« ^%. IMAGE EVALUATION TEST TARGET (MT-3) // /k^ 1.0 I! Li 12.8 2.2 lis ilM 1.8 1.25 1.4 1.6 '4 6" - p. V2 ^ ^ "c^l /}. /y el >> y >^^ /i Photographic Sciences Corporation d i\ V \ % <^ 6^ 23 WEST MAIN STREET WEBSTER, N.Y. 14580 (716) 872-4r>03 CIHM/ICMH Microfiche Series. CIHM/ICMH Collection de microfiches. Canadian Institute for Historical Microreproductions / Institut Canadian de microreproductions historiques O V Technical and Bibliographic Notes/Notes techniques et bibliographiques The Institute has attempted to obtain the best original copy available for filming. Features of this copy which may be bibliographically unique, which may alter any of the images in the* reproduction, or wliich may significantly change the usual method of filming, are checlted below. D D D D D Coloured covers/ Couvertura de couieur I 1 Covers damaged/ Couvertura endommagie Covers restored and/or laminated/ Couvertura restaur^e et/ou peliiculie Cover title missing/ Le titre de couvarture manque Coloured maps/ Cartes g6ographiques en couieur □ Coloured inic (i.e. other than blue or blacic)/ Encre de couieur (i.e. autre que bleue ou noire) I I Coloured plates and/or illustrations/ Planches et/ou illustrations en couieur Bound with other material/ Ralid avec d'autres documents Tight binding may cause shadows or distortion along interior margin/ La reiiure serr^e peut causer de I'ombre ou de la distortion ie long de la marge intdrieure Blank leaves added during restoration may appear within the text. Whenever possible, these have been omitted from filming/ II se peut que certaines pages blanches ajoutdes lors d'une restauration apparaissent dans le texte, mais, torsque cela dtait possible, ces pages n'ont pas 6t6 fiim6es. Additional comments:/ Commentaires suppl^mentaires; L'Institut a microfilm^ ie meilleur exemplaire qu'il lui a 6t6 possible de se procurer. Les details de cet exemplaire qui sont peut-6tre uniques du point de vue bibliographique, qui peuvent modifier une image reproduite, ou qui peuvent exiger une modification dans la mdthode normale de filmage sont indiqu6s ci-dessous. r~~| Coloured pages/ D Pages de couieur Pages damaged/ Pages endommagdas I I Pages restored and/or laminated/ ^ Pages rsstaur6es et'^ou pellicul6es Pages discoloured, stained or foxed/ Pages d6color6es, tacheties ou piqu6es □ Pages detached/ Pages d6tach£es Showthrough/ Transparence I I Quality of print varies/ D Quality indgalo de I'impression Includes supplementary material/ Comprend du materiel suppldmentaire Only edition available/ Seule 6diticn disponibie Pages wholly or partially obscured by errata slips, tissues, etc., have been refilmed to ensure the best possible image/ Les pages totalement ou partiellement obscurcies par un feuiilet d'errata, une pelure, etc., ont M filmdes d nouveau de fapon d obtenir la mailleure image possible. This item is filmed at the reduction ratio checked below/ Ce document est filmA au taux de reduction indiquA ci-dessous. 10X 14X 18X 22X 26X 30X 12X 16X / 20X 24X 28X 32X The copy filmed here ha» been reproduced thanks *o the generosity of: Health Sciences Library McMaster University L'exemplaire film^ fut reprodult grSce d la g6n6rosit6 de: Health Sciences Library McMaster University The images appearing here are the best quality possible considering the condition and legibility of the original copy and in keeping with the filming contract specifications. Les images suivantes ont 6t6 reproduites avec le plus grand soin, compte tanu d4 la condition et de la netteti de rexemplaire film6, et en conformity avec les conditions du contrat de filmage. Original copies in printed paper covers are filmed beginning with the front cover and ending on the last page with a printed or illustrated impres- sion, or the back cover when appropriate. All other original copies are filmed beginning on the firrt page with a printed or illustrated impres- sion, and ending on the last page with a printed or illustrated impression. The fast recorded frame on each microfiche shall contain the symbol — »- (meaning "CON- TINUED"), or the symbol V (meaning "END"), whruhever applies. Les exempiaires originaux dont la couverture en papier est imprimde sont film6s en commen9ant par le premier plat et en terminant soit par la derniAre page qui comporte une empreinte d'impression ou d'iliustration, soit par le second plat, selon le cas. Tous les autres exempiaires originaux sont film^s en commenpant par la premidre page qui comporte une empreinte d'impression ou d'iliustration et en terminant par la dernidre page qui comporte une telle empreinte. Un des symboles suivants appara'tra sur la dernidre image de cheque microfiche, selon le cas: le symbole ^h»> signifie "A SUIVRE", le symbole V signifie "FIN". Maps, plates, charts, etc., may be filmed at different reduction ratios. Those too large to be entirely included in one exposure are filmed beginning in the upper left hand corner, left to right and top to bottom, as many frames as required. The following diagrams illustrate the method: Les cartes, planches, tableaux, etc., peuvent dtre film6s d des taux de reduction diff^rents. Lorsque le document est trop grand pour dtre reproduit en un seul cliche, il est filmi it jjartir de Tangle sup^rieur gauche, de gauche d droite, et de haut en bas, en prenant le nombre d'images ndcessaire. Les diagrammes suivants illustrent la mdthode. 1 2 3 1 2 3 4 5 6 M LABORATORY HANDBOOK OF Experimental Chemistry FOR THE USE OF DENTAL STUDENTS. COMPILED BY WALLACE P. COHOE. B.A.. Demonstrator ok Practical Chkmistry IN the Koyal ollege of Dental Surgeons of Ontario, TORONTO, ONTARIO. \iuifr-, X TORONTO: Monetary Times Printing Company, Limited 1897. McMSSTER UNIVI f PREFACE. This book, as its title indicates, is intended for the use of dental students in the chemical laboratory. As such it is designed to satisfy the hitherto unsatisfied need for such. The course in chemistry which the dental student must cover is rather peculiar and one which is not found in the ordinary text books. His working know- ledge of chemistry must be essentially practical. One of the olijects of his course is to acquaint himself thoroughly with the operations which he must perform in his own laboratory. To this end the variety of subjects covered in this course is rather extensive. The elementary study of the principal non-metals is necessary as a founda- tion to all further study of chemistry. Then it is important that a working knowledge of fjualitative analysis both in a dry and wet way, should be obtained. Metals, such as are found in the dental laboratory, also must ccme in for examination and treatment. Many organic substances, including the alkaloids, must not be overlooked. Physiological chemistry also has a claim. Such a variety of work does not exist in any one work suitable for use in the laboratory. Hence the appearance of the present course. As a laboratory hand book it is not of course complete in itself, but must be supplemented by lectures and also by independent reading on the part of the student. By this means a knowledge of the science as well as the art of chem- istry will be gained. In conclusion the compiler would say that he claims nothing to be original but the arrangement. Many sources of information have been made use of, which are as varied in character as the course itself. W. P. C. Toronto, Oct. ist, 1897, TO THE STUDENT. I. Full notes should be made of every experiment performed. These should consist of a full description of the various phenomena noticed, and also of a statement of any inference to be derived from such phenomena. As this is not in any sense a text book, outside reading will be necessary. The result of this should appear in the form of explanations of experiments. The book may be called in any day for examination by the Demonstrator. Use formula' and equations where possible. 2. Cultivate the art of using small quantities in working. By this means greater nicety of operation will be secured. 3. Keep all apparatus in a clean, neat state. Do not allow acids to remain on the outside of your bottles. Let the drawers and locjs of paper from a scribbler. In a beaker place two giams of Potassium Permanganate crys- tals. On these pour some Sulphuric Acid. Do not heat. Hold some of the test paper above the mouth of the beaker. What occurs ? Explain. When the gas is coming off freely hang over it, but so as not to touch the liquor, a paper saturated with turpentine. Explain the resulting phenomenon. Explain the chemical actions of Ozone. ! ! ! 4.— HYDROGEN DIOXIDE (Hydrogen Peroxide.) -Symbol H,0„ Mol. Wt.. 34. To a quantity of dilute HgSO^ add some powdered Barium Dioxide, BaOg. Filter off the precipitate. What does the filtrate contain ? W'rite the equation. Divide the solution into three parts. Into one drop some litmus solution. Does any change take place ? Into another place a piece of the test paper used for Ozone. What do you observe ? Make a slightly coloured solution of Potassium Permanganate. To it add some Hydrogen Dioxide solution. Shake the two together and let them stand for some time. Does the Permanganate lose colour ? Explain fully the chemical action of Hydrogen Dioxide. What is meant by nascent state ? 5. -NITROGEN Symbol N At. Wt., 14. Place a small piece of dry Phosphorus on a porcelain crucible lid, and fix this on a flat piece of cork, so that the lid may be floated on the water in the pneumatic trough. Light the Phosphorus, and quickly surround it with a beaker. A portiun of the air will first be expelled by the heat, and the Phosphorus will continue to burn as long as any Oxygen remains in the air of the bell-jar ; when that is exhausted it will cease to burn. Observe that the water rises inside the bell- jar, replacing the Oxygen, which is no longer gaseous, but has com- bined with the Phosphorus to form Phosphorus Pentoxide. Wait a few minutes to allow the Pentoxide to be completely dissolved by the water. What is contained in the beaker ? Plunge a lighted taper into the jar. What are the properties of Nitrogen ? Compare them with those of Oxygen and Hydrogen. 6-NITROGEN MONOXIDE (NitPous Oxide.) Symbol. N.O. Mol. Wt., 44. Preparation. — Put 25 y ams of commercial Ammonic Nitrate, NH4NO3, into an Oxygen generating apparatus, connected with three wash bottles. The first bottle should contain a solution of Ferrous Sul- phate, the second, a solution of Caustic Potash, and the third, water. Heat the Nitrate gently and Nitrogen Monoxide will be given off. Collect four beakers of the gas over warm water. If the Nitrate be chemically pure, the wash bottles may be omitted. Write the equation for the above reaction. Perform the following experiments ; (a) Plunge a lighted taper into the first jar. (b) Burn a piece of Phosphorus, or Carbon, or Sulphur in the second jar. If burning strongly at first, they continue to burn. Write the equation expressing the reaction, (c) Explode a mixture of the gas with Hydrogen. Write the equation. with (d) Place the fourth jar, mouth downward, over cold water, and then shake. Why is the gas collected over warm water ? What are the properties of Nitrogen Monoxide ? Why are the wash bottles used ? 