filters, or bits 
 of tubing. 
 
 I have read the above directions carefully, and endeavored 
 to understand them. 
 
 (Name here.) .. 
 
MASSACHUSETTS INSTITUTE OF TECHNOLOGY. 
 
 First Year. 
 GENERAL CHEMISTRY. 
 
 EXERCISE I. PRELIMINARY WORK. 
 
 1. Ascertain the number of your desk. 
 
 2. Find coat-hook corresponding to your desk. 
 
 3. Obtain key of desk at the supply room. 
 
 4. Examine contents of desk. 
 
 5. Hand in the receipt at the supply room. 
 
 6. Take the piece of ignition tubing in your desk and report to one 
 of the instructors. 
 
 Experiment 1. Mix thoroughly 3 grams of coarsely powdered sul- 
 phur with 8 grams of copper filings or fine turnings. Put the mixture 
 into a tube of hard glass, No. 3, about 12 centimeters long, and closed 
 at one end. (For the manipulation of tubing, see Appendix, 1-4.) 
 Hold the tube by the open end with the wooden nippers, and heat the 
 mixture gently over the gas lamp. When no further change takes place, 
 allow the tube to cool, break it, and examine the contents. 
 
 2. Heat a small piece of lead foil on the lid of a porcelain crucible 
 as long as any change occurs. Warm slowly, as sudden heat will cause 
 the porcelain to break. While this is going on perform the following : 
 
 3. Fit to any small flask or bottle a perforated cork (for the manip- 
 ulation of corks, see Appendix, 9), to which has been adapted a short 
 piece of glass tubing, No. 7. Slip over the end of this glass tube a 
 short piece of caoutchouc tubing. Suck part of the air out of the flask, 
 and then nip the caoutchouc tube with thumb and finger, so that no air 
 shall re-enter. Immerse the neck of the flask in a basin of water, and 
 release the caoutchouc tube. 
 
8 
 
 4 - T^ke thebpttle a -prepared for Expt. 3, and into the upper end 
 of trie tnf of caoVtcftolact ttibmg insert the point of a small funnel. Fill 
 the funnel w.itl\ w^er ; Deport -t'ltp result ; loosen the cork ; report what 
 
 EXERCISE 2. CHEMICAL AND PHYSICAL CHANGES. 
 
 5. Burn some magnesium wire, observe carefully the result of the 
 combustion, and describe the product. 
 
 6. Mix thoroughly 4 grams of powdered sulphur and 7 grams of fine 
 iron filings. Examine the mixture with a lens ; also with a magnet by 
 putting some of the mixture on a slip of paper, and passing the magnet 
 to and fro on the under side of the paper. Now heat the mixture in 
 an ignition tube under the hood. After the action is over, break the 
 tube and examine its contents with lens and magnet. Place a small 
 portion of the contents in a test tube, and pour upon it i c. c. of dilute 
 chlorhydric acid (HC1), and note the result. Keep careful notes. 
 
 7. Heat 2 grams of red oxide of mercury in a matrass, thrusting into 
 the matrass a glowing splinter of wood from time to time. Observe 
 carefully all that happens. 
 
 8. Upon a small piece of "quicklime" put a few drops of water. 
 Note the result. 
 
 9. Heat a crystal of copper sulphate gently on a crucible cover. 
 When the mass is cool, add a drop of water, holding the cover in the 
 palm of the hand. 
 
 10. Pour into a test tube 5 c. c. of a solution of copper sulphate 
 (CuSO4) ; add 4 or 5 drops of ammonia water, and shake; finally add 
 3 c. c. of ammonia water, and shake. Record all that you observe. 
 
 11. Proceed as in Expt. 10, but use 5 c. c. of a solution of acetate 
 of lead and i c. c. of a solution of chromate of potassium instead of 
 sulphate of copper and ammonia water. 
 
 12. Warm 5 c. c. of a solution of potassium permanganate in a test 
 tube until you can just bear your hand on it ; then add three or four 
 drops of dilute sulphuric acid, and finally a few crystals of oxalic acid. 
 
 EXERCISE 3. MANIPULATION OF GLASS. 
 
 13. Bend glass tubing into the forms shown in the model. Make a? 
 many pieces of each form as are designated. These pieces of tubing 
 should be saved, as they are all to be used in subsequent experiments. 
 
Show your work to an instructor and have it approved, before doing 
 jther work. For instruction in glass working, read Appendix, pp. 3 to 5 
 nclusive. 
 
 EXERCISE 4. HYDROGEN. 
 
 14. Make a small cylinder of wire gauze, by rolling a piece of fine 
 *auze, about 6 c. m. square, around a thick piece of No. 6 glass tubing. 
 Twist fine wire around the cylinder in order to preserve its form ; then 
 slip the cylinder off the glass and close one end of it by pressure with a 
 stout pair of pincers. Within this cylinder of wire gauze place a piece 
 of metallic sodium as large as a pea, and then close the upper end of the 
 cylinder by pressure with the pincers, as before. 
 
 Attach the wire gauze cage firmly to the end of a piece of stout iron 
 wire, and thrust it quickly into the water pan, so that the cage will come 
 directly under the mouth of a small bottle of about 100 c. c. capacity, 
 which has been previously filled with water, and is held inverted in the 
 pan. Gas will collect and is to be tested with a lighted match. 
 
 15. Experiment indicated under 23.* Take an iron "gas pipe" 
 and fill the middle portion with bright iron turnings. Rest the tube on 
 the furnace lamp (without the iron trough) and connect one end with the 
 water pan, as in the last experiment. The other end is connected, by 
 means of delivery tubing and caoutchouc connectors, with a round- 
 bottomed flask, half full of water, and supported on a ring of the iron 
 stand. The flask should rest on a piece of wire gauze, and the bottom of 
 the flask should be about 4 or 5 c. m. above the top of the Bunsen lamp. 
 Light the furnace lamp, and wait until the iron pipe has become red hot ; 
 then heat the water in the flask until it boils slowly. As the steam 
 passes over the hot iron turnings it will be decomposed ; a gas will pass 
 off through the delivery tube, and is to be collected in bottles at the 
 water pan as soon as the air originally contained in the tubes and flask 
 has all been expelled. Test this gas with a lighted match. 
 
 16. Prepare a hydrogen generator similar to the pattern shown. 
 Within the bottle put 15 or 20 grams of granulated zinc, or small scraps 
 of the sheet metal, and as much water as will fill about one quarter of 
 the bottle. Replace the cork in the bottle, taking care to press it in 
 tightly, and satisfy yourself that the apparatus is perfectly tight before 
 proceeding further. Record your method of testing. Then, and not till 
 
 * Eliot and Storer's Manual. 
 
10 
 
 then, gradually pour in common muriatic acid through the thistle tube. 
 The thistle tube must reach nearly to the bottom of the bottle, so that its 
 point may dip beneath the water ; and the muriatic acid must be added 
 by small successive portions not more than a large thimbleful at a 
 time. On the addition of the first portions of the acid, chemical action 
 vill ensue, and after all the air has been expelled from the bottle, the 
 hydrogen may be collected over the water pan in inverted bottles filled 
 with water. The moment at which the hydrogen ceases to be contami- 
 nated with air can be determined by collecting small portions of the 
 escaping gas in wide-mouthed bottles of about 50 c. c. capacity, and test- 
 ing its quality by means of a lighted match. In doing this the small 
 bottle filled with gas must not be turned over, but should be carefully 
 lifted from the water without changing its vertical position, and the lighted 
 match should then be applied to the mouth of the bottle. If the hydro- 
 gen be pure, it will burn tranquilly at the mouth of, and within, the bottle ; 
 but, in case the gas is still mixed with much air, a sharp explosion will 
 occur at the moment when the match is touched to it. In experimenting 
 with hydrogen, no light should ever be brought into contact with the con- 
 tents of the bottle in which it is generated, or with any large quantity of 
 the gas, until the purity of the sample, or rather its noa- explosive charac- 
 ter, has been demonstrated by applying to a very small volume of the gas 
 the test above described. 
 
 17. Carefully lift from the water pan a bottle of 200 or 300 c. c. 
 capacity, completely full of hydrogea ; slowly carry the bottle, the mouth 
 of which is, of course, held downward, to a burning candle or splinter of 
 wood, and depress the bottle over this flame. After observing what hap- 
 pens, withdraw the candle slowly. 
 
 18. Take a glass tube 3 or 4 c. m. in diameter, and close one end with 
 a plug of plaster of Paris i or 2 c. m. thick. Set the tube aside to dry 
 until the next exercise. 
 
 EXERCISE 5. HYDROGEN. 
 
 19. Fill the plugged tube (prepared at the last exercise) with hydrogen 
 by upward displacement, taking care not to wet the plug. Set the tube 
 upright in a bottle of water, and allow it to remain until the close of the. 
 exercise, noting its condition from time to time. 
 
 20. Over a jet of burning hydrogen hold a dry cold bottle. 
 
II 
 
 21. Introduce two volumes of hydrogen and five volumes of air into 
 a strong bottle, such as is used for soda water. Close the mouth of the 
 bottle with a cork, and shake violently, in order that the gases shall be 
 mixed. A small quantity of water should be left in the bottle to act 
 as a stirrer. Grasp the bottle firmly in one hand, remove the cork with 
 the other, and apply the open mouth of the bottle to a lighted candle. 
 
 22. Light a small jet of hydrogen. Place over the jet a piece of 
 ignition tube 30 or 40 c. in. long, and move the jet up and down within 
 the tube until a place is found where a musical tone is given. 
 
 23. Place 5 grams of copper oxide in a piece of ignition tubing about 
 35 c. m. long ; place the tube upon a furnace lamp, heat, and pass a 
 stream of dry hydrogen through the tube until no more water is given off. 
 Allow to cool and weigh the contents of the tube 
 
 EXERCISE 6. CHLORINE. 
 
 [All experiments in this exercise must be performed under the hood.] 
 
 24. Place in a test tube i grain of potassium bichromate (K 2 Cr 2 O 7 ). 
 Pour upon it 10 c. c. of hydrochloric acid (HC1), and warm it. Note 
 the result. 
 
 25. In a flask of about 500 c. c. capacity, arranged as in the model 
 on the desk, place 8 or 10 grams of coarsely powdered manganese binox- 
 ide ; pour upon it 50 or 60 c. c. of common muriatic acid, and gently 
 heat the mixture. Chlorine will soon be disengaged, and may be recog- 
 nized by its peculiar color. Fill several bottles of at least half a liter 
 capacity with the dry gas, by displacement. 
 
 It is necessary, for the success of this experiment, that the gas be 
 thoroughly dried ; this is effected by heating the flask containing the 
 manganese binoxide and chlorhydric acid gently, and passing the chlo- 
 rine through a tube filled with chloride of calcium or other substances 
 which will absorb moisture. Gradually sift a gram or two of very finely 
 powdered metallic antimony into one bottle. 
 
 Drop a piece of Dutch metal foil into a jar of chlorine. 
 
 Introduce a thin slice of phosphorus into a bottle of dry chlorine. 
 
 Into another bottle of chlorine thrust a burning taper or a bit of 
 flaming wood or paper, or better a burning candle. 
 
12 
 
 26. Generate hydrogen as in Expt. 16; when the hydrogen is found 
 by testing, to be pure, connect with the generator a tube drawn to a fine 
 point. Light this jet of hydrogen and immerse it in a bottle of chlorine. 
 Apply a piece of litmus paper to the sides of the bottle. 
 
 Repeat, using a jet of illuminating gas. 
 
 27. In a soda water bottle mix equal volumes of chlorine and hydro- 
 gen ; then remove the cork and hold the mouth of the bottle in the flame 
 of a lamp. 
 
 28. Suspend a piece of calico in a jar of perfectly dry chlorine. See 
 if there is any change. Now wet the calico ; and again suspend it in the 
 chlorine. Explain the result. 
 
 EXERCISE 7. CHLORINE. 
 
 29. At the bottom of a large, tall bottle, or other wide-mouthed glass 
 vessel, of the capacity of two or three liters, place a small bottle contain- 
 ing 15 or 20 grams of bleaching powder. Cover the beaker with a glass 
 plate or sheet of pasteboard, provided with a small hole at the center ; 
 through this hole in the cover pass a thistle tube down into the bottle of 
 bleaching powder and pour upon it several small successive portions 
 of sulphuric acid diluted with an equal volume of water. Chlorine gas 
 will immediately be set free and is to be ladled out of the jar with a 
 dipper made of a small bottle and poured upon a solution of indigo to 
 show its bleaching power. 
 
 30. Soak a bit of printed calico in a half liter of water, into which 10 
 or 15 grams of bleaching powder have been stirred. After a short time 
 transfer the cloth to another bottle filled with very dilute chlorhydric or 
 sulphuric acid. Finally, wash the cloth thoroughly in water. 
 
 31. Pour into a test tube a quantity of chlorine water ; drop into it a 
 small quantity of a solution of indigo, and stir the mixture with a glass 
 rod. Repeat with solutions of aniline red, aniline violet, cochineal, log- 
 wood, and potassium permanganate. 
 
 After you have performed all the above experiments, perform any 
 which you may have omitted in the previous exercise. 
 

 EXERCISE 8. BROMINE AND IODINE. 
 
 32. From an assistant receive into a flask or bottle of I or 2 liters 
 capacity 3 or 4 drops of bromine. Cover the bottle loosely and leave 
 it standing ; immerse a piece of moist litmus paper in the gas. 
 
 33. Warm gently a few crystals of KBr with 0.2 gram MnO 2 and i 
 c. c. H 2 SO4 in a test tube and observe the vapor. (Under the hood.) 
 
 34. Take 5 c. c. of bromine water in a tube and warm under the 
 hood. Observe what happens. Test the remaining liquid with litmus 
 paper. 
 
 35. Receive a few drops of dry bromine in an ignition tube; throw 
 upon it a little powdered antimony. 
 
 36. Hold a dry test tube in the gas lamp by means of the wooden 
 nippers and warm it along its entire length, in so far as this is practica- 
 ble. Drop into the hot tube a small fragment of iodine. 
 
 37. Prepare a quantity of thin starch paste by boiling 30 c. c. of 
 water in a porcelain dish and stirring into it 0.5 gram of starch which 
 has previously been reduced to the consistency of cream by rubbing it in 
 a mortar with a few drops of water. Note the change in the starch. 
 
 38. Pour 3 or 4 drops of the paste into 10 c. c. of water in a test 
 tube, and shake the mixture so that the paste may be equably diffused 
 through the water ; then add a drop of an aqueous solution of iodine. 
 Heat the solution gently until the color disappears, and allow it to cool 
 again. This action affords a delicate test for iodine when not in 
 combination. 
 
 39. Dip a strip of white paper in the starch paste and suspend it, 
 while still moist, in a large bottle, into the bottom of which two or three 
 crystals of iodine have been thrown. What does the experiment show ? 
 
 40. To a portion of the starch paste made in Expt. 37 add a few 
 drops of potassium iodide solution. Into the paste thus prepared clip 
 strips of filter paper. This is " iodo-starch paper." 
 
 41. Repeat Expt. 38, using bromine water instead of the aqueous 
 solution of iodine. 
 
 42. Put i gram of MnC>2 in a test tube, pour upon it i c. c. of HC1, 
 and warm gently. Now hold a piece of iodo-starch paper over the 
 tube and notice the result. Explain the action. This affords a test 
 for chlorine. 
 
 43- Take a very dilute solution of potassium iodide, add a little 
 carbon bisulphide and a few drops of chlorine water; shake up and 
 
14 
 
 then allow to stand for a few moments. Repeat, using potassium bro- 
 mide instead of the iodide. Chloroform may be used instead of carbon 
 bisulphide. Their action is merely mechanical. This shows how we 
 may recognize bromine and iodine in compounds. 
 
 EXERCISE 9. IODINE AND FLUORINE. 
 
 44. Place 0.25 gram of finely powdered iodine in a porcelain capsule, 
 pour upon it enough concentrated ammonia water to somewhat more 
 than cover the iodine, and allow the mixture to stand during 15 or 20 
 minutes with occasional stirring. Collect in several small filters (Appen- 
 dix, 15) the insoluble dark brown powder which will be found at the 
 bottom of the liquid. Wash well with cold water and then remove the fil- 
 ter ;, together with their contents, from the funnels; pin them upon 
 bits of board and allow them to dry spontaneously. The powder is the 
 nitrogen iodide. As soon as it has become thoroughly dry, it will 
 explode upon being rubbed, even with a feather, or jarred, as by the 
 shutting of a door or by a blow upon the wall or table. 
 
