LIBRARY 
 
 OF THE 
 
 UNIVERSITY OF CALIFORNIA. 
 
 Class 
 
 ^^l 
 
 
crf)tttfcil 
 
 EDITOR OP THE SEE1ES, 
 
 PEOFESSOK SILYANUS P. THOMPSON, 
 
 D.Sc., B.A., M.I.E.E., &c. 
 
PEACTICAL WORK 
 
 IN 
 
 ORGANIC CHEMISTRY, 
 
 BY 
 
 FREDK. WM. STREATFEILD, F.I.C., &o,, 
 
 DEMONSTRATOR OP CHEMISTRY AT THE CITT AND GUILDS OP LONDON 
 
 INSTITUTE'S TECHNICAL COLLEGE, FINSBURT. 
 With a Prefatory Notice by 
 
 PROFESSOR R. MELDOLA, F.R.S., F.I.C., 
 
 FOREIGN SECRETARY OF THE CHEMICAL SOCIETY. 
 
 E. & F. N. SPON, 125, STEAND, LONDON. 
 
 NEW YOEK : 12, COKTLANDT STREET. 
 1891. 
 

 
PEEFATORY NOTICE. 
 
 IN modern schemes of Technical Education two dis- 
 tinct classes of students have to be catered for. The 
 day student who has completed his school education, 
 and who is about to qualify himself for some branch of 
 industry in which a knowledge of scientific principles 
 is essential, is enabled to distribute the whole of his 
 time among the various subjects which are likely to 
 be of importance in his subsequent career. There is 
 in addition a large and growing class of students whose 
 daily occupations prevent their attendance at college 
 day-courses, but whose commendable desire for self- 
 advancement leads them to seek instruction at evening 
 classes. For both kinds of students provision has been 
 made at the Finsbury Technical College, and the 
 scheme there carried out was originally framed so as to 
 carry on both kinds of instruction. During the six 
 years that it has been my privilege to be responsible 
 for the teaching carried on in the chemical department 
 of that College, the steady increase in the number of 
 evening students, and the zeal with which men who are 
 engaged all day, often in very arduous occupations, 
 will carry on supplementary work in these evening 
 
 T~ r* 
 
 o? 
 
VI PBEFATOEY NOTICE. 
 
 classes, has convinced me that such instruction 
 supplies a distinct want. That the training which the 
 City and Guilds of London Institute has enabled us to 
 impart is of real value, can be amply shown by the 
 numerous records of promotion or of improved positions 
 which the evening students have been enabled to take. 
 Another favourable sign is the fact that a considerable 
 number of day students who have completed their 
 studies, and who have obtained appointments in the 
 London district, re-enter the College as evening 
 students. Of equal or greater significance is the fact 
 that the competition produced by the spread of the 
 Polytechnic movement has had no appreciable effect 
 upon the evening attendances, and this in spite of the 
 fact that we cater for no examination, and that we 
 profess to qualify students in Chemical Technology 
 only. The importance of such a statement will appear 
 when it is remembered that London is not a first-class 
 centre of chemical manufacture, and that in so well- 
 worn a subject as Chemistry there are already in 
 existence numerous evening schools. The general 
 spread of evening instruction appears rather to have 
 had the effect of raising the standard among those 
 attending the College classes. 
 
 The main point in which the chemical training 
 given at a technical college should differ from the 
 ordinary examinational treatment of the subject is in 
 the greater importance which should be attached to 
 practical work in the laboratory. For this reason the 
 
PREFATORY NOTICE. Vll 
 
 preparation of various inorganic and organic compounds 
 has been made a special feature at .Finsbury as soon as 
 the student has acquired sufficient preliminary skill in 
 qualitative and quantitative analysis. Greater value is 
 attached to the knowledge acquired in this way than 
 to attendance at formal lectures, although a certain 
 number of these are also delivered throughout the 
 session. No student is considered qualified to carry 
 on work in organic chemistry until he has previously 
 been through a course on inorganic chemistry, includ- 
 ing the general elementary principles of the science. 
 Supposing such preliminary qualification to have been 
 acquired, either by attendance throughout one session 
 at the evening inorganic course at the Finsbury 
 College or elsewhere, the student may pass on to 
 organic work, and the various programmes of instruc- 
 tion which are contained in the present little volume 
 will, it is contemplated, be found of use to those who 
 are following up this branch of the subject. The chief 
 practical difficulty which must be experienced by all 
 teachers of chemical technology is due to the very 
 diverse fields of labour in which evening students 
 pursue their daily occupations.* With reference to 
 organic chemistry, for example, the training which is 
 required by a soap-maker is quite different from that 
 required by a brewer or a tar-distiller. After the 
 
 * With day students no such difficulty presents itself, because these 
 come to us while still young, and for the most part with no definite 
 line of future chemical work in view. 
 
Vlll PEEFATOKY NOTICE. 
 
 general elementary foundation has been laid it is im- 
 possible, therefore, to provide a single scheme suffi- 
 ciently wide to embrace all the chemical industries. 
 For this reason the laboratory work has been sub- 
 divided in such a manner as to meet the wants of the 
 various industries. The programmes which the author 
 has drawn up cover very fairly the elementary 
 principles concerned in all the branches of manu- 
 facture in which organic chemistry plays a part. If 
 the student wishes to limit himself entirely to his own 
 subject, he can do so after he has shown sufficient 
 evidence of knowledge and skill in the general pre- 
 liminaries. If he requires to obtain a wider range of 
 knowledge (and this is in all cases recommended), he 
 can work through all the programmes. This recom- 
 mendation applies especially to day students, who can 
 give more time to, and who are enabled to work more 
 continuously at, the subject. All the experiments 
 described are thoroughly practical, and have been 
 performed by successive classes of students under 
 Mr. Streatfeild's supervision throughout a period of 
 many years. The success with which this method of 
 instruction has been attended in our own College has 
 warranted the belief that the little laboratory com- 
 panion now offered may be of use in other technical 
 schools, and I have great pleasure in commending it to 
 the notice of teachers of Chemistry. 
 
 K. MELDOLA. 
 
AUTHOR'S PREFACE. 
 
 THE object of this little book is to meet a want which 
 the author has experienced in teaching the rudiments 
 of Practical Organic Chemistry to students who can 
 devote bu little time to the subject. 
 
 The subject matter of the following "Programmes 
 of Work " has been chosen partly on account of its 
 technical utility, and partly as affording practice in the 
 application of the more important reagents employed 
 in the investigation of the compounds of carbon. 
 
 The writer wishes it to be expressly understood 
 that the book is only intended to be a laboratory 
 guide, and its use should be supplemented by reference 
 to standard works, or still better by personal instruction 
 from the teacher. 
 
 For elementary students the author would recom- 
 mend Professor Ira Kemsen's * Organic Chemistry/ or 
 the excellent little book of Professor Emerson Reynolds, 
 'Organic Chemistry/ pt. iv.* For more advanced 
 
 * Professor Keynolds little books have been translated into Ger- 
 man by G. Seibert, under the title of ' Leitfaden zur Einfiihrung in 
 die Experimental-Chemie.' They form a series of excellent German 
 Headers for chemical students. 
 
AUTHOR'S PREFACE. 
 
 students, Bernthsen's 'Text Book of Organic 
 Chemistry,' translated by Dr. M'Gowan, will be 
 found very serviceable. 
 
 In preparing a work, however elementary, an author 
 feels how much he is indebted, either directly or 
 indirectly, to the labours of previous writers, and to 
 those from whom, as teachers or colleagues, he has 
 derived assistance. In the latter category the thanks 
 of the writer are due to Professor H. E. Armstrong and 
 to Mr. J. Castell-Evans. 
 
 The author wishes to acknowledge the help he has 
 received from many scientific and technical journals, 
 and to certain works dealing with organic analysis, 
 especially to Allen's 'Commercial Organic Analysis.' 
 
 Thanks are likewise due to Mr. F. C. Kobinson, 
 senior chemical student at the Finsbury Technical 
 College, for the great care and attention he has devoted 
 to the drawings, which for the most part were sketched 
 from apparatus in situ. 
 
 The author also most gratefully acknowledges the 
 encouragement which he has received from Professor 
 R Meldola, the present head of the chemical depart- 
 ment, who has kindly read all the proof sheets, and 
 has made numerous corrections and suggestions. 
 
TO THE STUDENT 
 
 BEFOKE commencing work, ascertain fully the object 
 in view. Eecollect that the mere preparation of 
 chemical compounds, however beautiful in themselves, 
 is not the sole end and aim of your work. Having 
 clearly understood the purpose of the experiment, then 
 set about its execution in a methodical manner. First, 
 find out as far as possible the properties of the pro- 
 posed preparation. You will then be in a position to 
 fit up the necessary apparatus in an intelligent manner. 
 Great attention must be paid to neatness in fitting 
 up apparatus; corks must be carefully bored, glass 
 tubes must be neatly bent and not unnecessarily long, 
 and all sharp edges must be taken off. Exercise 
 judgment in the selection of flasks, funnels, beakers, 
 dishes, &c. 
 
 During the progress of an experiment keep your 
 eyes open, and record in your note-book all changes 
 taking place. Weigh or measure, as the case may be, 
 the quantities prescribed. Note the yield of the pro- 
 duct in each case, and compare it with the quantity 
 theoretically obtainable. Examine all crystalline 
 
Xll TO THE STUDENT. 
 
 compounds under the microscope, and see now their 
 appearance tallies with that given in the books. Be 
 careful in your determinations of melting and boiling 
 points ; in short, keep steadily in view the fact that 
 you are qualifying yourself to become an original 
 investigator in Chemical Technology. 
 
r - 
 
 CONTENTS. 
 
 OPEEATIONS AND ANALYSIS. 
 
 OPERATIONS. 
 
 Purification of organic compounds Crystallisation Fractional 
 crystallisation Selection and application of solvents List of 
 solvents Use of charcoal; precautions to be observed in its 
 application Purification of charcoal Eecovery of solvents 
 Determination of melting-point Distillation ; fractional ; steam 
 Determination of boiling-point Subliming-point Specific 
 gravity Specific gravity-bottle Sprengel tube ; Perkin's modi- 
 fication Collection and drying of organic preparations Use of 
 separating-funnel Eefrigerating-funnel Page 1 
 
 ANALYSIS. 
 
 Detection of carbon, hydrogen, nitrogen, sulphur, phosphorus, and 
 the halogens Determination of carbon and hydrogen ; modi- 
 fications necessary when the compound contains nitrogen, 
 sulphur, or the halogens Arrangement of the results of 
 analysis Estimation of nitrogen as ammonia and by volume 
 Estimation of sulphur and the halogens Carius's method 
 Determination of molecular weight; method of V. Meyer; 
 method of Eaoult Acids and bases . 22 
 
 PROGRAMME I. 
 
 A STUDY OF OXALIC ACID AND ITS REACTIONS. 
 
 Preparation of oxalic acid from sugar Sublimation of oxalic acid 
 Determination of water of crystallisation Preparation and 
 
XIV CONTENTS. 
 
 analysis of salts of oxalic acid Titration of oxalic acid by 
 means of potassium permanganate Synthesis of oxalic acid from 
 cyanogen Ox amide Ethyl oxalate Action of phosphorus 
 pentoxide on oxamide Formic acid Copper formate Page 55 
 
 PEOGEAMME II. 
 
 ETHYL ALCOHOL AND ITS KEACTIONS. 
 
 Preparation of alcohol from malt Detection of alcohol; purifica- 
 tion, separation from water Purification of methylated spirit 
 Selection of dehydrating agents Absolute alcohol Separation 
 of fusel oil from alcohol Estimation of alcohol in beer, wine, 
 &c. Action of reagents on alcohol Sodium ethylate 
 Potassium ethyl sulphate Ethyl ether Ethylene dibromide 
 Acetaldehyde Aldehyde-ammonia Experiments with alde- 
 hyde Aldehyde-resin Oxidation of alcohol to acetic acid; 
 determination of small quantities of alcohol Preparation of 
 chloral Chloroform and its reactions 68 
 
 PEOGEAMME III. 
 
 A STUDY OF THE PREPARATION AND DECOMPOSITION OF ETHYL 
 ACETATE, AND OF THE COMPOSITION AND REACTIONS OF 
 SOME OF THE NATURAL FATS AND OILS. 
 
 Preparation of ethyl acetate ; study of its decomposition Saponi- 
 fication of a natural fat Preparation of stearic acid Separation 
 of stearic from palmitic acid by fractional precipitation 
 Experiments with stearic acid Salts of stearic acid ; action of 
 solvents on Action of halogens on stearic acid Titration of 
 stearic acid by standard alkali Saponification of olive oil 
 Isolation of glycerol Keactions of glycerol; distillation of; de- 
 termination of carbon and hydrogen in ; distillation of in vacuo 
 Estimation of glycerol by oxidation with alkaline permanganate 
 Allyl alcohol Oleic acid ; action of re-agents on Bromine 
 
CONTENTS. XV 
 
 and iodine absorption Ela'idic acid Elai'din Distinction 
 between drying and non-drying oils Titration of oleic acid 
 Determination of the percentage of potassium hydroxide for the 
 saponification of an oil ; saponification equivalent . . Page 93 
 
 PEOGEAMME IV. 
 
 COAL-TAB AND COAL-TAR PRODUCTS. 
 
 Distillation of coal-tar Composition of a sample of London tar 
 Fractionation of light oil ; isolation of benzene and toluene 
 Purification of benzene ; action of reagents on Potassium 
 benzene-sulphonate Action of fused potassium hydroxide on 
 sulphonate ; preparation of phenol Separation of phenol from 
 coal-tar Estimation of phenol Action of nitric acid on phenol ; 
 preparation of ortho- and para-nitrophenol Action of phos- 
 phorus pentachloride on potassium benzene-sulphonate ; benzene- 
 sulphon chloride ; benzene-sulphonamide Saccharin Action of 
 potassium cyanide on potassium benzene-sulphonate; phenyl 
 cyanide Action of nitric acid on benzene ; nitrobenene Action 
 of nitric acid on a mixture of benzene and petroleum Action 
 of reducing agents on nitrobenzene ; aniline Experiments with 
 aniline ; salts of Azobenzene Acetanilide Action of halogens 
 on benzene ; monobrom- and dibrom-benzene Action of nitrous 
 acid on aniline : a study of the Diazo-reaction Diazobenzene 
 nitrate ; reactions and decomposition of Sandmeyer's modifica- 
 tion of the diazo-reaction for the substitution of chlorine, bromine, 
 and cyanogen in aromatic compounds Monochlor benzene 
 Monobrom benzene Phenyl cyanide Benzoic acid from ani- 
 line Gattermann's reaction Phenyl isocyanate from aniline 
 Potassium cyanate Action of oxidising agents on aromatic 
 compounds Benzoquinone Phthalicacid Phenol-phthalei'n 
 Anthraquinone Estimation of anthracene Alizarin Cinnamic 
 acid; reactions of Synthesis of cinnamic acid Indigotin 
 Valuation of indigo ; experiments with Isatin ; reactions of 
 Indophenin test for thiophene in benzene 110 
 
 INDEX 151 
 
PEACTICAL WOKK 
 
 IN 
 
 ORGANIC CHEMISTRY. 
 
 OPERATIONS AND ANALYSIS. 
 
 OPERATIONS. 
 
 Purification of Organic Compounds. Before pro- 
 ceeding to .the investigation of the properties of 
 chemical compounds, it is essential that they should 
 be of definite composition ; that is, they must be ob- 
 tained in a state of purity. For the isolation and 
 purification of the carbon compounds a number of 
 processes are employed, varying according to the 
 nature of the substance to be dealt with. 
 
 Crystallisation. This process is more frequently 
 made use of than any other, and is effected by dis- 
 solving the substance in some suitable solvent, some- 
 times digesting with recently ignited charcoal to remove 
 colouring matter, filtering if necessary, and allowing 
 the solution to crystallise, concentrating by evaporation 
 if too dilute. The crystals are collected, well drained 
 from mother-liquor, and if still impure recrystallised. 
 
 Fractional Crystallisation. When two or more sub- 
 
A PRACTICAL WORK IN ORGANIC CHEMISTRY. 
 
 stances occur together, they may often be separated by 
 taking advantage of the different degrees of solubility 
 which they possess in a certain menstruum. The sub- 
 stance is dissolved and allowed to crystallise, care being 
 taken not to form a too concentrated solution. The 
 first deposit of crystals will consist of the less soluble 
 portion. It is filtered off and the filtrate (mother- 
 liquor) concentrated by evaporation, when the more 
 soluble compound will separate out. The successive 
 deposits are then recrystallised each in turn until 
 finally the deposits are found to be homogeneous. This 
 operation is called fractional crystallisation. 
 
 Selection and Application of Solvents. The selection 
 of a suitable solvent for purposes of purification requires 
 some consideration. The process generally followed 
 in the first instance is to submit a small portion of the 
 material contained in a test-tube to the action of several 
 solvents in succession, until one is found out of which 
 the compound readily crystallises. 
 
 The following is a useful list of solvents : 
 
 Water. Dissolves sugars, gums, starch, and other 
 highly organised bodies which are nearly insoluble in 
 ether or alcohol. It also dissolves most organic acids 
 and salts. 
 
 Alcohol. This substance is largely used as a solvent. 
 Purified methylated spirit may generally replace the 
 more expensive ethyl-alcohol as a solvent. Many 
 organic compounds crystallise well from a more or less 
 dilute spirit. 
 