7. -NITROGEN DIOXIDE (Nitric Oxide). Symbol, NO. Mol. Wt. 80. Preparation. — Place some copper filings in a Hydrogen generat- ing apparatus, add some warm water, and then pour down the funnel tube some strong Nitric Acid. The gas that first forms should be allowed to escape. Collect over water four beakers full of the gas and perform the following experiments : — (a) Allow the contents of the first beaker to escape into the air. (b) Ignite a piece of Phosphorus very slightly and plunge it into the second beaker. (c) Allow another piece of Phosphorus to burn strongly, and then place it in the third beaker. (d) Pour a solution of Ferrous Sulphate, FeS04, into the fourth beaker full of the gas. Then hold the hand over the beaker's mouth and shake vigorously. Note the two phenomena that occur. Write all the equations for the above experiments. Enumerate the properties of Nitric Oxide. 8.-NITRIC ACID. Symbol. HNO,. Mol. Wt, 63. Preparation. — Put into a tabulated glass retort 30 grams of powdered Nitrate of Potash, KNO3, and an equal weight of strong Sulphuric Acid, HgSO^. Place the end of the retort in a flask which is made to float on a basin of water. Apply heat to the retort. Soon a yellowish coloured liquor distils over and is collected in the cool flask. Write the equation. Nitric Acid an oxidizing agent : (a) Place a small piece of Phosphorus in a saucer, then drop on it a little of the acid. (b) On powdered piecesofglowingcharcoalpoura little Nitric Acid. Te?ts for Nitric Acid: (a) Add a few drops of the Nitric Acid prepared as above to a solution of Indigo contained in a test-tube. Notice that the blue colour speedily disappears. (6) Place a few bits of copper turnings in a test-tube, cover I :hil them with water, and add a little Nitric Acid. The Copper soon begins to dissolve, forming a blue solution, and at the same time brown vapours fill the test-tube. Explain the above reaction. (c) Dissolve a few crystals of Ferrous Sulphate, FeSO^, in water in a test-tube. Add a few drops of Sulphuric Acid and allow the whole to cool. Then turn the test-tube sideways and gently pour Nitric Acid or a nitrate in solution down its side. The phenomenon which results will always enable us to recognize Nitric Acid or a nitrate. To th^. formation of what substance is the black ring due ? 9.-AMM0NIA. Symbol NH, Mol. Wt. 17. Preparation. — Mix ten grams of Ammonic Chloride and the same weight of Quicklime. Place the mixture in a flask provided with a long delivery tube passing straight upwards. Heat gently. When the gas begins to come off invert a test tube over the end of the delivery tube. Is Ammonia lighter or heavier than air ? How then may it be collected ? Properties :— (a) Pass a lighted taper up into the test tube full of gas. (6) Pass some of the gas into reddened litmus. Upon the result of this, devise a means of knowing when a bottle is full of this gas. (c) Moisten a glass rod with Hydrochloric Acid, and then bring it near the end of the delivery tube. Do the same with other acids. (d) Fill a test tube with Ammonia, and invert it over a beaker of cold water coloured with red litmus. Account for the resulting phenomenon. Tests. — Will any of the above actions answer as tests for Ammonia? When present in mmute quantities, as it frequently is in drink- ing water, Ammonia is best detected by what is known as Nessler's test : " To a solution of Potassic Iodide add solution of Mercuric Chloride until the precipitate formed just ceases to be re-dissolved, then, add an equal volume solution of Caustic Potash, and allow the whole to stand until clear. A few drops of this solution will give a yellowish-brown precipitate, with even the slightest trace of Ammonia," What are the properties of Ammonia ? Explain by means of an equation the method of its preparation. nd the ■^i\_ ovided . gently, end of '• How ibe full ■■; on the full of bring • acids. 3ver a sts for drink- essler's ercuric solved, ow the ill give race of X ;J^K iration. 10 -CHLORINE. Symbol, CI At. Wt, 85.6. Preparation. — i. Into a test-tube put one part of Manganese Dioxide, two parts of salt, and three of Sulphuric Acid. Fit the test- tube with a coik and delivery tube. Heat gently and pass the gas that comes off into separate solutions of litmus and indigo. Cau- tiously stnell the gas. Note its colour. 2. To prepare the gas on a larger scale, take a Florence flask and place in it about 20 grams of Manganese Dioxide and 100 cos. of strong Hydrochloric Acid. The flask should be fitted with a delivery tube bent over so as to reach almost to the bottom of a collecting beaker. Tha beaker should set on the table and should be covered with a piece of cardboard through which the delivery tube passes. Why can not Chlorine be collected over water ? Apply a very gentle heat. Fill several jars, taking care that little or none of the gas escapes into the room. Afterwards pass the gas into a flask perfectly full of water ; in about ten minutes place this flask aside for future use. Smell the water. Properties. — {a) Take the flask full of Chlorine water pre- pared in the last experiment, and fit it with a cork and tube. The outer end of the tube must be drawn to a fine point. Insert the cork so that there is not a bubble of air left in the flask. Invert the flask and expose to direct sunlight for a day. Then place the flask on the table, remove the cork, and quickly bring a glowing splinter to the mouth of the flask. Test the water in the flask with blue litmus solution. Taste it. What happens the glowing splinter ? Why ? (6) Lower very slowly a lighted taper into a jar of Chlorine. At the same time suspend a piece of blue litmus paper at the mouth of the jar. Smell the gas that is formed duriui^ the combustion. How can you account for the action of the taper .'' (c) Wet a piece of blotting paper with Oil of Turpentine, CioH,g, and then place it in another jar of the gas. (rf) Take a few pieces of the metal antimony and powder them ; then place on a sheet of paper and shake the powder into a jar of Chlorine. What compound is formed in the above experiment ? {e) Place a piece of red cl'th, partly moistened and partly dry, in a jar of Chlorine. Explain fully the bleaching action of Chlorine and compare it with the similar action of Ozone and Hydrogen Dioxide. Make a list of the principal properties of Chlorine. m til 8 ll.-HYDROCHLORIC ACID. Symbol. HCl. Mol. Wt.. 36.5 Preparation. — In a flask provided with a thistle tube and deliv- ery tube suiiilar to the one used in the preparation of Chlorine, place 30 grams of common salt. Add by degrees 5c grams of strong HaS04. What is the specific gravity of H3SO4 ? After the first evolution of gas has taken place hea* gently. Collect by downward displacement of air. Describe the gas which comes off. Write the equation. Properties. — (a) Invert a test tube full of the gas over a beaker of water, coloured with red litmus. (6) Fill a beaker with the gas. Place a piece of Sodium in a de- flagrating spoon, heat the Sodium until ignition and lower it into the jar of gas, which must be tightly covered. After the action has ceased quickly bring a lighted taper to the mouth of the beaker. What has been formed ? Explain. Dissolve the solid on the spoon. Taste it. What is it ? Write all equations. Test for Hydrochloric Acid or a solable Chloride. To a solution of Hydrochloric Ac;id, or a Chloride, add a few drops of Nitrate of Silver solution. What is formed ? Write the equation. <§ 12.-I0DINE. Symbol, I. At.Wt..l27. Test for Free Iodine. — Powder a piece of starch (about the size of a pea) in a mortar, stir it up with about 25 c.c. of cold water, and then heat the mixture (preferably in an evaporating basin) till it boils. A thin, clear solution of starch is thus obtained ; add a portion of it to about a quarter of a litre of water, and then a few drops of one of the solutions of Iodine, and observe the deep blue colour which the liquid assumes. Heat a little of this blue liquid in a test tube, and observe that the colour disappears ; allow it to cool, and observe the reappearance of the colour. How may certain Iodine compounds be tested ? Why have substances the power to free Iodine from the Potassium Salt ? ).6 nd deliv- , place 30 H,,SO^. jlution of lacement ion. s over a 1 in a de- into the tion has beaker. e spoon. dd a few t)out the 1 water, n) till it portion irops of ir which st tube, observe ly have ? h SET 1 A. 13. -CARBON -Symbol. C. At. Wt.. 12. Properties. — (a) Place a wet filter paper inside a funnel, and then cover the inside of the filter paper with a thick coating of animal charcoal, or bone black. Now filter through the paper a wine-glass full of ale or porter. (b) Place a piece of charcoal in a test-tube and then pour upon it a little strong Sulphuric Acid. Observe whether the charcoal changes in any way. Try whether an alkali will produce any change in the charcoal. (c) Wet the inside of a large test tube with Liquor Ammoniae. Now drop into the tube some wood charcoal previously heated in a covered crucible. Cork the tube and after a few minutes remove the cork, and ascertain by smelling it whether there is any Ammonia left in the test tube. 14.-CARB0N DIOXIDE.-Symbol, CO,. Mol. Wt. 44. Preparation. — Place some pieces of marble (Calcium Carbon- ate) in a flask with funnel and conducting tube, pour some water over it, and then a little Hydrochloric Acid ; a rapid effervescence will begin, and the gas will be given off copiously. It may be collected over water, but as it is much heavier than air it is best collected by downward displacement. This is done by leading the conducting tube to the bottom of the gas jars, and allowing the heavy gas to collect in them and displace the air. As the gas extinguishes flame, the jars are ascertained to be full when a lighted taper placed in (he mouth is at once extinguished. When this is the case cover the jar and substitute another ; in this way collect four jars of the gas. Properties. — (a) Place a lighted taper in the gas. What takes place ? (b) Devise an experiment for proving whether COg is lighter or heavier than air. (c) Allow the gas to bubble through lime water Ca(OH)2. What is formed ? Continue to pass the gas through the liquid. What is the result ? What is the reason ? 1 i lO 15. CARBON MONOXIDE. Symbol. CO. Mol. Wt., 28. rRiii'AKATioN.^ — Into a llorrnre llask put 8 or lof^rains of Oxalic Acid, ami about 50 c.c. of Sulphuric Acid. Vh with a tif^lit <^oil< and tube and .ittach to a wash hotth? containin^j ' stronj; sohition of Caustic Potash. From the wash bottle a tielivery tube should pass to the pneumatic trou^^h. Apply heat cautiously to the (lask, rcf^ulating it so that tiie f;as uiay come oil" in a steaily stream. After the air has been expelled from the apparatus, collect three bottles of the gas, and allow these bottles to stantl over water for some time before using tlu-m. Meanwhile substitute for the delivery tube one whose end has been drawn to a line point. Apply a lighted match to the jet. Why is the wash bottle used ? Write the etiuation. PuoPKKTiKS. — {a) Raise one of the bottles of gas from the water, and apply a light(Hl taper to its niouth. (b) Try to pour the gas from one bottle to another, then test the result with a lighted paper. [c) Purify thoroughly the gas in a third bottle, by shaking it up well with Caustic Potash or Caustic Soda solution, then test the gas with clear Lime-water. Compare the properties of the two Oxides of Carbon. 16.