 45. [Under the hood.] Warm a slip of glass and rub it with bees- 
 wax so that it shall be everywhere covered with a thin, uniform layer of 
 the wax. With a needle, or other pointed instrument, write a name, or 
 trace any outline through the wax, so as to expose a portion of the glass. 
 Lay the etching, face downward, upon a bowl or trough of sheet-lead, in 
 which has been placed a teaspoonful of powdered fluor-spar and enough 
 strong sulphuric acid to convert it into a thin paste. 
 
 Cover the glass and the top of the dish with a sheet of paper, and then 
 heat the leaden vessel for a few moments very gently, taking care not to 
 melt the wax ; then set the dish aside in a warm place and leave it at 
 rest until the end of the exercise. Finally, melt the wax and wipe it off 
 the glass with a towel or bit of paper. 
 
 46. Into a perfectly dry matrass put a small quantity of a mixture of 
 equal parts of quartz and powdered fluor-spar. Moisten with a drop 
 of strong sulphuric acid and heat in the flame of the lamp. Hold a 
 drop of water in a loop of platinum wire at the mouth of the tube. 
 Show Vesult and ask for explanation. This shows how we may recognize 
 fluorides. The experiment will be performed in a subsequent exercise, 
 and will then be fully explained. 
 
EXERCISE 10. CHLORHYDRIC ACID. 
 
 47. Put 30 grams of dry, coarse salt into a flask of a liter capacity. 
 Arrange the apparatus as shown in the pattern. When you are sure that 
 the apparatus is all right, pour 50 grams of strong sulphuric acid upon the 
 salt, and immediately cork the flask, place it upon a sand bath on 
 the iron stand and connect the delivery tube with the Woulfe bottles. 
 
 Be sure that the tube from the flask does not dip into the water of the 
 first bottle. The contents of the flask must be very gradually and mod- 
 erately heated, else a violent frothing is liable to occur, which would 
 spoil the experiment. In your notes describe the apparatus ; and show 
 the use of safety tubes. 
 
 48. Perform Expt. 47, and while the gas is coining off disconnect 
 the flask for a moment and bring an open bottle of NH^HO into the 
 neighborhood. Also, while the experiment is going on, put into sepa- 
 rate test tubes small fragments of CaCl 2 and NH 4 C1, cover with strong 
 H 2 SC>4, warm gently and test for evolved gas by smell and by moistened 
 red and blue litmus paper. 
 
 49. Pour a few c. c. of the contents of the Woulfe bottle nearest the 
 flask into a test tube, add a strip of zinc and note the result. 
 
 50. To 5 c. c. of the contents of the first Woulfe bottle add 5 drops 
 of a solution of silver nitrate (AgNOs) and shake violently, and note the 
 result. Save the contents of the test tube. Put it into the jar provided 
 marked "silver residues." 
 
 51. Into each of two test tubes put a small bit of gold leaf. Into 
 one test tube put one or two c. c. of strong nitric acid ; into the other put 
 an equal quantity of strong chlorhydric acid. Warm gently. Finally 
 mix the contents of the two tubes. The mixture of nitric and chlorhy- 
 dric acid is known as aqua regia. 
 
 52. Place 10 c. c. of a solution of acetate of lead in a test tube and 
 add dilute HC1 until no further precipitation takes place. Let the pre- 
 cipitate settle, then pour off the liquid; add ten cr. c. of water to the 
 precipitate and boil for a minute or two, and then filter quickly but care- 
 fully, receiving the filtrate in a clean test tube kept warm by being im- 
 mersed in a beaker of hot water. When the liquid has filtered through, 
 remove test tube from the hot water and allow to cool. 
 
i6 
 
 EXERCISE II. OXYGEN AND OZONE. 
 
 53. In a clean bottle of i or 2 liters capacity place a piece of phos- 
 phorus 2 or 3 c. m. long, the surface of which has been scraped clean 
 (under water) with a knife ; pour water into the bottle until the phos- 
 phorus is half covered ; cover the bottle with a plate of glass and set it 
 aside in a place where the temperature is 20 or 30. Observe the ap- 
 pearance and odor of the contents of the bottle after 15 or 20 minutes. 
 Suspend in the bottle a strip of iodo-starch paper, and also a strip 
 of red litmus paper which is saturated with potassium iodide solution. 
 Explain the results. During this experiment perform those following. 
 
 54. Mix intimately 5 grams of potassium chlorate with 5 grams of 
 "black oxide of manganese," which has been previously well dried. 
 Place the mixture in a tube of hard glass, No. I, 12 or 15 c. m. in length. 
 Attach to this ignition tube, by means of a perforated cork or caoutchouc 
 stopper, a delivery tube of glass, No. 7, as in the model. Heat the mix- 
 ture in the ignition tube, and collect the gas which will be given off in 
 bottles or jars of the capacity of about 250 c. c. The first 100 c. c. or so 
 of gas should be rejected, since it will be contaminated with the air origi- 
 nally contained in the apparatus. Collect at least five bottles and one 
 test tube full of the gas for subsequent experiments. 
 
 In performing this experiment the following precautions should be 
 observed: i. Both the potassium chlorate and the manganese binoxide 
 should be perfectly dry and pure ; that is, free from moisture, dust or 
 particles of organic matter. They should not be ground together under 
 any circumstances. DANGER ! 2. As soon as the gas begins to be 
 delivered, the heat beneath the ignition tube should be diminished, if 
 need be, and so regulated that the evolution of gas shall be tranquil and 
 uniform. 3. The uppermost portions of the mixture should be heated 
 before the lower. 4. The ignition tube should never be filled to more 
 than one third its total capacity, lest solid matter be projected into the 
 delivery tube, and the outlet for the gas be thus stopped. 5. The igni- 
 tion tube should always be inclined and never placed upright in the 
 flame. 
 
 Place in a deflagrating spoon a bit of sulphur as large as a pea. Light 
 the sulphur and thrust it into a bottle of oxygen. 
 
 Burn a bit of phosphorus in oxygen in a similar manner, but with much 
 greater care. 
 
Place a piece of charcoal that of bark is best in a deflagrating 
 spoon. Kindle the charcoal by holding it in the flame of a lamp and 
 then introduce it into a bottle of oxygen. 
 
 Make into a spiral coil some fine iron wire or, better, a watchspring, 
 which has been rendered flexible by igniting it and allowing it to cool 
 slowly and to the end attach a bit of tinder or the tipped end of a 
 match. Light the kindling material and plunge the spiral into a jar of 
 oxygen in the bottom of which an inch or so of water has been left. 
 
 55. Support a rather wide tube of thin glass the neck of a broken 
 retort, for example in a vertical position and connect the upper open- 
 ing with a gas generator from which hydrogen is being evolved. Allow 
 the gas to flow until the tube is filled ; then apply a lighted match to the 
 mouth of the tube, and regulate the flow of gas so that the latter may 
 continue to burn slowly at the lower edge of the tube. Meanwhile, pre- 
 pare some oxygen as in Expt. 54, connecting the ignition tube with a 
 piece of narrow glass tubing, drawn out to a fine point; and, while the 
 oxygen is flowing through this tube, pass it up into the larger tube filled 
 with hydrogen. This experiment should be performed by two stu- 
 dents together as will be directed. 
 
 56. Dissolve a bit of potassium hydrate (KOH) hi a few c. c. of 
 water, add a teaspoonful of pyrogallic acid, and pour the solution into 
 the test tube containing the O, taking care that the O shall not escape. 
 Place the thumb over the end of the tube and shake. Notice the result. 
 Place the mouth of the tube under water and remove the thumb, and 
 observe what happens. 
 
 57. Heat some black oxide of manganese in a small matrass in the 
 blast lamp, and see whether oxygen is evolved. 
 
 EXERCISE 12. SULPHUR. 
 
 58. Place in a test tube, of about 30 c. c. capacity, 15 to 20 grams of 
 coarsely powdered sulphur ; melt the sulphur slowly over the gas lamp, 
 and continue to heat it until it begins to boil, noting, ' meanwhile, the 
 changes which the sulphur undergoes. Finally, pour the hot sulphur, 
 in a fine stream, into a large dish full of cold water, and examine its 
 appearance. 
 
 59. In a small beaker glass, or Hessian crucible, slowly heat 50 to 
 60 grams of sulphur until it has entirely melted. Remove the vessel 
 from the lamp and allow it to cool slowly until about a quarter part of 
 
i8 
 
 the sulphur has solidified; then pour off into a basin of water that por- 
 tion of the sulphur which is still liquid, breaking through, for this pur- 
 pose, the crust at the top of the liquid, if any such have formed. Show 
 the result. 
 
 60. In a test tube, melt enough sulphur to fill one quarter of the 
 tube ; place the tube in such a position that its contents may cool slowly 
 and quietly, and then watch the formation of crystals as they shoot out 
 from the comparatively cold walls of the tube towards the center of the 
 liquid. 
 
 61. Place i gram of sulphur in a dry test tube and pour upon it 
 5 c. c. of carbon bisulphide, cork tightly, and shake for a few moments. 
 [Carbon bisulphide is volatile and VERY INFLAMMABLE. HAVE NO LIGHTS 
 NEAR BY.] Pour a little of the clear solution upon a watch glass and 
 allow the carbon bisulphide to evaporate under the hood. Examine the 
 residue obtained. 
 
 62. Place a few bits of sulphur in a perfectly dry test tube and heat 
 gradually until the sulphur boils. Notice the sublimate. 
 
 63. Mix intimately 4 grams of flowers of sulphur and 7 grams of the 
 finest iron filings. Place the mixture in an ignition tube 10 to 12 c. m. 
 long, and heat the lower end of the tube gently over the gas lamp under 
 the hood. When chemical action once begins, take the tube out of the 
 flame. Don't be surprised if the tube breaks. 
 
 64. Heat a gram or so of sulphur in an ignition tube until it boils, 
 and allow a few bits of copper filings to fall into the melted sulphur. 
 
 65. Heat some powdered pyrite in a matrass. 
 
 EXERCISE 13. HYDROGEN SULPHIDE. 
 
 66. Put 10 or 12 grams of iron sulphide into a generator bottle. 
 Arrange the delivery tube so that it shall dip beneath the surface of 
 water contained in another (smaller) bottle. Through the thistle tube, 
 pour into the gas bottle water enough to seal the lower extremity of this 
 tube ; then add, through the thistle tube as before, 10 c. c. of strong 
 chlorhydric acid, and observe. When the disengagement of gas slackens, 
 a new portion of chlorhydric acid may be added through the thistle tube, 
 and this process continued until the water in the absorption bottle smells 
 strongly of the gas. 
 
 [The experiment must be performed under the hood.] 
 
19 
 
 67. To the delivery tube of the gas bottle employed in generating 
 hydrogen sulphide, attach a drying tube containing fragments of calcium 
 chloride, and with the tube connect a piece of No. 6 glass tubing drawn 
 out to a fine point. When the apparatus is full of the gas, apply a match 
 to the end of the tube. The gas will take fire. Hold a dry bottle over 
 the flame, and test the deposited moisture with litmus paper. 
 
 68. Put a drop of sulphureted hydrogen water on a bright piece of 
 lead, copper, or silver. 
 
 69. Dissolve a small crystal of lead nitrate in a test tube half full of 
 water, and to this solution add a few drops of the sulphureted hydrogen 
 water. 
 
 70. Take 20 c. c. of a solution of each of the following substances : 
 CuSO 4 , As 2 O 3 , SbCl 3 , ZnSO 4 , MnSO 4 , K 2 SO 4 . Place each solution in 
 a separate test tube and saturate each with H 2 S. Have solutions boiling 
 hot. Provide a short piece of delivery tube for each test tube, so that 
 there will be no danger of mixing the solutions. Observe what happens; 
 write the reactions. Then add I c. c. strong HC1 to each tube, shake, 
 and observe the effect. 
 
 71. Moisten a piece of filter paper with acetate of lead solution and 
 hold it near the delivery tube of an H 2 S generator. This is the test for 
 H 2 S. 
 
 72. Pass H 2 S through 10 c.c. of HNO 3 (i : i). 
 
 73. Prepare apparatus exactly as in Expt. 67, except make the tube 
 which ends in the jet straight and about 20 c. m. long. Heat this 
 tube gently with the Bunsen burner near the center while a stream of 
 H 2 S is passing through it, and observe the tube carefully. 
 
 EXERCISE 14. NITROGEN. 
 
 74. Into a small porcelain capsule, supported on a piece of stout 
 iron wire as will be shown, put about a cubic centimeter of phosphorus, 
 and set it on fire. Invert over the capsule a wide-mouthed bottle, of the 
 capacity of a liter or more, and hold this bottle so that its mouth shall 
 dip beneath the surface of the water. The dense white cloud which fills 
 the bottle at first is a compound of phosphorus and oxygen, which is 
 soluble in water. It will, therefore, soon be absorbed by the writer in 
 the pan, and will disappear. Remove the wire with the capsule, which 
 may be readily done by tipping the bottle to one side, taking care that 
 the mouth does not come out of the water, and slip a glass plate under 
 
2O 
 
 the mouth of the bottle ; invert the bottle so that it stands upright, and 
 thrust a burning splinter of wood or a lighted candle into the gas. 
 
 75. Take a piece of ignition tubing about 35 centimeters long, and 
 introduce into it enough copper turnings to fill loosely about 15 centim- 
 eters of its length. Support the tube upon one of the " furnace lamps," 
 resting the tube in an iron trough. Into one end of the tube fit a cork 
 through which passes a bent delivery tube leading to the water pan ; con- 
 nect the other end of the tube with a "gasholder bottle " similar to that 
 shown in the model. Light the furnace lamp and heat the tube gently 
 until the iron trough becomes red hot. Then pass a slow current of air 
 over the heated copper, which is accomplished by pouring water into the 
 gasholder bottle. Collect in bottles the gas which is delivered at 
 the water pan, and test it with lighted splinters. 
 
 76. Put 3 c. c. of ammoniacal cuprous chloride into a test tube, close 
 the end with the thumb, and shake vigorously. Invert the tube in the 
 water pan and remove the thumb. Note the result. Test the gas remain- 
 ing in the tube with a lighted splinter. 
 
 77. Determine accurately the contents of a narrow test tube in cubic 
 centimeters by filling it with water from a burette, and pour into the test 
 tube exactly 5 c. c. of potassium pyrogallate solution. Shake carefully 
 for several minutes, keeping the tube tightly closed with the thumb. 
 Now open under water as in Expt. 56, and allow the water to rise. Then 
 place the thumb underneath the tube and raise it from the pan and invert 
 it, still holding the thumb over the end. Determine the volume of the 
 unabsorbed gas by filling the tube with water from a burette. Calculate 
 the percentage of oxygen in the air by volume. 
 
 EXERCISE 15. AMMONIA. 
 
 78. Mix thoroughly 25 grams of ammonium chloride with an equal 
 weight of cold freshly slaked lime. Place the mixture in a flask of 500 
 c. c. capacity, cover with water, connect with a couple of Woulfe bottles, 
 as shown in the pattern, and then heat the flask. Describe the apparatus 
 and explain the action of the various tubes. When the experiment is 
 finished, examine the contents of the Woulfe bottles. Perform the 
 experiment under the hood if possible. 
 
 79. While Expt. 78 is going on, disconnect the flask for a moment 
 and bring an open bottle of strong HC1 into the neighborhood. Also, 
 fill a test tube with the gas by upward displacement close the mouth 
 
21 
 
 tightly with the thumb, place the tube, mouth downwards, in a vessel of 
 water, and then remove the thumb. 
 
 80. Mix together equal quantities of NH^NOs and CaH^O^ and 
 heat gently in a test tube. Test for evolved gas by smell and by mois- 
 tened red litmus paper. Also put a little solid NH^Cl and NH^NOg into 
 separate test tubes, cover with a solution of NaHO in each case, and 
 warm gently, testing as in previous instance. 
 
 82. Heat in an ignition tube 7 grams of fine iron filings and 0.5 gram 
 powdered KOH. Collect the gas in test tubes over the water pan, and 
 test it with lighted splinter. Perform the same experiment with 7 grams 
 of coarse iron filings and 0.5 gram KNO 3 . Now heat a mixture of 14 
 grams coarse iron filings, 0.5 gram KOH and 0.5 gram KNOa in a large 
 test tube, and test the gas evolved as in Expt. 79. 
 
 EXERCISE l6. PHOSPHORUS. 
 
 [Extreme care must be taken in all experiments with phosphorus.] 
 
 83. Put a piece of phosphorus as big as a grain of wheat upon a 
 piece of filter paper and sprinkle over it some lamp-black or powdered 
 bone-black. Allow it to stand for a while. 
 