PRACTICAL WORK IN ORGANIC CHEMISTRY. 3 
 
 Benzene. This is a very useful solvent. Substituted 
 haloid and many nitro-compounds crystallise well from 
 benzene. A peculiar characteristic of this solvent, in 
 which it differs from alcohol and ether, is that many 
 amorphous substances are insoluble in it. 
 
 " Coal Oil!' The fraction of coal oil after separation 
 of benzene, containing toluene, xylene, &c., is occa- 
 sionally useful when a solvent of a somewhat higher 
 boiling-point is required. Aniline, dimethylaniline, and 
 phenol are sometimes useful solvents. 
 
 Light Petroleum Oil, consisting principally of the 
 lower boiling paraffins, is also useful. Compounds 
 which are exceedingly soluble in benzene and ether 
 often crystallise well from petroleum. 
 
 Glacial Acetic Acid. A valuable solvent, and the 
 fact that it dissolves such substances as chromic acid, 
 nitric acid, and bromine, while it is not attacked by 
 them, renders it a particularly useful medium for the 
 moderate application of these reagents to organic 
 compounds. 
 
 Ether. From its low boiling-point, and from its 
 having no chemical action on most organic compounds 
 ether is especially valuable as a solvent. It has the 
 advantage of dissolving a very large number of sub- 
 stances which are indifferently soluble in other liquids. 
 
 Chloroform, Carbon disulphide, and Carbon fetra- 
 chloride are occasionally used, but are not often re- 
 sorted to until the commoner solvents have been triefr 
 
 In particular cases the mineral acids and alkalies are 
 
 B 2 
 
 o 
 
 * 
 
4 PKACTICAL WOEK IN ORGANIC CHEMISTRY. 
 
 made use of, but their employment requires great care 
 and judgment, as they often bring about decomposition 
 of the substance. 
 
 When a suitable solvent has been found, care must 
 be taken in the case of volatile inflammable liquids 
 that the solution of the substance is effected in an 
 appropriate vessel. In the case of alcohol, benzene, 
 ether, &c., it is a good plan to employ a flask attached 
 to a condenser, and the flask had better be heated by 
 means of a water-bath. (A saucepan answers very 
 well ; it should have a piece of cloth at the bottom to 
 prevent the flask touching the metal.) See Fig. 1. 
 
 Fig. 1. 
 
 Should it be found necessary to use animal charcoal 
 to remove colouring matter, care must be taken not to 
 add it too suddenly to the hot solution. The solution 
 
PRACTICAL WORK IN ORGANIC CHEMISTRY. 5 
 
 is cooled clown and the purified charcoal added in small 
 portions at a time.* 
 
 Very serious accidents may happen through care- 
 lessness in this matter ; the hot liquid may suddenly 
 froth up, and, if inflammable and in proximity to a 
 flame, take fire. 
 
 Should an inflammable liquid be employed in effect- 
 ing a fractional crystallisation, the mother-liquor had 
 better be distilled off to the desired extent ; it is safer 
 than evaporating down in a beaker. Of course, in par- 
 ticular cases these operations have to be modified. 
 
 Note. Kecovery of Solvents. Most chemical labora- 
 tories where much organic work is done, keep bottles or 
 jars for residues, such as alcohol, ether, benzene, &c. 
 When these residues have accumulated, they may be 
 " worked up " in an appropriate manner. Their recovery 
 offers good practice to a beginner. 
 
 Determination of Melting-point. The melting-point 
 is a very characteristic property of many solid bodies. 
 If a substance begins to melt at a certain temperature, 
 and does not melt completely at that temperature, 
 experience has shown that it is very probably impure. 
 
 In working with compounds of carbon, determinations 
 of melting-points are frequently made. In general, a 
 
 * This is prepared by boiling about 1 Ib. of freshly ground animal 
 charcoal in half a gallon of common hydrochloric acid diluted with 
 one gallon of water, for about two hours. The liquid is filtered 
 through a linen bag, and the residue washed with hot wate.r till free 
 from acid, dried, and ignited to full redness in a closed crucible. It 
 is bottled while still warm and kept carefully dry. 
 
PKACTICAL WORK IN OEGANIC CHEMISTEY. 
 
 sharp and constant melting-point is regarded as evidence 
 of "individualism " and purity in a compound. 
 
 The determination is made as follows : Small tubes 
 are prepared by heating a piece of scrap combustion 
 tube and drawing it out while hot to a narrow tube. 
 This can be cut up into a number of small tubes about 
 8 or 4 inches long, and one end of each tube is to be 
 neatly sealed up. These small tubes have thin walls, 
 and must be of such internal diameter that an ordinary 
 thick pin can easily be introduced into them. A small 
 quantity of the substance to be examined (it must le 
 quite dry), is placed on a watch-glass and scooped up by 
 the wide open part of the tube, when, by gently tap- 
 ping the tube, the substance slips down to the bottom, 
 where it forms a little column of about J inch in height. 
 The tube is fastened to a thermometer by means of a 
 little indiarubber band cut from a piece of tubing. The 
 band is placed round the upper part of the tube, and 
 the lower part of the tube containing the substance is 
 placed in contact with the bulb of the thermometer. 
 If the capillary tube is very slender it will adhere to 
 the side of the thermometer by virtue of the capillarity 
 of the liquid in the beaker, and the indiarubber ring 
 may then be dispensed with. 
 
 A reference to Fig. 2 will show how the thermo- 
 meter and tube are to be arranged. They are sus- 
 pended in a beaker containing either water, paraffin- 
 wax, or sulphuric acid. A piece of glass rod bent into 
 a ring at one end is also provided ; this is to act as 
 
PRACTICAL WORK IN ORGANIC CHEMISTRY. 
 
 stirrer during the process of heating, which is to be 
 very gradually conducted. The instant the substance 
 melts the temperature indi- Fig 2 . Fig. 3. 
 
 cated by the thermometer is 
 noted. This is the melting- 
 point required. 
 
 For substances melting 
 above 250 an " air-bath " is 
 very convenient. This can 
 be formed out of a small 
 wide-necked flask and two 
 test-tubes passing one within 
 the other (see Fig. 3). 
 The melting-point tube is 
 fastened to the thermometer by means of a piece of 
 thin wire. 
 
 Distillation. For the purification of volatile liquids 
 the process of distillation is used. For this purpose we 
 may effect our object by (a) simple distillation, (b) frac- 
 tional distillation, (c) steam distillation. As an illustra- 
 tion of simple distillation we will take the recovery of a 
 solvent, say, benzene. The impure benzene would be 
 placed in a retort or flask connected to a condenser, 
 and the benzene distilled off by the aid of a water-bath. 
 
 Fractional Distillation. It is often possible to separate 
 almost completely by a simple distillation two liquids 
 occurring together in a mixture, when their boiling- 
 points lie widely apart. The more volatile liquid first 
 passes over, the temperature suddenly rises, and the 
 
PRACTICAL WORK IN ORGANIC CHEMISTRY. 
 
 Fig. 4. 
 
 higher-boiling liquid distils. It is otherwise when we 
 have a liquid consisting of a mixture of bodies boiling 
 very near each other. One distillation only effects a 
 very imperfect separation ; a portion of the less volatile 
 liquid is carried over by the vapour of the more volatile 
 substance, the temperature rising 
 throughout the distillation. In 
 order to carry out the separa- 
 tion of volatile liquids recourse 
 must be had to the process of 
 fractional distillation. It will 
 be evident that if the vapours 
 which rise from a mixture of 
 boiling liquids are somewhat 
 cooled before reaching the con- 
 denser, the less volatile portion 
 carried upwards by the vapour 
 of the more volatile liquid will 
 be partially condensed. If this is allowed to flow back 
 to the retort, a greater proportion of the lower-boiling 
 liquid will be obtained in the receiver. In order to 
 carry out this partial condensation during the process 
 of distillation several forms of apparatus have been 
 devised. 
 
 A very effective, and at the same time inexpensive, 
 piece of apparatus is that of Hem pel, which consists 
 of a long glass tube containing glass beads or pieces of 
 broken glass. (See Fig. 4.) 
 
 Fig. 5 is the apparatus of Le Bel & Henninger ; it has 
 
PRACTICAL WOKK IN ORGANIC CHEMISTRY. 9 
 
 side tubes, down which the condensed liquid flows. At 
 the narrow parts of the tube a, b, c, are fixed small cups 
 of wire gauze. Little pools of condensed liquid form 
 in these cups, and this liquid washes, so to speak, the 
 vapour passing upwards ; in fact, a process of fractionat- 
 ing is carried on in these cups by the ascending vapours. 
 In carrying out a fractional distillation, the apparatus 
 is to be arranged as in Fig. 6. 
 
 Fig. 6. 
 
 The flask is heated over wire gauze, or, in the case of 
 a very volatile liquid, in a water-bath. If wire gauze 
 is employed, the burner should be placed in a deep tin 
 basin containing sand, in order to absorb the liquid in 
 the event of the flask or retort cracking. 
 
10 PKACTICAL WORK IN OEGANIC CHEMISTRY. 
 
 The fractionating bulb or tube is fitted with a 
 thermometer, the bulb of which is well below the exit- 
 tube (see Fig. 6). A number of clean dry flasks or 
 bottles, fitted with corks and having blank labels 
 attached, are provided for recording the B.P. of the 
 fraction. 
 
 In order to indicate the working of this apparatus 
 we will take the rectification of a sample of benzene. 
 
 Example. 200 ccm. of the sample of benzene are 
 introduced into an 8 oz. flask, a spiral of platinum wire 
 or two or three pieces of broken pipe-clay are added in 
 order that the liquid may boil quietly. The flask is 
 connected to the condenser by means of the fraction- 
 ating apparatus and heat so applied to the retort that 
 the distillate drops from the condenser ; it must not be 
 allowed to come over in a continuous stream. The 
 indications of the thermometer must be carefully noted 
 and the distillate between every five or ten degrees is to 
 be collected in a separate vessel. Each of these fractions 
 is to be redistilled in proper order. Thus, suppose we 
 have the fractions A, B, C, D, E, E. A would first be 
 redistilled, all that comes over within a range of 5 
 being collected ; B would then be added to the residue 
 of A in the flask, distillation continued as before, C 
 would be added to residue of A and B, and so on until 
 we have principally two large fractions, one boiling 
 79-82 and the other above 105. 
 
 The fraction 79-82, which is nearly pure benzene, can 
 . be further purified by freezing, pressing, and redistilling. 
 
PKACTICAL WOKK IN OBGANIC CHEMISTRY. 11 
 
 Note. In carrying out the process of distillation 
 care should be taken not to employ too great a heating 
 medium, as the vapour in the flask gets superheated 
 and so causes erroneous thermometric readings. The 
 distillation should be conducted in a place as much 
 sheltered from currents of air as possible. 
 
 Determination of Boiling-point. Just as the melting 
 point is characteristic of many solid compounds, so the 
 boiling-point is a very important physical property of 
 many liquids. It is determined with sufficient exact- 
 ness for ordinary purposes by employing the apparatus 
 used for fractional distillation. The temperature noted 
 on the themometer when the liquid is boiling is the 
 boiling-point. In exact determinations of boiling- 
 points, corrections have to be made for the cooling of 
 that part of the column of mercury which is not in 
 the vapour of the substance. The barometric pressure 
 must also be noted. 
 
 Steam Distillation. It occasionally happens that a 
 substance is volatile in a current of steam, and by 
 taking advantage of this property a compound can 
 often be very readily isolated and obtained in a pure 
 condition. In the following programmes it will often 
 be adopted, and therefore a description of the apparatus 
 employed may be here given. (See Fig. 7.) 
 
 A is a tin or copper can ; it is fitted with a cork and 
 two tubes a, b, one (6) conveying steam to the flask B 
 and the other (a) passing nearly to the bottom of the can, 
 and extending about a yard above the cork. It acts 
 
 , 
 
12 PRACTICAL WORK IN ORGANIC CHEMISTRY. 
 
 a kind of safety tube. The flask is connected to the 
 condenser by the bent glass f'piece D, which in 
 its turn is connected to the condenser by the india- 
 
 Fig. 7. 
 
 rubber tube F. The f-piece is closed at one end by 
 the cork E ; this cork can be removed when necessary 
 and a glass rod inserted to remove any obstruction in 
 the condenser. The T-piece an( i condensing-tube can 
 be made of one piece if desired, but is more liable to 
 fracture than if connected as at F by indiarubber tube. 
 When operating the flask B with its contents is heated 
 on a sand-bath and a gentle current of steam passed in, 
 when the volatile substance passes over with the steam 
 and is condensed in the usual way. 
 
 Sublimation. Fig. 8 represents a convenient form 
 of apparatus for the sublimation of an organic com- 
 pound. A sheet of asbestos cardboard supported on a 
 
PRACTICAL WORK IN ORGANIC CHEMISTRY. 
 
 13 
 
 tripod and having a circular hole cut out for the 
 reception of a small porcelain crucible, is covered with 
 an inverted, thin, shallow, flat glass basin, on the top 
 of which a precisely similar glass dish is placed con- 
 taining a little cold water. 
 
 The substance to be sublimed is placed in the 
 crucible, which is covered with a circular piece of filter 
 paper pierced with pin-holes. (This is to prevent the 
 sublimate from dropping back into the crucible; it is 
 not shown in the sketch.) One of the flat glass dishes 
 is then inverted over the whole, and this again sur- 
 mounted by its fellow, containing a little cold- water, 
 which is renewed from time to time as occasion may 
 require. A piece of moist bibulous paper placed be- 
 tween the two glass dishes greatly 
 facilitates condensation. Matters 
 being thus arranged the crucible 
 is cautiously heated by means of a 
 small burner. 
 
 Small quantities of substance 
 can often be readily sublimed be- 
 tween two watch-glasses ; a cir- 
 cular piece of filter paper pierced 
 with holes being interposed to pre- 
 vent the sublimate falling back into the lower 
 vessel. 
 
 A very moderate temperature suffices for the subli- 
 mation of the majority of organic compounds. 
 
 Sulliming-point. The temperature at which a sub- 
 
 Fig. 8. 
 
14 r PRACTICAL WOEK IN ORGANIC CHEMISTRY. 
 
 stance sublimes, called the subliming-point, is sometimes 
 an important characteristic, but its value depends very 
 much on the manner in which the operation is carried 
 out. 
 
 Determination of Specific Gravity. The determina- 
 tion of the specific gravity of an organic body, liquid or 
 solid, is often a most valuable indication of its purity 
 and identity. 
 
 The specific gravity of a solid or liquid is generally 
 referred to water taken as unity. 
 
 For determining the specific gravity of liquids, we 
 may employ either a specific gravity bottle or what is 
 known as a Sprengel tube. A gravity bottle may easily 
 be constructed as follows : A small glass flask with a 
 long neck, constructed from a piece of glass tube by 
 means of the blow-pipe, is fitted with a cork (Fig. 9). 
 The neck of the flask just above the bulb is narrowed 
 by drawing it out in the flame, and a horizontal mark 
 m etched or scratched on it with a file. The bottle, 
 which should have a capacity of about 20-30 com., 
 is thoroughly cleaned and dried ; when quite cold it 
 should be very carefully weighed plus the stopper. It 
 is then filled up to the mark with the liquid under 
 examination ; this can be done by means of a funnel, 
 the stem of which is drawn out so as to allow it to pass 
 through the constricted neck. The bottle with its 
 contents is placed in water and brought to a temperature 
 of 15 -50. 
 
 Note. Should the water of the laboratory be higher 
 
PRACTICAL WORK IN ORGANIC CHEMISTRY. 15 
 
 than this temperature it can be readily cooled down to 
 the desired extent, by dissolving in the water a few 
 crystals of sodium thiosulphate or ammonium nitrate. 
 After standing in the water for about a quarter to half 
 an hour, the liquid in the flask is so adjusted that the 
 meniscus coincides with the mark on the neck of the 
 flask. The addition of more liquid is made from a 
 small pipette with a capillary tube ; if some of the 
 
 Fig. 9. Fig. 10. 
 
 liquid has to be removed a small squill of filter paper 
 may be used to absorb it. When the adjustment has 
 been effected the bottle is removed from the water, 
 dried, and allowed to remain a quarter of an hour in 
 the balance case and weighed. The bottle is emptied, 
 cleaned and dried, and filled as before with cold, 
 recently boiled, distilled water. After adjustment at a 
 temperature of 15 '5 C. it is again weighed. Neglect- 
 ing certain minor corrections, the specific gravity is 
 
16 PEACTICAL WORK IN OEGANIC CHEMISTRY. 
 
 found by dividing the weight of substance by the 
 weight of water. 
 
 A very useful and delicate piece of apparatus is 
 Perkin's modification of Sprengel's specific gravity tube. 
 This modification is very readily constructed with the 
 blow-pipe out of glass tube. It consists (Fig. 10) of a 
 U-tube drawn out at each end into a fine capillary. 
 The ends are bent over as shown, one arm having a 
 small bulb blown on it. On this limb just below the 
 bulb a mark is scratched. The tube is dried and 
 weighed, and the liquid drawn in through the limb b 
 until it half fills the bulb on the limb a. The 
 apparatus is cooled down in water at 15, and the 
 meniscus adjusted to the mark a by tilting the tube 
 until the limb b has a horizontal position. From the 
 limb I, the liquid may be absorbed by cautiously 
 applying a piece of bibulous paper until it sinks to the 
 desired position in the limb a. The tube is then 
 dried and weighed, and the operation is repeated with 
 distilled water. In the case of volatile liquids little 
 caps of glass are placed over the ends of the tube. 
 