-METHANE. Symbol. CH,. Mol. Wt., 16. Take a hard glass test-tube or Florence llask, and fit with a cork and fine delivery tube. Place in the test-tube two grams of Acetate of Sodium NaCoHjOj, 8 grams of Sodium Hydroxide and 2 grams of finely pow^dered Quicklime, CaO, heat. After collecting a beaker or two of the gas, light the jet and observe the colour of the flame. Fill a small soda water bottle with a mixture of one part of the gas and two parts of Oxygen. Ignite the mixture. Express the re- action by an equation. Take a stoppered bottle and fill it with a mixture of equal volumes of Marsh Gas and Chlorine. Expose to sunlight for a day, then test the contents with blue litmus. Note any change in colour. Write the equations for the above reactions. What are the properties of Methane? How does it occur naturally? IZ 17.-ETHYLENE (Ethene, Olefraut Gas). Symbol. C,H«. Mol. Wt, 28. Into a flask provided with a delivery tube and thistle tube pour 50 to 60 cc. of strong H2SO4 and half the quantity of Alcohol. Heat gently. Collect the gas which comes off over water. Write the tHoh. Is the action of the H3SO4 in this case comparable wit iction in any previous experiment ? \\ ill the gas burn ? Try it. Devise simple experiments to prove that the gas contains Hydro- gen and Carbon. Find out whether the gas is heavier or lighter than air. Remove a jar of the gas, let it drain well, then turn it mouth upward and place over it another jar of the same size filled with Chlorine. After standing for some time, note whether the colour of the Chlorine changes. Observe closely what forms at the bottom of the lower jar — " Dutch li(|uid." Ascertain whether the ga.6 will explode when mixed with air or oxygen. 18.-ACETYLENE. Symbol, C»H,. Mol. Wt., 30. In an evaporating dish place some pieces of Calcium Carbide. Wet these with water from a wash bottle. What takes place ? Smell the gas which comes off. Will it burn ? Devise an experiment to find out whether it forms an explosive mixture with air. Write the equations. How is Calcium Carbide manufactured ? 19 -SULPHUR DIOXIDE. Symbol, SO,. Mol. Wt., 64. Put 20 grams of copper turnings into a Florence flask, fitted up like a Hydrogen generating apparatus. Just cover the copper with strong Sulphiiric Acid, and heat the flask very carefully. Collect the gas that escapes by downward displacement of the air. Compare its odour with that of burning sulphur. Collect three jars of the gas for further experiments. Keep them covered. Pour some water into one of the jars and then shake. Is the gas soluble in water ? Test the \vater with blue litmus solution. Taste it. Hang a red rose or other high-coloured flower in the second jar. If any change takes place in the flower, remove it and place it in pure air. ;h- Pour the third jar of Sulphur Dioxide into an " empty " jar with a burning candle at its bottom. Write the equation. What are the properties of Sulphur Dioxide ? i^^muis?? Vii 12 SULPHURETTED HYDROGEN. Symbol, H,S., Mol Wt. 34. Preparation. — Take a Hydrogen generating apparatus, and place in it some powdered Sulphide of Iron. Cover the Sulphide with water, cork the apparatus tightly, and then ydd a few drops of Sulphuric Acid. Collect two or three bottles of the gas over warm water. Do not allow much of the gas to escape into the rooin. It is poisonous. Write the equation. Bubble the gas through a solution of blue litmus. Devise an experiment to ascertain whether the gas is soluble in water. Place in a test glass a solution of Copper Sulphate, in another a solution of Iron Sulphate, and in a third a solution of Sodium Chloride ; to each add a few drops of Hydrochloric Acid, and then a little Sulphuretted Hydrogen water. Observe the black precipitate of Copper Sulphide in the first glass, and no precipitate in the other two glasses. To each of these add a little potash solution, and observe the black precipitate of Ferrous Sulphide in the one case, and the absence of a precipitate in the other. How may metals be classified on the basis of the solubility of their sulphides ? How would you separate copper from iron con- tained in a solution ? Attach a piece of glass tubing drawn to a fine point to the gen- erating apparatus and try whether the gas will burn. What are the products of combustion. us. and mlphide drops of ;r warm 1. It is iluble in lother a Sodium id, and ! black cipitate potash e in the bility of 3n con- he gen- are the SECTION II. EXAMINATION OF SUBSTANCES IN A DRY WAY. A. — Assay in a Glass Tube Closed at one End. Il I.— The Substance is Completely or Partially Volatilized. 1. Water is given off, which condenses in the upper part of the tube. This is examined with test paper. An alkahne reaction indicates Ammonia, an acid reaction the presence of a volatile acid such as H3SO4, HCl., HNO3, or HP. 2. Gas or vapour is evolved. (a) Oxygen, detected by means of a glowing splinter held in the mouth of the tube, indicates Peroxides, Nitrates, Chlorates, Bromates, or lodates. Example, KCIO3. (b) Sulphur Dioxide, detected by its odour and its acid reaction, indicates Sulphates or Sulphides. Example, CuSO^. (c) Hydrogen Sxilphide denotes Sulphides containing water. (d) Nitrogen Tetroxide, recognized by its colour and odour, indi- cates Nitrates or Nitrites. Ex. Pb (N03)2. (e) Carbon Dioxide is a decomposition product of Carbonates and some Oxalates. It will turn a drop of lime water held on the end of a glass rod milky. (/) Ammonia indicates Ammonium Salts. Ex., Microcosmic Salt, or organic substances containing Nitrogen. is) Hydrofluoric Acid etches the glass tube. 3. A Sublimate is formed. (a) — White Sublimates. (a) Ammonium Salts. If the sublimate be removed from the tube and heated with a little Na (OH) and a drop of water on platinum foil. Ammonia is evolved. Ex. NH^ CI. {b) Chlorides of Mercury. HgCl sublimes without previous fusion, whilst HgClg first fuses. The sublimate is yellow, hot, but white on cooling. of the action e acid in the nates, ction, , indi- >nates in the Dsmic 1 the jr on vious , but H |ii (c) Antimony Trioxufe fuses to a yellow liquor, then sublimes to needle-shaped crystals. (d) Arsenic Trioxide sublimes to octahedral crystals. (6) — Grey or Black Sublimates. (a) Metallic Arsenic and certain Arsenides. . {b) Mercury, ainalq^nms, and some Mer:;ury Salts. (c) Some Cadmium alloys. (c) — Coloured Sublimates. (a) Sulphur and certain Sulphides which contain much Sulphur yield a deep yellow to brownish red sublimate when hot, sulphur yellow when cold. Ex., Pyrite. (6) Antimony Sulphide when heated to a very high temperature yields a sublimate which is black while hot and reddish-brown when cold, (c) Arst the e in t. [QNS, scipi- to a ithe te is CHS cess, fH,) rhite y be 11 II ^ 22 5. KI precipitates brigiit-red Hglo, soluble in excess of either KI or HgCl2. 6. KgCrO^ precipitates an orange basic chromate easily soluble in HNO3. Write the equations. How would you distinguish between mer- curous and mercuric salts ? Lead. Pb 207. Solution for Reactions Pb (N03)2. 1. HoS produces a black precipitate of PhS, even in solutions of Pb Clj, so that a weak solution of a lead salt which has not been precipitated with HCl will be precipitated with H^S. Hence lead occurs both in the silver and copper groups. 2. Reaction, 2, 3, 4, and 3, for lead, in Group I., are also appli- cable in this group. How may lead be separated from the rest of the group ? Bismuth. Bi. 210. Solution for Reactions. BiClg. 1. Hg S produces a black precipitate of Bi^Sg, insoluble in KHS and KHO, but soluble in HNO3. 2. KHO or (NH4)H0 produces a white precipitate, which on boiling becomes yellow (BigOg); the precipitate is insoluble in excess of either reagent. *3, H^O, when added in considerable quantity to normal salts of Bismuth, produces an immediate white precipitate of basic salt of Bismuth. Bismuth Trichloride is most easily precipitated by H^O. If another salt of this metal is being examined, it is best to precipitate the oxide first by ammonia ; dissolve it in as little HCl as possible, and evaporate it almost to dryness. On adding water to this solu- tion, a precipitate of BiOCl at once forms, which is insoluble in Tartaric Acid (compare corresponding reaction with Antimony). Solutions of Bismuth Salts containing much free acid do not give this reaction with HgO until the excess of acid has been expelled by evaporation. 4. KgCrO^ produces a yellow precipitate of Big (Cr04)3, solu- ble in HNO3, and insoluble in NaHO. 5. Zn or Fe precipitates spongy Bi. *6. Heated on charcoal with Na^COg, in the reducing blowpipe > of either ly soluble •een mer- 2' solutions not been nee lead o appli- luble in hich on 1 excess al salts sic salt 2O. If :ipitate 3ssible, s solu- ible in mony). )t give led by , solu- wpipe ■^ 23 - K flame, compounds of Bi yield brittle metallic globules ; also a yellow incrustration of BigOg on the Charcoal. Bi is soluble in HNO, or aqua regia. Write the equations. Copper, Cu, 63.5. Solution for Reactions, CUSO4. 1. HgS precipitates black, CuS, soluble in HNO3 ; insoluble in KHS, and only slightly soluble in (NH4)2S3. CuS is also soluble in KCN, but insoluble in hot dilute HgSO^. 2. KHO precipitates a pale-blue Cu(H0)3, insoluble in excess. If KHO be added in excess and the mixture boiled, the precipitate becomes black. 3. (NH4)HO precipitates, when added in small quantities, greenish blue basic salt, soluble in excess of (NH4)HO, forming a dark blue solution which consists of double basic salt of copper and ammonium. 4. K4Fe(CN)g precipitates brown Cu2Fe(CN)g, insoluble in dilute acids, but decomposed by KHO. 5. Fe precipitates Cu in the metallic state, especially in the presence of a little free acid. 6. Zn also precipitates copper solutions. 7. KgCrO^, precipitates a brownish-red basic chromate, soluble in HNO3 and in (NHJHO. 8. Compounds of Cu, when heated in Bunsen flame, impart a green colour, especially after addition of AgCl. 9. Heated on charcoal with NaHCOg in reducing flame, yields brittle metallic globules of bright-red colour, soluble in HNO3 or concentrated HgSO^. Write the reactions. Cadmium, Cd, 112. Solution for Reactions, Cd(N03)2 1. HgS precipitates yellow CdS, soluble in HNO3, insoluble in KHS, KCN, and (NH JoS. CdS is dissolved by hot dilute H^SO^. Compare with copper reaction. 2. KHO precipitates Cd(H0)3, insoluble in excess of reagent. 3. (NH4)H0 precipitates Cd(H0)2 ; soluble in excess of reagent. 4. Zn precipitates Cd in brilliant scales. 5. Heated on charcoal with NaHCOg in reducing flame, yields a brown incrustation of CdO. Cd dissolves readily in HNO3. Write equations. How may copper and cadmium be separated ? & }' 1 , I . r 24 - ■» n TABLE B.— COPPER GROUP (II). Separation of Mercury, Lead, BIsmutb, Copper, and Cadmium (Sub-Qroap A.) To the filtrate from the Silver Group add an equal bulk of HCI, boil down nearly to dryness, (why ?) dilute with H.jO, and pass H,,S through the hot solu- tion. Filter. Residue. I Filtrate. HfirS, PbS, Bi.^S^, CuS, CdS, SnB, SnS^, 813.^8,, and As ,^8,. Groaps III., IV., and V. Wash with hot H^O containing H,^S, until free from CI; [digest residue* with (NH^)gSj for about fifteen minutes. Filter. Residue Filtrate. RgB, PbS, Hi 8 . Cu8, and Cd8. Sub-Group B. (8n Sb, and As.) (See Table E.) •In the abs nee of the sub-group omit that which is in parenthesis, and treat w'th HNO,, as below. Wash with hot H,jO till no longer alkaline]; add a small quantity of boiling HNOg, pouring it on several times. Filter. Residue. Filtrate. BgS. Pb, Bl, Cu, Cd. Dissolve in aqua regia, boil down to Add H^SO*, and boil down. White expel acid, and test with SnCl,^. . White precipitate indicates Lead. Filter from precipitate changing to grey indicates PbSO^, and add (NH^)HO to filtrate. Mercury. Confirm by reduction test. Filter. Residue. Filtrate. BL Cu, Cd. A white precipi- A blue solution tate Dissolve in indicates Copper. HCI, evaporate to Adopt Method I. or a small bulk, and II. add to H^O. A white precipitate indicates Bismuth. Method I. Add to the blue solution KCN till col- ourless ; pass a few bubbles of H.