 84. In a narrow glass tube, No. 6, about 30 c. m. long and closed at 
 one end, place a quantity of red phosphorus as large as a small pea; 
 heat the phosphorus gently over the gas lamp and note the character of 
 the sublimate which forms. When the tube is perfectly cold, cut it 
 off just below the sublimate and scratch the coating with an iron wire. 
 
 86. In order to observe the comparative difficulty of inflaming red 
 phosphorus, lay an inverted cover of a porcelain crucible upon an iron 
 triangle upon the lamp stand ; place upon the cover, at some distance 
 from each other, a small bit of ordinary phosphorus and an equal quan- 
 tity of red phosphorus ; heat the cover gently and gradually over the 
 gas lamp. [This experiment should be performed under the hood, if 
 possible.] 
 
 86. In a thin-bottomed flask of about 140 c. c. capacity, put I gram 
 of phosphorus and 115 c. c. of hydrate of sodium, obtained by dissolving 
 40 grams of common caustic soda in noc. c. of water. Pour two or 
 
three drops of ether upon the liquid in the flask, then close the flask 
 with a cork carrying a long delivery tube of glass, No. 5. Place the 
 flask over the gas lamp upon a piece of wire gauze, and immerse the end 
 of the delivery tube in the water pan ; then gently heat the flask. The 
 ether is added in order that the last traces of air may be expelled from 
 the flask by the heavy vapor into which this highly volatile liquid is 
 converted as soon as it is warmed. As soon as bubbles of gas begin to 
 be expelled, the heat should be moderated or the lamp wholly removed. 
 Perform the experiment under the hood, if possible. 
 
 EXERCISE i;. SULPHUROUS ANHYDRIDE. 
 
 87. Light a piece of sulphur in a deflagrating spoon and suspend the 
 latter in a two liter bottle full of air. Observe the odor. Immerse a 
 lighted taper in the gas obtained. 
 
 88. Place a pinch of copper filings in a test tube, cover with con- 
 centrated 113804, and warm GENTLY. Observe the odor of SOg. En- 
 deavor to bleach a rose or other flower, previously moistened, by holding 
 it in the fumes. 
 
 89. Repeat Expt. 88, but use charcoal in the place of the copper. 
 
 90. Charge a bottle, of the capacity of a liter or more, with sulphur- 
 ous acid by burning in it a bit of sulphur. Fasten a shaving, or, better, 
 a tuft of gun-cotton, upon a glass rod or tube bent at one end in the form 
 of a hook ; wet the shaving in concentrated nitric acid, and hang it in the 
 bottle of sulphurous acid. Interpret what you observe. 
 
 Pour a little BaCl2 solution into the bottle before beginning the 
 experiment, and notice its condition at the end after shaking the bottle. 
 Write the reaction. 
 
 91. Arrange a generator flask as shown in the model. Place in the 
 bottom 15 grams of charcoal and add 50 c. c. of concentrated H 2 SO4. 
 Warm gently upon a sand bath, and SOg will be evolved. Place 5 grams 
 of PbO2 in a piece of ignition tube, and pass a slow current of SO2 
 through the tube, and at the same time heat the tube containing the 
 PbOg moderately upon a furnace lamp. Perform this experiment imder 
 the kood. 
 
EXERCISE l8. SULPHURIC ACID. 
 
 92. Place in a pint bowl 30 c. c. of water; pour gradually into the 
 water 120 grams of concentrated sulphuric acid, stirring the mixture with 
 a narrow test tube containing a few c. c. of water. So much heat will be 
 evolved during the union of the water and the acid that the water in the 
 test tube may actually boil. Save the dilute acid. * 
 
 93. Pour 30 grams of strong H 2 SC>4 upon 120 grains of snow, and 
 observe the temperature of the mixture with the thermometer. 
 
 94. Repeat Expt. 93, but use 120 grams of H 2 SC>4 and 30 grams of 
 snow. Save the acid. 
 
 95. Into a test glass pour a tablespoonful of sulphuric acid, and 
 immerse in it a splinter of wood. 
 
 96. Place 5 grams of sugar in an evaporating dish and pour 10 c. c. 
 of strong sulphuric acid upon it. 
 
 97. Place 27 c. c. of water in a beaker, and add slowly 73 c. c. of 
 concentrated H 2 SC>4. When cool, transfer the mixture to a graduate, 
 and note the volume. Save the acid. 
 
 98. Pour a few drops of H 2 SO4 into a test tube and dilute with 20 
 c. fi. of \vater. Add a little BaCl 2 solution, and observe the effect. This 
 is the test for HgSO^ (See Expt. 90.) 
 
 99. Dissolve a crystal of PbN 2 O 6 in water in a test tube, and add a 
 few drops of dilute H 2 SC>4. 
 
 100. Boil 0.2 gram flowers of sulphur with I c. c. concentrated 
 HNOs, dilute with 20 c. c. of water, and add a few drops of BaCla 
 solution. 
 
 EXERCISE 19. PHOSPHORIC ACID. 
 
 101. Dry thoroughly a large porcelain plate, a small porcelain cap- 
 sule, and a wide-mouthed bottle of two liters capacity. Put in the capsule 
 a bit of dry phosphorus, of the weight of about half a gram, and place 
 the capsule on the plate; light the phosphorus, and cover it at once with 
 the inverted bottle. Drop a little of the white powder obtained into water. 
 Test the solution with litmus paper. 
 
 102. Touch a piece of blue litmus paper to a piece of moist phos- 
 phorus. 
 
 103. To 10 c. c. of Na 2 HPO 4 solution add BaCl 2 in excess. Filter 
 the mixture, and test the solubility of the precipitate in ammonia water 
 and in dilute chlorhydric acid. 
 
104. (I) To 2 c. c. of Na 2 HPO 4 add 10 c. c. of water, and 2 c. c. of 
 NH 4 C1, and i c. c. of ammonia water. Now add slowly 3 c. c. of a mixed 
 solution containing MgSO 4 and NH 4 C1. Observe carefully under the 
 microscope the character of the precipitate formed. Filter and test as 
 in 103. 
 
 105. (II) To 5 c.c. of Na 2 HPO 4 , add AgNO 3 solution in slight 
 excess. Note the color of the precipitate. Filter and test its solubility 
 in ammonia water, dilute nitric acid and dilute chlorhydric acid. Save 
 the silver residues. 
 
 106. (Ill) To a few c. c. of Na 2 HPO 4 add an equal volume of 
 a solution of molybdate of ammonium in nitric acid. [The last three 
 experiments are the usual tests for phosphoric acid and phosphates.] 
 
 107. To a few c.c. of Na 2 HPO 4 add a few c. c. of ferric chloride 
 solution. Now add ten c. c. of NaC 2 H 3 O 2 solution, and observe the 
 effect. Test the solubility of the precipitate in HC1 and in HO(C 2 H 3 O). 
 
 108. Weigh a small porcelain dish very carefully. Next weigh out 
 15 grams of crystallized sodic phosphate and place it in the dish. Heat 
 carefully over the burner until the substance is reduced to a white mass, 
 and then weigh. Heat again for a few moments, and repeat the weighing 
 until the weight of the dish containing the substance shows no further 
 diminution. Calculate the per cent of water that has been driven out. 
 Fuse a little of the dry substance on platinum foil and then dissolve it in 
 water and add AgNO 3 , and compare the precipitate with that obtained 
 in Expt. 105. Ask for explanation. Save the silver residues. 
 
 EXERCISE 20. NITRIC ACID. 
 
 109. Into a tubulated glass-stoppered retort of 250 c. c. capacity put 
 40 grams of powdered potassium nitrate, or, better, 34 grams of powdered 
 sodium nitrate, if it can be obtained ; and through the tubulure pour 50 
 grams of strong sulphuric acid, which has been weighed out in a bottle 
 previously counterpoised upon the balance with shot or coarse sand. 
 Imbed the bottom of the retort in sand contained in a small iron pan 
 placed over the gas lamp on a ring of the iron stand. Thrust the neck 
 of the retort into a flask of from 500 to 700 c. c. capacity ; the retort neck 
 should fit quite loosely in the neck of the flask in order to avoid the pos- 
 sibility of any pressure being created within the retort during the opera- 
 tion. Place the flask in a pan of cold water, and cover it with cloth or 
 
25 
 
 bibulous paper, which must be kept wet during the distillation. Heat 
 the sand bath moderately (that the frothing which occurs may not become 
 too violent). When all frothing has ceased, and the mass in the retort is 
 in a state of tranquil fusion, while very little liquid passes over into the 
 receiver, the lamp is to be put out. Allow the retort to cool on the sand 
 bath, and do not attempt to wash it out. 
 
 Transfer the nitric acid to a tared beaker and weigh. Put the acid 
 into the bottle prepared for it. Calculate the amount which should be 
 obtained theoretically. Save the acid for further experiments. 
 
 110. To i c. c. of the nitric acid of Expt. 109 add 10 c. c. of water. 
 Touch a drop of the mixture to the tip of the tongue. Dip a piece of 
 blue litmus paper into the liquid. 
 
 111. Dissolve about one gram of caustic potash in 20 c. c. of water. 
 Rub a little of the solution between the fingers. To one c. c. of this solu- 
 tion add 20 c. c. of water, and cautiously taste of it. Immerse a piece of 
 red litmus paper in it. 
 
 112. Into a flask of about 500 c. c. capacity put 50 c. c. of strong 
 nitric acid and 5 grams of starch. Warm the flask gently, and as soon 
 as the mixture begins to turn reddish brown remove the lamp. The 
 experiment must be performed under the hood. When the flask is cool, 
 fill it with water and empty it into the sink under the hood. 
 
 113. Treat a piece of lead foil in a test tube with HNO 3 , strong and 
 dilute, and observe the result. 
 
 114. To 5 c. c. of indigo solution in a test tube, add i c. c. of HNOa 
 and warm. 
 
 EXERCISE 21. NITRIC ACID. 
 
 [Hereafter write the equations when possible.] 
 
 115. To 5 c. c. of nitric acid, diluted with twice its bulk of water, 
 add cautiously a rather dilute solution of caustic potash (potassium 
 hydrate, KHO) until the mixture turns litmus paper neither red nor blue. 
 Evaporate the solution in a porcelain dish, taking care that the liquid 
 does not actually boil, until a drop taken out on the end of a glass rod 
 becomes nearly solid on cooling. Then remove the lamp, and allow the 
 dish to become cold. Show the result, and learn the significance of the 
 experiment. 
 
 116. Take 5 c. c. of the nitric acid, diluted as in Expt. 115, then add 10 
 grams of PbO. Warm the mixture and filter the liquid, while hot, into 
 
26 
 
 another evaporating dish. Evaporate the solution carefully, but take 
 away the lamp when four fifths of the liquid have disappeared. 
 
 117. Fill a perfectly dry ignition tube about one third full of lead 
 nitra'.e which has been finely powdered and thorottghly dried. Connect 
 the ignition tube with a dry bottle and finally with the water pan, as 
 shown in the model. The small bottle must be surrounded by a mixture 
 of ice (or snow) and salt. Heat the ignition tube gently, and when the 
 evolution of gas has once begun, care must be taken that the tube is not 
 suffered to cool, so as to allow the water to suck back from the water 
 pan. Red fumes will fill the delivery tubes, and will condense in the 
 small bottle to a brownish yellow liquid if the experiment is successful. 
 Test the gas which collects at the water pan. 
 
 118. Neutralize I c. c. of dilute nitric acid with ammonium hydrate, 
 evaporate to dryness, and heat a portion of the residue gently upon 
 platinum foil. 
 
 EXERCISE 22. OXIDES OF NITROGEN. 
 
 119. Into a dry flask of thin glass of about 300 c. c. capacity, intro- 
 duce 10 or 15 grams of ammonium nitrate. From the flask carry a 
 delivery tube, No. 6, to the water pan ; but interrupt the tube at some 
 convenient point to interpose, by means of a cork or caoutchouc stopper 
 with two holes, a small bottle, which can be kept cool with water. Heat 
 the flask moderately and cautiously. When gas begins to escape from 
 the melted mass, the heat must be so controlled that the evolution of the 
 gas shall not be tumultuous. Collect the gas in bottles of 300 to 
 400 c. c. capacity. When two bottles of gas have been filled, the delivery 
 tube may be withdrawn from the water and the lamp extinguished. 
 
 Insert a glowing splinter of wood into a bottle of the gas. 
 
 Burn a bit of sulphur in nitrous oxide. 
 
 Test the liquid collected in the interposed bottle. 
 
 120. Heat a bit of ammonium nitrate gently on platinum foil, and 
 note the result. 
 
 121. Place 15 or 20 grams of copper turnings or filings in a bottle 
 arranged precisely as for generating hydrogen, and pour about 25 c. c. of 
 dilute nitric acid made by adding to the common strong acid its own bulk 
 of water. Collect three bottles, of 300 to 400 c. c. capacity, of the evolved 
 gas, adding acid from time to time as may be necessary. Save the blue 
 solution (copper nitrate) which remains in the generator. 
 
27 
 
 122. Dip a lighted candle into a bottle of the gas. Into the same 
 bottle thrust a glowing splinter. 
 
 123. Lift a bottle of the gas from the water so that air may enter 
 the bottle and the gas may escape into the air. Bring into contact with 
 the fumes a piece of moistened litmus paper. 
 
 124. Thoroughly ignite a bit of sulphur in a deflagrating spoon, and 
 introduce it into a bottle of the gas. Into the same bottle thrust a piece 
 of phosphorus as big as a pea, burning actively. 
 
 125. Fill a test tube with a concentrated acid solution of ferrous 
 sulphate. Invert the tube in a water pan over a delivery tube, from 
 which NO is issuing. When half of the liquid has been driven from the 
 tube, place your thumb over the bottom and remove the tube from the 
 pan and shake. Boil the contents of the tube. Notice all the changes. 
 
 EXERCISE 23. CARBON. 
 
 t!26. Put into an ignition tube 12 or 15 c. m. in length, enough 
 tuminous coal, in coarse powder, to fill one third of the tube. Fit to 
 this ignition tube a large delivery tube, and support the apparatus upon 
 the iron stand, having the ignition tube nearly horizontal. Heat the 
 tube and collect in bottles the gas which will be evolved. Test the gas 
 with a lighted match. 
 
 As soon as gas ceases to be given off from the coal, take the end of 
 the delivery tube out of the water, and when the ignition tube has 
 become cold, break it and examine the coke which it contains. 
 
 127. Repeat the previous experiment, using wood shavings or saw- 
 d*ust instead of coal. Collect and test the gas evolved. After the flow 
 of gas has ceased, remove the end of the delivery tube from the water, 
 plug it so that no air can enter the ignition tube, and lay the apparatus 
 aside until it has become cold. Finally remove the cork from the ignition 
 tube and take out the charcoal which is contained in it. Heat a portion 
 of this charcoal upon platinum foil and note the manner in which it 
 burns. 
 
 128. Over a burning candle invert a wide-mouthed bottle of the 
 capacity of a liter or more, one edge of the mouth of the bottle being 
 propped up on a small block of wood, so that some air may enter the 
 bottle. Explain the formation of lamp-black. Also press down upon 
 the flame of an oil lamp or candle an iron spoon or a porcelain plate in 
 
such manner that the flame shall be almost, but not quite, extinguished. 
 Explain the results. 
 
 129. Mix two and a half grams of copper oxide with a quarter of 
 a gram of powdered charcoal ; place a portion of the mixture in an igni- 
 tion tube, and heat it strongly in the gas lamp. Test the gas evolved, 
 and examine what is left in the tube. 
 
 130. Take from the fire a piece of charcoal which has been heated 
 to full redness for some time ; thrust it under water so that it may be 
 suddenly cooled, and compare its behavior with that of a piece of common 
 charcoal. Also, attach a lead sinker to a piece of common charcoal and 
 sink it in a beaker of warm water. 
 
 131. Put a small quantity of powdered charcoal into a bottle con- 
 taining hydrogen sulphide, close the bottle tightly with the palm of the 
 hand and shake for a few moments. Observe how much the odor is 
 affected ; observe other attendant phenomena. 
 
 132. Provide four small bottles of the capacity of 100 or 200 c. c., 
 and place in each of them a tablespoonf ul of bone-black ; into the first 
 bottle pour a quantity of the blue compound of iodine and starch obtained 
 in Expt. 39 ; into the second, a decoction of cochineal ; into the third, a 
 dilute solution of soluble indigo blue ; into the fourth, a solution of blue 
 litmus, of logwood, or indeed of almost any other vegetable coloring 
 matter; enough of the solution being taken in each instance to nearly 
 fill the bottle. Cork the bottles and shake them violently, then pour the 
 contents of each upon a filter and show the several filtrates. 
 