 The apparatus is adapted for small quantities of 
 liquid as it can be made to hold from 1-10 ccm. or 
 more. It is very useful for determining the densities 
 of many fixed oils which are solid or semi-solid at the 
 ordinary temperature. The determination of the 
 density of such substances at the boiling-point of water 
 is very convenient for many reasons. The weight of 
 the Sprengel tube and that of the water contained in it 
 
PRACTICAL WORK IN ORGANIC CHEMISTRY. 17 
 
 at 15 '5 C. being known, the tube should be filled with 
 the oil or fat, previously melted if necessary, and sus- 
 pended in a beaker of boiling water, and the adjustment 
 made in the usual way. When the expansion ceases 
 the tube is removed, cooled, wiped, and weighed. The 
 weight of the contents divided by the weight of water 
 at 15 "5 C., previously known to be contained by the 
 tube, will give the density of the oil at the temperature 
 of boiling water, water at 15 '5 C. being taken as unity. 
 There is no necessity to make any correction for the 
 expansion of glass as all the determinations are com- 
 parative. 
 
 Collection and Drying of Organic Preparations. 
 Some judgment has to be exercised as to the mode of 
 collecting organic preparations from the solutions from 
 which they have separated. Certain well crystalline pro- 
 ducts can be very conveniently collected in the ordinary 
 crystal drainers, or the substance may be collected in a 
 funnel, having a glass stopper or marble placed loosely 
 in the apex (made still more effective by the addition 
 of a little asbestos fibre). 
 
 It more frequently happens, however, that the com- 
 pound to be collected is in a finely divided condition, 
 not capable of being retained by a loose stopper. A 
 more general method for small preparations is to filter 
 on paper aided by a " filter pump." 
 
 To carry out this method properly we require some 
 good filter-paper and a supply of parchment paper: 
 The filter-paper is folded in the usual way, but 
 
 c 
 
18 PKACTICAL WORK IN ORGANIC CHEMISTRY. 
 
 before placing in the funnel it is fitted with a small 
 parchment cone. The mode of fitting this cone is 
 as follows : A small circular piece of parchment 
 paper, rendered pliable by just moistening with 
 warm water, is pierced with a few holes, and theu 
 folded up with the filter-paper in the same way as we 
 should fold a " double filter." The paper is now 
 dropped into a selected funnel (the sides should be 
 inclined at an angle of 60), pressed evenly against the 
 sides, and moistened with water or alcohol as the case 
 may be. The stem of the funnel is now pushed through 
 the caoutchouc cork of the filter-flask, or bottle, the 
 substance brought on the funnel, and the pump gently 
 started. 
 
 When the parchment cone is properly fitted, it will 
 support a filter filled with liquid under a pressure of 
 an atmosphere without the paper breaking. After the 
 substance has been well drained on the funnel, it may 
 be removed with the filter-paper bodily from the funnel 
 and opened out on some bibulous paper spread on a 
 porous tile, where it may be left to dry spontaneously, 
 or placed in the water or air-oven. 
 
 The collection and drying of liquid or oily products 
 requires some consideration. For separating two 
 liquids of different specific gravities we may employ a 
 pipette or a separating funnel. A suitable pipette may 
 easily be constructed by the student. A more con- 
 venient apparatus, however, for this purpose is the 
 separating funnel, which consists of a pear-shaped 
 
PRACTICAL WORK IX ORGANIC CHEMISTRY. 19 
 
 (Fig. 11) or cylindrical (Fig. 12) glass vessel, furnished 
 with a tap below and a stopper at the top. The funnel 
 should be cleaned immediately after use, and the tap 
 and stopper slightly greased to prevent 
 them sticking. The application of the 
 funnel for the mere separation of two 
 liquids requires no explanation. The 
 funnel is, however, often applied to 
 other purposes. Suppose that it is 
 desired to effect the separation of a 
 substance from an aqueous liquid by 
 agitation with ether: the former is 
 introduced into the funnel, of which it 
 should not occupy more than one-third, 
 acid or alkali added as may be desired, and then a 
 volume of ether about equal to that of the aqueous 
 liquid. The stopper is then inserted, the funnel grasped 
 in such a manner as to prevent the tap and stopper 
 from falling out, and the whole thoroughly shaken 
 together for a minute or two, and then set aside. As 
 a rule, the contents will readily separate into two 
 well-defined layers, the lower of which is aqueous, and 
 the upper ethereal. Sometimes separation into layers 
 does not readily occur, the liquid remaining apparently 
 homogeneous, forming an emulsion. In such a case the 
 addition of a little more ether and reagitation generally 
 bring about separation. The addition of a few drops 
 of alcohol, or, when admissible, strong hydrochloric 
 acid, followed by a gentle rotatory motion of the 
 
 c 2 
 
20 PRACTICAL WOEK IN OEGANIC CHEMISTRY. 
 
 liquid, will almost invariably cause prompt separa- 
 tion. 
 
 Separation having taken place, the aqueous layer 
 should, if necessary, be run off by the tap into another 
 separator, where it can again be agitated with ether. 
 The ethereal liquid remaining in the separator can be 
 shaken with a fresh quantity of water, made acid or 
 alkaline, which is then tapped off as before, and the ether 
 further washed by treating it with a little pure water. 
 This having in turn been run off to the last drop, the 
 ethereal solution can next be removed by the tap, but 
 a better plan is to pour it out of the top of the funnel, 
 by which means any contamination by traces of water, 
 &c., adhering to the sides of the glass will be avoided. 
 
 The separated ether may be dried by standing over 
 fused chloride of calcium or other drying agent. 
 
 Refrigerating Funnel. It occasionally happens that 
 we have to collect a substance melting at a very low 
 temperature (see Purification of Benzene, p. 114). A 
 very useful piece of apparatus for this purpose is 
 described by J. W. Bnihl.* 
 
 Fig. 13 shows how the apparatus is put together. 
 B is the funnel made by drawing out a piece of wide 
 glass tube, the narrow part being drawn out to a jet ; 
 it is fastened to the tube D carrying the glass tap h, 
 by fusing before the blow-pipe at/. The tube D passes 
 through a cork into the filter-flask E. A is the vessel 
 containing the freezing mixture ; an ordinary bottle 
 * Ber. Deut. Chem. Gesell., 1889, vol. xxi. p. 236. 
 
PRACTICAL WORK IN ORGANIC CHEMISTRY. 21 
 
 Fig. 13. 
 
 Fig. 14. 
 
 with the bottom cut off serves for this purpose. The 
 tube a, which can be closed by a clip, is useful for 
 running off melted ice, &c. The glass cover C, 
 furnished with a calcium chloride tube, and fastened 
 to the funnel B by an india- 
 rubber band c, is a needful ad- 
 junct, where it is necessary to 
 freeze a substance out of contact 
 with air or moisture. The funnel 
 is improved and simplified by 
 employing a narrower piece of 
 tube, which can be closed by an 
 india-rubber stopper carrying the 
 calcium chloride tube. The 
 capacity of the funnel tube is in- 
 creased to the desired extent by 
 softening and blowing out before 
 the blow-pipe (see Fig. 14) B'. 
 
 To use the apparatus the tap h 
 is closed, the cone g of platinum 
 or asbestos placed in position, and 
 the liquid which is to be frozen 
 carefully introduced. The funnel is closed, and the 
 freezing mixture placed in the outer vessel. 
 
 When properly frozen, the tap h is cautiously opened, 
 when any unfrozen liquid drains into the flask E, 
 previously rendered vacuous by means of the pump. 
 
22 PRACTICAL WORK IN ORGANIC CHEMISTRY. 
 
 ANALYSIS. 
 
 Having briefly described some of the more important 
 operations involved in the isolation and purification of 
 organic compounds, we will now proceed to consider 
 the ultimate analysis of such bodies. Notwithstanding 
 the vast array of the carbon compounds, the number 
 of elements entering into their composition is usually 
 very small. The great majority consist of carbon, 
 hydrogen, and oxygen only. The members of another 
 very large class contain four elements carbon, hydro- 
 gen, oxygen, and nitrogen ; others contain chlorine, 
 bromine, iodine, or sulphur, whilst a smaller proportion 
 contain phosphorus, silicon, or the metals; but these 
 are comparatively rare. 
 
 QUALITATIVE ANALYSIS. 
 
 Detection of Carbon and Hydrogen. The presence of 
 these bodies may be demonstrated by mixing the sub- 
 stance with recently ignited copper oxide and heating 
 to redness in a hard glass tube. The products of com- 
 bustion are passed first through a cold, dry tube, and 
 then into lime-water. If hydrogen be present it is 
 oxidised to water, which condenses in the tube, while 
 if carbon be present it is burnt to carbon dioxide, of 
 which the presence is shown by the production of 
 turbidity in the lime-water. 
 
PKACTICAL WORK IN ORGANIC CHEMISTRY. 23 
 
 Liquid or volatile substances are conveniently ab- 
 sorbed for the purpose of the above experiment by a 
 little recently ignited asbestos. 
 
 Detection of Nitrogen. Many nitrogenous compounds, 
 when heated with caustic soda or potash, evolve the 
 whole of their nitrogen in the form of ammonia. In 
 certain cases, viz. where the nitrogen is contained as 
 an oxide, ammonia is not generated by heating with an 
 alkali. A general test for nitrogen in an organic com- 
 pound is as follows : A small quantity of the substance 
 under examination (if liquid, a small piece of asbestos 
 fibre is added to absorb it) is heated with a small pellet 
 of sodium contained in a narrow test-tube. A violent 
 action usually takes place, accompanied by deposition of 
 carbon, whilst the nitrogen and a portion of the carbon 
 combine with the sodium, forming sodium cyanide. 
 On dissolving the product in water, filtering, and adding 
 a few drops of a mixed solution of ferric chloride and 
 
 <S <B 
 
 ferrous sulphate, ^potassium , ferroeyanidej is formed. 
 The whole is now acidulated with an excess of hydro- 
 chloric acid; this dissolves the precipitated oxide of 
 iron, which now forms Prussian blue with the ferro- 
 cyanide. The presence of very small quantities of 
 nitrogen can be ascertained by this method. 
 
 Detection of the Halogens. These elements may be 
 detected by heating the substance in a small hard glass 
 tube with a little pure quicklime ; the tube is broken 
 by plunging while hot into water, slight excess of 
 dilute nitric acid is added to dissolve the lime, 
 
24 PKACTICAL WOKK IN OKGANIC CHEMISTEY. 
 
 solution is filtered from carbonaceous matter, and the 
 filtrate tested with silver nitrate in the usual way. 
 
 Detection of Sulphur and Phosphorus. Sulphur may 
 be recognised by heating the substance with a small 
 piece of sodium. Sodium sulphide is formed, which on 
 treatment with a dilute mineral acid will generate sul- 
 phuretted hydrogen. Another method is to heat the 
 compound under examination with a mixture of pure 
 nitre and dry sodium carbonate. If sulphur is present, 
 a sulphate is formed which, after acidulation with 
 hydrochloric acid, may be precipitated as barium 
 sulphate. 
 
 Phosphorus, when fused with the foregoing mixture, 
 is oxidised to phosphoric acid, which can be recognised 
 by the ordinary reagents, 
 
 QUANTITATIVE ANALYSIS. 
 
 Determination of Carbon and Hydrogen. The prin- 
 ciple employed in the detection of carbon and hydrogen 
 in organic compounds, that is, the oxidation of the carbon 
 to carbon dioxide, and the hydrogen to water by ignition 
 with copper oxide or some other body which easily 
 parts with its oxygen, is also adopted in the quantitative 
 determination of these constituents. In order to obtain 
 accurate results, strict attention must "be paid to details 
 of manipulation. These details can only be obtained 
 from actual practice in the laboratory. The following 
 suggestions are offered as a guide to the student in this 
 branch of analysis. Before proceeding to the deter- 
 
PKACTICAL WORK IN OEGANIC CHEMISTRY. 25 
 
 mination of the carbon and hydrogen, we must ascertain 
 what other constituents are present, as the method 
 employed will vary according to the nature and com- 
 position of the substance to be examined. 
 
 In the modern process of combustion the substance 
 is burnt in a glass tube with cupric oxide or chromate 
 of lead by the aid of a current of air or oxygen. 
 
 We will consider by way of example the combustion 
 of a substance containing carbon, hydrogen, and oxygen, 
 such as sugar or oxalic acid. 
 
 A combustion furnace is too well known to need 
 description. Various kinds will be found figured in the 
 catalogues of the instrument maker. A good form is 
 that of Erlenmeyer ; it is sold with special fire-clay tiles 
 and trough, but as these are somewhat expensive, a 
 commoner tile may be had and the fire-clay trough 
 may with advantage be replaced by one of iron. A 
 thin layer of asbestos fibre is evenly distributed along 
 its entire length to prevent the combustion-tube coming 
 in contact with the heated metal. 
 
 Having selected a furnace fitted with a trough, we 
 shall require the following additional articles to make 
 a combustion by means of this apparatus. 
 
 1. A Piece of Combustion-tube. This must be of hard 
 glass, 4 inches longer than the trough of the furnace, 
 and of such internal diameter as to readily admit the 
 passage of the little piece of apparatus termed a boat. 
 The sharp edges of the tube should be fused in the 
 blow-pipe flame, so that two caoutchouc stoppers pierced 
 
26 PRACTICAL WORK IN ORGANIC CHEMISTRY. 
 
 with holes, may be introduced without being cut or 
 torn. 
 
 2. Copper Oxide and Asbestos. Sufficient granulated 
 copper oxide must be provided to fill three-quarters of 
 the combustion-tube. Loose plugs of asbestos are 
 added to keep the oxide in position. 
 
 3. A Platinum or Porcelain Boat, to contain the sub- 
 stance. This should be of such size as to readily pass 
 into the combustion-tube. 
 
 4. A "Boat-house" Two tubes sliding one within the 
 other to contain the boat whilst being carried back- 
 wards and forwards from the laboratory to the balance 
 room. 
 
 5. A Glass Bulb formed by drawing out a piece of 
 hard glass tube before the blow-pipe ; it must be of such 
 external diameter as to readily pass into the combustion- 
 tube. It is placed behind the boat in the combustion- 
 tube, and while permitting the passage of the current 
 of air or oxygen, tends by constricting the channel to 
 prevent the vapour of the substance undergoing 
 combustion from subliming back in the tube. 
 
 6. An Apparatus for absorbing tlie Water formed during 
 Combustion. This is an important piece of apparatus, 
 and one of the best forms is that shown in Fig. 15. It 
 is readily made by bending up, and drawing out before 
 the blow-pipe a piece of J-inch glass tube. The arm 
 containing the bulb is drawn out so as to be slightly 
 tapering; in this form it is readily introduced and with- 
 drawn from the caoutchouc stopper of the combustion- 
 
PRACTICAL WORK IN ORGANIC CHEMISTRY. 27 
 
 tube, and at the same time a well-fitting connection 
 may be secured. Before the other arm is drawn out the 
 (J-tube is filled to the extent Fig 15 
 
 indicated with small pieces 
 of prepared pumice.* 
 
 In order to prepare the 
 tube for use, strong sul- 
 phuric acid is sucked in 
 through one arm ; it is 
 allowed to stand for some 
 time and then the excess of 
 acid drained off through the 
 same arm ; the outside of the tube is wiped and the 
 adhering acid expelled from the limb by gently warming 
 in the Bunsen flame. Sufficient acid 
 remains in the tube in contact with 
 the pumice to serve for half a dozen 
 experiments. Most of the water 
 resulting from the combustion 
 condenses in the little bulb, from 
 which it may be expelled after 
 weighing, by tilting the tube, aided 
 by a few gentle jerks, or by cauti- 
 ously warming and aspirating. 
 
 7. An Apparatus to absorb Carbon Dioxide. Of the 
 various forms sold for this purpose the one shown in 
 
 * To prepare the pumice for this purpose pieces are selected of 
 about the size of large peas. They are digested for some time in a 
 small porcelain basin with strong sulphuric acid, drained f 
 of acid, and then ignited. This treatment destroys carbona 
 
 Fig. 16. 
 
 _-# 
 
28 PRACTICAL WORK IN ORGANIC CHEMISTRY. 
 
 Fig. 16, and known as Geissler's, is preferred. It has 
 a small additional tube containing broken pieces of 
 potassium hydroxide, attached at one end. 
 
 The bulbs are filled to the extent indicated in the 
 figure with a strong solution of potassium hydroxide 
 (1 part by weight of potash to 2 parts of water). 
 
 The sulphuric acid tube and potash bulbs are stop- 
 pered when not in use, by short lengths of narrow 
 caoutchouc tube closed at one end by small pieces of 
 glass rod. 
 
 8. An Apparatus for drying and removing Moisture 
 and Carbon Dioxide from the Air and from Oxygen. 
 This may be arranged as in Fig. 17, which represents a 
 convenient form of apparatus for this purpose, and also 
 indicates the manner in which it is connected to the 
 combustion-tube, &c. A is a vessel containing water 
 supported at about 24 inches above the operation table. 
 On opening the screw-clip a water flows into the bottle 
 B, containing oxygen, which is conveyed by means of the 
 bent tube to the (J or rather y tubes, C, C', packed to 
 the extent indicated with broken pumice. The shanks 
 of these tubes pass through caoutchouc stoppers and 
 dip, C .into a strong solution of potash (1 part potash 
 2 parts water) and C' into concentrated sulphuric acid. 
 Before connecting the apparatus to the combustion-tube 
 the stoppers at e c' and d d' (short lengths of caoutchouc 
 tube stoppered with glass rod) are removed, when on 
 applying a gentle pressure from the lips at dd" the 
 liquids are forced up into the tubes containing the 
 
PRACTICAL WORK IN ORGANIC CHEMISTRY. 29 
 
 pumice. On removing the pressure the liquids flow 
 back into their receptacles. The stoppers are securely 
 replaced and the connection completed. 
 