^S through the solution. Yellow precipitate indicates Cadmium. (Excess of HjS must be avoided, because traces of mercury may be present.) Method II. Add HCI till acid ; pass H,S through ; filter ; wash rapidly and thoroughly, and treat with hot dilute H.^SO^. Black residue indicates Copper. ' To filtrate, add HjS. Yellow precipitate indicates Cadmium. Note.— The student should be able to trace by means of equations the sepa- ration of all the elements of this and other groups. He should, also, practice writing out on paper the separation of mi.\tures of two or more metals and amal- gams. '• J- ! .; f 1 , < < i • J 1 ^ ( j 1 1 rpTTTT- 25 SUB-GROUP B. SULPHIDES SOLUBLE IN (NHJj S,, VIZ.: THOSE OF TIN, ANTIMONY AND ARSENIC. Tin. Sn 118 (Stannous Salts) Solution for Reactions Sn Clg. 1. HgS precipitates dark brown SnS, soluble in yellow (NH4)2S3 (nearly insoluble in colourless (NH4)3S ; re-precipitated as yellow SnSg by HCl. 2. KHO precipitates Sn (HO) 3, soluble in excess of reagent. 3. (NH4)HO precipitates Sn (H0)2, not soluble in excess. *4. HgClj precipitates at first white HgCl; on boiling with excess of reagent, grey Hg. 5. AuClg, on addition of a little HNO3, precipitates purple (royal purple of Cassius). 6. Zn precipitates metallic tin. 7. Mixed with NaHCOg-fKCN, and heated on charcoal in reducing flame, yields small globules of Sn and a white incrustation of SnOn. Stannic Salts, Sn. Solution for Reactions, SnCl^. Stannous Salts are converted into Stannic by oxidizing agents, HNO3, CI, FeClg, etc. 1. HjS precipitates yellow SnS.^, soluble in (NH4)3S, in KHO, and in boiling concentrated HCl. It is with difficulty soluble in (NH4)H0, and insoluble in (NH4)3C03. 2. KHO or (NH JHO precipitates white SNO(HO)a, soluble in an excess of precipitant. 3. Zn produces same reaction as with Stannous Salts. 4. The blow-pipe reaction for Stannic is the same as for Stan- nous. How are Stannous distinguished from Stannic Salts ? Write the equations. Antimony, Sb, 122.3. Solution for Reactions, SbClg. 1. HgS precipitates orange SbgSg, soluble in (NH^jgS, NaHO, and in hot concentrated HCl; insoluble in (NH4)2C03. 2. KHO precipitates SbjOg, soluble in excess of reagent. 3. (NH4)HO precipitates SboOg, insoluble in excess. 26 *5 4. H3O produces in solutions of SbClg a white precipitate of SbOCl, soluble in tartaric acid. 5. Zn in presence of HCl and platinum precipitates Sb as a black powder, which adheres to the platinum. The black stain on the platinum is not removed by HCl, but is immediately dissolved by warm UNO.,. 6. (Marsh's Test.) If a solution of Sb be placed in a liask in which hydrogen is being generated, SbHg is given off as a gas, which is decomposed by heat, Sb being deposited. This is best done by holding in the SbH, flame a piece of cold porcelain ; a dull-black stain of metallic Sb will be deposited on it. Add to the stain on the porcelain a drop of NaClO ; the stain will remain undissolved. lie very careful that all the air is expelled from the apparatus be- fore lighting. 7. Heated with NaHCO, on charcoal in the reducing blow-pipe flame, yields brittle globules of the metal and a white incrustation of SbgOg on the charcoal. ■ I Arsenic. As, 75.2. Solution for reaction. NagAs O^. 1. HgS produces in acid solutions a yellow precipitate of AsgS,, soluble in alkaline sulphides, in KHO, m HNO,, and in (NH4)2 CO3, but nearly insoluble in boiling concentrated HCl. (Compare reactions for Sb.) 2. AgNOg produces in neutral solutions of the a^senites a pale yellow precipitate of Ag^AsOg. This is best obta.. ed by adding AgNOg to an aqueous solution of As^Og, and then drop by drop a very dilute solution of (NH4)H0 prepared by adding one or two drops of ordinary (NH4)HO to a test-tube full of H^O. The pre- cipitate is readily soluble in excess of (NH4)HO, hence the necessity for using a very dilute solution of that reagent. 3. CUSO4 addtd under the same conditions as the AoiNOg , produces a pale green precipitate of CuHAsOg (Scheele's green), soluble in (NH4)HO. 4. Acetic acid, added to solutions of AsgO, and then KHO in slight excess, yields (after evaporation to dryness), on ignition in a small tube, oxide of cacodyl 2(As(CH3)2)0, readily recognized by its powerful and ch.iracteristic odour. If SnClg be added to the contents of the tub;? after ignition, the equally characteristic smell of cacodyl chloride, As (CH3)2C1, is observed. These experiments itate of lb as a tain on Ived by [iask in , which one by 1-black ain on Ived. tus be- w-pipe tion of \i xi K' ^ AsgSa, NH,), )mpare a pale adding drop a Dr two le pre- cessity ?N03. screen), ' HO in )n in a •ced by to the niell of iments 37 |i# ^^1 m (and also Marsh's test (5) ) must be done with an exceedingly smalt quantity of substance, owing to the poisonous properties of the products. *5. Proceed exactly as in Marsh's test for Sb, substituting a solution of As for one of Sb, and observe the bluish flame with which the mixture of H and AsH, burns, and also the production of white fumes of AS3O3. Obtain, as in the case of Sb, stains on porcelain lids. Compare these with the antimony stains. Observe also the distinction in colour of the stains : dark brown or almost black in the case of Sb, and, when seen in thin films, pale brown and lustrous in the case of As. Add to one of the stains on porcelain a drop of NaClO : it will be rapidly dissolved. Make a full statement of the chemical distinctions between arsenic and antimony. 6. Reinsch's Test : Add to the solution of arsenic, HCl and a few strips of bright copper wire or foil : As is deposited on the copper, which may be removed from the solution, dried by filter paper, and heated in a dry test-tube to obtain the octahedral crystals of 7. Place the dry arsenic compound in a bulb tube along with a mixture of equal parts of dry NagCOg and KCN, and heat the bulb. A mirror of As will be formed on the inside of the tube. TABLE C— (SUB GROUP B). Solution in (NH^)Sj contains sulphides of As, Sb, and Sn. Add HCl until acid (Why?). The metals are re-precipitated as sulphides. Filter, wash precipitate with hot water till free from HCl ; digest precipitate with one or two pieces of solid (NHJ.CO, and H,0. Filter. Residue. Bn8,.8b,,8,. FiL.'RATE. Ab. Wash and dissolve in strong boiling HCl, dilute with water, filter, ^nd divide the filtrate into two parts. In one place a piece of platinum foil and a frapinent of zinc touching it. Bb forms a black stain on the platinum. Dissolve by warming with a few drops of HNO,, dilute with water and add H^S. An orange precipitate indicates Antimony. Boil the other portion of the filtrate for at least five minutes with some metal- lic copper. Pour off the liquid and add HgClj White or grey precipitate indi- cates Tin. Add HCl until acid ; wash precipi- tated sulphide, and dissolve in HCl and a little KCIO3, boil down to a small bulk, and apply Marsh's test. Metallic mirror, yielding octahedral crystals on heating, indicates Arsenic. Dissolve in H4O, ai: con6rm by adding AgNOg and dilute (NH^)HO, to obtain yellow precipitate of AggAsO,. ^ smalt of the iting a which white rcelain Iso the : in the rous in it will itween and a on the paper, (tals of with a e bulb. 'If CI until ecipitate of solid precipi- ICl and a small Metallic 'Stals on ;solve in AgNO, n yellow I> >: !f 28 r.Roiip III. Reactions of the Metals of the Iron Oroup. Metals whose sulphides and hydrated oxides are insoluble in water, and are precipitated on addition of the group reagent (NH^).jS in presence of (NH4)HOand NH4CI. Iron, Nickel, Cobalt, Zinc, Aluminium. Manganese, and Ohromltim. Iron. Fe, 56. Fkkrous Salts. Solution for Kicactions FeClj^. 1. (NH^^gS produces a black precipitate of FeS, insoluble in alkalies, but soluble in HCl. In dilute solutions of ferrous salts (NH4),S produces at first a green colour; on standing, however, FeS separates as a black precipitate. 2. KIIO or (NH4)HO produces a white precipitate of ferrous hydrate I""e(HO)a, which rapidly ac(iuires a dirty green, and ulti- mately a reddish-brown colour, owing to absorption of oxygen and conversion into ferric hydrate Fe(H0)3. 3. (NH4)2C03 or Na^COg precipitates white FeCOj, which rapidly darkens in colour. 4. K4Fe(CN)g precipitates white KgPeglCN)^, which rapidly becomes blue by oxidation on Fej(CN)j 3 (Prussian blue). 5. K3Fe(CN)a precipitates " Turnbull'sblue," FcgFeg (CN),3. 6. KCNS produces no colouration. 7. BaCOg produces no precipitate in cold solution of ferrous salts. 8. Ferrous compoumls are converted into ferric by oxidizing agents, such as HNO,, KCIO3, HCl, CI. g. Fused with borax in the oxidizing flame, yellowish-red beads are produced; in the reducing flame the beads become green. Fkrric Salts, Fe. Solution, FeCl,. 1. H,S in acid solutions produces a precipitate of sulphur, and the salt is reduced to protosalt : — FeCl3 + H,S = 2 FeCla-f 2 HCl+S. 2. (NH4)2S precipitates black FeS and S, soluble in HCl and HNO3. 3. (NH JHO or KHO precipitates reddish brown Fe(H0)3, insoluble in excess of reagent. 4. K4Fe(CN)g precipitates "Prussian blue," Fe5(CN)i3, in- soluble in HCl, soluble in CgHgO^. oliible in tn. s FeC 3lul)le )us salts lowever, in ferrous nd ulti- fen and which ra pidly CN) 12' ferro us id izin g isli-red green , r, and 1 and W). in- Hi n - 1 29 5. K3Fe(CN)3 produces a reddish-brown colour. 6. KCNS produces even in dilute solutions a blood-red coloura- tion, due to the formation of a soluble iron sulphocyanide. HCI does not destroy the colouration, but it is destroyed by C^HjO^Na, HgClg, H3PO,, and by C^HeO^. 7. BaCOg precipitates ferric solutions completely as Fe (HO), mixed with basic salt. 8. The blow-pipe reactions are the same as for ferrous com- pounds. How do you distinguish between ferrous and ferric salts ? Nickel. Ni, 58.7. Solution, Ni(N03)2. 1. (NH4),S prodi • es a black precipitate of NiS, slightly solu- ble in excess, forming a brown solution from which NiS is precipi- tated on boiling. The precipitate is very difficultly soluble in HCI, but dissolves in HNO, and in aqua regia. 2. NaHO or KHO produces a light green precipitate of Ni(HO)., insoluble in excess of the reagent, and unalterable in air. 3. (NH4) HO produces also a precipitate of Ni(HO)2, readily soluble in excess, yielding a blue fluid, which is reprecipitated by KHO or NaHO. Acid solutions, or those containing Salts of Ammonia, yield no precipitate with (NH4)H0. 4. KCN precipitates yellowish-green Ni(CN)2, soluble in excess and reprecipitated by HCI or H2SO4, and if boiled with a strong s Wution of NaClO, yields a black precipitate of Ni(H0)3. 5. KNO3 in presence of CjH^Og produces no precipitate. 6. Fused with borax compounds of Ni, yields reddish-yellow beads when hot in oxidizing flame. In reducing flame the bead be- comes grey. Characteristic reactions, 2, 3. Cobalt, Co, 58.7. Solution, Co(N03)3 1. (NH4)2S precipitates black CoS, insoluble in excess of re- agent and in HCI, soluble in aqua regia. 2. KHO or NaHO precipitates blue basic salts, which turn green on exposure to air by oxidation. 