 133. Mix 4 grams of potassium nitrate with 2 grams of powdered 
 charcoal. Place the mixture upon an iron plate and touch it with a 
 lighted stick. Perform this experiment under the hood. 
 
 EXERCISE 24. CARBONIC ACID. 
 
 134. Place a live coal (charcoal) upon a deflagrating spoon and 
 thrust it into a bottle full of air, or, better, oxygen gas ; when the coal 
 has ceased to glow, pour into the bottle some lime water a solution of 
 common slaked lime in water and shake the bottle. 
 
 135. Mix ii grams of red oxide of mercury with 0.33 gram of char- 
 coal ; heat the mixture in an ignition tube, and collect over water the gas 
 which is evolved. Test the product with lime water, as in Expt. 134. 
 Examine what is left in the tube. 
 
2 9 
 
 136. In a gas bottle of 500 or 600 c. c. capacity, arranged precisely 
 as for generating hydrogen, place 10 or 12 grams of carbonate of calcium 
 (marble or limestone). Cover the end of the thistle tube with water and 
 then add strong chlorhydric acid by small portions, in such quantity as 
 shall insure a continuous and equable evolution of gas. Collect several 
 bottles of the gas over water, then replace the anterior portion of the 
 delivery tube with a straight tube and collect one or two bottles of the gas 
 by downward displacement. 
 
 137. Thrust into a bottle of the gas, obtained in Expt. 136, a lighted 
 candle, or, better, a large flame of alcohol burning upon a tuft of cotton. 
 
 138. From a large bottle full of the gas, pour a quantity of carbonic 
 acid upon the flame of a lamp or candle ; that is to say, hold the mouth 
 of the open bottle of carbonic acid obliquely over the candle flame, so 
 that the gas shall fall like water upon it. 
 
 139. Take a beaker of about 300 c. c. capacity and balance it, very 
 carefully, upon the pan of a balance. Fill a large dry bottle with CC2 
 and pour it into the beaker. Notice the increase of weight. 
 
 140. Into a long-necked flask or phial filled with carbonic acid, 
 pour a quantity of water, close the bottle with the finger, and shake it; 
 immerse the mouth of the bottle in water and remove the finger ; water 
 will rush into the bottle to supply the place of the gas which has been 
 dissolved. Again place the finger upon the mouth of the bottle, shake 
 the bottle as before, and subsequently open it beneath the surface of the 
 water, and so on. 
 
 141. Fill a test tube, by displacement, with CO 2 . Pour in 5 c. c. 
 of a solution of KOH, place your thumb over the end, and shake. 
 Immerse the tube in the water pan and remove your thumb. 
 
 142. Dissolve 10 grams of honey or molasses in 100 c. c. of water; 
 fill a large test tube with the mixture and add to it a few drops of bakers' 
 or brewers' yeast ; close the open mouth of the test tube with the thumb 
 and invert it in a small saucer or porcelain capsule filled with the diluted 
 syrup. Place the saucer and tube, with their contents, in a warm place, 
 having a temperature of about 20 or 30, and leave them there during 24 
 hours. In a short time fermentation sets in, and the sugar of the syrup 
 is gradually converted into alcohol and carbonic acid. 
 
 143. Take two small bottles and into each put 15 or 20 c. c. of clear 
 lime water. Through one of the bottles force a stream of ordinary air 5 
 through the other force a stream of air from the lungs. 
 
EXERCISE 25. MARSH GAS, ETC. 
 
 144. Mix together 2 grams of crystallized sodium acetate, 4 grams of 
 caustic soda, and 8 grams of slaked lime. Heat the mixture gently upon 
 an iron plate, until all the water of crystallization of the acetate has been 
 expelled and the mass has become dry and friable. Charge an ignition 
 tube 20 c. m. long with the dry powder, heat it above the gas lamp, and 
 collect the gas at the water pan. Marsh gas is evolved from the mixture, 
 at a temperature below redness, and a residue of sodium carbonate is 
 left in the ignition tube. The purpose of the lime is to render the mass 
 porous and infusible, or nearly infusible, so that the tube may be heated 
 equably. Attempt to write equation. 
 
 145. Fill a tall bottle of at least one liter capacity with warm water, 
 invert it over the water pan and pass marsh gas into it, until a little more 
 than one third of the water is displaced ; cover the bottle with a thick 
 towel, to exclude the light, and then fill the rest of the bottle with chlo- 
 rine. Cork the bottle tightly, and shake it vigorously, in order to mix 
 the gases together, keeping the bottle always covered with the towel. 
 Finally, "open the bottle and apply a light to the mixture. After the 
 action has taken place test the moisture on the sides of the bottle. 
 
 146. Mix 8 grams of powdered magnesium carbonate with 16 grams 
 of zinc dust. Place the mixture in an ignition tube, tapping it so as to 
 leave a passage over the top for the gas which will be evolved. Heat 
 strongly on a furnace lamp and collect the gas in the ordinary manner 
 over the water pan. Test the gas. 
 
 147. Heat 4 grams of CuO in a piece of ignition tubing over a fur- 
 nace lamp and pass a stream of CO over the hot oxide. Collect the gas 
 over water and test with a lighted splinter and with lime water. 
 
 148. Sprinkle fine iron filings into the flame of an alcohol lamp or 
 into the non-luminous flame of the gas lamp. Also, rub together two 
 pieces of charcoal above a non- luminous flame, in such manner that 
 charcoal powder shall fall into the flame. 
 
 149. Press down a piece of white letter paper, for an instant, upon 
 the flame of a candle until it almost touches the wick, then quickly 
 remove the paper before it takes fire and observe how its upper surface 
 is charred. 
 
 150. Study the flame of a candle. Thrust the phosphorus end of 
 a match into the flame, and see whether you can withdraw it without 
 lighting the match. 
 
EXERCISE 26. SILICON AND BORON. 
 
 151. To a concentrated solution of water glass contained in a small 
 evaporating dish, add enough strong chlorhydric acid to make the solu- 
 tion acid. There will separate a thick jelly-like mass of silicic acid 
 (1148104). Evaporate the contents of the dish to dryness on a water 
 bath and then heat the residue gently over the gas lamp. The mass will 
 contract in bulk and, on adding water, there will remain undissolved 
 a fine white powder of silicic anhydride. 
 
 152. Take a very dilute solution of water glass and add dilute chlor- 
 hydric acid drop by drop until the liquid has a decidedly acid reaction. 
 Compare the result with that of the first part of the previous experiment. 
 
 153. Into a perfectly dry matrass put a small quantity of a mixture 
 of equal quantities of quartz and powdered fluor-spar. Moisten with a 
 drop of strong sulphuric acid and heat in the flame of a lamp. Hold 
 a drop of water in a loop of platinum wire at the mouth of the tube. 
 Show result and see blackboard for reactions. This shows how to recog- 
 nize silicon in its compounds. 
 
 154. Dissolve 4 grams of powdered borax in 10 grams of boiling 
 water, in a beaker glass or porcelain capsule of 30 or 40 c. c. capacity, 
 and add to the solution 5 c. c. of concentrated chlorhydric acid. Allow 
 the solution to cool. 
 
 155. Dissolve a little crystallized boracic acid in a teaspoonful of 
 alcohol in a small porcelain capsule. Set fire to the alcohol and stir the 
 burning solution with a rod or agitate it by jarring the dish. Repeat, 
 using borax instead of boracic acid. Now put 3 c. c. of H 2 SC>4 upon a 
 small portion of borax; and then add 3 c. c. of alcohol. Light the mix- 
 ture and note the result. What does the experiment show ? 
 
 156. In a clean iron spoon heat some crystallized boracic acid. The 
 crystals will melt, and if the heat be continued, the mass will become 
 pasty and will swell up as the water is expelled. After all the water has 
 been driven off by strong heat, the anhydride is left as a clear, viscous 
 liquid, from which long threads may be drawn out by touching to*the 
 surface of the liquid the end of a stick or glass rod and then gently pull- 
 ing away the stick with the matter which has adhered to it. Allow the 
 fused mass to cool, and examine its appearance. 
 
EXERCISE 27. SOLUBILITY. 
 
 [Prepare a wash bottle and a couple of stirring rods. See models.] 
 Solubility in water. 
 
 1. Weigh 3 portions of I gram each of powdered Na 2 SO 4 , CaSO 4 , 
 and PbSO 4 . Take three test tubes and place in each 10 c. c. of water. 
 Into one of the tubes pour one portion of Na 2 SO 4 and shake, and, if this 
 dissolves, add the second, and if the second dissolves, add the third. 
 Repeat the process with the CaSO 4 and PbSO 4 in the other tubes. If, 
 however, the first lot fails to dissolve, ascertain whether any dissolves by 
 filtering (see Appendix, 15) some of the mixture very carefully and 
 evaporating a few drops of the filtrate on a clean slip of platinum foil. 
 
 Solubility in hot and cold water. 
 
 2. Weigh 4 portions of i gram each of powdered BaN 2 O 6 . Place 
 10 c. c. of water in a test tube and add one portion and shake. Note the 
 result. Warm slowly, and as often as the salt is entirely dissolved add 
 a new portion of i gram. Finally, bring the liquid to boiling. What 
 does the experiment show ? 
 
 Comparison of solubility in water. 
 
 3. [The salts must all be powdered ! ] Take 5 test tubes and place in 
 each 10 c. c. of water. Into a test tube put 12 or 15 grams of potassium 
 carbonate (KgCOg). Weigh the tube and contents and record the weight. 
 From this test tube pour successive small portions of K 2 COs into one of 
 the test tubes containing water as long as it will dissolve. Again weigh 
 the test tube and contents. The loss in weight will be the weight of the 
 K 2 CO3 dissolved in the water. Calculate the number of parts of the salt 
 which have dissolved in 100 parts of water. In like manner test the sol- 
 ubility of KNO 3 , K 2 SO 4 , SrSO 4 , and BaSO 4 , starting with 5 grams of the 
 first, 3 grams of the second, and i gram of the third and fourth. Bring 
 the results of the experiment into the form of a table. (See blackboard.) 
 
 4. [For students who are doing extra work.] Measure and pour into 
 a fl^sk 100 c. c. of water. Insert a thermometer in the flask by means 
 of a perforated cork so that the temperature can be accurately observed. 
 Note the temperature. Add Na 2 SO 4 in weighed portions of 2 grams 
 each until no more can be dissolved after thorough shaking, and make 
 note of the amount required. Raise the temperature by means of a lamp 
 underneath to 15, remove the lamp and then add portions of 2 grams of 
 NaaSO 4 until you have determined the amount soluble at this tempera- 
 
33 
 
 ture. Now raise to 20 and repeat the operation. Finally raise also to 
 25, 30, 35, 40. Make careful'note of the amount added at each point 
 and the total amount in solution at each temperature. Plot a curve of 
 solubility upon a piece of cross section paper similar to the example upon 
 the blackboard. This curve must be handed to the professor before the 
 next exercise. 
 
 EXERCISE 28. SOLUBILITY. 
 
 State clearly what is taught by each of the experiments 
 which follow. 
 
 Use of different solvents. 
 
 5. Compare the solubility of bone ash in H 2 O, dilute HC1, and dilute 
 H 2 SO 4 . 
 
 6. Compare the solubility of iodine in water, alcohol, and carbon 
 disulphide. Apply no heat. In such cases as this it is advisable to take 
 exceedingly small quantities of iodine and drop them into about 3 c. c. 
 of the liquid ; and watch the rapidity with which the iodine disappears, 
 and judge from this in which liquid it is the most soluble. 
 
 7. Compare the solubility of NaCl in H 2 O, strong HC1 and alcohol. 
 
 Solubility in Mixtures. 
 
 8. Attempt to dissolve I gram of BaClg in 3 c. c. of strong HC1. 
 Finally add 10 c. c. of water. 
 
 9. Dissolve 2 grams of NaaSO^ in 4 c. c. of water, and add an equal 
 volume of alcohol. 
 
 10. Dissolve 0.5 gram iodine in 2 c. c. alcohol and add 5 c. c. of 
 water. 
 
 Neutralization of the solvent. 
 
 11. Take some calcium phosphate, dissolve in warm dilute HC1, and 
 then add ammonia to alkaline reaction. Repeat the experiment, using 
 oxalate of barium. 
 
 12. Dissolve a little AgCl in ammonia water and add dilute HNOs 
 to acid reaction. 
 
 Absorption and development of heat. 
 
 13. Place 25 c. c. of strong HC1 in a beaker. Note the temperature 
 of the acid ; dissolve 20 grams of Glauber's salt in the acid, and again 
 note the temperature. 
 
34 
 
 14. Place 10 c. c. of water in a small beaker. Note the temperature. 
 Dissolve 10 grams of KOH in the water and again note the temperature. 
 
 EXERCISE 29. SOLUBILITY. 
 Saturation. 
 
 15. Heat together 10 grams of alum and 8 c. c. of water, and allow 
 to cool. Pour off the clear liquid and boil it for a few moments, and 
 allow to cool again. 
 
 16. Place 10 grams of sodic acetate in a test tube, add 10 c. c. of 
 water, and warm until the sodic acetate has entirely dissolved. Place a 
 little cotton-wool in the mouth of the tube, set it aside, and allow to cool 
 perfectly without moving. The liquid should be clear. Now drop into 
 the liquid a small crystal of sodic acetate and observe the effect. 
 
 26. See exercise 30. Begin the experiment at this place. 
 
 Solution of liquids. 
 
 17. Test the solubility of the following liquids in water: alcohol, 
 ether, olive oil, glycerine, carbon bisulphide. Proceed in each case as 
 follows : Take 5 c. c. of water in a clean test tube ; pour I c. c. of the 
 liquid to be tested upon the water in the tube. Shake several times, and 
 then observe the depth of the liquid layer above or below the water, if 
 any such layer there be. Ether and carbon bisulphide are very inflam- 
 mable and very volatile, and must not be brought anywhere near a flame. 
 
 18. Test the solubility of benzol in water and alcohol. 
 
 Physical and chemical solution. 
 
 19. Take two portions of 5 grams each of sal-soda. Dissolve one 
 portion in 10 c. c. of water, evaporate to dryness slowly, and compare the 
 substance obtained with the original salt in appearance, crystalline form, 
 and taste. Dissolve the second portion in dilute chlorhydric acid, evap- 
 orate and compare. 
 
 20. Place 5 c. c. of alcohol in a test tube and add I c. c. of HC1, and 
 shake. Drop a small piece of fused potassium carbonate into the tube. 
 Place 5 c. c. of water in a test tube and add I c. c. of HC1. Drop a small 
 piece of fused potassium carbonate into this tube. Explain. 
 
 2 1 Repeat Expt. 20, but use marble instead, of potassium carbonate. 
 
35 
 
 EXERCISE 30. CRYSTALLIZATION. 
 
 Crystallization by solution. 
 
 22. Put about 0.5 gram PbClg into a test tube with some 10 c. c. of 
 water. Boil for a minute or two, and then filter quickly but carefully, 
 receiving the filtrate in a clean test tube kept warm by being immersed in 
 a beaker of hot water. When the liquid has filtered through, remove the 
 test tube from the hot water and allow to cool. Examine the product 
 under a microscope. 
 
 23. Place 5 grams of oxalic acid in a test tube, and add 10 c. c. of 
 water. Heat until the acid has dissolved, and then allow to cool. 
 
 Crystallization by sublimation. 
 
 24. Heat a small lump of benzoic acid gently in a dry test tube. 
 Repeat Expts. 36 and 62. 
 
 Crystallization by precipitation. 
 
 25. To a few drops of concentrated common salt solution add 5 c. c. 
 of alcohol. Examine the precipitate under the glass. 
 
 Crystallization by solution and evaporation. 
 
 26. Place upon small watch glasses i c. c. each of solutions of potas- 
 sium nitrate, potassium chlorate, potassium chromate, mercuric chloride, 
 and sodium acetate, and allow the glasses to stand in your desk until the 
 next exercise. Then observe carefully with the lens the forms of crystals 
 obtained. 
 
 Piirification by crystallization. 
 
 27. Weigh 25 grams of soda ash. Place in a beaker, and pour upon 
 the ash 50 c. c. of water. Heat until the ash has dissolved, filter the tur- 
 bid solution while hot, and allow to cool. Remove some of the crystals, 
 place in an evaporating dish, and heat until they are reduced to a fine 
 powder. Compare this powder with the original ash. . 
 
 Water of Crystallization. 
 