 The small conical flask D, containing a little of the 
 potasli solution, serves to regulate the supply of air or 
 oxygen by indicating the speed with which the gas 
 travels through the apparatus, this being controlled by 
 the screw-clip b. 
 
 The little tube E contains a few fragments of pumice 
 saturated with concentrated sulphuric acid; one arm 
 of this tube passes directly through the caoutchouc 
 stopper of the combustion-tube, Its adoption ensures 
 a most perfect desiccation of the air or oxygen. The 
 arrangement of the rest of the combustion apparatus 
 requires little or no explanation. F is the little glass 
 bulb to prevent backward sublimation, G is the " boat," 
 H represents the cupric oxide kept in position by loose 
 plugs of asbestos, I shows the attachment of the 
 apparatus for absorbing the water resulting from 
 the combustion of the substance. This apparatus 
 is connected with the potash bulbs J by means 
 of a piece of narrow bore thick-walled caoutchouc 
 tube. 
 
 The Process. When everything is arranged, heat 
 the combustion-tube to low redness, having previously 
 removed the boat and glass bulb ; detach the caoutchouc 
 tube at 6, and connect the aspirator to the other end 
 of the combustion-tube, when a slow current of dry air 
 may be drawn over the copper oxide to expel hygro- 
 
30 PKACTICAL WORK IN ORGANIC CHEMISTRY. 
 
 scopic moisture, and burn any organic impurity. While 
 the tube is being heated, weigh the potash bulbs and 
 sulphuric acid tube without their caoutchouc stoppers. 
 
 When you have determined their weight, replace 
 the stoppers. In about thirty minutes turn out the 
 flames underneath that part of the combustion-tube 
 not containing the copper oxide, and allow to cool down 
 in the current of dry air. Now adapt the weighed 
 sulphuric acid tube to the combustion-tube by means 
 of the caoutchouc stopper (having previously removed 
 the aspirator), and connect the potash bulbs by a piece 
 of well-fitting caoutchouc tube in the manner repre- 
 sented in Fig. 17. In the diagram this caoutchouc 
 tube is seen fastened on to the glass arms of the 
 absorption-tubes by means of thin wire, but this is 
 not necessary if an aspirator is employed, since the 
 reduced pressure within the apparatus caused by the 
 column of water effectually prevents leakage. Remove 
 the stopper and small (J'tube at further end of the 
 combustion-tube, insert the boat containing the weighed 
 amount of substance (about 0*2 gram), and then the 
 glass bulb. Again fit in the stopper and connect the 
 caoutchouc tube b with the bottle containing the 
 oxygen. Attach the aspirator to the end of the potash 
 bulbs, and cautiously open the stopcock. Now relight 
 the last two or three burners at the other end of the 
 tube, immediately under the glass bulb, so as to heat 
 it gently, and turn on a slow stream of oxygen (about 
 a bubble every two seconds suffices at the commence- 
 
32 PEACTICAL WORK IN ORGANIC CHEMISTRY. 
 
 rnent of the process) ; continue to ignite successive 
 burners until the boat is approached. Carefully observe 
 the movements of the liquid in the potash bulbs, and 
 regulate the heat so as to preserve a uniform passage 
 of the gas into the bulbs. 
 
 As soon as the substance in the boat appears to be 
 completely charred, increase the heat beneath the boat 
 (by this time the whole of the burners should be 
 lighted), and send a slightly brisker current of oxygen 
 (about one bubble per second) through the apparatus. 
 The carbonaceous matter within the boat gradually burns 
 away; as soon as it has disappeared gradually diminish 
 the flames underneath the glass bulb and boat; turn 
 on a little more oxygen. After a few minutes, disconnect 
 at b, and by means of the aspirator send a slow current 
 of air through the tube, &c., to displace the oxygen. 
 In a few minutes detach the potash bulbs and sul- 
 phuric acid tube (taking care that in withdrawing the 
 latter from the caoutchouc stopper the water which 
 has condensed in the small bulb does not flow out), fit 
 in their respective stoppers, wipe them, and after 
 standing in the balance room for an hour to cool down, 
 reweigh them (without the stoppers). Allow the com- 
 bustion-tube to cool gradually ; if proper care be 
 exercised in this matter, it will serve a great number 
 of times. The heat must not be so high as to distort 
 the tube. The great majority of organic compounds, 
 especially if they contain oxygen, burn with compara- 
 tive ease with copper oxide and free oxygen. 
 
PRACTICAL WORK IN ORGANIC CHEMISTRY. 33 
 
 The entry of the combustion should thus appear in 
 the note-book : 
 
 ANALYSIS OF OXALIC ACID (for example). 
 Determination of Carbon and Hydrogen. 
 
 Weight of boat + substance 
 
 Weight of boat empty 
 
 Substance .. .. = 
 
 Weight of H 2 S0 4 tube (after) 
 
 (before) 
 
 Water = 
 
 Weight of KOH bulbs (after) 
 
 (before) 
 
 Carbon dioxide . . = 
 
 From the knowledge that 44 parts of carbon dioxide 
 contain 12 parts of carbon, and that 18 parts of water 
 contain 2 parts of hydrogen, the student can readily 
 calculate the amount of carbon and hydrogen in the 
 substance analysed. If the sum of the amounts of 
 carbon and hydrogen is equal to the weight of the 
 body taken, the substance contains only these elements ; 
 if the body contains oxygen in addition, the difference 
 indicates the amount of this constituent. 
 
 Analysis of Organic Substances containing Nitrogen. 
 Nitrogenous organic substances when burnt with 
 copper oxide, particularly if free oxygen be present, 
 are apt to evolve oxides of nitrogen, which condense in 
 the sulphuric acid tube arid potash bulbs and vitiate 
 
 D 
 
34 PRACTICAL WORK IN ORGANIC CHEMISTRY. 
 
 the results of the carbon and hydrogen determinations. 
 In the combustion of organic substances containing 
 nitrogen, it is necessary therefore to introduce some 
 substance in the front part of the tube capable of 
 decomposing nitroxy - compounds. Metallic copper 
 cannot well be employed, as this would quickly become 
 oxidised in the current of air or oxygen. The most 
 effective agent is metallic silver : a cylinder of silver 
 gauze,* about six inches long, rolled, on a thin glass 
 rod or piece of tobacco pipe, is placed in the anterior 
 part of the combustion-tube and kept at a bright red 
 heat during the operation. The carbon and hydrogen 
 may then be determined in the ordinary way. 
 
 Analysis of Organic Substances containing Sulphur, 
 Phosphorus, and the Halogens. When an organic com- 
 pound containing a halogen (chlorine for example), is 
 burnt with cupric oxide, cuprous chloride is formed, 
 which, being volatile, is carried forward in the stream 
 of gas and condenses in the sulphuric acid tube, and 
 thus renders the determination of the hydrogen inexact. 
 By inserting a roll of silver gauze or a layer of silvered 
 pumice in the anterior portion of the tube any chlorine 
 would be arrested. 
 
 * In the absence of silver gauze, which is somewhat expensive, 
 " silvered pumice " may be employed. Boil some pumioe (broken iiito 
 pieces about the size of an ordinary pea) in strong hydrochloric acid, 
 collect in a funnel and wash thoroughly with hot water till free from 
 acid ; transfer to a crucible and strongly ignite. Now digest with a 
 pasty solution of silver acetate, dry and ignite strongly. Metallic 
 silver in a finely divided state is left behind on the pumice, which is 
 very effective in breaking up any nitroxy-compound.^ 
 
PRACTICAL WORK IN ORGANIC CHEMISTRY. 35 
 
 The determination of carbon and hydrogen in com- 
 pounds containing chlorine or bromine is best effected 
 by heating with lead chromate. This substance is 
 readily made by precipitating a solution of lead acetate 
 with potassium chromate, thoroughly washing the 
 dense yellow precipitate, drying, heating to redness in 
 a covered clay crucible, and coarsely powdering it. The 
 combustion is made in the manner already described 
 in the case of copper oxide. 
 
 The combustion of organic compounds containing 
 sulphur is most accurately made with lead chromate, 
 care being taken to maintain the anterior portion of 
 the tube, to the extent of 6 or 7 inches, at a very low 
 red heat. Under these circumstances no sulphur 
 dioxide passes into the absorption apparatus. 
 
 Should the organic substance contain nitrogen in 
 addition to sulphur or the halogens, it is only necessary 
 to introduce a layer of silvered pumice in the front 
 part of the tube ; the carbon and hydrogen may then 
 be accurately determined in the usual way. 
 
 Determination of Nitrogen. Many organic sub- 
 stances containing nitrogen, when heated with a caustic 
 alkali, give up the whole of their nitrogen in the form 
 of ammonia. This reaction constitutes the principle 
 of a convenient method for estimating nitrogen in a 
 number of organic compounds. 
 
 The following articles are required for this 
 method : 
 
 (a) Comlustion-tule. This should have the 
 
 l^ 
 
36 PRACTICAL WORK IN ORGANIC CHEMISTRY. 
 
 seen in Fig. 18 ; it is about 24 inches long, and i inch 
 in internal diameter. 
 
 (b) Soda-Lime. Heat a sufficient quantity of the 
 coarsely powdered substance in a porcelain basin just 
 before it is wanted, and allow it to cool. 
 
 (c) A substance to evolve Carbon Dioxide. This is 
 conveniently prepared by mixing recently ignited 
 sodium carbonate with potassium bichromate in mole- 
 cular proportions. 
 
 (d) Asbestos. Ignite a small quantity in the 
 Bunsen flame before use. 
 
 (e) A lulled \J-tube, fitted with caoutchouc stopper 
 and lent tube. On the end of the bent tube is a cork, 
 which fits tightly into the combustion-tube. 
 
 Fig. 18. 
 
 TJie Process. Introduce a layer of about 4 inches in 
 length of the C0 2 -mixture into the posterior end of the 
 tube, and afterwards an equal bulk of soda-lime. Weigh 
 out about * 2 gram of the substance to be analysed 
 into a small dry porcelain mortar, and mix it with a 
 small quantity of soda-lime. Bring the mixture with- 
 out loss of time into the tube, and rinse out the mortar 
 with a fresh portion of soda-lime. Fill up the tube to 
 
 
PRACTICAL WORK IN ORGANIC CHEMISTRY. 37 
 
 within two inches of its length with the same, and 
 insert a loosely fitting plug of recently ignited asbestos. 
 Fit in the cork of the (J-tube, transfer a known volume 
 of standard acid to the U'tube, and add sufficient water 
 (if necessary) to fill the bulbs to the extent indicated 
 in the figure. Gently tap the combustion-tube on the 
 table so as to form a channel for the evolved gases. 
 Place the tube in the furnace and gradually heat it 
 along its entire length, beginning at the end nearest 
 the (J" tu be. The heat must be sufficient to cause a 
 steady evolution of gas ; towards the end of the opera- 
 tion it should be increased, to break up any cyanides 
 which may have been formed. Do not heat the 
 extreme end of the tube where the C0 2 -mixture is 
 situated until the evolution of the gas has almost 
 ceased. When the combustion is at an end and no 
 more gas bubbles through the bulbs, cautiously heat 
 the C0 2 -mixture. This occasions a brisk current of 
 carbon dioxide, which sweeps out all the ammonia 
 remaining in the tube. Kemove the (J-tube when the 
 evolution of the gas has nearly finished. Transfer the 
 liquid to a beaker, wash out the bulbs, and titrate with 
 standard alkali, employing methyl orange as indicator. 
 If much empyreumatic matter be present in the liquid 
 of the bulbs, pour the solution through a moistened 
 filter and evaporate the filtrate nearly to dryness with 
 excess of platinum tetrachloride. Pour over the pasty 
 mass about 25 ccm. of rectified methylated spirit, 
 impart a gentle rotatory motion to the contents of the 
 
38 PKACTICAL WORK IN ORGANIC CHEMISTRY. 
 
 dish in order to facilitate the solution of the excess of 
 platinum tetrachloride in the alcohol, pour the clear 
 liquid through a filter, and repeat the digestion with 
 spirit a third and fourth time. Bring the precipitate 
 on to the filter paper and wash the paper carefully until 
 the filtrate is absolutely colourless. Transfer the double 
 chloride to a weighed platinum crucible and dry it 
 slowly; heat the crucible gently to bright redness, and 
 weigh the residual platinum. 197*2 parts of platinum 
 are equivalent in round numbers to 28 of nitrogen. 
 The amount of the nitrogen cannot be calculated from 
 the weight of the double salt, since it is apt to con- 
 tain considerable quantities of compounds of platinum 
 with organic bases. These bases, however, contain 
 the same proportion of nitrogen and platinum as the 
 ammonio-platinic chloride. By weighing the amount 
 of platinum left on ignition, the proportion of the 
 nitrogen is therefore readily calculated. 
 
 Estimation of Nitrogen ly Volume. This process is 
 applicable to all nitrogenous bodies. The substance 
 is burnt by cupric oxide in a tube from which the air 
 has previously been removed by a current of carbon 
 dioxide or by the aid of a mercury pump. The mixed 
 gases resulting from the combustion are passed over 
 strongly heated metallic copper, which serves to break 
 up any oxides of nitrogen ; the remaining gases are 
 collected in a measuring tube containing a strong 
 solution of caustic potash, which absorbs the carbon 
 dioxide : the residual nitrogen is accurately measured, 
 
PRACTICAL WORK IN ORGANIC CHEMISTRY. 39 
 
 corrected for temperature, barometric pressure, and 
 tension of aqueous vapour, and from the known weight 
 of a litre of nitrogen under the standard conditions its 
 weight is readily calculated. 
 
 To carry out the determination, we require the fo] 
 lowing apparatus and materials : 
 
 (a) A piece of strong Combustion Tube, carefully 
 cleaned and dry, about 24 inches long, sealed and 
 rounded at one end like a test-tube. Sharp edges to 
 be rounded in the blow-pipe, so that a caoutchouc 
 stopper, pierced with one hole, may be introduced 
 without being cut or torn. 
 
 (b) Cupric Oxide. Strongly heat some clean copper 
 scales in a muffle, and when cold coarsely powder in an 
 iron mortar ; pass the powder through a sieve of wire 
 gauze, to separate the fine portions. When a good 
 supply of coarse and fine oxide has accumulated, it is 
 reignited (of course separately) and preserved in stop- 
 pered bottles. 
 
 (c) Metallic Copper; prepared by reducing some of 
 the coarse granular cupric oxide in a stream of 
 hydrogen. 
 
 (d) A substance to evolve Carbon Dioxide. The mix- 
 ture of sodium carbonate and potassium bichromate 
 may be employed for this purpose. 
 
 (e) Ignited Asbestos. This must be kept in a stop- 
 pered bottle. 
 
 (/) A Mortar and Pestle. An agate mortar is pre- 
 ferred, but one of the usual kind sold for organic 
 
40 PRACTICAL WORK IN ORGANIC CHEMISTRY. 
 
 analysis will answer ; it should be about 3J inches in 
 diameter, not too deep, and free from scratches. 
 
 (g) A small Glass or Copper Funnel. This is for in- 
 troducing the substance, mixed with fine copper oxide, 
 into the combustion-tube. 
 
 (h) A small Feather. This is for brushing out the 
 final particles of copper oxide from the mortar, &c. ; 
 the feather is cut down so as to form a moderately 
 stiff brush. 
 
 (i) A measuring Tube. Various kinds of measuring 
 tubes will be found described in the catalogues of the 
 apparatus dealers. A very useful piece of apparatus 
 for collecting and measuring nitrogen is that of Hugo 
 Schiff, represented in Fig. 19. 
 
 The burette A, which is fitted with a glass stop- 
 cock, contains about 100 ccm. down to the side tube a, 
 and stands in a wooden foot, which may be rendered 
 more stable by being weighted with lead. At about 
 1J inches beneath the side tube a is a second tubulus Z>, 
 inclined upwards in the manner seen in the figure. 
 Through this tube mercury is poured to a height of 
 J inch above the lower opening. The vessel B, holding 
 about 150 ccm., is supported by the clamp, and may 
 thus be placed at any desired height ; B is connected 
 by strong caoutchouc tubing, previously soaked in 
 melted paraffin, with the side tube a. B is filled with 
 a strong solution of caustic potash of sp. gr. 1 5, pre- 
 pared by dissolving potash in an equal weight of water ; 
 .its neck is closed by a cork pierced with a small hole. 
 
PKACTICAL WOKK IN ORGANIC CHEMISTRY. 41 
 
 On closing the tubulus I with a piece of thick-walled 
 caoutchouc tube pinched by a brass clip, and on open- 
 ing the stopcock and raising B, the potash solution 
 
 Fig. 19. 
 
 flows over into the burette and completely fills it. The 
 stopcock is now closed, and the vessel B is lowered 
 nearly to the foot of the burette ; the brass clip may 
 then be removed from b without the mercury being 
 forced out. 
 