3. (NH4)H0 precipitates the same as above, soluble in excess, yielding a reddish-brown fluid; reprecipitated by NaHO or KHO. Acid solutions, or those containing Salts of Ammonia, are not pre- cipitated. )loura- HCl DjNa, [HO), com- r solu- recipi- HCl, ite of a air. sadily id by Its of ;xcess trong ellow d be- >f re- turn cess, HO. pre- R!*il 30 4. KCN precipitates light-brown Co(CN)2, soluble in excess of the reagent by formation of 2KCN, Co(CN)2. This solution is re- precipitated by addition of HCl or HgSO^. If to the solution in excess of KCN a few drops of HCl be added, and the solution boiled for some time, K3Co(CN)6, Potassium Cobaltic Cyanide, is formed which is not reprecipitated by HCl or H^SO^, nor by NaClO. 5. KNOg added to Cobalt solutions with addition of Acetic Acid, precipitate, on standing, a yellow crystalline double salt. 6. Compounds of cobalt fused with borax in either blow pipe flame yield deep- blue beads. Zinc, Zn, 65.2. Solution ZnS04. 1. (NH^)2S produces a white precipitate of ZnS, insoluble in excess of the reagent and in KHO, but soluble in the mineral acids. 2. KHO or NaHO produces a white precipitate of Zn(HO)2, soluble in excess of either reagent and in (NH4)HO. This solution is reprecipitated by diluting and boiling, but is not precipitated by addition of NH^Cl. 3. Na._,C03 produces a white precipitate of basic carbonate, insoluble in excess of the reagent. 4. (NH^)^CO., also precipitates the basic carbonate, but it is soluble in excess of the reagent. 5. Heated on charcoal with NagCOg in the reducing blow- pipe flame, a yellow incrustation of ZnO is obtained, which becomes white when cold. *6. Heated on charcoal by the blow-pipe flame after moistening with Co(N0.5)2 solution, an infusible green mass is obtained. Aluminium, A1, 27.3. Solution, Al2(S04)3. 1. (NH^jgS produces a white flocculent precipitate of Al(HO)3. 2. KHO or NaHO produces also a precipitate of Al(HO)3, soluble in acids, even in hot acetic acid and m excess of the reagent. This solution is not precipitated by HgS, but is reprecipitated by NH^Cl, or by adding (NH JHO after acidifying with HCl. 3. (NH4)HO also precipitates A1(H0)3, soluble in a very large excess of the reagent, more difficultly soluble in presence of Salts of Ammonia. 4. HaCOg produces a precipitate of A1(0H)3 mixed with basic salt. 5. Na., HPO4 precipitates aluminium phosphate, insoluble in NH4(OH) and in NH^Cl, but soluble in KHO or NaHO and in acids. It does not, however, dissolve in hot Acetic Acid like Al(OH)3. ;ss of is re- on In oiled rmed ^cid, pipe lie in cids. ition dby late, it is low- )mes ning of ent. by rery 3 of vith ; in [ in 1)3- 31 f •• ■ < n I 6. Heated on charcoal in tlie blow-pipe flame and then moist- ened with Co(No3)2 and reheated, an infusible blue mass is obtained. Manganese, Mn, 55. Solution, MnS04 I. (NH4)2S produces a flesh coloured precipitate of MnS, solu- ble in acids, even in Acetic Acid. z. KHO or NaHO produces a dirty-white precipitate of Mn (HO)^, insoluble in excess of the reagent; the precipitate rapidly darkens in colour by absorption of Oxygen. The freshly-precipitated hydrate is dissolved by NH^Cl, but the higher oxide is insoluble. 3. (NH4)HO produces the same precipitate of Mn (HO)2, in- soluble in excess of the reagent ; but it gives no precipitate if the Manganese solution contain NH4CI. Such a solution on standing precipitates the dark-brown hydrate. 4. NagCOg produces a white precipitate of MnCOg, which darkens in colour by absorption of Oxygen. 5. If any Manganese solution (free from Chlorine) be treated with PbOg and then boiled with HNO3, it is converted into Permanganate, which is recognized by its pink colour as soon as the mixture has settled. =^=6. If any Manganese compound be fused on platinum foil with NagCOg, and a trace of KNO3, it is converted into NagMnO^, re- cognized by its bright-green colour. 7. Fused with Borax in the oxidizing flame an amethyst-coloured bead is obtained, which becomes colourless in the reducing flame. Chromium, Cr, 52.1. Solution, Cr2(S04)3. 1. (NH4)2S produces a bluish green precipitate of Cr(H0)3, insoluble in excess of the reagent, soluble in acids. 2. (NH4)HO also precipitates the hydrate, soluble to some extent in excess, yielding a pink fluid, but on heating the precipita- tion is complete. 3. KHO or NaHO precipitates also Cr(H0)3, soluble how- ever in excess, yielding a green or bluish-violet solution. On con- tinued boiling or addition of NH^Cl and heating, the hydrate is reprecipitated. 4. BaCOj produces a precipitate of Cr(H0)3 along with basic salt ; the precipitation is not complete till the mixture has stood some time. 5. Fused with NagCOg and KNO3 on platinum foil, yellow NagCrO^ is obtained. 6. Fused with Borax in either flame (but best in the reducing flame), green beads are obtained. Characteristic reactions, colour of solutions and bead. ?r f o I— < O v. o h W Cfi e I* «i •^« I/) b a: a U N § D I— < h <1 CQ O U J . w ^, a: u o O o O w m h Eh rt . a '" ■~ a >'2. ■3 rt c 0)0 M ti U W ll -;* uz |i " 5 .S o ~ u « . . •5° a _ .s c O * rt 3C--_- m; < c ' ^ u 2 1(1 o u s I. (U " I^ ° Is ^Ti 32 » c .5 rt Zos Wi*?! O „« C"J "-,- n ^ S H z:o^ O Z T! c/} 1. A old. lear. .o K Lj ?L, O " u ■ OJ o " . n ) o_. ) Slj : o s : ".S S'S 5P ^ :d c i o •v C _• J. -: ■ 1 A 5f n C O p :§-* (« •- ='° = T3 2 " •. >,'=Z S rt a2 u: a; S"r.i.f "ort ft< 0) - J) '5 L" S " ^z u M O u OS <« o S 2 c J 0) / o 0.2 C rt U3 a.S ? — O M*-" J- ij (/) 'o (U (U .•^^ Vo " = X - -^ - u =. a<: • (>. E o ■•' Z « ocj w m^ , "1 0) o o ui.S c - OJ — -K 1/) . 9 K B '^:s 1 — M a a- 1-5 K < sX SZ ffiZ •o n I 5 > O S • W rt »Jt3 ui rt re «■£ ':z-=N zSSaS •60_ZS < £o!§ « >>x:j3 a •'^ .s .s "" 0) a u O "* (u ""^ ''fflUZ rt «rt"E^ ax ■(« o . t-l ■3- H Z ■•-. OJ -^ « '" =£ < " .^ I q 2 c N 2 '4,'<-5.?E!^ (U n ._ -D p " S "S! o . " "Its 6«= c > u u ■•5t3 :; / c 02 5o.p«ci^SoO SH'g. 5.x '^ S c = ■■ t-.- 'JfcuO M 3" ^-0 = 4) m o o ■a OS .2 1^ K '' « h C O 1- "a « !i,«^-d c -^ g-s^-^o.sos<«artg^^^-cs|u m Ez ■" -'B. — D.-^ O.S rt u - m ?;0.-W..^«-=«S4,«?s^«S'^|rt «_ u 0-- fe-c o n J) a ,_ rt (uT3 r, a .:= U g o -:;<: rt.-T3 4) O rt ''■ u 4) V (^ J3 J3 _Q •»-' -^ ill § Si s 5, o. b c Q S 4JTJ _, r' w a CQ u 4) > O <4 2"° [« a o o X rt O > u g § H U w i; s ••» - Qi P-a (d :z;.:i 1) H O ffi ? > o U3 (4 Z J3 4) < *-H ---» > a to gg en «i in V o Q ° u U ^2 0) > o c o U 0) > o nl e o U 36 f 1 i • < lillii '11, i li ti Reactions of the Metals of the Potassium Group. (Group V.) Metals whose solutions are unprecipitated by the preceding group reagents, and having no common precipitant. They are therefore recognized by individual tests. Magnesium, Potassium, Ammonium, Sodium. Magnesium, Mg, 24. Solution, MgSO^. I. (NH4)HO and (NH4)2C03 give no precipitates in the pre- sence of salts of ammonium. *2. NagHPO^ in presence of (NH^)HO and (NH4)C1 a crystal- line white precipitate of MgNH4P04. The precipitation is slow from dilute solutions, but may be hastened by stirring with a glass rod and warming. Precipitate soluble in dilute mineral acids and in CgH^Og, almost insoluble in dilute solution of (NH^)!^©. 3. H2SO4, HgSiFg, and €2(^^4^)20^ give no precipitates. *4. Heated on charcoal in the blow-pipe flame, and then moist- eiied with CoClg or Co(N03)2 ^^^ reheated, gives a pink mass. Potassium, K, 39.1. Solution, KCl. 1. PtClj, except in dilute solutions, gives a crystalline yellow precipitate of 2KCl-f-PtCl4. The precipitation is hastened by stir- ring or the addition of alcohol. 2. HgTr or NaHTr precipitates white crystalline KHTr from concentrated solutions, 3. HgSiFg precipitates white gelatinous KgSiFg. "^'4. Pleated on platinum wire, potassium compounds colour the flame violet, appealing reddish-violet through blue glass. Ammonium, NH^, 18. Solution, NH^Cl. 1. PtCl4 gives acrystallineyellowprecipitateof 2NH^Cl4-PtCl4, except in dilute solutions. Precipitate insoluble in alcohol and ether. On ignition, precipitate leaves a rtsidue of spongy platinum. 2. NaHTr or HgTr give in strong solutions a white precipitate of (NHJHTr. 3. HgSiFg gives no precipitate. =^=4. Nessler's solution gives a brown precipitate, or in any dilute solutions a yellow colouration. (receding 'hey are th e pre- crystal- is slow a glass and in tes. moist- yellow y stir- from ir the tci^, ther. tate lute 37 *5' Heated with NaHO or KHO, compounds of Ammonium evolve Ammonia gas, recognized by its odour, alkaline reaction, and fuming with KCI. *6. Heated on platinum foil, all compounds of Ammonia vola- tilize completely. I»t: ■ >j I 9 rl I .1 Sodium, Na, 23. Solution, NaCl. 1. PtCl^, NaHTr, and HgTr gives no precipitates. 2. HjSiFg gives precipitate of white gelatinous NajSiFg. *3. The Salts of Sodium being almost without an exception soluble in water, the flame test alone serves to distinguish the metal. Heated on platinum foil or wire in non-luminous flame, an intense yellow colour is produced, not seen when viewed through blue glass. TABLE F. -GROUP V. Separation of Magnesium, FotasBium, Sodium and Ammonium. The filtrate from the Harium Group is concentrated by evaporation, and a por- tion ignited on Platinum Foil. If no residue is left on ignition, Mg, K, and Na are absent. Detection of NH^ The original sub- stance or solution is heated with NaHO in a test tube. Pre- sence of Ammonium shown by smell, by the white fumes with HCl, and by its action on red litmus paper. Detection of Mg. To a portion of the concentrated cold solution add (NHJHO and Na.HPO,. White Crystalline Precipi- tate denotes Mag- nesium. To Detect Na. Evaporate alcoholic solution (whicl must have a yellow colour, showing that excess of Pt Cl^ has been added) nearly to dryness, add a grain or two of sugar, and ignite residue. Exhaust with water, filter, evaporate to dryness ; and if a residue be left, test it by flame reac- tion for Na. Yellow colouration indicates Sodium. Detection of K and Na. (i) Mg. being ab- sent. Evaporate an- other portion of the solution to dryness, ignite residue, dis- solve in a small quantity of water, filter if required, and add to the clear liquid PtCl^, eva- porate nearly to dry- ness, and add alco- hol. Yellow Preci- pitate indicates Potassium. pre- (2) Mg. being sent. Evaporate the so- lution to dryness, ignite residue, dis- solve in water, and add Baryta Water until the solution has an alkaline re- action ; boil ; filter. To filtrate add (NHJ4CO,, heat, filler, evaporate to dryness, and test the residue for K and Na. tlH! III 33 TABLE SHOWING THE SOLUBILITY IN WATER AND ACIDS OF THE COMMON METALLIC SALTS. QJ (5 U u < c 1 'c tn < V u 6 •0 1 V rt B Xi u C9 a •c u E u •V 'a •V ■5 a >> 'u fa V "i u 2 u ."2 a fa -a '■5 1—* 1 '■z "a M i M *^ n a a. a; CO £ "5 73 t ■3 w Ag S i i I s I i I s s s Pb S i i sl s si i S s s i 1 I Hg, s i i s i i i S s s Hg S i s s S s S S Si Si Bi S i Si s Si i s s Si Si Si Cu S i i S s S s i I s Si S • i S Cd s s s s s i i i s S s i S Sn" s i i s Si i i S S Si S Sni' s s S S Si Si s S Sb s Si Si i S Si Si Fe" s S i s S i I s S S S Fe'v s S s S s S s S S s S 1 Cr s S s s i i s S s s S Al s S s s i s s Mn s i s s s s i I i i S s S Zn s s s s S i i i s S s S Co s i s s s i I 1 s S s S Ni s i s s s i I I s S s S Ba s s s s s s s s S s I s Sr s s s s s s S s S s i I s Ca s i s s s s S S s s s s sl s Mg s i s s s s S S S s i s s s i S s K s s s S s S s s S S s s S s s s s S S s s NH, .... s s S S s S s s S S s s S s s s S s s Na s s S S s s s s S S s s s s s s S s S s s S, soluble in water ; s, sparingly soluble in water; /, insoluble in water, but made soluble by acids ; /, insoluble in water or acids ; 5/, sparingly soluble in water, not transposed by acids ; Si, soluble in acidulated water. ir » t " aiiicate. Sulphate. Sulphide. — s i I i s i Si i Si i S i S i S i S i Si i S i S i S i S i S i S i S i S i I S I S si S s s S S s s s s II m SECTION IV. I REACTIONS OF THE ACIDS. '■i ill jtilf Mi Orouplng of the Acids. The acids do not admit of being grouped with the same precision as the bases, but they can be approximately classified by means of certain group reagents. They are divided into two great classes, Inorganic and Organic Acids. These are readily distingviished by the action of heat. Salts of Inorganic Acids when heated to redness are not charred ; salts of Organic Acids, with the exception of acetic and formic acids, are at once charred, owing to decomposition and consequent separation of carbon. Grouping of the Inorganic Acids. GROUP I. (SULPHLRIC ACID GROUP). Group reagent, BaCl, in presence of HCl. Sulphuric Acid, Hydrofluo-silicic Acid. The acids of this group are precipitated by BaClj, and the pre- cipitate is not dissolved on addition of HCl. GROUP II. (phosphoric ACID GROUP). Group reagent, BaCig. Phosphoric, Boric, Oxalic, Hydrofluoric, Carbonic, Silicic, Sulphurous, Hyposulphur- ous, ArseniouB, Arsenic, Iodic, and Chromic Acids. The acids of this group are precipitated in neutral solutions by BaClg. GROUP III. (hydrochloric ACID GROUP.) Group reagent, AgNOg. Hydrochloric, Hydrobromic, Hydriodic, Hydrocyanic, Hypochlorous, Nitrous, and Hydrosulphuric Acids. The acids of this group are precipitated by AgNOg, and not by BaCl 8' icision lans of lasses, led by sdness acetic m and e pre- ilphur- 1^5 by 8, and ot by 40 GROUP IV. (nitric acid GROUP). Nitric, Chloric, and Perchloric Acids. These acids are not precipitated by any reagent, as all their salts are soluble in water. iH flit Reactions of the Inorg;anic Acids belonging to Qroup 1. 1. Acids precipitated by BaClg in presence of HCl. Sulphuric Acid, Hydrofluo-silicic Acid. Sulphuric Acid. HgSO^, c.w. 98. I. BaClg produces a white precipitate of BaSO^, insoluble in HCl or HNO3. In very dilute solutions the precipitation is not im- mediate, but on standing the solution becomes clouded, and ulti- mately the precipitate subsides. ■■'■2. Pb(N03)3 produces a heavy white precipitate of PbSO^, soluble in NaHO, and in boiling HCl (on allowing this solution to cool, PbCl^ crystallizes out.) *3. Fused on charcoal with Na^CO^ in the reducing flame of the blow-pipe, a sulphide is produced. If the fused mass be moist- ened with HCl, the odour of HjS is at once perceptible ; or if it be placed on a bright piece of silver and moistened with water, a black stain of AggS is produced. As the latter reaction is very delicate, care must be taken to use Na^COg perfectly free from NagSO^, and it must be borne in mind that the other sulphur acids give the same reaction when heated with NagCOg. 2. Hydrofluo-silicic Acid. HgSiFg, c.w. 144. 1. BaClg produces a crystalline precipitate of BaSiFg, insolu- ble in HCl. 2. KCl produces a gelatinous precipitate of KaSiFg. 3. Heated with Sulphuric Acid in a platinum or leaden cruci- ble covered with a watch-glass, the latter is etched owing to the dis- engagement of HF. Reactions of the Acids belonging to Group II. 3. Acids precipitated by BaClg in neutral solutions. Phosphoric, Boric, Oxalic, Hydrofluoric, Carbonic, Silicic, Sulphurous, H^posulphurous, Arsenious, Arsenic, Iodic, and Chromic Acids. Phosphoric Acid. H3PO4, c.w. 98. (Ortho-phosphoric Acid.) 1. BaCU produces a white precipitate of BaHPO^, readily soluble in HNOg or HCl, but with difficulty in NH^Cl. r salts i ble in 3t im- . ulti- )SO„ ion to me of noist- it be black icate, , and same solu- :ruci- e dis- iirous, CID.) adily 41 si: 2. M^'SO^ along with (NH J HO and NH^Cl, produces a white crystalline precipitate of Mg(NH4)P04+6H.^O, insoluble in (NHJMO, but soluble in HCl, HNO^, and Acetic Acid. In dilute solutions the precipitation does not take place till after the lapse of some time, but is promoted by stirring and gentle warming. 3. AgNOg products a jellow precipitate of AggPO^, soluble in HNO3, and also in (Nil JHO. 4. Lead acetate produces a white precipitate of Pb3(P04)3, soluble in HNO3, but almost insoluble in Acetic Acid. 5. P'ejjClg, in presence of excess of Sodium Acetate, produces a yellowish precipitate of FeP04, soluble in HCl, and in excess of FcgCle, which ought therefore to be added drop by drop. '■'6. Ammonium molybdate produces in so'utions made acid with HNO3 a yellow colouration and ultimately a precipitate. The reaction is hastened by warming the mixture. The following acids of phosphorus are distinguished from each other and from ortho phosphoric acid by the following reactions : — I- 1 i : 1. 1 Pyrophusphoric Acid, H^PgO^, c.w. 178. 1. AgNOg produces a white precipitate of Ag^PgO,, soluble in PINO3, and in (NHJHO. 2. Albumen gives no precipitate. iiiil II Metaphosphoric Acid. HPO3, c.w. 80. 1. AgNOg produces a white gelatinous precipitate of AgPOg. 2. Albumen produces a flocculent white precipitate when added to metaphosphoric acid, and the same precipitate when added to a solution of a metaphosphate acidified with acetic acid. 3. MgS04 + NH4Cl4-(NH4)HO produces no precipitate. Tabulate your results. *If the test be applied to an acid solution of a phosphate insoluble in water (e.g. Ca^ (1^0.,Kj in HCl, the free acid is first nearly neutralized with (NH,)HO, sodium acetate next added, and then Fe^Ci^ ; after this the mixture is boiled. The precipitate, which is of a reddish-brown colour, contains all the iron and phosphoric acid: the filtrate contains the base. The phosphoric acid can easily be separated from the iron, and obtained as a soluble ammonium salt by treating the ferric phos- phate with (NH^jjS. m m iiifii in «« ^?i^^^>o. IMAGE EVALUATION TEST TARGET (MT-3) 1.0 |so "^^ MI^H ■^ 1^ 12.2 I.I ^ lis IIIIM 1.8 1.25 1.4 16 ^ ^ 6"' ► •//" >^^ '^A. V J^^^" *^.1^^ /A ''W '/ Photogrephic Sciences Corporation 23 WEST MAIN STREET WEBSTER, NY. 14580 (716) 872-4503 %^ ,\ ;\ \ "% V ^ % '-U^ 6^ ^s 1 % i I v\ 42 si: «- 1 f ■'■ ■ ;>: 4, Boric Acid. B(H0)3, c.w. 62. 1. BaClg produces a white precipitate of 63(603)3, soluble in acids. 2. AgNOg produces in strong solutions a yellowish white pre- cipitate. In dilate solutions AggO is precipitated. 3. HgSO^or HCl.added to hot concentrated solutions of alkaline borates, produces on cooling a crystalline precipitate of B(HO)3. '*^. If alcohol containing free boric acid be kindled, it burns with a green flame, best seen on stirring the mixture. Borates may be examined in this way by first adding strong HjSO^, to liberate the B(H0)3. 5, If the solution of a borate be made distinctly acid with HCl, and turmeric paper dipped into it, the latter on gentle warming acquires a brown tint, which is turned blue by caustic soda. 6. Moistened with H^SO^ and heated in the lamp flame, a green colouration is produced. CO H 5. Oxalic Acid. C^HgO^, /-q'^tt c.w. go. 1. BaClg produces in neutral solutions a white precipitate of CgO^Ba, soluble in HNO3, in HCl, and in C2H3O4. 2. AgNOg produces a white precipitate of C20^Ag3, soluble in HNO3, and in (NHJHO. 3. CaClg produces even in dilute solutions a white precipitate of C204Ca, soluble in HNO3, and in HCl, but nearly insoluble in (NH4)HO, and in acetic acid. On igniting 0,0403, a white residue of CaCOg is left, which effervesces on the additiim of an acid. *4. Heated with strong H3SO4, effervescence takes place from the escape of a mixture of CO and COg, and the former may be kindled at the mouth of the test tube, and will burn with a pale blue flame. No blackening of the mixture occurs as in the case of organic acids, which yield CO on heating with HjSO^. 6. Hydrofluoric Acid. HF, c.w. 20. 1. BaClj produces a white precipitate of BaFj, soluble in HCl, and sparingly in NH^Cl. 2. CaClj p)roduces a gelatinous and almost \ansparent precipi- tate of CaFg, difficult to discern in the fluid, but made more appar- 43 ent on addition of (NH^)!^©. The precipitate is very difficultly soluble in HCl, even on boiling, and is nearly insoluble in Acetic Acid. * 3. Heated with H3SO4, all fluorides are decomposed with evo - lution of HF, which is recognized by its power of etching glass. A very characteristic oily appearance is noticed whenever a fluoride is warmed with H.^SO^, in a test tube. The etching is best done by placing the fluoride in a platinum crucible, or small leaden cup, along with strong H0SO4, and cover- ing the mouth with a waxed watchglass, convex side downwards, on which a few scratches have been made with a needle. The concave side of the watchglas.s is filled with water to prevent the wax on the other side from melting, and the crucible or cup is then gently heated. On removing the glass and melting off the wax by gentle warming, the glass will be found etched at the unprotected parts.* 4. Heated with a mixture of Borax and HKSO4, on a loop of platinum wire in the non-luminous gas flame, BFg is produced, which momentarily colours the flame green. 7. Carbonic Acid. HgCO,, HgO+COo or CO r 1 1 'I! /I litii l> 46 15. Chromic Acin. H.^CrO^, c.w. 118.2. 1. BaClg produces a yellow precipitate of BaCr04, soluble in IlCl and HNO3, but insoluble in Acetic Acid. 2. II.jS in presence of HCl reduces the solution to CrgClg (green), with separation of S. In neutral solutions, Cr3(HO), is pre- cipitated along with S. 3. SO3 reduces solutions of chromates to the chromic salt, the colour of which is green. Chromates are likewise reduced by zinc and a dilute acid, by Oxalic Acid and dilute Sulphuric Acid, by strong H3SO4, by strong HCl, and by boihng the solution acidified with HCl or H3SO4 along with Alcohol. 4. AgNOg produces a dark-red precipitate of Ag^CrO^ soluble in HNO3 and in (NHJHO. '''5. Lead acetate produces a briglit yellow precipitate of PbCr04, soluble in NaHO, but soluble with difficulty in dilute HNO,. (See also reactions for Chromium.) Reactions of the Acids belonging to Group III. 16. Acids precipitated by AgNO,, and not by BaClg. Hydrochloric, Hydrobromlc, Hydrlodlc, Hydrocyanic, Hypochlorous, Nitrous, and HydroBulphurlc Acids. Hydrochloric Acid. HCl, c.w. 36.5. I. AgNOg produces a white curdy precipitate of AgCl, which becomes violet on exposure to light. The precipitate is insoluble in HNO3, but soluble in (NHJHO, in KCN, in Na2S303,.and also to some extent in NaCl. *2. Heated with HgSO^ and MnOg, Chlorides yield chlorine gas, recognized by its smell, bleaching action and green colour. 3. Dry Chlorides, when heated in a retort with HgSO^ and KjCrgO^, yield CrOgClg (chromium oxychloride), which distils over into the receiver as a dark red liquid, decomposed by addition of water or (NH4)H0, yielding a yellow solution, which on addition of a lead salt, gives a yellow precipitate of PbCrO^. 17. Hydrobromic Acid. HBr, c.w. Si. I. AgNOg produces a pale yellow precipitate of AgBr, insoluble in dilute HNOg, soluble in strong (NH4)HO, and readily in KCN and NagSgOg. Ill luble in Cr^Cle , is pre- ialt, the by zinc ' strong ed with soluble bCrO^, }us, and which luble in also to hlorine r. O4 and ils over tion of ition of u i soluble i KCN 47 *2. Chlorine passed through a solution of a Bromide decomposes it with Mberation of Ur, which dissolves in the liquid and colours it yellow. If this sol'ition be shaken np with Ether, the Hromine is dissolved by it, and the yellow ethereal solution floats above the liquid which becomes colourless. If the ethereal solution be then separated from the liquid, and NaHO be added, the yellow colour disappears and NaBr and NaBrO., are produced. On evaporation c .id ifjnition, Oxygen is evolved and >fabr alone remains, which may be tested as in 3. 