 28. Grind together in a mortar 4 grams of crystallized sodium sul- 
 phate (Glauber's salt) and 2 grams of potassium carbonate. 
 
 29. Heat a crystal of copper sulphate in a test tube until no more 
 steam passes off. Also repeat Expt. 9. What is taught ? Heat a crystal 
 of common salt in a test tube. How does it differ from the former case ? 
 Why? 
 

 EXERCISE 31. SODIUM AND AMMONIUM SALTS. 
 
 157. Cover the bottom of a large bottle (at least a liter bottle) with 
 hot water, drop in a piece of sodium as large as a small pea, and imme- 
 diately cover the mouth of the bottle with a card or glass plate. Test 
 the liquid with litmus paper. Also perform the experiment using cold 
 water. 
 
 158. Place a bit of sodium upon charcoal, and ignite by means of 
 the blow-pipe. 
 
 159. Wrap a bit of sodium in tissue paper and lay it upon a piece of 
 ice. 
 
 160. Place in a test tube 5 c. c. of concentrated NaOH, and add 
 slowly 5 c. c. of strong HC1. Write the equation. 
 
 161. Weigh out exactly 9 grams of fine salt, and add it to 25 c. c. 
 (measured) of water at the ordinary temperature. Shake until the salt 
 has dissolved, then add another gram. If this fails to dissolve, bring the 
 mixture to boiling. If all dissolves, show the solution. 
 
 162. Heat a crystal of NaCl upon platinum foil. State what action 
 takes place and why. Observe the color of the flame due to the presence 
 of sodium. 
 
 163. Mix i gram of powdered anhydrous Na 2 SC>4 with an equal 
 weight of powdered charcoal. Add a few drops of water and make a 
 paste. Heat a portion of this paste before the blow-pipe on charcoal 
 as strongly as possible. The Na 2 SO4 will be reduced to Na 2 S. Treat 
 a piece of the fused mass with dilute HC1. Also place a bit upon a 
 silver coin and moisten with a drop of water. 
 
 164. Soda by lime. Dissolve 15 grams of crystallized sal-soda in 
 60 c. c. of water. Mix 4 grams of slaked lime with 15 c. c. of water. 
 Heat the solution of sal-soda in an iron dish nearly to boiling, and add 
 slowly the milk of lime, and boil for a few moments. 
 
 Na 2 CO 3 + CaH 2 O 2 = 2 NaHO -f CaCO 3 . 
 
 By decantation and evaporation the liquor obtained will yield NaOH. 
 Pour the liquid from the iron dish into a beaker, allow to settle, decant 
 a portion of the clear liquor back into the iron dish, and evaporate until 
 the NaOH separates. 
 
 165. To a few cubic centimeters of a solution of ammonium chloride 
 
37 
 
 in a test tube, add a few drops of a solution of caustic soda, and boil the 
 liquid. Observe the odor. 
 
 What similar experiment has already been performed ? 
 
 166. Place a bit of sal-ammoniac in the bottom of a dry test tube 
 and heat it slowly. Place bits of litmus paper at different positions in 
 the test tube, and notice the action. Ask for explanation. 
 
 EXERCISE 32. AMMONIUM SALTS AND POTASSIUM. 
 
 [Those who did not perform experiments 165 and 166 will do so before 
 proceeding.] 
 
 167. Mix thoroughly 5 grams of NH^Cl and 10 grams of CaCOs by 
 grinding in a mortar, and heat in a small evaporating dish upon a sand 
 bath under the hood. As soon as white fumes begin to rise place a large 
 dry bottle or funnel over the dish and collect the white sublimate. Test 
 this for a carbonate. 
 
 While the experiment is going on proceed with other experiments. 
 
 168. Place 100 grains of wood ashes on a filter and pour hot water 
 over them, collecting the filtrate in a bottle and returning it upon the 
 ashes two or three times, in order to obtain a strong solution. To exhaust 
 the ashes of their potash they must, of course, be treated with successive 
 portions of hot water. Test the solution with litmus paper and then 
 evaporate it to dryness while succeeding experiments are being per- 
 formed. Finally weigh the residue obtained and calculate the per cent 
 of soluble matter in the ash. Treat the residue with HC1 after the 
 weight has been recorded. 
 
 169. Heat in a dry test tube strongly 3 grams of potassium tartrate. 
 When the tube has become cool pour in boiling water, shake and filter. 
 Add acid to the filtrate and notice that CO 2 is given off. This illustrates 
 the formation of K 2 CO8 in the ashes. 
 
 170. Throw a piece of potassium, as large as a small pea, upon 
 some cold water in the bottom of a large bottle, and place a card or glass 
 plate over the mouth of the bottle. Test the liquid with litmus paper. 
 
 171. To a gas bottle in which carbonic acid is being steadily evolved 
 according to Expt. 136, attach a chloride of calcium tube, and beyond 
 
38 
 
 this drying tube a short tube of hard glass, from which an exit tube leads 
 into a small open bottle. When the extinction of a lighted match in 
 the open bottle proves the apparatus to be full of carbonic acid, thrust 
 into the hard glass tube a bit of potassium as big as a pea, previously 
 dried between folds of blotting paper; then gently heat the potassium 
 with a lamp. When the tube has become cold, place it in a tube or 
 bottle of water, filter the solution, note the appearance of the particles 
 in the filter, evaporate the filtrate to dryness, add a few drops of dilute 
 HC1. 
 
 172. Test for potassium. I. Dip a platinum wire in a solution of 
 KC1, and place the wire in the flame of a Bunsen burner. 2. To I c. c. 
 of a solution of KC1 add i drop of PtCl 4 . 3. Place in a test tube 
 3 c. c. of KC1 solution, add an equal volume of a solution of tartaric acid, 
 and shake. 
 
 EXERCISE 33. BARIUM, CALCIUM, AND STRONTIUM. 
 
 At this exercise each student will have an opportunity to examine the 
 spectroscope. 
 
 173. By means of iron wire, suspend three small bullets of well- 
 burned coke from a ring of the iron stand. Heat the fragments in turn 
 with the flame of the gas lamp, and observe the slightly yellowish flame 
 which will be produced in each case ; then moisten one of the pieces of 
 coke with a solution of calcium chloride, the second with a solution of 
 barium nitrate, the third with a solution of strontium nitrate, and again 
 heat them in turn with the gas flame and observe the colors of the 
 flames. 
 
 174. Mix carefully 3 grams of powdered KC1O 3 , 5 grams of dry 
 SrN 2 O 6 and 2 grams of flowers of sulphur. Place the mixture upon an 
 iron plate and ignite under the hood. 
 
 175. Repeat Expt. 174 but use 3 grams KC1O 3 , 5 grams BaN 2 O 6 , 
 i gram of sulphur, and 0.5 gram powdered charcoal. 
 
 176. Pour a few drops of BaH 2 O 2 solution upon a watch glass. 
 Notice how quickly it absorbs CO 2 from the air. 
 
 177. Prepare a solution of " bicarbonate " of calcium by passing CO 2 
 into lime water (dilute) until clear. Boil a part of the solution and 
 observe; to another portion add Na 2 CO 3 solution, and observe. 
 
39 
 
 178. Mix together 5 c. c. of a concentrated solution of CaClg and 
 5 c. c. of a saturated solution of Na2SO 4 . Examine the precipitate under 
 the microscope. Write the equation. 
 
 179. Place a small piece of CaCl2 upon a watch glass. Notice its 
 condition at the end of the exercise. Illustrates deliquescence. 
 
 180. Into each of two test tubes of equal size put the same amount, 
 say six drops (not more), of a CaCl 2 solution, marked " For Expt. 180." 
 Into one of the tubes put 1 5 c. c. of NH 4 C1 solution, into the other put 
 1 5 c. c. of water. Then add an equal quantity, say 5 c. c. of carbonate of 
 ammonium to each. Show the result. 
 
 181. Fill an ignition tube one third full of bleaching powder, and 
 arrange the apparatus so that any gas which is evolved may be collected 
 over water. Heat the tube and test the gas collected 
 
 EXERCISE 34. MAGNESIUM, CADMIUM AND ZINC. 
 
 182. Pour 5 c. c. of MgSO 4 solution into each of two test tubes. 
 To the first add a few drops NH 4 OH, to the second add 5 c. c. NH 4 C1 
 and then a few drops of NH 4 OH. Repeat the experiment, but use 
 (NH 4 ) 2 CO 3 instead of NH 4 OH. Explain. 
 
 183. Place 3 c. c. of MgSO 4 solution in a test tube. Add 5 c. c. 
 NH 4 C1 and 5 c. c. NH 4 OH. Dilute with an equal volume of water, add 
 3 c. c. Na2HPO 4 solution and allow to stand. The crystalline precipitate 
 thus obtained is the test for magnesium. 
 
 184. Take 10 c. c. of cadmium sulphate solution in a beaker, and 
 dilute with 20 c. c. of water and add a few drops of HC1. Saturate with 
 H^S. Observe the appearance of the precipitate. Test its solubility in 
 dilute HC1 and dilute H 2 SO 4 , also in NaHS. 
 
 185.. Place a bit of zinc in each of three test tubes. To the first add 
 dilute HNO 3 , to the second dilute HC1, and to the third dilute H 2 SO 4 , 
 and warm. 
 
 186. Place in a test tube 2 grams of zinc dust; pour upon it 
 5 c. c. of caustic soda solution, and warm the mixture. Explain the 
 results. 
 
 187. Place 5 c. c. of zinc sulphate solution in a test tube, and add 
 to it caustic soda solution in small quantity say three or four drops. 
 Finally add a larger quantity say 3 c. c. Explain the results. 
 
 188. Immerse a piece of zinc in a solution of copper sulphate. 
 
189. Place in each of two test tubes 5 c. c. of ZnSO 4 solution, dilute 
 with an equal volume of water, and to one add i c. c. of dilute HCl and 
 to the other i c. c. of acetic acid. Now saturate both tubes with H 2 S 
 and state what happens and why. 
 
 190- Heat 2 grams of ZnO in a dry test tube nearly to redness and 
 observe the color. Allow to cool and notice again. 
 
 EXERCISE 35. MERCURY. 
 
 191. Examine the action o dilute acids upon mercury as usual, but 
 use a very small quantity of the metal. 
 
 192. To a solution of mercuric chloride add a solution of caustic 
 soda as long as a precipitate falls. 
 
 HgCl 2 + 2 NaHO = HgO + 2 NaCl + H 2 O. 
 
 193. To a solution of mercurous nitrate, add in the same way a solu- 
 tion of caustic soda. 
 
 Hg 2 N 2 O 6 -}- 2 NaHO = Hg 2 O + 2 NaNO 3 -f- H 2 O. 
 
 194. Take 10 c. c. of HgCl 2 solution, dilute with 20 c. c. of H 2 O, 
 heat to boiling, and pass in H 2 S to saturation, meanwhile observing 
 changes in color. Filter, and test the solubility of the HgS in HCl, 
 HNOs, and aqua regia. 
 
 195. Take two test tubes. Place in one 5 c. c. of Hg 2 N 2 Oe, and in 
 the other 5 c. c. of HgN 2 Oe. Add HCl slowly, and notice the difference 
 in the result. Explain. 
 
 196. Compare the solubility in hot and cold water of HgCl 2 and 
 H g2 Cl 2 . 
 
 197. To a solution of albumin add a few drops of corrosive subli- 
 mate. See 497, p. 279 of Eliot and Storer's Manual. 
 
 198. Make a solution of ammonia to contain i part NHs by weight 
 in 500,000 parts of water. See blackboard. Take two test tubes of 
 equal diameter and place in one 25 c. c. of the dilute ammonia and in the 
 other 25 c. c. of distilled water. Add a few drops of Nessler's solution 
 (a solution of HgI 2 in KI and KOH) to each tube and allow to stand for 
 five minutes. Notice the strong yellow color imparted to the solution 
 containing the NHs. This is the best test for NH 3 when present in 
 minute quantities. 
 
 199. Take 5 c. c. of HgCl 2 solution and add 10 drops of KI. Filter 
 the precipitate and dry. Into a clean and perfectly dry test tube put a 
 
small amount of the HgI 2 . Warm the middle portion of the tube until 
 you cannot quite bear your hand upon it; then heat rather gently the 
 lower part of the tube where the HgI 2 is. Explain. 
 
 EXERCISE 36. COPPER. 
 
 200. Examine the action of dilute acids upon copper in the usual 
 manner. 
 
 201. Mix equal weights of powdered CuCl 2 and Na 2 CO3, and reduce 
 upon charcoal. 
 
 202. Bind a bright copper coin with wire, in such manner that a 
 strip of wire 8 or 10 c. m. long shall be left projecting from the coin; 
 thrust the free end of the wire into a long cork or bit of wood, and by 
 means of this handle hold the coin obliquely in a small flame of the gas 
 lamp. Thrust the hot coin into water, and observe that it is at this 
 stage covered with a red coating of copper suboxide. Replace the coin 
 in the lamp and hold it in the hot oxidizing portion of the flame ; it will 
 soon become black from the formation of copper protoxide. After a 
 rather thick coating of oxide has been formed, again quench the coin in 
 water. Note what happens. 
 
 203. Dissolve a gram of copper in as small a quantity as possible of 
 HNOs diluted with an equal bulk of water. Evaporate the solution to 
 dryness; and finally ignite the residue until red fumes are no longer 
 given off. 
 
 204. Place in a test tube, or small bottle, 8 or 10 c. c. of a cold 
 dilute solution of copper sulphate, and add to it enough of a solution of 
 caustic soda to render the mixture alkaline to test paper. 
 
 205. Repeat Expt. 204, with the difference that the solutions of 
 caustic soda and copper sulphate are both heated to boiling, and are 
 mixed while hot. 
 
 206. Again repeat Expt. 204, but instead of soda lye add to the 
 copper salt ammonia water, drop by drop, and shake the tube after each 
 addition of the ammonia. 
 
 207. To a cold dilute solution of copper sulphate add a few drops 
 of a solution of grape sugar ; then add enough caustic potash solution to 
 dissolve the precipitate which forms at first. Warm the mixture ; a yel- 
 lowish precipitate of cuprous hydrate forms in the liquid, and by further 
 heating is converted into the red cuprous oxide. Other reducing agents, 
 
4 2 
 
 such as arsenious acid, for example, may be substituted for the grape 
 sugar. 
 
 208. Acidify 10 c. c. of copper sulphate solution with acetic acid. 
 Add a few drops of potassium ferrocyanide. This test for copper is even 
 more delicate than the one given in Expt. 206. 
 
 209. Take 10 c. c. of CuSO 4 solution and saturate with H 2 S. Fil- 
 ter and examine the solubility of the CuS in HC1, HNO 3 and Na 2 Sx. 
 
 210. Prepare a little moist CuS, collect on a filter and leave for a 
 day or two. Then put paper and all into a test tube, shake up with say 
 10 c. c. of water, let stand for a few minutes, filter, and add ammonia 
 water to the filtrate. Explain the results obtained. 
 
 EXERCISE 37. SILVER. 
 
 [Finish Expt. 210 if you began it.] 
 
 211. Place one or two dimes in a small flask, and cover them with 
 nitric acid diluted with twice its bulk of water. Warm the flask gently 
 in a place where there is a good draught of air ; add more nitric acid, 
 from time to time, if necessary to complete the solution, but carefully 
 avoid having a great excess of the acid. Note the character of the 
 evolved fumes and the color of the solution. Dilute the solution with an 
 equal volume of water, place in it two or three copper coins and leave 
 until the next exercise. Then collect the little plates of pure silver, 
 which have separated from the solution, upon a filter, and wash them, 
 first with water, and then with ammonia water, until the ammonia water 
 no longer shows any tinge of blue. This silver washed finally with 
 water and dried, is well-nigh pure; if it be again dissolved in nitric acid, 
 the solution will contain nearly pure silver nitrate. 
 
 212. Fill three test tubes one third full of water, and pour into each 
 a few drops of a moderately strong solution of silver nitrate. Add to 
 the first test tube 2 or 3 c. c. of a solution of sodium chloride, to the sec- 
 ond tube 2 or 3 c. c. of a solution of potassium bromide, and to the third 
 tube I or 2 c. c. of a solution of potassium iodide ; shake the mixture in 
 each case and describe the precipitates.* 
 
 Withdraw from each test tube a portion of the precipitate it contains, 
 and try to dissolve each precipitate in dilute nitric acid. 
 
 * Save all the silver residues. 
 
43 
 
 Withdraw from each test tube another portion of the precipitate it 
 contains, and treat each precipitate with ammonia water. Lastly, pour 
 upon the remnants of the original precipitates in the three test tubes a 
 solution of sodium hyposulphite. 
 