 The Process. Introduce a layer, about 5 inches long, 
 of the sodium carbonate and bichromate of potash 
 mixture into the combustion-tube. Insert a plug of 
 recently ignited asbestos, pushing it down to within 
 J inch from the mixture, and afterwards add 2 inches 
 of the coarse copper oxide, and then J inch of the 
 fine oxide. Weigh out about * 2 to 3 gram of the 
 
42 PRACTICAL WORK IN ORGANIC CHEMISTRY. 
 
 nitrogenous substance on to a thin layer of fine copper 
 oxide, contained in the small mortar provided for this 
 purpose, and mix it carefully with an additional quantity 
 of the oxide. Transfer the mixture to the tube, by 
 means of the funnel, without loss, and rinse the mortar 
 and funnel with fresh portions of the fine oxide, adding 
 the rinsings to the tube, employing the feather to brush 
 out final particles. Push down a second plug of 
 asbestos, and then a layer, about 8 inches in length, of 
 coarse copper oxide, and lastly a layer, not less than 
 4 inches long, of granular metallic copper. Insert 
 another plug of asbestos to keep the copper in position, 
 and introduce the caoutchouc stopper provided with 
 the bent delivery tube. 
 
 Heat a portion, say the posterior half, of the carbon- 
 dioxide mixture, and drive out the air within the tube 
 by a brisk current of the gas. At the same time com- 
 mence to heat the portion of the tube occupied by the 
 metallic copper, including two or three inches of the 
 pure cupric oxide. As soon as the escaping gas is free 
 from air (which is readily ascertained by allowing a 
 quantity to pass into a test-tube filled with potash 
 solution, when no bubble should be left), and the 
 anterior portion of the tube is well heated, the delivery 
 tube of the combustion-tube is then pushed through 5, 
 and successive portions of the combustion-tube occupied 
 by the mixture of cupric oxide and nitrogenous sub- 
 stance are gradually heated, beginning with the part 
 nearest to the pure copper oxide. As soon as no further 
 
PRACTICAL WORK IN ORGANIC CHEMISTRY. 43 
 
 evolution of gas is observed, and the whole length of 
 the tube (with the exception of the part occupied by 
 the undecomposed carbon dioxide mixture) is at a low 
 red heat, heat the remainder, so as to cause an evolu- 
 tion of carbon dioxide, by which the nitrogen still 
 existing in the tube is expelled. Withdraw the de- 
 livery tube from the tubulus and close the latter by 
 means of the caoutchouc tube and clip. After allowing 
 the gas to remain over the caustic potash solution for 
 about an hour to absorb the last traces of carbon dioxide, 
 the volume of nitrogen is directly measured, the vessel 
 B being raised until the levels of the potash solution 
 in both pieces of apparatus are coincident. The nitrogen 
 may without sensible error be assumed to be dry. 
 Alter correcting for temperature and pressure its 
 weight may be calculated : a litre of nitrogen under 
 the standard conditions of temperature and pressure 
 weighs 1 ' 255 gram. 
 
 Determination of the Halogens in Organic Compounds. 
 A narrow piece of combustion-tube about 12 inches 
 long is sealed and rounded at one end like a test-tube. 
 A small quantity of coarsely powdered and recently 
 burnt lime (previously ascertained to be pure) is intro- 
 duced into it, so as to occupy a length of 2^ inches. 
 The compound to be analysed, if solid, is weighed out 
 into a thin layer of moderately pow dered lime contained 
 in a small porcelain mortar. The substance is covered 
 with a little more lime, carefully mixed by means of 
 the pestle, and transferred without loss to the tube ; the 
 
44 PKACTICAL WORK IN ORGANIC CHEMISTRY. 
 
 mortar and pestle are then rinsed with fresh portions 
 of lime, and the tube is filled with coarsely powdered 
 lime to within two inches from the open end. Before 
 placing the tube in the furnace tap it gently on the 
 table in order to leave a channel for the escaping 
 gases. The tube is placed in a clean trough, and one 
 end of the furnace is so raised that the open end of 
 the combustion-tube is about three inches higher than 
 the closed end : this allows of the ready escape of 
 moisture, &c. 
 
 Commence the operation by heating the anterior 
 portion of the tube, and gradually approach the part 
 containing the substance as the lime becomes red hot. 
 Having lighted all the burners beneath it, continue to 
 heat the tube until the whole length is red hot, then 
 push the tube slightly forward so that three or four 
 inches of the open end may cool down. Turn out all 
 the burners, and after a few minutes take the tube from 
 the furnace and plunge it gently, while hot, into a little 
 cold water contained in a moderately thick beaker. The 
 tube cracks and breaks up into small pieces and with 
 ordinary care no loss takes place, nor need any danger 
 be apprehended. Cool down the contents of the beaker 
 and acidify with dilute nitric acid (one part acid, sp. gr. 
 1*4, to 2 parts water).* 
 
 * In the estimation of iodine in organic compounds by the fore- 
 going process, it is necessary to add an excess of sodium or potassium 
 sulphite to the contents of the beaker before acidifying with nitric acid. 
 This reduces any iodate which would escape precipitation by silver 
 nitrate. 
 
PBACTICAL WORK IN ORGANIC CHEMISTRY. 45 
 
 An excess of nitric acid is indicated by the change 
 of colour of the suspended carbonaceous matter. When 
 all the lime is dissolved the precipitate becomes quite 
 black. The liquid is filtered, the residue well washed, 
 and the filtrate treated with silver nitrate solution and 
 the precipitated silver salt, washed, dried, and weighed. 
 
 Liquids containing chlorine, &c., are weighed out in 
 bulbs : after the introduction of a layer of lime about 
 2 g inches long, the bulb is allowed to slide down the 
 tube, which is then filled up with lime. When about 
 half the anterior part of the tube has been heated, 
 expel the liquid from the bulb by gently heating the 
 tube where the bulb is situated, and conduct the re- 
 mainder of the operation as described. 
 
 The combustion of volatile liquids demands great 
 care and attention ; the operation must not be hurried, 
 or portions will escape un burnt. 
 
 Determination of Sulphur. Solid substances con- 
 taining sulphur may be decomposed by fusion with 
 potassium hydroxide and pure potassium nitrate. Place 
 a moderate quantity of pure potassium hydroxide in a 
 silver dish, add about one-fifth of its weight of potassium 
 nitrate, and fuse the mixture. Allow it to cool and add 
 to it the weighed quantity of the sulphur compound. 
 Heat gently, and stir continually with a silver spatula, 
 adding from time to time a small quantity of nitre in 
 order to complete the combustion of the carbon. When 
 the mass is cold, dissolve it in water, acidify 
 hydrochloric acid, heat to boiling, and precipitate 
 
46 PRACTICAL WORK IN ORGANIC CHEMISTRY. 
 
 sulphuric acid with barium chloride in the usual 
 way. 
 
 Cariuss Method. Applicable to the estimation of 
 Sulphur and Phosphorus in solid and liquid compounds. 
 From 0'2 gram to 0'3 gram of the substance is 
 weighed out into a thin glass bulb or small test-tube 
 according to the nature of the body dealt with. The 
 bulb or small tube is brought into a tube of hard glass of 
 about f of an inch in internal diameter, sealed and 
 rounded at one end like a test-tube, together with from 
 30 to 60 times its weight of nitric acid of sp. gr. 1 2. 
 
 Note. The tube must not be more than half filled 
 with the liquid. The open end of the tube is now 
 cautiously warmed to expel adhering acid, and then 
 softened in the blow-pipe flame at about an inch from 
 the end ; when the softened gLiss has sufficiently 
 thickened it is drawn out into a thick-walled capillary 
 tube, which is carefully sealed. If the substance is 
 contained in a bulb this may be broken by shaking it 
 smartly against the ends of the tube. Heat the tube 
 to 120-150 for some hours in the air-bath. Allow the 
 bath to cool before withdrawing the tube, wrap it in a 
 towel, and cautiously warm the point so as to expel the 
 liquid which collects in the capillary tube. Soften the 
 end in the blow-pipe flame, the enclosed gases will 
 force their way through the softened glass. Care- 
 fully examine the tube, and if you have reason to 
 believe that the oxidation is incomplete, reseal the 
 tube and heat it to 180 for an hour or so. Allow it to 
 
PKAGTICAL WORK IN ORGANIC CHEMISTRY. 47 
 
 cool, and open with the same precautions as before. If 
 no more gas escapes the operation is finished. Cut off 
 the end of the tube, rinse its contents into a beaker, 
 dilute with water, and, in the case of sulphur, add 
 barium chloride. In the case of phosphorus, add 
 ammonia, ammonium chloride, and magnesia mixture, 
 and convert the precipitate by ignition into magnesium 
 pyrophosphate. 
 
 Determination of Molecular Weight. The most 
 satisfactory determinations are those in which the 
 compound is volatilised at a temperature well above its 
 boiling-point and the specific gravity of its vapour, i. e. 
 its vapour density referred to hydrogen as unity. The 
 vapour density when doubled gives the molecular 
 weight in accordance with Avogadro's law. 
 
 The various methods for determining the specific 
 gravity of vapours are assumed to have been described 
 in the course on inorganic chemistry, which the student 
 should have followed before beginning the study of 
 organic chemistry. It may, however, here be stated that 
 the method of Victor Meyer, being simpler and more 
 rapid in practice, is now almost universally employed. 
 It involves the use of the apparatus shown in the sketch 
 (Fig. 20). The long glass bulb-tube is corked at the 
 top, near to which point a side tube is sealed, which 
 serves to deliver gas to the measuring tube full of 
 water and standing in the little trough. The bulb- 
 tube is full of air, which is heated to a constant 
 temperature well above the boiling-point of the 
 
48 
 
 PRACTICAL WORK IN ORGANIC CHEMISTRY. 
 
 Fig. 20. 
 
 substances whose vapour density is to be determined. 
 This is accomplished, in the case of a liquid which 
 boils below 100, by immersing the bulb-tube in a 
 
 steam bath obtained by boiling 
 water or other suitable liquid 
 in the large outer vessel. As 
 the air expands on heating, it 
 is allowed to escape without 
 passing into the measuring 
 tube. As soon as the tem- 
 perature becomes constant, as 
 indicated by no further ex- 
 pansion of the air taking place, 
 the cork is removed from the 
 bulb-tube, a weighed quantity 
 of the substance (0 1 to 2 
 gram) contained in a small 
 bulb or tube is dropped in,* 
 the cork quickly replaced 
 
 the time occupied in doing this is so short that no serious 
 error from diffusion arises and the graduated cylinder 
 filled with water is placed over the orifice of the gas 
 delivery tube. The substance is quickly converted into 
 vapour, which latter expels its own volume of air into 
 the measuring vessel. When no more bubbles collect 
 in the graduated cylinder it is removed to a larger 
 
 * In practice the glass bulb or tube containing the substance is 
 allowed to drop on to a cushion of asbestos or glass wool, arranged at 
 the bottom of the bulb-flask ; this avoids risk of fracture. 
 
PEACTICAL WORK IN ORGANIC CHEMISTRY. 49 
 
 cylinder filled with water, the internal and external 
 liquids brought to the same level, and after a time the 
 volume of the air (V) read off. The temperature (t) t 
 indicated by a thermometer whose bulb is placed about 
 half way up and close to the measuring cylinder, and 
 the height of the barometer (B), are at the same time 
 observed ; then if S = weight of substance employed, 
 and w the tension of water vapour at the temperature 
 t, the vapour density of the substance may be found 
 from the following equation : 
 
 S (1 + 0-0036650 x 587780 
 Vapour density = ~~TR -r-^ 
 
 This value, when multiplied by 14*47, is the vapour- 
 density of the compound in terms of hydrogen. 
 
 When the compound is an acid and its basicity is 
 known, its silver salt is prepared and the percentage of 
 silver determined in it. If the acid be monobasic, 
 then whatever weight of the compound is united with 
 108 parts of silver is the molecular weight less one 
 atom of hydrogen replaced by silver. 
 
 In a similar manner the potassium, sodium, barium, 
 lead, or other salts may be employed. 
 
 In the case of basic compounds, such as ethylamine, 
 aniline, &c., either the amount of substance combined 
 with one or more molecules of an acid is determined 
 by analysis, e. g. the hydrochloric acid in the hydro- 
 chloride of the base, or the amount of platinum con- 
 tained in the double salt which many of the hydro- 
 chlorides of bases form with platinic chloride. 
 
50 PRACTICAL WORK IN ORGANIC CHEMISTRY. 
 
 Determination of Molecular Weight by observation 
 of the depression of Freezing-point. The method of 
 fixing the molecular formula of a substance by deter- 
 mining its vapour density is only applicable to a 
 comparatively limited extent, as many substances 
 cannot be volatilised without undergoing decomposi- 
 tion. The method of determining this value by the 
 analysis of salts or double salts, as previously explained, 
 is also inapplicable in the case of compounds which have 
 neither acid nor basic properties. In such cases the 
 probable molecular formula can only be ascertained by 
 a careful study of the chemical and physical properties 
 of the compound, and a careful investigation of a 
 number of its derivatives. This naturally is not very 
 satisfactory, but till recently no other means was at the 
 disposal of the chemist. 
 
 The following method is due to Eaoult, and is the 
 outcome of some elaborate investigations on the " Law 
 of the sodification of solvents." * 
 
 Eaoult has shown that the depression of the freezing 
 point of a solvent, caused by the presence of a liquid 
 or solid in solution, is directly proportional to the 
 amount of substance dissolved, and inversely propor- 
 tional to its molecular weight. 
 
 Thus, let d = depression in degrees C, a = amount 
 in grains of substance of molecular weight M, dissolved 
 in 100 grams of solvent, and R = a constant called the 
 
 * ' Annales de Cliiiire et de Physique,' 1884-86. 
 
PRACTICAL WORK IN OEGANIC CHEMISTRY. 51 
 
 "molecular reduction" (to be determined for each 
 solvent). Then 
 
 Consequently 
 
 Ka 
 
 B may also be calculated from Yan't HofFs equation 
 
 ., _ 0-02T 
 ~L~ 
 
 (where T = freezing-point of solvent on the absolute 
 scale, and L = latent heat of fusion). 
 
 In carrying out the operation, any liquid may be 
 used as a solvent provided that it is capable of solidify- 
 ing at a definite temperature and exerts no chemical 
 action on the substance. It suffices merely to know 
 the value of K for that particular solvent and for 
 certain groups of bodies analogous- to the one under 
 experiment. 
 
 The solvents recommended by Kaoult are water, 
 acetic acid, and benzene. The respective values of K 
 for these solvents with organic compounds (with few 
 
 exceptions) are as follows : 
 
 R 
 
 Water ..... 19 
 Acetic acid . . . .39 
 Benzene . . . .49 
 
 The accompanying diagram shows a convenient form 
 of apparatus for this operation (Fig. 21). 
 
 E 2 
 
52 PRACTICAL WORK IN ORGANIC CHEMISTRY. 
 
 Fig. 21. 
 
 A large test-tube, widened out at the lower end, is 
 closed by a caoutchouc stopper, A, perforated with two 
 holes. Through one of these a 
 piece of wide glass tubing, B, 
 passes, in which a stirrer, C C, 
 moves freely up and down. The 
 & thermometer, D, graduated to t^th 
 of a degree C. and observed through 
 a telescope, serves to show the 
 temperature of the liquid, while, 
 by surrounding the tube with a 
 beaker, F, with ice-water, &c., as 
 required, the temperature may be 
 raised a few degrees above, or de- 
 pressed a few degrees below, the 
 freezing-point of the solvent. 
 
 The Process. A quantity of the 
 solvent sufficient to fill the tube to 
 the extent indicated by the dotted 
 line is weighed out it suffices to weigh to a tenth of a 
 gram the caoutchouc stopper, carrying the thermo- 
 meter and stirrer inseited, and the tube immersed in 
 the outer vessel containing the freezing medium. Near 
 the solidifying point, the column of mercury first sinks 
 slightly, then subsequently a sensible rise takes place ; 
 the mercury remains stationary for at least one 
 minute, and then slowly sinks. This highest point of 
 the thermometer Baoult regards as the true solidifying 
 or freezing-point of the solution. During the whole 
 
PRACTICAL WORK IN ORGANIC CHEMISTRY. 53 
 
 operation the solution must be kept well agitated by 
 means of the stirrer. After the highest point has been 
 noted, the test-tube is removed from the beaker and 
 the contents completely melted by the aid of the water 
 bath. The tube is again submitted to the freezing 
 medium and the solidification point of the solvent re- 
 determined. Tho two readings should agree ; if not, 
 the operation must be repeated. The contents of the 
 tube are now melted, the caoutchouc stopper momen- 
 tarily withdrawn, and a weighed quantity of the 
 substance contained in a small tube or bulb introduced 
 (thin glass bulbs of the form shown are readily broken 
 by means of the stirrer). When completely dissolved 
 the freezing point of the solution is determined as 
 before. (It is sometimes necessary to induce solidifica- 
 tion by introducing a small crystal of the pure solvent, 
 previously frozen in a separate vessel.) 
 
 It will be found that the introduction of the substance 
 has lowered or depressed the freezing-point of the 
 solvent. From this depression we calculate the mole- 
 cular weight in accordance with the foregoing equation. 
 
 Example. The following results were obtained with 
 naphthalene Ci H 8 , dissolved in glacial acetic acid 
 (R = 39). 
 
 Weight of solvent = 101 * grams. Weight of sub- 
 stance = 1*7865 grams. 
 