3. Heated with H2SO4 and MnO„, Bromides yield red vapours of Br, recognized by its powerful odour. 4. Heated in a retort with KjCrjOj and HaS04, dry Bro- mides yield dark red vapours, which condense in the receiver to a liquid of the same colour which consists of pure Bromine, and is decolourized on adding excess of {NH4)H0. (Compare Hydrochloric Acid test). 18. Hydriodic Acid. HI,c.w. 128. 1. AgN03 produces a pale yellow precipitate of Agl, insoluble in dilute HNO3, and very difficultly soluble in (NH4)HO, but readily in KCN and Na3S203. 2. Cuprous sulphate"''' produces a dirty-white precipitate of CU3I2. which separates most completely if the solution be made slightly alkaline with NagCOj. The reagent produces no precipitate in solutions of chlorides or bromides. 3. KNOg produces no reaction in solutions of Iodides until a few drops of HCI or H2SO4 are added, when Iodine is at once liberated and colours the solution yellow If a little starch solution be now added, a deep blue colouration results from the formation of Starch Iodide. On warming the blue liquid the colour disappears, but reappears on cooling. The production of Blue Starch Iodide is the most characteristic test for Iodine. *4. Chlorine water (or the gas) liberates Iodine from Iodides, but excess of CI causes the formation of ICI3, which is colourless, and gives no blue colouration with starch solution. If therefore Chlorine Water be added drop by drop to a solution of an Iodide mixed with starch solution, a blue coloration is produced, which dis- appears on further addition of the reagent. 'Prepared by dissolving a mixture of two parts CuSO^ and five parts FeSO^ in water, or by the action ot SO.^ on CuSO^. m\ 48 5- Free Iodine (liberated by either of the above methods) is dissolved by CSj, forming a violet-coloured solution. If then, a solution of Iodine be shaken up with CS^, the latter acquires a violet colour. Chloroform may be substituted for CSj. 6. Heated with IvInOg and dilute H2SO4, violet vapours of Iodine are obtained, whi^jh colour paper moistened with starch, blue. i 19. — Hydrocyanic Acid. H — C — N, c.w. 27. 1. AgNO-j produces a white precipitate of AgCN, insoluble in HNO3, with difficulty in (NHJHO, but readily in KCN and Nag S3O3. AgCN is decomposed on ignition, and metallic Ag remains ; this serves to distinguish it from AgCl, which is not decomposed on ignition. 2. If a solution of FeS04, which has become oxidized by exposure to the air, be added to the solution of a Cyanide made alkaline with NaHO, a bluish green precipitate is formed, which is a mixture of Prussian blue with the hydrated oxides of iron. On adding HCl, these last are dissolved, and the blue precipitate re- mains. *3. HCl decomposes nearly all Cyanides with evolution of HCN, recognized by its odour, resembling bitter almonds. If a Cyanide be thus decomposed in a small porcelain basin, covered by a similar basin on which a drop of (NH4)2S3 (yellow) adheres, the latter is converted into (NH4)CNS, which gives a blood-red coloura- tion on addition of FcgClg and HCl. Note. — Hg(CN)2 cannot be detected by the above methods. The dry substance is detected by igniting in a small tube, when Cyanogen Gas is evolved, or the solution is decomposed by H._,S and filtered from the HgS ; the filtrate contains HCN. 20. — Hypochlorous Acid. HCIO, c.w. 52'^. 1. AgNOg produces a white precipitate of AgCl. 2. Pb(NO.j).^ produces a white precipitate, which changes in colour to red, and ultimately to brown from formation of PbOg. 3. MnCl2 produces a dark brown precipitate of MnO(HO)3. 4. Indigo and litmus solutions are decolourized, especially on addition of an acid. '•'5. Dilute acids decompose hypochlorites with evolution of CI. HNO3 evolves HCIO from hypochlorites. s) is a, a iolet s of )lue. e in Nag ins ; i on by lade h is On ; re- n of If a by a the ura- lods. v^hen and IS in y on f CI. 49 tl s 21. Nitrous Acid. HNO.^, c.w. 47. 1. AgNO^ produces a white precipitate of AgNO^, soluble in a large excess of water. 2. HgS, in presence of acid, produces a precipitate of S, and (NH4)N03 remains in solution. ''3. FeSO^, in presence of an acid, produces a black colouration from solution of NO in the FeSO^. 22. Hydrosulphuric Acid (Sulphuretted Hydrogen). HgS, c.w. 34, 1. AgNOg produces a black precipitate of AggS, insoluble in dilute acids. 2. Lead Acetate, even when highly dilute, produces a black pre- cipitate of PbS. 3. Sodium Nitro-Prusside, in preserce of NaHO, produces a reddish-violet colouration, even in very dilute solutions. The colour disappears in a very short time. "4. HCl or HgSO^ decomposes most sulphides with evolution of HgS, recognized by its disagreeable odour, and by its blackening paper moistened with solution of lead. Reactions of the Acids belong^g to Group IV. 23. Acids not precipitated by any reagent. Nitric, Chloric, and Perchloric Acids. Nitric Aciix HNO.,, c.w. 63. 1 . Nitrates when heated evolve Oxygen, and in some cases nitrous vapours also. On fusing a nitrate and adding a fragment of charcoal, vivid deflagration occurs. See Section I. 24. Chloric Acid. HCIO3, c.w. 84.5. I. H3SO4 decomposes chlorates with evolution of ClgO^, a greenish yellow gas, having a powerful odour. If heated, violent explosions occur : the mixture ought therefore to be kept cold, and only very small quantities should be used. 2. When chlorates are heated. Oxygen is evolved and a metallic chloride remains, which may be dissolved in water and precipitated, as AgCl, by AgN03. m .'t: ill ii •'in i IB i Wm i IB ■ : |l! ' '■' 1 '. ■ 50 3. Chlorates are reduced by SO3, with Hberation of Chlorine or its oxides, hence, if the solution of a chlorate be coloured blue with indigo solution, it is decolourized on addding HjSO^ and solution of NajSO,. (Distinction from perchlorates). *4. HCl decomposes chlorates with evolution of CI and ClgO^, a mixture called euchlorine. 5. iieated with charcoal, chlorates deflagrate violently. Perchloric Acid. HCIO^, c.w. 100.5. 1. HgSO^ does not act upon perchlorates in the cold, and on heating white fumes of HCIO^ are given off, but no explosions occur. '•'2. KCl produce in strong solutions a white precipitate of KCIO4. 3. Indigo solution is not decolourized when added to perchlorates warmed with HCl, as euchlorine is not evolved. 4. Dry perchlorates evolve Oxygen on heating. 5. Anhydrous Perchloric Acid is a colourless fuming liquid, which explodes with great violence when dropped on wood charcoal. (^Roscoc.) 6. Perchlorates are not reduced by SO.,. 25.— TABLE G. Detection of Inorganic Acids in Mixtures. [The following acids are found in the examination for bases, which ought always to precede the examination for acids :—H„SO.,, H,^S.p.^, H.fiO,^, H.^S, Si(HO)^, H.,CrO^, H.^AsO.^, and H./lsO,. {a) Acids in Soluble Bodies. 1. Neutralize a portion of the solution with (NHJ HO and add BaCl„ (or Ba(NO.,).^ if Ag, Hg.^, or Pb be present) : precipitate inriicates H.jSO,, H. PO^, H,,As O,, H.,As 0„ Si (HO),, H^CrO,, O x7 CT. T," and large quantities of B(HO)., and riF. To precipitate, add water and then HCl : if a precipitate remain, H„SO^ was piesent. 2. To another portion of the neutralized solution add AgNO., : a precipitate indicates one or more of the following acids : — (a) HCl. HBr, HI, HCN, H^Fe(CN)„, H,,Fe(CN)„, H^S. * Oz, Ci, and T are contractions for oxalic, citric and tartaric acids. (For the further separ- ation of these organic acids, see Table H.) 5' |i (6) H,,PO,, H AsO,. H,AsO,,. H^CrO,. Si(HO),, B(HO),, Ox, T, and Ci. To the precipitate add cold dilute HNO,. Acids undsr (a) are insoluble, those under (i) soluble. Detection of Acids Under (a). To a portion of the solution add starch paste nd one drop of a solution of N„0., in HjSO^. Blue colouration in- dicates HI. Add now chlorine water till the blue colour disappears, and shake with chloroform. If this becomes red- dish-brown in colour, the presence of H Br is indicated, HCl is detected in the presence of the others by boiling down the solution to dryness and distilling the residue with K..Cr„0, and H.^SO^. See also note below. Dectection of Acids Under (6). Test separately for each acid by the methods already given. Separation of H„AsO, H.;AsO,. and H,PO, Acidify solution with HCl, add Na^- SO.,, and heat until no smell of SO., fs given off. Pass H^S through the hot solution, filter, and test for H,,PO, with ammonium molybdate : yellow preci- pitate indicates H,,P04. Precipitate another portion with magnesia mixture, and test both precipitate and filtrate for arsenic. TEST FOR THE REMAINING ACIDS BY THE FOLLOWING REACTIONS GIVEN UNDER EACH ACID. For HCN by test 3, 19, For H^Fe(CN)„ by tests 3 and 4, 32. For H.,Fe(CN)„ by tests 2 and 3, 33 For H^S, by test 4, 22. *For HNO.,, see section I. For HCIO.,, by tesls i and 2, 24. For Ox and HF, by CaCU4-acetic acid. Confirm Ox by test 4, 6, and HF by test 3, 6. For B (HO),, by tests 4 and 5, 4, For Si(HO)^, by tests 2 and 4, 8 For H.,CrO^, by tests 4 and 5. 16 For H.'SO,, by test 3, 10, and smell of SO., 'on adding HCl. For CO„ by test 2, 7. For H„S.^O,, by tests 2 and 3, 11 {b) Acids In Insoluble Bodies. If the compound is not dissolved by the ordinary reagents, the substance mus' be fused with aboui four times its weight of a mixture of Na.,CO and K.,CO,.. When cold, extract the fused mass with water, and filter if necessary. The filtrate contains the acid, and is neutralized with HC'l or HNO.,. and examined by the methods given under (a). The sulphates of Barium, Strontium, and Calcium are decomposed by boiling with a concentrated solution of Na„CO.,. Filter, and examine the filtrate for the acid. Nitric Acid and Aqua Regia oxidize sulphides to sulphates : hence the solution of a sulphide in these acids always contains H„SO^. In such cases a separate portion of the substance must be examined for H„SO^ by boiling with HCl, diluting with water, and then testing with BaCl^, Note. — In mixtures of chlorides, bromides, and iodides, or any two of them, proceed as follows :— Place a small quantity of the mixture in a test tube, add water and a few pieces of MnOf (free from chlorides), then oh<; drop oh/v of dilute Sul phuric Acid and boil : violet vapour indicates Iodides. Add another drop of the *If HI be present, it must first be removed by addition of Fe SO,-!- CuSO^. I Powdered MnO.^ prodnces too much 'bumping " to be used for this purpose. Ci. lose the AND <&.,- '„ IS hot ivith reci- tate ure, i for LN ill of tance L„CO 5sary. nined oiling Dr the :ion of ortion y with them, water ;e Sul of the m .■; ' t: ft • ( 52 dilute acid and boil again. Proceed in this way till no more violet vapour is given off. Then add about 2 c.c. dilute Sulphuric Acid and boil: brown vapour indicates Bromides. Boil till all bromine is expelled, allow to cool completely, add to the residue an equal bulk of strong Sulphuric Acid and warm; a green gas indicates Chlorides. Confirm by observing if a piece of moistened red blotting-paper held in the mouth of the tube is bleached. 26.