 213. Precipitate some curdy silver chloride by adding sodium chlo- 
 ride solution, or chlorhydric acid, to a solution of silver nitrate, so long 
 as any precipitate is produced. Throw the precipitate upon a filter, and 
 wash it with water ; then open the filter, spread the chloride evenly over 
 it, and place it in direct sunlight.* 
 
 214. (i) To a solution of AgNO & add NaOH. (2) Pass H 2 S 
 through a solution of AgNOs. (3) Take three test tubes and place 
 2 c. c. of AgNOg solution in each. To the first add a few drops of 
 Na 2 HPC>4, to the second a few drops of Na 2 CC>3, and to the third a few 
 drops of K 2 CrO 4 . Write the reactions.* 
 
 215. Precipitate AgCl as in Expt. 213, filter, dry and mix a portion 
 or the whole with four times its bulk of carbonate of sodium and reduce 
 upon charcoal.* 
 
 EXERCISE 38. ALUMINUM. 
 
 216. Place a piece of aluminum in each of three test tubes and 
 examine the action of acids upon the metal as in Expt. 185. 
 
 217. Precipitate a considerable quantity of A1 2 H 6 O6 and filter. 
 Place two thirds of the precipitate in a small porcelain dish and dry 
 slowly over the lamp. Finally, when steam is no longer given off, heat 
 strongly and observe the properties of the residue. Compare the solu- 
 bility of the original precipitate and of the residue in HC1. 
 
 Al 2 H 6 6 = Al 2 O3 + 3 H 2 O. 
 
 218. Ignite a small quantity of A1 2 H 6 O 6 before the blow- pipe upon 
 charcoal. Moisten the white powder so obtained with CoN 2 O 6 and con- 
 tinue the heating. Notice the blue color obtained. This is a test for 
 aluminum. 
 
 219. Take a small quantity of a solution of cochineal, add to it an 
 equal bulk of a solution of aluminum sulphate (or of common alum), and 
 then add to the mixture ammonia water. A colored precipitate, consist- 
 ing of aluminum hydrate and of the coloring matter of the cochineal, 
 will be thrown down ; it is the substance called carmine lake. 
 
 * Save all the silver residues. 
 
44 
 
 220. Prepare an acetate of aluminum solution as follows : Dissolve 
 6 grams of sugar of lead (lead acetate) in 8 c. c. of hot water; also 
 dissolve 8 grams of common alum in 12 c. c. of hot water; mix the two 
 solutions and filter off the insoluble lead sulphate which is formed. In 
 the solution thus prepared, soak a piece of cotton cloth, and then dry 
 it. Treat this cloth, as well as a piece of ordinary cotton of the same 
 size, with a solution of logwood, and observe the difference in the 
 amount of color imparted to the fabric. 
 
 221. Place a considerable quantity of powdered aluminum sulphate 
 in a test tube, add 10 c. c. of water and shake until a saturated solution 
 is obtained. Take a second test tube and obtain a saturated solution of 
 powdered K^SO-*. Now in a third test tube mix 5 c. c. each of these 
 saturated solutions Shake and observe the precipitate. Filter and 
 examine the precipitate under the microscope and test its solubility in 
 I^O. Examine a piece of aluminum. 
 
 EXERCISE 39. TIN, GOLD, AND PLATINUM. 
 
 222. Heat a piece of common tinned iron over the gas lamp until 
 the tin has melted, thrust the plate into cold water in order that the tin 
 may harden quickly, then remove the smooth surface of the metal by 
 rubbing it first with a bit of paper moistened with dilute aqua regia, and 
 then with paper wet with soda lye. Show the result. 
 
 223. Pour 20 c. c. of SnClg solution into a beaker and then pour 
 an equal volume of water upon it, but do not allow the two layers of 
 liquid to mix. Thrust a slip of zinc through the liquid and observe 
 what happens. 
 
 224. Examine the action of HC1, HNO 3 and H 2 SO 4 upon metallic 
 tin, both in dilute and concentrated state. 
 
 225. Dry some of the white powder obtained by the action of 
 HNOg on tin, mix it with 2 or 3 times its bulk of powdered "binoxalate 
 of potash " and endeavor to reduce upon charcoal. 
 
 228. Take two test tubes and place in each i c. c. of SnCl2 solution. 
 Dilute with 10 c. c. of water. To one of the tubes add potassium per- 
 manganate until a faint color is obtained. Now saturate both tubes with 
 H 2 S. Explain. Test the solubility of the precipitates in HC1, concen- 
 trated and dilute, and Na 2 S. Explain. 
 
 227. Take I c. c. of SnCls solution and dilute with 10 c. c. of water. 
 Add a few drops of HgCl2. Give equation. 
 
45 
 
 228. Place two drops of AuCls in a beaker and dilute with 20 c. c. of 
 water. To a few c. c. of SnCl 2 solution in a test tube add a few drops 
 of Fe^Cls and then add a few drops of this mixture to the water contain- 
 ing AuClg. Notice the coloration due to the formation of "purple of 
 Cassius." This is the most delicate test for gold. 
 
 229. Pour 3 c. c. of a solution of ammonium chloride into a test 
 tube, acidulate the liquid with chlorhydric acid, and add to it a drop of 
 the solution of platinum chloride, and examine the precipitate under the 
 microscope. Repeat the experiment, and this time take enough of the 
 platinum solution and of the ammonium chloride to make half a teaspoon- 
 ful of the yellow precipitate, taking care that at last there shall be a slight 
 excess of free ammonium chloride rather than of platinum chloride in 
 the supernatant liquid. Allow the precipitate to settle, separate it from 
 the clear liquor by decantation, and dry it partially at a gentle heat. 
 When the precipitate has acquired the consistence of slightly moistened 
 earth, transfer it to a cup-shaped piece of platinum foil, and heat it to 
 redness in the gas flame, as long as fumes of ammonium chloride con- 
 tinue to escape. All the chlorine, hydrogen and nitrogen will be driven 
 off, and there will remain upon the foil a gray, loosely coherent, sponge- 
 like mass of metallic platinum ; it is called platinum sponge. 
 
 230. Hold the dry platinum sponge of Expt. 229 in a stream of 
 hydrogen or of common illuminating gas issuing from a fine jet. 
 
 EXERCISE 40. LEAD. 
 
 231. Heat a small fragment of lead upon charcoal in the oxidizing 
 flame of the blow-pipe. 
 
 232. Fill a small ignition tube one fourth full of lead tartrate. 
 Heat the tube gently until no more fumes are given off. Metallic lead 
 will be left in the tube in a very finely divided condition. Cork tightly 
 while hot and allow to become perfectly cold, then pour some of the 
 powder into an evaporating dish, holding the tube high over the dish. 
 Observe what happens. 
 
 233. Place a small piece of lead in each of three test tubes. Pour 
 a few c. c. of dilute HNOs upon the first, a few c. c. of dilute HC1 upon 
 the second, and a few c. c. of dilute H 2 SC>4 upon the third. Warm and 
 observe the action. 
 
 234. Mix equal bulks of litharge and sodic carbonate and reduce 
 upon charcoal. 
 
4 6 
 
 235. Dissolve 0.5 gram lead acetate in i liter of water. Take loo 
 c. c. of this solution and dilute with about a liter of water ; then take a 
 small portion of this solution and pass H 2 S through it. This is a most 
 delicate test for Pb. 
 
 236. To .a solution of PbN 2 O 6 add HC1 until no further precipitate 
 is formed. Write the equation. Filter off the precipitate, and to one 
 third of the filtrate add dilute H 2 SO 4 ; to another third, add H 2 S water; 
 to the remainder, add K 2 CrO4 solution. Write equations. Dissolve the 
 original precipitate in the least possible quantity of boiling water, filter 
 and allow to cool. 
 
 EXERCISE 41. CHROMIUM AND MANGANESE. 
 
 237. Weigh out 2 grams of chromic oxide, 4 grams of sodic car- 
 bonate and 2 grams of potassic nitrate. Mix thoroughly and fuse in an 
 iron ladle until no more black specks are to be seen in the fused mass. 
 Pour out the fused mass upon a broken piece of porcelain, allow to cool 
 and break into small pieces. The fusion oxidized the chromium to the 
 condition of chromic acid. The fused mass contains sodic chromate. 
 Dissolve in water and add to a portion of the solution acetic acid to acid 
 reaction and then acetate of lead. Acidify likewise two other portions, 
 and to one add ZnCl 2 and to the other BaCl 2 . 
 
 238. To 10 c. c. of chrome alum solution add NH-iOH in excess. 
 Filter the precipitate and ignite a portion in a porcelain crucible. Test 
 the solubility of the original and of the ignited precipitate in HC1. 
 
 239. Place 20 c. c. of a saturated solution of bichromate of potas- 
 sium in a beaker surrounded by cold water. Add slowly 25 c. c. of 
 strong H 2 SC>4. Observe the deposition of chromic anhydride. Remove 
 some of the crystals and test their solubility in water. 
 
 240. To a solution of MnCl 2 or MnSO 4 add NHJIS. Collect the 
 precipitate on a filter and allow to remain exposed to the air for some 
 time. 
 
 241. Fuse together upon platinum foil 0.5 gram dry Na^COs, o.i 
 gram KNO 3 and a few milligrams of MnO 2 . The color given to the 
 fused mass is one of the best tests for manganese. 
 
 242. Place in a test tube 10 c. c. of dilute HNOs and 0.5 gram 
 PbO 2 . Add a few milligrams of MnO 2 and boil. Allow to settle and 
 observe ; ask for an explanation of what you have observed. 
 
47 
 
 243. In a beaker or flask dissolve 0.25 gram of crystallized oxalic 
 acid in 50 c. c. of water, add 5 c. c. strong sulphuric acid, and warm the 
 solution to about 60. Then add a solution of potassium permanganate 
 tlrop by drop, and observe that the color is at first immediately destroyed. 
 Continue to add the permanganate until it is no longer decolorized. The 
 reaction that has taken place may be thus represented : 
 
 K 2 Mn 2 O 8 + 5 C 2 H 2 O 4 + 3 H 2 SO 4 = 
 2 MnS0 4 -fK 2 SO 4 + 8 H 2 O-J-10 CO 2 . 
 
 The oxalic acid (C2H 2 O4) is entirely converted into water and carbonic 
 acid : the potassium permanganate gives up its oxygen and is converted 
 into a mixture of manganese and potassium sulphates. 
 
 244. Mix together in an iron ladle 5 grams KOH, 3.5 grams pow- 
 dered KClOg, 4 grams powdered MnO 2 and 10 c. c. water. Evaporate to 
 dryness rapidly and then heat for a few moments until the mass has half 
 fused, stirring constantly. The MnO 2 has been converted into potassium 
 manganate. Treat with water, decant the clear green liquid and place 
 20 c. c. in an evaporating dish and notice any changes of color. Place 
 another portion in a test tube and add a few drops of dilute H 2 SC4. On 
 account of these changes of color, potassium manganate is called chame- 
 leon mineral. 
 
 EXERCISE 42. IRON. 
 
 245. Dissolve 2 or 3 small tacks in 8 or 10 c. c. of dilute sulphuric 
 acid in a small, beaker ; when the evolution of hydrogen slackens, dilute 
 with an equal bulk of water and filter into a small flask. To the liquid 
 add a few drops of strong nitric acid, and heat it to boiling. The liquor 
 will soon be colored dark brown by the nitrous fumes resulting from the 
 decomposition of the nitric acid, which are for a short time held dis- 
 solved by the liquid ; but this deep coloration soon passes away, and 
 there is left only the yellowish red color of the ferric sulphate which has 
 been formed. Add to the solution ammonia water, until the odor of the 
 latter persists after agitation, and collect upon a filter the flocculent red 
 precipitate of ferric hydrate. 
 
 246. Repeat Expt. 217 but make use of the Fe 2 H 6 O 6 obtained in 
 Expt. 245. Compare the solubility of Fe 2 O 3 and P'e 2 H 6 O 6 in HC1. 
 
 247. Compare the actions of the dilute acids upon metallic iron. 
 
4 8 
 
 248. Pour a solution of copperas into an open capsule, and leave it 
 exposed to the air for a day or two ; the solution will gradually become 
 yellow as the oxidation proceeds, and after a while a rusty precipitate of 
 ferric oxide, or of highly basic ferric sulphate, will fall. 
 
 249. Place 20 c. c. of copperas solution in an evaporating dish and 
 add ammonia water in excess. Observe the color of the precipitate. 
 Allow to stand for half an hour, stirring frequently, and observe any 
 change in the color of the precipitate. Write the equation. 
 
 250. Dip a small piece of cotton cloth in the solution of nutgalls, and 
 allow it to become dry ; then dip it in the solution of copperas and hang 
 it up in damp air. Finally, try to wash out the color. 
 
 251. Dissolve one gram of copperas (iron sulphate) in 100 c. c. of 
 water in a bottle of 200 c. c. capacity. Into the solution stir a mixture 
 of i gram of finely powdered indigo and 1.5 grams of freshly slaked lime; 
 fill up the bottle with water and cork it. Shake the bottle occasionally, 
 and, at the next exercise, pour off, or remove with a pipette, a portion of 
 the clear and nearly colorless liquid without disturbing the precipitate 
 In the bottom of the bottle. Expose this liquid to the air in a shallow 
 dish. 
 
 EXERCISE 43. IRON, COBALT, AND NICKEL. 
 
 252. Dissolve a small crystal of copperas in water and add to the 
 liquid a drop or two of a solution of ammonium sulphydrate. 
 
 Finish 251. 
 
 253. To a solution of a ferric salt add a few drops of sulphocyanate 
 of potassium and notice the color. This is a very delicate test for iron. 
 
 254. Dissolve 2 or 3 iron tacks in dilute HC1. Filter, and to a small 
 portion of the filtrate add a few drops of potassium ferrocyanide solu- 
 tion. To a similar portion of the filtrate add a few drops of potassium 
 ferricyanide. Notice the difference. These are tests for ferrous salts. 
 Now to the remaining part of the filtrate add a few drops of HNOs and 
 boil. Test small portions of this oxidized filtrate with ferro- and ferri- 
 cyanide of potassium and show the results. If you have been success- 
 ful in oxidizing the solution divide it into two portions. Through the 
 first pass H 2 S and note the effect. To the second add SnCl2 and warm, 
 and then test with ferro- and ferri- cyanide of potassium. 
 
 255. Prepare a borax bead, as will be shown. Place upon it a parti- 
 cle of any cobalt salt and heat in both reducing and oxidizing flame be- 
 
49 
 
 fore the blow-pipe. Prepare i second bead and add a nickel salt. The 
 colors obtained are good tests for the respective metals. 
 
 256. Write your name upon a piece of filter-paper, using CoCl2 solu- 
 tion for ink. Allow to dry and observe that the writing is invisible. 
 Now warm gently and observe the effect. Explain. Finally breathe 
 upon the writing. 
 
 257. To 2 c. c. of CoN2Oe solution add an equal volume of dilute 
 silicate of soda solution. 
 
 258. Pour 5 c. c. of a solution of any cobalt salt into a test tube and 
 add i c, c. of acetic acid. Now add an equal volume of potassium nitrite 
 solution. Allow to stand and observe the precipitate. It is a double 
 nitrite of potassium and cobalt, and its formation is one of the best tests 
 to show the presence of cobalt. 
 
 259. Take 10 drops or less of a solution of CoCl2. Dilute with 
 water, then add ammonia water to alkaline reaction ; if any precipitate 
 appears, filter, and to the clear filtrate add a few drops of NH 4 HS solu- 
 ;tion and note what happens. Now take the same amount of cobalt 
 solution as before, and two teaspoonfuls of NELtCl solution, then add 
 ammonia to alkaline reaction, note what happens and explain. 
 
 260. Heat gently in a dry test tube a few crystals of NiCl 2 . 
 
 261. Take two test tubes and place in one 2 c. c. of Coda and in 
 e other 2 c. c. of NiCl 2 . Add to each NaOH to alkaline reaction, then 
 
 a little KCN and then an equal volume of sodium hypochlorite and 
 I warm. The NiCl2 gives a dark precipitate of NioIIeOe while the CoCl 2 
 I is unaffected. The reaction is often used to distinguish nickel in the 
 
 presence of cobalt. 
 
 EXERCISE 44. ARSENIC. 
 
 [Use great caution in performing all the experiments in this exercise.] 
 
 262. Place a few particles of " arsenious acid " in an open tube of 
 lard glass about 10 c. in. long and heat over the lamp, holding the tube 
 u a sloping position. Examine the sublimate with a microscope. 
 