 Freezing-point of solvent (3 exps.) . . 16 '100 
 + substance 15 
 
 . _ 
 
 Depression = 0'505 
 
54 PEACTICAL WOKK IN ORGANIC CHEMISTRY. 
 
 The depression so obtained, calculated for 1 gram 
 substance and 100 grams of solvent, becomes, 
 
 and 
 
 0-505 x 1 X 101 
 1-7865x100 
 
 _ 39 (= B) _ 
 0286 
 
 The true molecular weight of naphthalene is 128. 
 This experiment serves to show the degree of accuracy 
 that may be expected by this method. The results 
 are sufficiently close when the object is merely to 
 control the molecular weight of a substance. 
 
PRACTICAL WORK IN ORGANIC CHEMISTRY. 55 
 
 PROGRAMME I. 
 
 A STUDY OF OXALIC ACID AND ITS REACTIONS. 
 
 Preparation of Oxalic Acid. Into a 30-40 oz. flask put 
 100 grams of lump sugar broken into coarse fragments ; 
 now introduce half a litre of nitric acid, sp. gr. 1 30 ; 
 place the flask on wire gauze, and apply a gentle heat 
 until the reaction begins. A small funnel is placed in 
 the neck of the flask to prevent project ion of the acid by 
 spirting. As soon as the reaction commences withdraw 
 the flame, when the oxidation will proceed with some 
 violence, accompanied by a copious evolution of red 
 fumes. It is occasionally necessary to plunge the flask 
 into cold water to moderate the reaction. The operation 
 must be conducted under a hood, or in some situation 
 where the fumes can cause no inconvenience. After 
 the reaction has somewhat slackened, apply a small 
 flame and continue to heat gently for an hour or so, 
 then set aside in a cool place to crystallise. After 
 standing some time, crystals will separate out. These 
 are to be collected on a funnel plugged with a small 
 glass stopper, allowed to drain, and washed once or 
 twice with a small quantity of cold water, to remove 
 most of the adhering nitric acid. 
 
 The acid mother-liquor will furnish another crop of 
 
56 PRACTICAL WOKE IN ORGANIC CHEMISTRY. 
 
 crystals on careful evaporation. Recrystallise from 
 water the acid thus obtained. After draining well in 
 the funnel, transfer to a pad of filter paper. When the 
 greater portion of the moisture has been removed, the 
 acid is wrapped in a fresh sheet of dry paper, and 
 placed under a moderately heavy weight for a few 
 hours. 
 
 With the pure substance the following experiments 
 have to be performed : (a) Dissolve a few crystals in 
 water, and test the solution with red and blue litmus 
 paper. (I) Add a crystal or two of sodium carbonate. 
 (e) Heat some in a small test tube with strong sulphuric 
 acid, and prove that both oxides of carbon are formed. 
 (d) Add a few drops of ammonia, and then a solution 
 of calcium chloride. 
 
 The foregoing tests will suffice to show the identity 
 of the substance produced by the oxidation of sugar, 
 with the oxalic acid of commerce. Oxalic acid can be 
 obtained by the action of nitric acid on many organic 
 substances, such as starch, cellulose, &c. On the com- 
 mercial scale it is manufactured by heating wood 
 shavings or sawdust with potassium or sodium hydroxide 
 to about 250. The resulting mass is extracted with 
 water, which on evaporation to crystallisation gives the 
 potassium or sodium salt of the acid. 
 
 Sublimation of Oxalic Acid. Commercial oxalic acid 
 very often contains mineral matter; this results from, 
 its mode of preparation. Now the acid, when heated 
 to a sufficiently high temperature, sublimes, and ad- 
 
PRACTICAL WORK IN ORGANIC CHEMISTRY. 57 
 
 vantage is often taken of this fact to obtain a sample 
 of the pure substance. The method of carrying out 
 this operation on a small scale will readily appear 
 from p. 13 (Operations). The acid must be pre- 
 viously dried by heating in the water-oven for some 
 time. Oxalic acid sublimes without decomposition at 
 150-160 C. 
 
 Determination of Water of Crystallisation. Crystal- 
 lised oxalic acid contains water of crystallisation, which 
 it loses when maintained at 100 C. for some time. 
 Procure two medium sized watch-glasses with ground 
 edges; they must be of the same diameter, and when 
 placed one over the other should fit perfectly ; they 
 are kept in position by a brass clip. Carefully clean 
 the glasses and clip and weigh them, then, keeping the 
 clip on the balance pan, weigh into one of the glasses 
 about 1 gram of oxalic acid, transfer to the water-oven, 
 and so arrange matters that the watch-glass containing 
 the acid is loosely covered with its fellow. (The brass 
 clip is kept in the desiccator.) After heating for an 
 hour or so, remove from the oven, clamp together by 
 means of the clip, and allow to cool down in the desic- 
 cator ; when cold, weigh. The foregoing operation 
 must be repeated until the acid no longer loses weight, 
 or until the weighings do not differ more than half a 
 milligram. Calculate the percentage of loss. 
 
 Preparation of Potassium Salt. To about 30 grams 
 of oxalic acid dissolved in water add a solution of 
 potassium carbonate until the acid is neutralised ; filter 
 
58 PEACTICAL WORK IN ORGANIC CHEMISTRY. 
 
 if necessary, and evaporate to crystallisation ; drain off 
 mother-liquor and recrystallise. Collect the crystals in a 
 stoppered funnel, drain, and dry between folds of filter 
 paper. With the resulting salt determine water of 
 crystallisation and potassium. 
 
 To determine the Potassium : Weigh off about 1 
 gram of the crystallised salt into a platinum crucible. 
 Place the crucible on a triangle in a slanting position, 
 and add a few drops of strong sulphuric acid ; cautiously 
 decompose by the gradual application of heat, great care 
 being taken that no loss takes place by spirting. The 
 crucible is finally ignited over a Bunsen burner to low 
 redness, and the resulting potassium sulphate weighed. 
 The crucible is again ignited, and so on until a constant 
 weight is obtained. Calculate the percentage of potas- 
 sium in the crystallised salt. Calculate also the equiva- 
 lent of acid (carbon and oxygen) in the anhydrous salt. 
 
 Preparation of the Calcium Salt. Dissolve about 
 10 grams of oxalic acid in water, neutralise with a little 
 ammonia, and then add a solution of calcium chloride, 
 collect the precipitate on a filter and wash with cold 
 water until the washings are free from chlorine. Dry at 
 110, and determine the calcium as sulphate. This 
 operation is conducted as in the foregoing potassium 
 salt. Calculate the percentage of calcium, and the 
 amount of acid (carbon and oxygen) combined with 
 forty parts of the metal. 
 
 Preparation of Ammonium Salt. Neutralise about 
 10 grams of oxalic acid with ammonium hydroxide, 
 
PRACTICAL WORK IN ORGANIC CHEMISTRY. 59 
 
 evaporate to crystallisation, and determine the ammonia 
 in a sample of the salt carefully dried between filter 
 paper. 
 
 To determine the Ammonia: Weigh off 0'2-0*3 
 gram into a small Wurtz flask furnished with a 
 caoutchouc stopper, wash down the sides of the flask 
 with a little water, and connect with the condensing 
 arrangement shown in Fig. 22. The flask, of about 
 200 ccm. capacity, and connected air-tight with the 
 
 N 
 condenser, contains 50 ccm. of standard ^ sulphuric or 
 
 nitric acid. The flask also carries the small upright 
 tube, containing fragments of broken glass moistened 
 
 Fig. 22. 
 
 with water or a few ccm. of the standard acid. When 
 matters are properly arranged, the caoutchouc stopper 
 is removed from the Wurtz flask, and a small fragment 
 (about half an inch) of solid caustic potash added ; the 
 stopper is quickly replaced, and the contents sub- 
 mitted to careful distillation. After about half an hour, 
 disconnect the apparatus, wash down the condenser 
 
60 PKACTICAL WORK IN ORGANIC CHEMISTRY. 
 
 and side tube into the flask, and proceed to titrate with 
 standard alkali. 
 
 During the preparation and analysis of the fore- 
 going salts, the necessary apparatus for estimating the 
 carbon and hydrogen in the oxalic acid may be got 
 ready. See Analysis, p. 21. 
 
 In particular cases a modification of the programme 
 may be here introduced. The oxalic acid can be 
 titrated by a standard solution of potassium perman- 
 ganate. From the information gained in the analysis 
 of the potassium, calcium, and ammonium salts, it will 
 readily appear that one atom of oxygen suffices to 
 oxidise one molecule of oxalic acid completely into 
 carbon dioxide and water 
 
 C 2 H 2 4 + = 2C0 2 + H 2 0. 
 
 A standard solution of potassium permanganate is to 
 be prepared, and its value determined by the usual 
 methods. About 2 gram of the pure crystallised acid 
 is dissolved in a little water, a few ccrn. of dilute 
 sulphuric acid added, and the permanganate run into 
 the solution (warmed up to 60 C.) until a slight 
 permanent tint is developed. 
 
 Knowing the amount of oxygen available from each 
 ccm. of the permanganate, calculate from your experi- 
 ments the quantity of oxygen required for 100 parts of 
 the acid. Compare the experimental numbers with 
 those demanded by the foregoing equation. 
 
 Note. The water of crystallisation in the crystallised 
 
PEACTICAL WOKK IN ORGANIC CHEMISTRY. 61 
 
 acid is not represented in the equation, as it is not 
 concerned in the oxidation, but it must be taken into 
 account in the calculations. 
 
 With the standard permanganate we may estimate 
 the acid (and also the base) in the salts of oxalic acid. 
 A weighed quantity of the salt is digested with dilute 
 sulphuric acid, and titrated with the permanganate. 
 Determine the amount of acid and base in the fore- 
 going potassium and calcium salts. The details of the 
 calculations need no explanation. 
 
 Synthesis of Oxalic Acid from Cyanogen : 
 
 A. Formation of Oxamide. Into a hard glass tube, 
 about 8 inches long by J inch wide, sealed and rounded at 
 one end like a test tube, introduce a sufficient quantity 
 
 Fisr. 23. 
 
 of mercuric cyanide * to occupy three-fourths of the 
 length of the tube. The cyanide is kept in position by 
 a loosely-fitting plug of asbestos. Fit in a cork and 
 connect up with glass tube, as in Fig. 23. The three 
 
 * Instead of mercuric cyanide, a mixture of two parts of thoroughly, 
 dried potassium ferrocyanide and three of mercuric chloride may be 
 employed. 
 
 
62 PRACTICAL WORK IN ORGANIC CHEMISTRY. 
 
 small flasks contain strong hydrochloric acid. Gently 
 tap the tube on the table so as to make a passage for 
 the evolved gases. Place the tube in a small furnace, 
 and gradually heat it along its entire length, beginning 
 at the end nearest the flasks. The heat must be 
 sufficient to cause a steady evolution of gas, which 
 bubbles through the acid in the flasks. 
 
 Hg(CN) 2 = Hg + (CN) 2 . 
 
 When the evolution of gas is finished, the apparatus 
 is disconnected at A (note the residue in the tube), and 
 the flasks allowed to stand in a cool place for a few 
 hours. A beautiful white crystaline compound will 
 gradually separate out. This substance is called 
 " Oxamide," and its formation from cyanogen may be 
 expressed by the following equation : 
 
 C 2 N 2 + 2H 2 = C 2 2 (NH 2 ) 2 . 
 
 Pour off the acid and wash the oxamide on a filter with 
 cold water until free from acid. Dry in the air-oven. 
 With portions of the product thus obtained make the 
 following experiments, (a) Examine the substance 
 for carbon, hydrogen, and nitrogen, (b) Test its solu- 
 bility in water and alcohol, (c) Ascertain what happens 
 when heated. Determine quantitatively the carbon, 
 hydrogen, and nitrogen in a sample of the oxamide. 
 
 B. Conversion of Oxamide into Oxalic Acid. Place 
 some oxamide in a small flask with a little water; 
 heat, and add a few drops of potassium hydroxide. 
 
PEAOTICAL WOKK IN OEGANIC CHEMISTRY. 63 
 
 What gas is given off? When the oxamide has dis- 
 solved, evaporate the solution to crystallisation, and 
 compare the crystals by the aid of a powerful lens or 
 microscope with those obtained by adding potassium 
 carbonate to oxalic acid (p. 57). 
 
 On applying the usual tests for an oxalate, the pro- 
 duct obtained by the action of potash on oxamide will 
 be found to be identical with ordinary potassium 
 oxalate. 
 
 The conversion of oxamide into ammonium oxalate 
 may also be effected by heating with water in a sealed 
 tube to 200 C. 
 
 C 2 2 (NH 2 ) 2 + 2H 2 = C 2 4 (NH 4 ) 2 . 
 
 Preparation of Ethyl Oxalate C 2 4 (C 2 H 5 ) 2 . Method I. 
 Mix 80 ccm. of strong alcohol with 80 ccm. of con- 
 centrated sulphuric acid, employing for this operation 
 the apparatus described on page 77. When cold, pour 
 on to 40 grams of potassium oxalate contained in a 
 Wurtz flask attached to a condenser; mix well, and 
 distil over about one-third ; return this to the distilling 
 flask and again distil, changing the receiver when about 
 one-third has distilled over. The distillation must be 
 pushed almost to dryness. The first distillate consists 
 of water, alcohol, and a small quantity of ethyl oxalate. 
 To this solution add a little concentrated aqueous 
 ammonia, when oxamide will separate out in the form 
 of a white crystalline powder. 
 
 C 2 4 (C 2 H 5 ) 2 + 2NH 3 = C 2 2 (NH 2 ) 2 + 2C 2 H 5 OH. 
 
64 PRACTICAL WORK IN ORGANIC CHEMISTRY. 
 
 The second part of the distillate is washed with a 
 little water containing a small quantity of sodium 
 carbonate to remove acid, separated from the aqueous 
 liquid, dried over CaCl 2 , and distilled from a small 
 Wurtz flask furnished with a thermometer. Pure 
 ethyl oxalate boils at 186; sp. gr., 1-082. 
 
 Method II. To about 50 corn, of absolute alcohol 
 add 30 grams of oxalic acid dehydrated at 100 ; warm 
 gently so as to dissolve most of the acid, and into the 
 warm solution pass a current of dry hydrogen chloride. 
 The operation is most conveniently conducted in a 
 tubulated retort to the neck of which is attached a 
 reflux condenser. When the oxalic acid has disappeared, 
 continue to pass the gas for some time and then allow 
 the mixture to stand for some hours. Rearrange the 
 apparatus for distillation and distil off (from a water 
 bath) about a third of the volume. This portion, when 
 treated with ammonia, will furnisli a small quantity of 
 oxamide. The residue in the retort is poured into 
 water containing a little sodium carbonate, when the 
 ethyl oxalate will separate out in oily droplets, which 
 can be separated from the aqueous liquid and dried 
 over calcium chloride, or may be converted into oxamide 
 by treatment with ammonia. 
 
 Note. The samples of oxamide accumulating in the 
 preparation of ethyl oxalate must be carefully examined 
 and compared with the specimen prepared by the action 
 of hydrochloric acid on cyanogen. 
 
 Action of Phosphorus Pentoxide on Oxamide. Place 
 
PRACTICAL WORK IN ORGANIC CHEMISTRY. 65 
 
 two or three grams of dry oxamide in a test tube fitted 
 with a cork and delivery tube ; cover the oxamide with 
 a thick layer of P 2 5 ; heat gently, and collect the gas 
 given off in a small test-tube over mercury. The gas 
 is inflammable, burning with a purple flame which will 
 be recognised as cyanogen. 
 
 Note to Student. What change has the phosphoric 
 anhydride effected ? 
 
 Preparation of Formic Acid, H-COOH. 100 grams 
 of ordinary crystallised oxalic acid and 100 grams of 
 commercial glycerol (glycerine) dehydrated at 175 C. 
 are heated in a retort of li litre capacity, placed in a 
 brine bath, and provided with condenser and receiver. 
 At about 80 to 90 a brisk reaction begins, carbon 
 dioxide is evolved, and aqueous formic acid distils. When 
 the temperature has beon maintained for some time at 
 90 to 105 and the evolution of carbonic anhydride has 
 nearly ceased, the contents of the retort are cooled to 
 almost 80 and a further quantity of 100 grams of 
 oxalic acid added. The reaction recommences with the 
 formation of more aqueous formic acid. A quantity 
 of formic acid remains in the retort as glycerol mono- 
 formin. 
 
 C 3 H 5 (OH) 3 + C 2 H 2 4 = V& 2 R + C0 2 +H 2 0. 
 
 Glycerol monoformin 
 
 In order to recover this formic acid, the contents of the 
 retort are diluted with about half a litre of hot water 
 
 F 
 
66 PRACTICAL WORK IN ORGANIC CHEMISTRY. 
 
 and distilled in a brisk current of steam until the dis- 
 tillate has only a faintly acid reaction. 
 
 C.IT. + H 2 = H-COOH + C 3 H 5 (OH) 3 . 
 
 Formic acid 
 
 Fig. 24. 
 