— Grouping of the Organic Acids. GROUI' I. (tartaric ACID GROUP). Group reafijent, CaCU. Tartaric, Citric, and Malic Acids (Oxalic Acid, see S). Acids which are precipitated by CaClg in the cold or on boiHng. GROUP II. (benzoic acid GROUP). Group reagent, FcgClg. Benzoic and Succinic Acids. Acids which are not precipitated by CaClg, but which give precipitates with FcgClg in neutral solutions. GROUP HI. Group reagent, AgNO.j. Ferro-cyanic, Ferri-cyanic, Sulpho-cyanic, Acetic and Formic Acids. Acids precipitated by AgNOg in neutral solutions, and not by CaClg, or FegClg. Acetates and Formates are only precipitated in concentrated solutions. I Reactions of the Organic Acids belonging to Group I. (Tartaric Acid Group.) Acids precipitated by CaCl.^ in the cold or on boiling. Tartaric and Citric Acids. 27. Tartaric Acid C^HeOg or ch(OH)CO^H. I. CaCl.j in neutral solutions produces a white precipitate of C^H^CaOg, soluble in acids, and in ammoniacal salts. The precipi- tate is soluble in KHO, but is re-precipitated when the solution is boiled, and on cooling is re-dissolved. t I liiii iiii i 53 "'2. KCL produces in solutions containing T in excess a white crystalline precipitate of C^IIjKO,, soluble in mineral acids and alkalies, insoluble in Acetic Acid. The precipitation is promoted by stirring, or by addition of alcohol. 3. Lime-water produces in neutral solutions a white precipitate C4H^CaOg (flocculent at first, afterwards crystalline), soluble in tar- taric acid and NH^Cl, but re-precipitated in crystals from these solu- tions after standing some time. 4. Add to some Calcium Tartrate which has been washed two or three times by decantation (after pouring off the wash water as completely as possible), a drop or two of (NH4)HO and a crystal of AgNOg, and heat the mixture in a test tube. A lustrous mirror of silver will deposit on the tube. 5. Heated with strong H3SO4, the mixture darkens rapidly from separation of Carbon, and SO2, CO, and CO3 are evolved. 6. Heated to redness, the substance darkens in color, and gives off the characteristic odour of burnt sugar. , (CO3H. 28. Citric Acid. CcH80,.=C3H4 COoHI \ (COgHA I. CaClg produces no precipitate in neutral solutions in the cold, but on boiling, Ca3(CgH507)2 is precipitated, and is not soluble in KHO, but soluble in (NH4)HO. ■''2. Lime-water produces no precipitate in cold neutral solutions, but on boiling, Ca3(C(5H 507)3 is precipitated. 3. AgNOg produces in neutral solutions a white flocculent pre- cipitate of CeHgAggOj, soluble in (NH4)H0 ; this solution does not blacken on boiling. 4. Heated with strong H^SO^, COg and CO are evolved with- out any darkening in color ; on continued heating, however, the mix- ture darkens, and SOg is evolved. 5. Heated to redness, irritating fumes are given off, readily dis- tinguished from those given off by heating the preceding acid. 29. Malic Acid. C^H^O^.U^^^^^^' ^^^H I. CaClj produces no precipitate in neutral solutions in the cold, but upon boiling, C^H^CaOg separates from strong solutions. The precipitate when heated with (NH4)H0 and AgNO, causes no separation of silver. ite nd by ite ar- lu- wo as of of dly /es the ble ns, »re- oes th- lix- Jis- the )ns. no I Wr h i ^1 ' 54 2. Lime water does not precipitate solutions of Malic Acid or of nialatcs even on boiling. (Compare 28, 2.) *3. AgNO, produces in neutral solutions a white f,'ranular pre- cipitate of C^H^AgjjOft, which becomes grey on boiling. 4. Heated with strong H3SO4, COg and CO are evolved, the lluid then darkens and SO3 is evolved. Reactlona of the Acids belone^lng to Group II. (Benzonlc Acid Group.) 80. Acids precipitated by FcjClg, and not by CaClg. Benzoic and Succinic Acid. Benzoic Acid. C^HoOg. (^^CaH^. CO3H). 1. FcjClg produces, in neutral solutions, a buff-colored precipi- tate of ferric benzoate, decomposed by (NH4)HO with formation of a more basic Benzoate and Ammonium Benzoate. is soluble in HCl with liberation of Benzoic Acid. Ferric Benzoate 2. Heated with HjSO^ Benzoic Acid does not blacken. *3. Heated in an open tube, the acid sublimes in needle-shaped crystals, and an irritating vapour is given off. When kindled, the crystals burn with a smoky flame. 31. Succinic Acid. CJI^O^. [- CcH4(C02H),] 1. FegCIg produces, in neutral solutions, a reddish brown bulky precipitate of Ferric Succinate, soluble in mineral acids, and decom- posed by (NH4)H0 in a similar manner to Ferric Benzoate. « 2. Lead Acetate produces a white precipitate of Lead Succinate, soluble in excess of the reagent and in HNO3. *3. BaCla, in presence of (NH4)HO and alcohol, produces a white precipitate of Barium Succinate ; this reaction serves to dis- tinguish this acid from Benozic, which does not give a similar pre- cipitate. 4. Heated in an open tube, the acid sublimes in fine needles ; and when kindled, the crystals burn with a bluish but not smoky flame. Reactions of tbe Acids belonging to Group III. 32. Acids precipitated by AgN03, in strong neutral solutions. len>cyanic, Ferrl-cyanlc, Sulpho-cyanic, Acetic, and Formic Acids. Ferro-cyanic Acid. H4Fe(CN)g. [=4HCN. Fe(CN)2] . I. AgNOg produces a white precipitate of Ag^FefCN)^,, in- soluble in dilute HNO3 and in (NH4^HO, but soluble in KCN. ar of pre- the cipi- n of oate iped the ulky :om- late, es a dis- pre- lles ; loky IS. in- 55 ■'2. CuSO^ produces a reddish brown precipitate of CugFe (CN)e. 3. FegClg produces a deep blue precipitate of Prussian blue, insoluble in dilute mineral acids, soluble in Oxalic Acid, and decom- posed by NaHO with separation of Fe2(H0)g. 4. FeS04 gives a light blue precipitate, which rapidly darkens in color by oxidation. it 33. Ferri-cyanic Acid. H3Fe(CN)c [ = 3HCN. Fe(CN)3] I. AgNO, produces an orange-colored precipitate of Ag3Fe (CN)e, insoluble in dilute HNO3, soluble in (NHJHO and KCN. ^^''2. FeSO^ produces a blue precipitate of Fe3Fe2(CN)i2 (Turnbull's blue, insoluble in acids, but decomposed by alkalies.) 3. FcgClg produces no precipitate, but alters the colour to a green- ish brown. 34. SuLPHO-cYANic AciD. HCNS. or H-S-C-N. 1. AgNOg produces a white curdy precipitate of Ag(CN)S insoluble in dilute acids, but soluble in (NH^)HO, and in solution of K(CN)S. From the solution in (NH4)HO it crystallizes in shining scales. 2. CuSO^ produces in strong solutions a black crystalline preci- pitate of Cu(CN)3S3 which changes on standing to the cuprous salt Cu3(CN)oS2 which is white. This change takes place at once by the addition of reducing agents {e.g. SO3 or FeSO^) lo the cupric salt. *3. FegClg produces a blood-red colouration from formation of a soluble sulpho-cyanate of iron. The colour is destroyed by addition of alkalies, by HgClg and by many acids {e.g. HNO3, H3PO4, H2C3O4, HIO3), but not by HCl even when concentrated. 35. Acetic Acid. CgH^Oa- ( = CH3.C02H.) 1. AgNOg produces, in neutral solutions, a white crystalline precipitate of C2H3Ag02, soluble in (NH4)H0 and in hot water. 2. FegClg, in neutral solutions, produces a deep red colouration. On boiling, all the iron separates as a light brown precipitate of basic acetate, and the fluid becomes colourless. ■ 56 3. '"A strong solution heated with H2SO4 and Alcohol yields Acetic Ether, recognized by its characteristic and pleasant odour. If 36. Formic Acid. CH202.(-.H.C02H). 1. AgNO,^ produces, in neutral concentrated solutions, a white precipitate of CHAgOo, which rapidly darkens, especially on heat- ing, owing to separation of Ag. 2. FcgClg produces a similar reaction with formates as with acetates. ''3. Hg(N03)2 produces a white precipitate of the formate of mercury, which, however, soon becomes grey from separation of Hg. •'4. Cold strong HgSO^ decomposes formates with efferve'^'^'^nce, CO being evolved. On heating, the gas comes off rapidh id if lighted, burns with a blue flame. 37. Stearic Acid. Ci8H3302( = 0,51135. CO3H). I. Heated with alkalies, a soap is formed. If mutton fat (which contains the acid combined with glycerine) be heated with NaHO, sodium stearate is formed, which dissolves in warm water and the glycerine separates. Soaps are decomposed by acids, which unite with the base, and the fat separates and may be dissolved in alcohol. From this solution the fat crystallizes in needles. OH 38. Salicylic Acid. CeH4 ^ S.2 /^ ij ^ o ^ 2 H " r, < ■^ s 2i >, «< < ^ T3 Cm .^ -• 3: c <" o -^ U] 2 rt l-H J3 ^H in 23 h - u V- rt (i ^U CO Q.T3 O rB U rt in 2 ^ K CO o (A -a I u > rS X o U H > CO < 1 K S 2 ys o u. o 1 W TO T3 « l» T3 H ol. d O. bo U u u OS 8 - El Ri U3 O-QQ ..-4 O cd O !£ — ^- ^ (U " ■^ c ^X) ii u p •- — . c U taj-n Stj jjS Si's rt c3 ^ nl ;?5 I w w ro h— I 3 r, E 4> 'o <: o E u O C cS «1^ TO * ■^■°ois -- ^ < (U 2 13 c! .He "=2 .y^i2^ (/I a o _ o 4) 2.2 3 - ° •= « " P I-. W 4) u) x: 4) *4 2m I- . 13 J3 D.eo d fe " .2"^ - 3 ° tn C P 'O Ui b£ . o j3 < -g P "" 4) - O .2'o rt S-< o >- F H •5 2'2-i- c — t; 4) •* •*- S 2 o-d ° c g ^ '1;; j£ = £ . ^ 5 - a •^•2 >,o « O-ta r.S rt D • O IT. to ,0 1 0) ^ •^ .a * *^ s ^ C 1) » _ 5 Carbo Hydrates 43. 50 Cadmium 64 Cements ' '4. 15. if'. 18. 22, 24 Chlorine (10) 61 Chloric Acid .. .... 7 Chlorates 4. 5o Hydro fluo- silicic Aciu ,. ,[ M. 42, 50 Hydro Bromic Acid .. 40.5° Hydriodic " .. ,_ 4f>. 5° Hypochlorous " 47. 5" 4«. 50 I Iodine, Test for {12) lodates 8 Iodic Acid '5 Iron 45. 50 " Oxide.. .'. 15.28,32 16 Lead " Oxide.. .. ,] ][ _ 15.17.18,19,21,22,24 Lithium M " 17 M Magnesium Oxide .. .". .'." .*' "' " 36, 37 Malic Acid '] * "7 Manganese 53. 57 Manganese Oxide \\ 3i, 32 Marsh's Test for Antimony '^ " " Arsenic. .'. .[ [[ " [ ^^ Metaphosphoric Acid ^7 Methyl Alcohol . . .. ,, \\ \ 4i . Methane (16) ^3 Mercury 10 Mercury, Purifying of .* . .* .'." " 18,19,21,24 Mercury. Chlorides of . . .[ [[ [[ 59 Mercury, Amalgams [ " ^3 Mercuric Oxide ^4 Mercurous Salts ^4 Mercuric " . , i9 .Morphine .... .... 24 67 IV. I'AGE .. 14 .. 63 • 15 .. 58 ^'4. 73 i'''. 37 • 17 3. 57 I, 32 . 16 , 26 27 41 63 10 I, 24 59 13 14 14 19 24 67 N » Narceine I'A(;k • Narcotine * 68 Nesslers Test (9) . . . ] | 68 'Nicotine " " 6 Nickel " " " 68 " ^^xide ■■ ■■ 15.29,32 Nitrates (8t) 16 Nitrogen (5) .. .. '' " ' C. 15 " Monoxide (6) 4 Dioxide (7) 4 Nitric Acid, I'reparation (8) .. .*.*.*' 5. ij " Test (8t) ] 5.17.49,50 Nitrous Acid 6 49. 50 Organic Acids. Separation of Impurities in Water .. [ 57 Orthophosphoric Acid . . . . 70 Oxalic Acid 41.50 Oxygen (2) ' " 42.50 Oxychloride Cements \ 2,13 Oxyphosphate •• .. ,_ " " "• 61 Ozone (3) 6r 3 Perchloric Acid . . Permanent Hardness Phenol., .. 50 70 Phosphoric Acid 63 Platinum ** 17.40.41,50 Refining of .** .*.' *' *' 15 Potassium i;8 -PyrogaUic Acid, Test for Oxygen (2) .. .*. •^7. 36, 37 3 Q Quinine • Salicylic Acid Saliva, Testing of Silicic Acid.. .. Silver .. .. ■' Refining of Sodium Solubilities .. Stannous Salts .. Stannic Salts . . Starch . . • ' • • • • " Test for Iodine (12) 68 • • • • ■ • • • 56. 57 71 ■• • • 43. 50 15. 16. 18. 19, 21 •• •• •• 59 •• •• ^7.37 38 25 25 65 8 V. PAGE f°"^'7- 17.33.35 Stearic Acid s6 S7 Strychnine go Succinic Acid r , ^^ „ d4> 57 ^"R^"- 64.65 Sulphur and Sulphides j. Dioxide (Kj) 11.13,15 Sulphuretted Hydrogen (20) 12,13 Sulphuric Acid ^o[ ^o Sulphurous Acid ^ . -^ 44' 5" Sulpho-Cyanic Acid SS "57 T Table of Solubilities ,y Tartaric Acid S2 "i? Teeth, Analysis of _ „2 Temporary Hardness „q Theine g Thio Sulphuric Acid 415 so '^'" 15.18.25.27 " """^^ 14. 15. 17 " Refining of 5^ U Urea 65 """« 72,73 V Veratrine (3„ W Water, Testing of 70,71 Z '^'"^ 15,16,18,30,32 " o^'^i^ 14. 15, 17 I'AGR •17. 33 .35 .. 56 . 57 .. 68 • 54 57 64.65 . . . M •II. 13 15 . 12 13 40, 50 • 44- 50 • 55. 57 . .. 3» . 52, 57 . .. 72 . 70 . .. 67 • 45. 50 18. 25, 27 14. IS, 17 .. 65 72, 73 69 70. 71 18, 30, 32 14. 15. 17