 263. Drop into the point of a drawn out tube of hard glass, No. 5, a 
 .norsel of arsfcnious oxide, and above it place a splinter of charcoal ; heat 
 1 he coal red hot in the lamp flame, and then volatilize the arsenious acid. 
 
 264. Throw a particle of arsenious acid upon a piece of red hot char- 
 coal. Notice any peculiar odor. 
 
 r 
 
50 
 
 265. [Under the Hood.] Arrange a hydrogen generator as in 
 the model, having a delivery tube beyond the calcium chloride tube 
 drawn down to a narrow bore in several places. Generate hydrogen 
 from zinc and dilute chlorhydric acid, and when pure hydrogen escapes 
 from the delivery tube light the jet. Into the generator through the 
 thistle tube pour a ^^ = * few drops =4$ of a solution of arsenious acic 
 in chlorhydric acid ; watch the flame to see whether it appears to alter in 
 character. Hold a concave bit of cold porcelain in the flame ; a brownish 
 black deposit of arsenic is formed ; collect several of these spots and 
 reserve them for future experiment. While the stream of arseniuretec 
 hydrogen is passing through the delivery tube, heat the tube with the 
 flame of a Bunsen lamp, a little behind one of the constricted portions 
 The arseniureted hydrogen is decomposed, and arsenic is deposited in 
 the tube as a metallic mirror. Produce several of these mirrors and save 
 them, and then wash out the generator, zinc and all, into the sink under 
 the small hood. [This is Marsh's test.] 
 
 266. Into a small bottle put several teaspoonfuls of a chlorhydric 
 acid solution of arsenious acid, add water enough to nearly fill the bottle 
 and allow H 2 S -to bubble through the liquid until the liquid smells 
 strongly of sulphureted hydrogen. Collect the precipitate (what is it?] 
 upon a filter ; and test its solubility in HC1 and Na 2 Sx solution. 
 
 267. Take two test tubes and place in each 5 c. c. of arsenite oi: 
 sodium. Make one strongly acid with HC1 and the other strongly alka- 
 line with NaOH. Pass H 2 S into each tube and note the result. Explain. 
 Acidulate with HC1 the one that is alkaline. 
 
 268. Take two test tubes. Place in one 5 c. c. of arsenite of sodium, 
 in the other 5 c. c. of arseniate of sodium. Acidify with HC1 and pass in 
 H 2 S. Explain. 
 
 269. Place in one test tube 5 c. c. of arsenite of sodium, and in 
 another 5 c. c. of arseniate of sodium and add a few drops of AgNOg to 
 each. This difference is the distinguishing test between the two acids 
 and their salts. Save the silver residues. 
 
 I 
 
EXERCISE 45. ANTIMONY AND BISMUTH. 
 
 270. [Under the hood.] In a flask of about 200 c. c. capacity, heat 
 gently 0.5 gram of finely powdered antimony with 30 c. c. of strong 
 chlorhydric acid, to which ten drops of nitric acid have been added. 
 When complete solution has been effected, evaporate to less than one 
 half its bulk ; pour a little of the chloride into water. Evaporate the rest 
 of the solution to the consistency of a thick syrup ; it is the butter of 
 antimony. 
 
 271. Pour some of the antimony terchloride into a small bottle 
 nearly full of water, and then add just enough chlorhydric acid to dis- 
 solve the white precipitate which is formed. Through the clear solution 
 pass a stream of hydrogen sulphide. Filter and test the solubility of 
 Sb 2 S 3 in dilute HC1, in hot strong HC1, and in Na 2 Sx. 
 
 272. Perform precisely as 265, except that a solution of an antimony 
 compound is to be substituted for the solution containing arsenic. 
 Reserve the mirrors as in Expt. 265. 
 
 273. Compare together the spots obtained on porcelain from arse- 
 niureted hydrogen (Expt. 265) and from antimoniureted hydrogen (Expt. 
 272). i. The arsenical spot has a metallic luster and a brown color 
 when thin ; the stain of antimony has a feeble luster, and is smoky black. 
 2. The arsenical stain disappears readily on the application of a heat 
 below redness ; the stain of antimony is volatile only at a red heat. On 
 account of the comparative want of volatility which characterizes the anti- 
 mony deposit, the mirrors of antimony obtained in the glass tube are 
 always deposited nearer the heated portion of the tube than the arsenic 
 mirrors are. 3. The arsenical stains may be distinguished, moreover, 
 from the antimonial stains by means of "chloride of lime," which 
 immediately dissolves arsenical spots, but leaves antimonial spots unaf- 
 fected for a long time. 4. An antimony stain will dissolve readily in a 
 few drops of a solution of sulphydrate of ammonium which has become 
 yellow by keeping; when such a solution is evaporated to dryness, a 
 bright orange stain remains. The arsenical stain, on the contrary, is not 
 perceptibly affected by the yellow sulphydrate of ammonium solution, 
 unless heat is applied. 
 
 274. Connect the tube of hard glass in which the arsenic mirrors 
 were formed, in Expt. 265, with a sulphureted hydrogen generator, inter- 
 posing between the tube and the generator a suitable drying-tube or bottle 
 filled with calcium chloride ; then transmit through the tube a wry slow 
 
52 
 
 stream of hydrogen sulphide gas, and heat the mirrors with a small gas 
 flame, proceeding from the outer to the inner border of the mirrors in 
 the direction opposite to that of the gas current. 
 
 Repeat the same process with the tube containing the antimony mirrors 
 obtained in Expt. 272. 
 
 275. Place 5 c. c. of tartar emetic (tartrate of antimony and potas- 
 sium) in each of two test tubes, and make one slightly acid with HC1 and 
 and the other strongly alkaline with NaOH, and saturate with H^S. 
 Explain. 
 
 276. Repeat Expt. 270 but use bismuth. 
 
 277. Repeat Expt. 275 but use Bids instead of tartar emetic. 
 
 278. Weigh out 15 grams of bismuth, 8 grains of lead and 8 grams 
 of tin. Heat a beaker of water to boiling, and convince yourself that 
 neither the bismuth, lead or tin will melt in the hot water. Now fuse the 
 metals together in an iron spoon. Allow the mass to cool and place it 
 in a beaker of boiling water. This alloy is known as fusible metal. 
 Pour a little of the fused metal into a narrow test tube and allow to cool. 
 Explain its action. 
 
 EXERCISE 46. CHEMICAL CHANGES. 
 
 Analyze the following reactions, and tell whether they are analytical, 
 synthetical, or metathetical. Also explain any modifications from the 
 action which would be naturally expected. 
 
 1. To 0.5 c. c. of sodic carbonate solution add dilute HC1. 
 
 2. Place a bit of copper in a test tube and add dilute HNOs. 
 
 3. Repeat Expt. 88. Test, before warming, for SO2, and again after 
 warming. 
 
 4. Mix 2 grams NFLiCl and 2 grams CaH 2 O2- Place in a dry test 
 tube and test for NH 3 . Now warm and repeat the test. 
 
 5. To 5 c. c. of sodium hyposulphite solution add dilute HC1. To a 
 second 5 c. c. add acetic acid. 
 
 6. Place 5 c. c. of CuSO 4 solution in each of three test tubes. To 
 one add an equal volume of NaCl solution, to another a few c. c. of 
 BaCl2 solution and compare the three tubes. 
 
 7. Shake a few grams of CaSO* with water, filter and add 
 (NH 4 ) 2 C0 3 . 
 
53 
 
 8. Take 2 c. c. of a solution of As 2 O 3 in HC1 and dilute to 10 c. c. 
 with water. Add (NH.i)oSx drop by drop at first, finally a large excess 
 .UK! boil. Now acidify with HCL 
 
 9. Repeat the last experiment, but use CdCl 2 instead of As2O 3 . 
 
 10. Place 3 c. c. of Fe 2 Cle in each of two test tubes and dilute with 
 20 c. c. of water. To one add a few drops of K 4 FeCye, to the other 
 a few drops of KSCN. 
 
 11. Into a test tube put 10 c. c. of water. Add to it 3 drops of 
 KSCN solution; then add one drop of Fe 2 (NO 3 ) 6 . Now add AgNO 3 
 solution drop by drop until there is a change of color. Explain. Save 
 all silver residues. 
 
 12. To 5 c. c. of CuSO 4 solution add NH 4 OH in excess. 
 
 13. Heat a mixture of mercuric sulphate and sodic chloride in a 
 matrass. 
 
 14. Pass a current of CO 2 through a dilute solution of sodium 
 silicate. 
 
 EXERCISES 47 AND 48. PRINCIPLES OF QUALITATIVE ANALYSIS. 
 
 1. Take i c. c. of an aqueous solution of CuSO 4 and i c. c of AgNOs 
 solution. Add dilute HC1 a few drops at a time ; shake and allow to 
 settle after each addition. When further addition of HC1 produces no 
 further precipitation (of what? Answer from past experience), collect 
 the precipitate on a filter. To the filtrate add ammonia little by little 
 to alkaline reaction and explain the observed result (also from past 
 experience). 
 
 2. Take about i c. c. of each of the following solutions and add to 
 each, in a test tube, a few drops of HC1 (dilute): AgNO 3 , PbN 2 O G , 
 CuN 2 O 6 , Hg 2 N 2 O 6 , HgN 2 O 6 , FeSO 4 , ZnSO 4 , MgSO 4 , KNO 3 . Note in 
 which cases a precipitate appears. 
 
 3. To i c. c. of a solution of AgNO 3 add z c. c. or so of water and 
 then HC1 (dilute) a little at a time with shaking unti) further addition 
 produces no more precipitate. Wash by decantation. Boil one portion 
 of precipitate with water; treat a second portion with ammonia water. 
 
 Repeat this procedure, using a solution of PbN 2 Oe instead of AgNO 3 , 
 also using Hg 2 N 2 Oe. To small portions of solutions of AgNOg, PbN 2 O$ 
 and Hg 2 N 2 O 6 , add H 2 SO 4 (dilute). 
 
54 
 
 4. Mix together some of each of the three solutions (AgNOg, 
 PbN 2 Oe, Hga^Oe), and proceed as indicated in the following scheme. 
 Add HC1 and filter. 
 
 I I 
 
 Filtrate. Precipitate (wash). 
 
 Throw away. Transfer to a test tube, add water and 
 boil several times; filter or decant. 
 
 | 
 
 I I 
 
 Filtrate. Precipitate. 
 
 Add dil. H 2 SO 4 . Add NH 4 OH and warm ; filter. 
 
 I I 
 
 Filtrate. Precipitate. 
 
 Add dil. HNO 3 Dry, mix with Na 2 CO 3 , 
 
 to acid reaction. and heat in a matrass. 
 
 Then take an unknown solution which may contain compounds of one or 
 more of the elements lead, silver or mercury (ous). 
 
 5. Three general methods by which the presence of a given element 
 may be ascertained. 
 
 1. By isolating the element itself. Recall or perform, if you do not 
 remember exactly what happened, Expts. 215, 234, 188. 
 
 2. By producing a characteristic compound of the element sought, as 
 we have already proved the presence of Ag, Pb or [Hg 2 ] " by the appear- 
 ance and action of their chlorides." 
 
 3. By producing a precipitate not containing the element sought, but 
 which could be formed only in presence of that element or some partic- 
 ular compound of it. Expt. 227. The precipitate is mercurous chloride 
 (Hg 2 Cl 2 ) and the HgCl 2 may be used as a test for tin. 
 
 2 HgCl 2 + SnCl 2 = SnCl 4 + Hg 2 Cl 2 . 
 
 6. Make a solution containing say i c. c. of each of the following 
 solutions: Fe 2 Cl 6 , ZnCl 3 , CaCl 2 , MgCl 2 , and a teaspoonful of NH 4 C1. 
 Add ammonia until the odor persists after shaking, collect the precipi- 
 tated Fe 8 HjjO 6 on a filter, and to the filtrate add (NH 4 )HS. Collect the 
 
55 
 
 precipitated ZnS on a filter and to the filtrate add (NH^COs. Collect 
 the precipitated CaCO 3 on a filter and to the filtrate add Na 2 HPO 4 . 
 The precipitate is a phosphate of Mg and 
 
 EXERCISES 49-53. PREPARATIONS. ' 
 
 1. Purification of Sal- Ammoniac. 
 
 Place 100 grams of commercial NH 4 C1 in a six- inch evaporating dish 
 :md add 300 c. c. of water. Heat and stir until the NH^Cl has dissolved. 
 Add a few c. c. of NH^OH to precipitate any iron present, and filter while 
 hot through a large filter. The filtrate should be colorless. Carefully 
 wash the dish and return the filtrate to it and evaporate with continual 
 stirring. Continue the evaporation not too rapidly until the NH^Cl is 
 obtained as a fine white powder free from lumps. Weigh. 
 
 2. Glauber's Salt. 
 
 Place 200 c. c. of water in a beaker which will hold 500 c. c. Weigh in 
 a small beaker 20 grams of H^SO^ and pour this slowly into the 200 c. c. 
 of water. Weigh 60 grams of sal -soda and dissolve by warming in the 
 least possible quantity of water. Add the solution of sal- soda little by 
 little to the dilute H 2 SO4, carefully avoiding all loss by foaming. Test 
 with, litmus paper, and if the liquid is still acid, add sal- soda solution 
 until it has become slightly alkaline. Evaporate in a large dish to one 
 third of the original volume and filter while hot. Set the filtrate aside 
 in the dish until the next exercise. Cover the dish with paper to protect 
 it from dust. Pour off the supernatant liquid from the crystals when 
 they are formed. 
 
 3. Ammonium Iron Alum. \ 
 Ferric Sulphate. Weigh 30 grams of H^SO^ in a beaker and dilute 
 
 with 15 c. c. of water. Stir thoroughly into the acid 20 grams of 
 Fe 2 H 6 Oc. Add 20 c. c. of water, warm gently and stir frequently while 
 the ammonium sulphate (see below) is being prepared. The Fe 2 H O6 
 will gradually dissolve. Finally dilute with water, filter and evaporate 
 until the liquid becomes turbid from the separation of the ferric sul- 
 phate. Mix this solution with that of the ammonium sulphate prepared 
 in the mean time, stir, cover with paper and set aside until the next 
 exercise. 
 
56 
 
 Ammonium Sulphate. Weigh 10 grams of H 2 SO4 and place it in an 
 evaporating dish. Dilute with 25 c. c. of water. Now add in small por- 
 tions ammonia until a permanent smell of the same is obtained after 
 stirring the liquid. Filter and evaporate to 1 5 c. c. 
 
 4. Sugar of Lead. 
 
 Place 20 grams of PbO in an evaporating dish, cover with water and 
 reduce to a thin paste with a pestle. Add 45 grams of HO(C 2 H 3 O) 
 and warm until the PbO has dissolved. Filter and evaporate until a 
 drop of the liquid cooled upon a watch glass deposits numerous crystals. 
 Cover and allow to stand. 
 
 5. Barium Carbonate. 
 
 Dissolve 1 8 grams of BaCl 2 in 150 c. c. of water by warming in a flask, 
 filter and pour into a large bottle. Powder in a porcelain mortar some 
 (NH^COs and weigh out 6 grams. To this add 10 c. c. of ammonia 
 water and then 10 c. c. of water, and stir without warming until the 
 (NH4) 2 CO 3 is dissolved. Filter if necessary. Pour the solution of 
 (NH4) 2 CO 3 into the solution of BaCl 2 , shake well and allow to settle. 
 Pour a few c. c. of the liquid on the top into a test tube and add a little 
 (NH^COg. If a precipitate is obtained, more (NH 4 ) 2 CO3 must be 
 added to the BaCl 2 . Repeat the test until a small excess of (NH^COa 
 is present. Allow the precipitate to settle and wash by decantation four 
 times. Test the last wash-water with AgNO 3 for chlorine. If chlorine 
 is present in any considerable quantity, continue to wash by decantation 
 until only a trace remains. Then filter, wash and dry the precipitate 
 carefully, and give the BaCO 3 to the assistant. 
 
 6. Chrome Yellow. 
 
 Dissolve 25 grams of sugar of lead in 50 c. c. of water and filter. Pour 
 the solution into a large bottle. Dissolve 10 grams of bichromate of 
 potassium in 20 c. c. of water and pour this solution into the one of sugar 
 of lead in the large bottle and shake. Add 100 c. c. of water and allow 
 the precipitate to subside, and if the supernatant liquid is yellow add a 
 further small quantity of sugar of lead solution and shake again. Con- 
 tinue this until the sugar of lead is present in slight excess. Fill the 
 bottle full of water and wash the precipitate by decantation until the 
 wash-water gives no further brown color when H 2 S is passed through it. 
 Now bring the precipitate upon a filter. 
 