 
 On neutralising the united acid distillates by boiling 
 with excess of copper carbonate and concentrating 
 the filtered solution, the copper salt of formic acid 
 is obtained in large bright blue monoclinic prisms. 
 From the salt we may obtain the anhydrous acid by 
 decomposing with sulphuretted hydrogen. A portion 
 of the powdered salt, well dried at 100-110, is intro- 
 duce 1 in a long layer into the inner tube (as wide in 
 the bore as possible) of a condenser loosely stoppered 
 at the lower end by a plug of glass-wool or asbestos. 
 To the end of the condenser a receiver is attached, 
 which is guarded from moisture by a drying tube. The 
 salt is heated by passing steam into the outer tube of the 
 condenser. Sulphuretted hydrogen, washed and dried 
 by passing .first through water and then caaeeatra-ted 
 1 V c1^ is passed over the salt in not too rapid 
 
PRACTICAL WOKE IN ORGANIC CHEMISTRY. 67 
 
 a stream. The arrangement of the apparatus is shown 
 in Fig. 24. The copper formate blackens and is slowly 
 converted into copper sulphide and formic acid, the 
 latter flowing down into the receiver. The acid, which 
 retains a strong smell of SH 2 , is further purified by 
 a second distillation over dry copper formate. 
 
 Formic acid when pure boils at 99 C. ; it has the 
 specific gravity I '223 at 0, and solidifies below C. 
 to colourless plates, melting at 8 6 C. 
 
 F 2 
 
PRACTICAL WORK IN ORGANIC CHEMISTRY. 
 
 PKOGRAMME II. 
 
 ETHYL ALCOHOL AND ITS REACTIONS. 
 
 Preparation of Alcohol from Mali. Procure about two 
 quarts of recently crushed and freshly malted barley, 
 and mix with about 50 grams of powdered starch. 
 IStir up this mixture with cold water in a large 
 evaporating dish until a thin cream is formed. Now 
 place the dish on a sand-bath and apply a gentle heat, 
 which is to be so regulated that a temperature of 
 65-70 C. may be maintained for some time. With- 
 draw a few drops of the extract at intervals by means 
 of a pipette, and test with a dilute solution of iodine. 
 
 Note that the colour produced changes as the heating 
 proceeds until the liquid no longer causes a blue tint 
 with iodine, and only affords a reddish brown coloura- 
 tion. The diastase present in the malt, has converted 
 the starch into dextrine and a fermentable sugar termed 
 maltose, 
 
 3C 6 H 10 5 + H 2 = C 12 H 22 U + C 6 H 10 5 . 
 
 Maltose. Dextrine. 
 
 When this conversion is complete, the solution is no 
 longer coloured by iodine; but a few drops when 
 
PRACTICAL WORK IN ORGANIC CHEMISTRY. 69 
 
 warmed with alkaline copper tartrate solution* cause 
 a precipitate of cuprous oxide, Cu 2 0. (Fehling's test.) 
 The solution in the basin (" sweet wort ") is now 
 strained off, the filtrate being received in a large flask. 
 When the contents of the flask have cooled down to 
 30 C. add a little fresh brewer's yeast or " barm," and 
 mix thoroughly. Fit a cork, carrying a thermometer 
 and a gas delivery tube, to the flask, and let the tube 
 dip under the surface of some clear lime water con- 
 tained in a cylinder, and protect the latter from the 
 
 Fig. 25, 
 
 air by means of a tube containing caustic potash 
 (Fig. 25). Let the whole stand in a warm place so 
 that the contents of the flask may be maintained at a 
 temperature of about 25 C. 
 
 * Prepared by adding tartaric acid to a solution of copper sul- 
 phate and rendering strongly alkaline by caustic soda. A clear blue 
 solution is obtained if sufficient tartaric acid be added. 
 
70 PRACTICAL WORK IN ORGANIC CHEMISTRY. 
 
 After some time the process of fermentation com- 
 mences, the mixture develops a frothy " head," and 
 much gas is evolved, and, as this passes through the 
 lime water, a precipitate of calcium carbonate will be 
 formed. 
 
 The evolution of gas ceases after some hours, and 
 fermentation is at an end. Now, observe that the 
 contents of the flask are rather more turbid than they 
 were at first ; in other words, the quantity of yeast has 
 increased during the process of fermentation. 
 
 Connect the flask which contains the fermented 
 liquid with a condenser, and rapidly distil over about 
 one-third the total volume of liquid. The unpleasant 
 smelling distillate contains the alcohol formed during 
 the process of fermentation. 
 
 The dilute spirit obtained in this experiment may be 
 concentrated by redistillation. Place the distillate 
 obtained as above in a small flask, add a few drops of 
 caustic potash (to neutralise any acid formed during 
 fermentation), and distil over quickly about half the 
 total volume of liquid. 
 
 In order to detect the alcohol, warm a small quan- 
 tity of the distillate in a test tube and apply a light to 
 the escaping vapour. To about 30 com. of the distil- 
 late add 4 or 5 drops of a dilute solution of potassium 
 bichromate and then a few drops of sulphuric acid, and 
 warm gently. Note appearance and odour produced. 
 (See " Preparation of Aldehyde," p. 85). 
 
 A good way to detect alcohol in a dilute solution is 
 
PRACTICAL WORK IN ORGANIC CHEMISTRY. 71 
 
 as follows : Warm the solution to be tested, add a 
 small crystal of iodine and then a solution of caustic 
 potash until the colour is destroyed. On cooling a 
 yellow crystalline powder of iodoform, CHI 3 , is de- 
 posited, having a very characteristic appearance and 
 odour. 
 
 The production of alcohol and carbon dioxide from 
 maltose during fermentation may be represented as 
 follows : 
 
 C 12 H 22 U + H 2 = 4C 2 H 6 + 4C0 2 . 
 
 PURIFICATION OF ALCOHOL. 
 
 The dilute spirit prepared in the foregoing experi- 
 ment owes its unpleasant smell to a small proportion 
 of a liquid termed " fusel oil"; it also contains many 
 other impurities. The quantity of alcohol obtained 
 is usually too small to attempt a complete purification ; 
 it may, however, be shaken up with a little recently 
 ignited charcoal, decanted off, allowed to stand over 
 quicklime, and then distilled from a water-bath. By 
 this treatment it will be found to have lost much of its 
 bad odour and to have increased in strength. This 
 latter can be tested by taking its specific gravity and 
 reference to tables. 
 
 Separation of Water from Alcohol ly Fractional 
 Distillation. Mix 100 ccm. of strong alcohol, of known 
 
72 PRACTICAL WORK IN ORGANIC CHEMISTRY. 
 
 specific gravity and boiling point, with 100 ccm. of 
 distilled water. 
 
 Note to Student. What happens when the liquids 
 are mixed ? Determine the specific gravity of the 
 mixture by means of the "gravity bottle" and, employ- 
 ing a dephlegmating apparatus, proceed to fractionally 
 distil, carrying out the operation as indicated on p. 9. 
 
 Measure the various fractions obtained, and determine 
 the percentage of alcohol in the principal ones. The 
 strongest spirit obtained by fractional distillation still 
 contains 8-10 per cent, of water. To obtaiu a 
 stronger spirit the principal fractions are poured 
 into a flask containing small lumps of fresh quicklime 
 and allowed to stand over the lime for about 24 
 hours ; the dehydrated liquid is then distilled off with 
 the aid of a water-bath. The first few ccm. are 
 collected apart ; the rest of the liquid which distils over 
 may then be preserved as a specimen of nearly anhy- 
 drous (its specific gravity should be recorded on the 
 label) alcohol. 
 
 Purification of Methylated Spirit. This useful sub- 
 stance is a mixture of about 90 parts ethyl alcohol and 
 10 parts crude methyl alcohol (wood spirit) ; in addition 
 it contains water, " fusel oil," acetaldehyde and acetone. 
 It may be freed from aldehyde and acetone by boiling 
 with 4-5 per cent, of solid potash on the water-bath in a 
 flask fitted with an upright condenser for an hour or two, 
 and then distilling. The alkali converts the aldehyde 
 and acetone into resinous bodies, so that after distilla- 
 
PRACTICAL WORK IN ORGANIC CHEMISTRY. 73 
 
 tion it contains little besides methyl and ethyl alcohols. 
 The spirit may be dehydrated by allowing it to stand 
 over quicklime for 24 hours and then distilling. By 
 repeated treatment with good quicklime, and subsequent 
 distillation, all but a trace of water may be removed ; 
 such spirit is said to be " absolute." Methylated spirit, 
 purified as described, may generally replace the more 
 expensive ethyl alcohol as a solvent. 
 
 The presence of water in alcohol may be shown by 
 agitating a sample with a little anhydrous copper 
 sulphate, when the salt will become blue if a notable 
 quantity of water be present. 
 
 A more delicate test is to add a crystal of potassium 
 permanganate ; the formation of a pink colouration 
 indicates water. 
 
 It may here be added that an excellent process for 
 the complete dehydration of alcohol consists in allowing 
 the spirit, after distilling from lime, to stand over some 
 anhydrous oxide of barium (BaO) contained in a 
 stoppered bottle ; after the latter has removed all the 
 water, the dry alcohol then dissolves some of the oxide, 
 the solution acquiring a yellow colour; it is then 
 distilled. 
 
 Note to Student. Great care has to be exercised in 
 the selection of a dehydrant. Many substances having 
 an affinity for water cannot be used for drying alcohol ; 
 zinc chloride, calcium chloride, &c., are not suitable, 
 inasmuch as they either combine to form alcoholates or 
 effect decomposition. 
 
74 PRACTICAL WORK IN ORGANIC CHEMISTRY. 
 
 Separation of Fusel Oil from Ethyl Alcohol. Redistil 
 from a Wurtz flask fitted with a thermometer, about 
 200 ccm. of the purified " absolute " methylated spirit 
 which you have prepared in a former operation. Mix 
 150 ccm. of the distillate, which will be found to boil 
 near 80 C., and for the purpose of this experiment 
 may be regarded as ethyl alcohol, with 50 ccm. of 
 " fusel oil," or amyl alcohol, of which you have 
 previously determined the boiling point (it will lie 
 somewhere near 130 C.) Pour the mixture into a 
 flask of 400 or 500 ccm. capacity, introduce a few 
 pieces of broken tobacco pipe or scrap platinum foil 
 (to prevent " bumping "), insert cork with fractionating 
 column and thermometer, and proceed to fractionate, 
 employing a small " rose " burner, and so regulate the 
 flame that steady and continuous, but not violent, 
 ebullition shall be maintained. Collect in bottles or 
 flasks having blank labels, three or four fractions of 
 about 50 ccm. each, marking them " No. 1 fraction," &c. 
 Be careful to record temperatures. The degree of 
 separation effected by the distillation can be roughly 
 tested by treating the various fractions with water. 
 Put about 5 ccm. of each fraction into separate test 
 tubes, add about 25 ccm. of water to each, and mix 
 thoroughly. State in note-book the result of each 
 experiment. 
 
 Determination of Alcohol ly Distillation. Into a tared 
 flask which can be connected air-tight to a condenser, 
 weigh about 50 grams of the sample to be tested (beer, 
 
PRACTICAL WORK IN ORGANIC CHEMISTRY. 75 
 
 wine, &c.), neutralise any free acid by cautious addition 
 of sodium hydroxide solution, sufficient being added to 
 impart a slightly alkaline reaction. Now add about 
 ' 1 gram tannin (to prevent frothing) and make up the 
 liquid with water to about 150 ccm. Connect flask to 
 condenser, and distil by a gentle heat, collecting the 
 
 Fig. 26. 
 
 distillate in a tared flask of about 150 ccm. capacity, 
 furnished with an india-rubber stopper pierced with 
 two holes through one of which passes the end of the 
 condensing tube, while the other carries a safety tube 
 or funnel, closed by mercury (see Fig. 26). The retort 
 and receiver are thus connected air-tight with the 
 condenser, a certain contraction and expansion of the 
 contained air is permitted, while all loss is prevented. 
 When the distillate has a volume of about 100 ccm. 
 the operation is arrested, and the receiver with its con- 
 tents carefully weighed. Now thoroughly mix the 
 contents, cool to 15 -5 C. (= 60 F.), and determine 
 
76 PRACTICAL WORK IN ORGANIC CHEMISTRY. 
 
 the density by specific gravity bottle. Eefer to 
 alcohol tables for corresponding percentage of alcohol, 
 when 
 
 Weight of distillate x percentage of alcohol found in distillate by table 
 Weight of sample taken. 
 
 = percentage of absolute alcohol by weight contained 
 in the sample. 
 
 ACTION OF EEAGENTS ON ALCOHOL. 
 Action of Sodium. 
 
 Preparation of Sodium Ethylate, C 2 H 5 ONa. Into 
 a small flask containing about 10 ccm. of absolute 
 alcohol throw a small pellet of clean sodium (note what 
 happens), continue the addition of sodium until it no 
 longer dissolves. (What gas is given off?) Apply 
 gentle heat to effect solution of last particle of metal 
 and distil off excess of alcohol. When dry, heat gently 
 in a current of hydrogen, and preserve in a stoppered 
 bottle. 
 
 Note. Potassium acts on alcohol in the same way 
 as sodium. 
 
 Action of Sulphuric Acid at different Temperatures. 
 
 Preparation of Potassium Ethyl Sulphate, C 2 H 5 KS0 4 . 
 To 200 grams cone, sulphuric acid, contained in a 
 beaker or small earthenware jar, add slowly 250 grams 
 commercial absolute alcohol. A reference to Fig. 27 
 will show how this operation is to be conducted. 
 
PRACTICAL WORK IN ORGANIC CHEMISTRY. 77 
 
 Fig. 27. 
 
 The alcohol is contained in the funnel, which is 
 connected to a piece of glass tube by means of india- 
 rubber tube having a screw-clip, by which the flow 
 of spirit can be regulated. The 
 sulphuric acid is contained in the 
 beaker, which in its turn stands on 
 a pad of paper, the whole standing 
 in an outer vessel in case of an 
 accident. The manner in which the 
 glass tube is connected to the funnel 
 allows of a stirring motion during 
 the addition of the alcohol. It is 
 unnecessary to cool the beaker, but 
 care must be taken that the end of 
 the glass tube dips well beneath 
 the surface of the sulphuric acid. During the mixing 
 the temperature rises to 80-90. After all the alcohol 
 is added, heat the mixture for an hour on the water- 
 bath, and then allow to stand a few hours. Pour the 
 cold liquid into some water contained in a pan, and 
 add chalk ground into a thin paste with water until 
 all acid is neutralised. It is now filtered and the 
 filtrate, after the addition of lime water until slightly 
 alkaline, is concentrated on the water-bath. When 
 somewhat evaporated a concentrated solution of potas- 
 sium carbonate is added until the calcium is all precipi- 
 tated. The soluble potassium salt of ethyl sulphate is 
 formed and the solution, after filtering from the pre- 
 cipitated calcium carbonate, can be concentrated over 
 
78 PRACTICAL WORK IN ORGANIC CHEMISTRY. 
 
 the water-bath until crystallisation begins. By slowly 
 concentrating the liquid, a well-crystallised product 
 may be obtained. 
 
 The product is collected on a funnel fitted with filter 
 and parchment-cone. After draining thoroughly it is 
 wrapped in dry ing paper and allowed to dry on a porous 
 tile. Weigh the product obtained, and test its solu- 
 bility in water and alcohol. 
 
 Note to Student. Write out all reactions involved in 
 the preparation of this salt. 
 
 Preparation of Ethyl Ether, Q 2 g 6 |0. (Action of 
 
 sulphuric acid at about 140 C.) 
 
 Mix 100 grams 90 per cent, alcohol with 180 grams 
 
 Fig. 28, 
 
 cone, sulphuric acid, employing funnel, clip, &o., as in 
 foregoing experiment. Allow mixture to cool down. 
 Arrange an apparatus as shown in Fig. 28. The 
 
PRACTICAL WORK IN ORGANIC CHEMISTRY. 79 
 
 flask containing the mixture is closed with a cork 
 pierced with three holes ; through one of these holes a 
 thermometer is inserted and dips into the liquid ; 
 through the second a tube is fitted which reaches 
 beneath the surface of the mixture, and is connected at 
 its upper end with a vessel containing alcohol. A bent 
 tube passing through the third hole connects the flask 
 with a long condenser and receiver, both of which 
 must be kept well cooled during the experiment. 
 Commence the operation by heating the mixture, (this 
 must be done cautiously, the fla<k standing on one or 
 two plates of wire gauze), until the thermometer indi- 
 cates 140. At this point the mixture boils, and ether 
 begins to distil over. As soon as this is noticed 
 cautiously open the stop-cock of the vessel A, and let 
 a slow stream of alcohol pass into the distilling flask 
 through the tube B. Eegulate this stream so that the 
 temperature remains constant at 140-145. In this 
 way the operation can be kept up for a considerable 
 time, the alcohol admitted to the flask passing out as 
 ether, and being collected together with some alcohol 
 in the receiver. After about half a litre has been col- 
 lected, stop the operation. Note. The mixture in the 
 distilling flask is to be kept in a stoppered bottle ; it 
 will be useful in subsequent experiments. 
 
 Pour the distillate into a stoppered separating- funnel 
 and shake up with a dilute solution of sodium 
 hydroxide. The ether will rise to the surface, and the 
 aqueous portion may be run off. It should now be 
 
80 PRACTICAL WORK IN ORGANIC CHEMISTRY. 
 
 shaken up a few times with water, separated, and 
 allowed to stand over fused calcium chloride, poured off 
 into a dry flask fitted with a thermometer, and distilled 
 over a water-bath. Note the temperature. 
 
 The ether thus purified still contains traces of 
 alcohol and water, which it obstinately retains. To 
 further purify the ether, it is digested in the cold for 
 some time with fresh metallic sodium, cut into thin 
 slices (pure ether has no action upon sodium). When 
 the sodium has no further action, the ether is distilled 
 off over the water-bath. 
 