57 
 
 7 Chrome Orange. 
 
 Take one half of the precipitate obtained in the last experiment, place 
 it in a small evaporating dish, add a few c. c. of water and rub carefully 
 with a pestle until all the lumps are broken up. Dissolve 3 grams of 
 NaOH in 10 c. c. of water and pour this solution upon the chrome yel- 
 low, stir constantly and keep at the boiling point for 10 minutes. Pour 
 into the bottle, taking care to wash out all adhering chrome orange. 
 Wash now by decantation until the wash-water gives no further test for 
 an alkali with litmus paper. Filter, dry and weigh. Give both chrome 
 yellow and chrome orange to assistant. 
 
APPENDIX. 
 
 CHEMICAL MANIPULATION. 
 
 1. Glass-tubing. Two qualities of glass-tubing are used in chem- 
 ical experiments, that which softens readily in the flame of a gas- or 
 spirit-lamp, and that which fuses with extreme difficulty in the flame 
 of the blast-lamp. These two qualities are distinguished by the 
 terms soft and hard glass. Soft glass may be used for all purposes, 
 except the intense heating, or ignition, of dry substances. Fig. I 
 represents the most convenient sizes of glass-tubing, both hard and 
 soft, and shows also the proper thickness of the glass walls for each 
 size. 
 
 FIG. i. 
 
 8 7 
 
 2. Cutting and Cracking Glass. Glass-tubing and glass-rod 
 must generally be cut to the length required for any particular ap- 
 paratus. A sharp triangular file is used for this purpose. The stick 
 of tubing, or rod, to be cut is laid upon a table, and a deep scratch is 
 made with the file at the place where the fracture is to be made. The 
 stick is then grasped with the two hands, one on each side of the 
 25 
 
II APPENDIX. 
 
 mark, while the thumbs are brought together just at the scratch. By 
 pushing with the thumbs and pulling in the opposite direction with 
 the fingers, the stick is broken squarely at the scratch, just as a stick 
 of candy or a dry twig may be broken. The sharp edges of the fracture 
 should invariably be made smooth, either with a wet file, or by soften- 
 ing the end of the tube or rod in the lamp. (See Appendix, 3.) 
 Tubes or rods of sizes 4 to 8 inclusive may readily be cut in this man- 
 ner ; the larger sizes are divided with more difiiculty, and it is often 
 necessary to make the file-mark both long and deep. An even frac- 
 ture is not always to be obtained with large tubes. The lower ends 
 of glass funnels, and those ends of gas delivery- tubes which enter the 
 bottle or flask in which the gas is generated, should be filed off, or 
 FIG. II. ground off on a grindstone, obliquely (Fig. II), to 
 
 facilitate the dropping of liquids from such extremi- 
 ties. 
 
 In order to cut glass plates, the glazier's diamond 
 must be resorted to. For cutting exceedingly thin 
 glass tubes and other glass ware, like flasks, retorts 
 and bottles, still other means are resorted to, based upon the sudden 
 and unequal application of heat. The process divides itself into 
 two parts, the producing of a crack in the required place, and the 
 subsequent guiding of this crack in the desired direction. To pro- 
 duce a crack, a scratch must be made with the file, and to this scratch 
 a pointed bit of red-hot charcoal, or the jet of flame produced by 
 the mouth blowpipe, or a very fine gas-flame, or a red-hot glass-rod 
 may be applied. If the heat does not produce a crack, a wet stick or 
 file may be touched upon the hot spot. Upon any part of a glass sur- 
 face except the edge, it is not possible to control perfectly the direc- 
 tion and extent of this first crack ; at an edge a small crack may be 
 started with tolerable certainty by carrying the file-mark entirely over 
 the edge. To guide the crack thus started, a pointed bit of charcoal 
 or slow-match may be used. The hot point must be kept on the glass 
 from 1 c. m. to 0.5 c. m. in advance of the point of the crack. The 
 crack will follow the hot point, and may therefore be carried in any 
 desired direction. By turning and blowing upon the coal or slow- 
 match, the point may be kept sufficiently hot. Whenever the place 
 of experiment is supplied with common illuminating gas, a very small 
 jet of burning gas may be advantageously substituted for the hot coal 
 or slow match. To obtain such a sharp jet, a piece of hard glass 
 tube, No. 5, 10 c. m. long, and drawn to a very fine point (see Ap- 
 

 APPENDIX. 
 
 pendix 3), should be placed in the caoutchouc tube which ordinarily 
 delivers the gas to the gas-lamp, and the gas should be lighted at the 
 fine extremity. The burning jet should have a fine point, and should 
 not exceed 1.5 c. in. in length. By a judicious use of these simple 
 tools, broken tubes, beakers, flasks, retorts and bottles may often be 
 made to yield very useful articles of apparatus. No sharp edges 
 should be allowed to remain upon glass apparatus. The durability 
 of the apparatus itself, and of the corks and caoutchouc stoppers and 
 tubing used with it, will be much greater, if all sharp edges are re- 
 moved with the file, or, still better, rounded in the lamp. 
 
 3. Bending and Closing Glass-tubes. Tubing of sizes 5 
 to 8 inclusive can generally be worked in the common gas- or spirit- 
 lamp ; for larger tubes the blast-lamp is necessary (see Appendix, 
 6). Glass tubing must not be introduced suddenly into the hottest 
 part of the flame, lest it crack. Neither should a hot tube be taken 
 from the flame and laid at once upon a cold surface. Gradual heating 
 and gradual cooling are alike necessary, and are the more essential 
 the thicker the glass ; very thin glass will sometimes bear the most 
 sudden changes of temperature, but thick glass and glass of uneven 
 thickness absolutely require slow heating and annealing. When the 
 end of a tube is to be heated, as in rounding sharp edges, more care is 
 required in consequence of the great facility with which cracks start 
 at an edge. A tube should, therefore, always be brought first into the 
 current of hot air beyond the actual flame of the gas- or spirit-lamp, 
 and there thoroughly warmed, before it is introduced into the flame 
 itself. If a blast-lamp is employed, the tube may be warmed in the 
 smoky flame, before the blast is turned on, and may subsequently be 
 annealed in the same manner ; the deposited soot will be burnt off in 
 the first instance, and in the last, may be wiped off when the tube is 
 cold. In heating a tube, whether for bending, drawing or closing, 
 the tube must be constantly turned between the fingers, and also 
 moved a little to the right and left, in order that it may be uniformly 
 heated all around, and that the temperature of the neighboring parts 
 may be duly raised. If a tube, or rod, is to be heated at any part but 
 an end, it should be held between the thumb and first two fingers of 
 each hand in such a manner that the hands shall be below the tube, or 
 rod, with the palms upward, while the lamp-flame is between the 
 hands. When the end of a tube, or rod, is to be heated it is best to 
 begin by warming the tube, or rod, about 2 c. m. from the end, and 
 from thence to proceed slowly to the end, 
 
tv APPENDIX. 
 
 The best glass will not be blackened or discolored during heating. 
 The blackening occurs in glass which, like ordinary flint glass, contains 
 lead (silicate). Glass containing much lead is not well adapted for 
 chemical uses. The blackening may sometimes be removed by put- 
 ting the glass in the upper or outer part of the flame, where the 
 reducing gases are consumed, and the air has the best access to the 
 glass. The blackening may be altogether avoided by always keeping 
 the glass in the oxidizing part of the flame. 
 
 Glass begins to soften and bend below a visible red heat. The con- 
 dition of the glass is judged of as much by the fingers as the eye ; the 
 hands feel the yielding of the glass, either to bending, pushing or 
 pulling, better than the eye can see the change of color or form. It 
 may be bent as soon as it yields in the hands, but can be drawn out 
 only when much hotter than this. Glass-tubing, however, should not 
 be bent at too low a temperature ; the curves made at too low a heat 
 are apt to be flattened, of unequal thickness on the convex and con- 
 cave sides, and brittle, 
 
 In bending tubing to make gas delivery-tubes and the like, attention 
 should be paid to the following points : 1st, the glass should be equally 
 hot on all sides ; 2d, it should not be twisted, pulled out or pushed 
 together during the heating ; 3d, the bore of the tube at the bend 
 should be kept round, and not altered in size ; 4th, if two or more 
 bends be made in the same piece of tubing (Fig. Ill, a), they should 
 all be in the same plane, so that the finished tube will lie flat upon 
 the level table. 
 
 When a tube or rod is to be bent or drawn close to its- extremity, a 
 temporary handle may be attached to it by softening the end of the 
 tube, or rod, and pressing against the soft glass a fragment of glass 
 tube, which will adhere strongly to the softened end. The handle 
 may subsequently be removed by a slight blow, or by the aid of a file. 
 If a considerable bend is to be made, so that the angle between the 
 arms will be very small or nothing, as in a siphon, for example, the 
 curvature can not be well produced at one place in the tube,but should 
 FIG. m. be made by heating, progressively, several cen- 
 
 timetres of the tube, and bending continuous- 
 ly from one end of the heated portion to the 
 other (Fig. Ill, &). Small and thick tube may 
 be bent more sharply than large or thin tube. 
 
 In order to draw a glass tube down to a finer bore, it is simply 
 necessary to thoroughly soften on all sides one or two centimetres' 
 
 a 
 
APPENDIX. v 
 
 length of the tube, and then, taking the glass from the flame, to 
 pull the parts asunder by a cautious movement of the hands. The 
 larger the heated portion of glass, the longer will be the tube 
 thus formed. Its length and fineness also increase with the rapidity 
 of motion of the hands. If it is desirable that the finer tube 
 should have thicker walls in proportion to its bore than the origi- 
 nal tube, it is only necessary to keep the heated portion soft for two 
 or three minutes before drawing out the tube, pressing the parts 
 slightly together the while. By this process the glass will be thick- 
 ened at the hot ring. 
 
 To obtain a tube closed at one end, it is best to take a piece of 
 tubing, open at both ends, and long enough to make two closed tubes. 
 In the middle of the tube a ring of glass, as narrow as possible, must be 
 made thoroughly soft. The hands are then separated a little, to cause 
 a contraction in diameter at the hot and soft part. The point of the 
 flame must now be directed, not upon the narrowest part of the tube, 
 but upon what is to be the bottom of the closed tube. This point 
 is indicated by the line a in Fig. IV. By FIG. rv. 
 
 withdrawing the right hand, the narrow part ^ 
 
 of the tube is attenuated, and finally melted 
 off, leaving both halves of the original tube 
 closed at one end, but not of the same form ; 
 the right-hand half is drawn out into a long 
 
 point, the other is more roundly closed. It is not possible to close 
 handsomely the two pieces at once. The tube is seldom perfectly 
 finished by the operation ; a superfluous knob of glass generally 
 remains upon the end. If small, it may be got rid of by heating the 
 whole end of the tube, and blowing moderately with the mouth into 
 the open end. The knob being hotter, and therefore softer than any 
 other part, yields to the pressure from within, spreads out and disap- 
 pears. If the knob is large, it may be drawn off by sticking to it a 
 fragment of tube, and then softening the glass above the junction. 
 The same process may be applied to the too pointed end of the right- 
 hand half of the original tube, or to any misshapen result of an unsuc- 
 cessful attempt to close a tube, or to any bit of tube which is too short 
 to make two closed tubes. When the closed end of a tube is too thin, 
 it may be strengthened by keeping the whole end at a red heat for two 
 or three minutes, turning the tube constantly between the fingers. It 
 may be said in general of all the preceding operations before the 
 lamp, that success depends on keeping the tube to oe heated in constant 
 
vi APPENDIX. 
 
 rotation, in order to secure a uniform temperature on all sides of the 
 tube. 
 
 9. (Abridged.) Corks. The best corks generally need to be soft- 
 ened before using; this may be effected by rolling the cork under a 
 board upon a table, or under the foot upon a clean floor, or by gently 
 squeezing it on all sides with a " cork-squeezer." 
 
 In boring holes through corks to receive glass tubes use is made of a 
 round file, and the aim is to make the hole as cylindrical as possible 
 and not too large. 
 
 A flask which presents sharp or rough edges at the mouth can 
 seldom be tightly corked, for the cork cannot be introduced into the 
 neck without being cut or roughened ; such sharp edges must be 
 rounded in the lamp. In thrusting glass tubes through bored corks : 
 (1.) The tube should be grasped very close to the cork, in order to 
 escape cutting the hand which holds the cork, should the tube break. 
 (2.) A thistle tube must never be held by the thistle in driving it 
 through the cork, nor a bent tube grasped at the bend, unless the bend 
 comes immediately above the cork. (3.) The tube must not be pushed 
 straight into the cork, but screwed in, as it were, with a slow rotary as 
 well as onward motion. Joints made with corks should always be 
 tested before the apparatus is used by blowing into the apparatus and 
 at the same time stopping up all legitimate outlets. Any leakage is 
 revealed by the disappearance of the pressure created. 
 
 15. Filtering. Filtration is resorted to in order to separate a 
 finely divided solid from a liquid. The filter may be made of paper, 
 cloth, tow, cotton, asbestos, and other substances. Paper is the sub- 
 stance oftenest used. A good filtering paper must be porous enough 
 to filter rapidly, and yet sufficiently close in texture to retain the 
 finest powders ; and it must also be strong enough to bear, when wet, 
 the pressure of the liquid which must be poured upon it. 
 
 Filtering paper is commonly sold in sheets, which may be cut into 
 circles of any desired diameters for use, according to the various 
 scales of operation and quantities of liquids to be filtered, or pack- 
 ages of " cut-filters " may be procured ready-made from the dealers 
 in chemical ware. 
 
 There are two ready methods of preparing filters for use. Accord- 
 ing to the first method, shown in Fig. XXIV, a circle of paper is 
 folded over on its own diameter, and the semicircle thus obtained 
 is doubled once upon itself into the form of a quadrant ; the paper thus 
 folded is opened so that three thicknesses shall come upon one 'side, 
 
XXIV 
 
 APPENDIX. 
 
 Fie. xxiv. and one thickness upon the other, as shown in the 
 upper half of Fig. XXIV ; the filter is then placed 
 in a glass funnel, the angle of which should be pre- 
 cisely that of the opened paper, viz., 60. The 
 paper may be so folded as to fit a funnel whose 
 angle is more or less than 60, but this is the 
 most advantageous angle, and funnels should be 
 selected with reference to their correctness in this 
 respect. 
 
 In the second method of folding filters, the circle of paper is 
 doubled once upon itself as before into the form of a semicircle, and 
 a fold equal to one quarter of this semicircle is turned down on each 
 side of the paper. Each of the quarter semicircles is then folded 
 back upon itself, as shown in the lower half of Fig. 
 XXV ; the filter is opened, without disturbing the 
 folded portions, and placed in the funnel. Filtration 
 can be rapidly effected with this kind of filter, for 
 the projecting folds keep open passages between the 
 filter and the funnel, and thus facilitate the passage 
 of the liquid. That portion of the circle of paper 
 which must necessarily be folded up in order to give 
 the requisite conical form to a paper filter retards 
 filtration in the first manner of folding, but helps it in the second. 
 
 FIG. XXV. 
 
 Fia. XXVI. 
 
 FIG. xxvn. 
 
 Coarse and rapid fil- 
 tering can be effected 
 with cloth bags ; also 
 "by plugging the neck 
 of a funnel loosely 
 with tow or cotton. If 
 a very acid or very 
 caustic liquid, which 
 would destroy paper, 
 cotton, tow or wool, 
 is to be filtered, th 
 best substances wherewith to 
 the neck of 
 
 plug 
 the funnel are asbestos 
 
 and gun-cotton, neither of which is 
 attacked by such corrosive liquids. 
 The glass funnel which holds the filter generally requires an inde- 
 pendent support, for it is seldom judicious, or possible, to support 
 
APPENDIX. xxv 
 
 the funnel directly upon the vessel which receives the filtrate, as tho 
 clear liquid which rues through the filter is called. The iron stand 
 (Fig. XVII) may be used for this purpose ; and wooden stands, of the 
 form represented in Fig. XXVI, adapted expressly for holding funnels, 
 are very convenient and not expensive. In general, care should bo 
 taken that the lower end of the funnel touch the side or edge of the 
 vessel into which the filtrate descends, in order that the liquid may not 
 fall in drops, but run quietly down without splashing. Sometimes 
 there is no objection to thrusting a funnel directly into the neck of a 
 bottle or flask, but in this case an ample exit for the air in the bottle 
 must be provided (Fig. XXVII). 
 
 [The " Appendix " is taken from Eliot and Storer's Elementary Man- 
 ual by permission of the authors and publishers.] 
 
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