 N.B. Great care must be taken when working with 
 ether. Never distil directly over a flame ; always use a 
 water-bath, and do not heat the water to boiling. Care- 
 fully avoid the neighbourhood of flames. 
 
 Preparation of Ethylene Dibromide,\ ,,-rr i/ (Action 
 
 of sulphuric acid on alcohol at about 160-180). 
 
 Into a flask of 2 to 3 litres capacity put a mixture 
 of 25 grams alcohol (strong methylated spirit may be 
 substituted), and 150 grams concentrated sulphuric 
 acid. Heat on a sand-bath or wire gauze until ethylene 
 is evolved in a steady stream. Now add gradually 
 through a tap-funnel a mixture of one part alcohol and 
 two parts concentrated sulphuric acid at such a speed 
 that the evolution of gas continues without interruption, 
 and at the same time without causing the contents of 
 the flask to froth up too violently. The gas is purified 
 from alcohol, ether, sulphurous acid, and carbon dioxide, 
 
PRACTICAL WOKK IN ORGANIC CHEMISTRY. 81 
 
 by conducting it through a series of Woulfe's bottles 
 fitted with safety tubes, and connected with the 
 generating flask (Fig. 29). The first of these bottles 
 (a) is empty, the second (b) contains concentrated sul- 
 phuric acid, the third (<?) and fourth (d) not shown in 
 
 Fig. 29, 
 
 the sketch dilute caustic soda solution. Thus puri- 
 fied, the ethylene passes into two smaller bottles (e) 
 and (/), containing bromine covered with a layer of 
 water. The last bromine bottle is connected with an 
 arrangement for absorbing bromine vapours. This is 
 half filled with pieces of broken brick (moistened with 
 soda solution), and then filled up with lumps of common 
 washing soda. 
 
 The corks of the bromine bottles must be well 
 soaked in melted paraffin before use, to protect them 
 from the action of bromine vapour. The bromine 
 bottles are cooled, if necessary, in cold water, 
 
 G 
 
82 PRACTICAL WORK IN ORGANIC CHEMISTRY. 
 
 Continue to pass the gas until the bromine is 
 decolourised and converted into ethylene dibromide, 
 then remove and shake up with dilute caustic soda 
 solution. After washing with water to remove soda 
 solution, separate the aqueous portion as far as possible 
 by means of the separating-funnel arid dehydrate over 
 calcium chloride. After decanting from the calcium 
 chloride the product is rectified. 
 
 Note. The student should have a measured quantity 
 of bromine given to him, and must state in his note 
 book the yield of ethylene dibromide obtained. 
 
 ACTION OF HYDROCHLORIC ACID ON ALCOHOL. 
 
 Preparation of Ethyl Chloride, C 2 H 5 C1 (affording 
 practice in the preparation and isolation of a substance 
 gaseous at ordinary temperatures). 
 
 Into a small retort, which is connected to a reflux con- 
 denser (Fig. 30), introduce 50 ccra. of absolute alcohol 
 and about 20 grams of fused zinc chloride. Now pass 
 a rapid current of dry hydrogen chloride into the alcohol, 
 which is at first kept cool by cold water. A large 
 volume of the gas is absorbed. When nearly saturated 
 the contents of the retort are gently warmed, the 
 current of hydrochloric still maintained, and the 
 ethyl chloride which is given off, together with hydro- 
 chloric acid, led through the reflux condenser, where 
 any alcohol vapour is condensed. The ethyl chloride 
 is freed from acid by passing through one or two wash 
 
PRACTICAL WORK IN ORGANIC CHEMISTRY. 83 
 
 .^5 
 
 o 2 ,^r^ *v 
 
s PRACTICAL WOEK IN ORGANIC CHEMISTRY. 
 
 bottles containing dilute caustic soda solution, and 
 afterwards dried by bubbling through strong sulphuric 
 acid, conveniently contained in a set of Geissler 
 bulbs. It is now condensed by passing through the 
 spiral condenser containing ice and salt, and is finally 
 led nearly to the bottom of a piece of moderately 
 broad tube, sealed at one end and constricted at the 
 upper part in the manner shown in the sketch. This 
 tube is also kept in a freezing-mixture of ice and salt. 
 When the tube is about half full of ethyl chloride, the 
 narrow leading tube is withdrawn, and the tube 
 carefully sealed up at the constricted part. It is 
 advisable to keep the tube in the freezing-mixture as 
 much as possible during the process of sealing. When 
 properly sealed the tube may be preserved as a speci- 
 men in a box containing cotton wool. 
 
 Ethyl chloride boils at 12 C. 
 
 When a specimen has been obtained in the manner 
 indicated, the operation should be continued, and the 
 following experiments made : (a) Collect a little 
 ethyl chloride in a narrow test-tube, remove from 
 freezing-mixture, and apply a light to the mouth of 
 the test-tube; note colour of the flame, and bring a rod 
 moistened with ammonia close to the burning gas. This 
 experiment will serve to demonstrate the presence of 
 chlorine in the substance, (b) To an aqueous solution 
 of ethyl chloride (it is sparingly soluble in water) add 
 a few drops of silver nitrate ; no turbidity is produced 
 if the ethyl chloride is pure. 
 
PRACTICAL WORK IN ORGANIC CHEMISTRY. 85 
 
 Note. The alcoholic residue in the retort may be 
 preserved in a stoppered bottle, and used again when 
 needed. 
 
 Preparation of Ethyl Bromide. Dilute 17 ccm. of 
 strong sulphuric acid with 10 ccm. of water, and cool 
 thoroughly : add this to 20 ccm. of strong alcohol 
 contained in a flask of 200 ccm. capacity. Shake con- 
 tents of flask, and when cold add 16 grams of powdered 
 potassium bromide ; connect flask to condenser, and 
 distil carefully from a sand-bath. Ethyl bromide 
 passes over along with some water. Frothing takes 
 place at the end of the operation, but this does not 
 give trouble if a flask of sufficient size be employed. 
 
 The ethyl bromide is formed in accordance with the 
 equation 
 
 H 2 S0 4 + KBr + C 2 H 5 OH = C 2 H 5 Br + KHS0 4 
 + H 2 0. 
 
 Wash the ethyl bromide with dilute soda solution, 
 dry over calcium chloride, and rectify from a dry flask 
 over the water bath, noting the temperature. 
 
 Note to Student. Weigh the resulting ethyl bromide 
 and see if the yield corresponds to that demanded by 
 the above equation. 
 
 Action of Oxidising Agents on Alcohol. 
 
 Preparation of Acetaldehyde, CH 3 -COH. Arrange an 
 apparatus as shown in Fig. 31. Into the flask A, 
 which must have a capacity of 1J to 2 litres, put 
 
86 PRACTICAL WORK IN ORGANIC CHEMISTRY. 
 
 120 grams granulated potassium bichromate (made by 
 dissolving the salt in a little hot water and evaporating 
 to dryness with constant stirring). Make a mixture 
 of 160 grams cone, sulphuric acid, 480 grams water, and 
 
 Fig. 31. 
 
 120 grams alcohol (methylated spirit). Cool the mixture 
 down to the ordinary temperature, and then pour it 
 slowly through the funnel-tube B into the flask con- 
 taining the potassium bichromate. The flask stands in 
 a water-bath containing cold water. The flasks C and 
 D are half filled with ordinary ether ; they are placed 
 in an outer vessel F containing ice water. A consider- 
 able evolution of heat occurs, the liquid becomes green, 
 and water, alcohol, and aldehyde distil over into the re- 
 ceiver. By conducting the vapours through the inverted 
 
PEACTICAL WORK IN ORGANIC CHEMISTRY. 87 
 
 condenser, whi<-h is maintained at a temperature of 
 25-30, most of the alcohol and water condense, while 
 the aldehyde (B.P. 21) passes over and is absorbed by 
 the ether. The reaction is assisted by gently warming 
 the flask, and when completed the apparatus is detached 
 at E, and connection is made with an apparatus furnish- 
 ing dry ammonia gas. The gas is passed into the cold 
 ethereal solution of aldehyde to the point of saturation. 
 The aldehyde separates out in the form of a beautifully 
 white crystalline deposit of aldehyde-ammonia. It is 
 separated from the mother-liquor by draining well on 
 the filter-pump, washed with ether, and finally dried 
 on bibulous paper over calcium chloride. From this 
 compound the aldehyde may be isolated by dissolv- 
 ing in a little water, adding dilute sulphuric acid 
 (1^ parts of acid to 2 parts of water), and distilling on 
 the water-bath, the receiver being kept cool with ice. 
 The distillate is dehydrated over coarse calcium 
 chloride, poured off into some fresh calcium chloride and 
 distilled from the same, the temperature of the water 
 bath being about 30. The anhydrous acetaldehyde is 
 kept in sealed tubes. 
 
 Experiments with Aldehyde. After a sample of an- 
 hydrous aldehyde has been secured in the manner 
 indicated, the following experiments may be performed 
 with it and its solution in water. 
 
 (a) Add a few drops to solution of ammoniacal 
 nitrate of silver, in a test-tube, and heat. The tube 
 becomes coated internally with a beautiful specular 
 
88 PRACTICAL WORK IN ORGANIC CHEMISTRY. 
 
 layer of metallic silver. (What is the explanation of 
 this?) 
 
 (&) Shake up 10 ccin. with about 50 ccm. of a 
 nearly saturated solution of hydrogen sodium sulphite, 
 HNa S0 3 . On standing crystals separate, which consist 
 of G 2 H 4 0, HNaS0 3 . Heat a little of this compound 
 with sodium carbonate and note what comes off. 
 
 (e) Add a few drops of the solution of aldehyde to 
 some strong caustic potash and warm the mixture in a 
 test-tube; a peculiar resinous-looking body, termed 
 aldehyde resin, is formed. (See application of this 
 reaction to the purification of alcohol, page 72.) 
 
 Oxidation of Alcohol to Acetic Acid. Determination of 
 small quantities of Alcohol. 
 
 Into a 3-4 oz. narrow-necked bottle, 20 ccm. of iveak 
 alcohol (containing 0'1-0'2 gram of pure alcohol) 
 are introduced, together with 10 ccm. of a solu- 
 tion of chromic acid, made by adding 10 grams of 
 potassium bichromate to 12 ccm. of strong sulphuric 
 acid and making up to 100 ccm. The bottle is then 
 securely closed by an india-rubber stopper, tied down, 
 wrapped in cloth, and suspended in a bath of boiling 
 water for two hours, by which time all the alcohol will 
 have been oxidised to acetic acid. After cooling, the 
 bottle is opened and sulphuric acid and granulated zinc 
 added to reduce the excess of chromic acid. The green 
 liquid is then transferred to a flask, a few pieces of 
 
PEACTICAL WORK IS ORGANIC CHEMISTRY. 89 
 
 pumice or tobacco-pipe added to prevent bumping, and 
 the liquid carefully distilled. When nearly dry, water 
 is added and the distillation repeated. The acetic acid 
 in the distillate is determined by standard decinormal 
 soda, phenol-phthalein being used as indicator. It is 
 desirable before titrating to add a drop or two of barium 
 chloride as a test for sulphuric acid. Any precipitate 
 must be filtered off, and 46 parts of alcohol subtracted 
 
 for every 233 of BaS0 4 found. 
 
 N 
 1 ccm. of JQ soda = 0046 gram of C 2 H 5 OH in 
 
 sample. 
 
 Action of Chlorine on Ethyl Alcohol. Preparation 
 of Chloral. 
 
 Pass a current of dry chlorine gas* through about 
 100 ccm. of absolute alcohol contained in a retort, which 
 can be cooled in water containing ice if necessary, so 
 that the temperature shall not rise above 10. The 
 chlorine is quickly absorbed, and, after a short time, 
 aldehyde can be detected in the liquid when a few drops 
 are removed, diluted with water, and warmed with 
 ammoniacal nitrate of silver. In testing the liquid for 
 aldehyde an excess of ammonia must be added in order 
 to prevent the precipitation of silver chloride. The 
 primary action of chlorine is therefore one of oxida- 
 tion. The retort being connected with a reflux con- 
 
 * The chlorine is generated by gently warming a mixture of man- 
 ganese dioxide in lumps and concentrated hydrochloric acid. The gas 
 is dried by passing through strong sulphuric acid. 
 
90 PRACTICAL WORK IN ORGANIC CHEMISTRY. 
 
 denser (Fig. 30), gently warm the liquid to 60 C. 
 and continue to pass the gas as long as any of it is 
 absorbed. The liquid is then boiled gently for a short 
 time and allowed to cool (it ought to have a density of 
 1*400); after which it is cautiously mixed with an 
 equal volume of strong sulphuric acid. Hydrochloric 
 acid and ethyl chloride are evolved, and the mixture is 
 distilled from a water-bath. The distillate is neutralised 
 with chalk and again distilled, afterwards fractionated. 
 Chloral is a colourless mobile liquid, B.P. 94 * 5 C. 
 It reduces ammonio-silver nitrate like aldehyde, and 
 forms crystalline compounds with the acid sulphites ; 
 it acts generally like an aldehyde; the formula is 
 CC1 3 .COH, or trichloraldehyde. 
 
 When mixed with about one-fifth of its weight of 
 water, the mixture slowly solidifies to a crystalline 
 mass of chloral hydrate which has probably the formula 
 
 CC1 
 
 Dissolve about half a gram of chloral or its hydrate 
 in a little water ; then add a few drops of caustic soda 
 solution. The mixture soon becomes milky, owing to 
 the separation of minute drops of chloroform, while the 
 liquid in which it is produced will give the characteristic 
 reactions of a formate. (Try it.) 
 
 The following equation explains the change brought 
 about by the alkali : 
 
 NaOH + CC1 3 .COH = CC1 3 H + H.COONa. 
 
PRACTICAL WORK IN ORGANIC CHEMISTRY. 91 
 
 Preparation of Chloroform, CHC1 3 . Mix 430 grams 
 of good bleaching powder with 100 grams quicklime, 
 introduce into a capacious flask and add about 100 ccm. 
 of ordinary methylated spirit diluted with 1 J litres of 
 water. Agitate the contents of the vessel so as to secure 
 complete mixture, connect the flask with a condenser, 
 and distil from a water-bath. A mixture of alcohol, 
 water, and chloroform collects in the receiver, where the 
 chloroform settles to the bottom as a heavy oil. The 
 chloroform is freed from alcohol by shaking with water 
 and dehydrated over calcium chloride. It is finally 
 rectified on the water bath. Pure chloroform boils at 
 62 C.; the specific gravity is 1-525 at 0; it does 
 not readily burn. 
 
 The formation of chloroform is here due to a second- 
 ary reaction. By the action of bleaching powder on 
 alcohol, chloral is first formed, which, in presence of 
 the calcium hydrate, decomposes into chloroform and 
 calcium formate. (See preparation of chloral and its 
 decomposition, p. 90.) 
 
 The ultimate change which takes place is represented 
 by the equation : 
 
 4C 2 H 6 -f 8Ca(OCl) 2 = CC1 3 H + 3Ca(OOCH) 2 
 + 5CaCl 2 + 8H 2 0. 
 
 Reactions of Chloroform. Shake up a few drops of 
 chloroform with a little water in a test-tube ; to the 
 aqueous solution add a drop or two of aniline and a 
 
92 PRACTICAL WOKE IN ORGANIC CHEMISTRY. 
 
 little alcoholic potash. Either immediately, or on 
 gently warming the mixture, a strong and peculiar 
 smell will be observed, due to the formation of phenyl- 
 carbamine (phenyl isocyanide) C 7 H 5 N. In the absence 
 of chloral and similarly constituted bodies, the reaction 
 with aniline is a very delicate test for chloroform. (See 
 also p. 124.) 
 
 Another delicate test for chloroform is the formation 
 of cuprous oxide when heated with Fehling's alkaline 
 copper solution, the following reaction taking place : 
 
 CHC1 3 + 5KOH +2CuO = Cu 2 + K 2 C0 3 
 + 3KC1 + 3H 2 0. 
 
PRACTICAL WORK IN ORGANIC CHEMISTRY. 93 
 
 PEOGEAMME III. 
 
 A STUDY OF THE PREPARATION AND DECOMPOSITION 
 OF ETHYL ACETATE, AND OF THE COMPOSITION 
 AND REACTIONS OF SOME OF THE NATURAL 
 FATS AND OILS. 
 
 Preparation of Ethyl Acetate. Mix 60 grains of 
 strong alcohol (97 per cent.) with 150 grams of 
 ordinary concentrated sulphuric acid. (This operation 
 must be done with care, see p. .77.) Allow to stand 
 some time, and when quite cold pour into a half- 
 litre flask ; now add slowly 100 grams of fused and 
 coarsely powdered sodium acetate. After standing a 
 few hours distil first from a water-bath, and finally 
 from a sand-bath. Shake up the distillate with a strong 
 solution of brine containing a little sodium carbonate. 
 Remove the upper layer of liquid by means of a sepa- 
 rating-funnel, and distil from calcium chloride in a 
 water-bath. Redistil from water-bath, employing a 
 thermometer. The portion distilling below 74 contains 
 ether, that coming over at 74-79 is principally ethyl 
 acetate. Tins is separately collected and purified by 
 redistillation. 
 
 Ethyl acetate boils at 77 and has a specific gr, 
 
94 PRACTICAL WORK IN ORGANIC CHEMISTRY. 
 
 of '9068 at 15. Determine the boiling-point of the 
 sample prepared as above, and also its specific gravity 
 at 15. 
 
 Write out the reactions involved in the foregoing 
 preparation. 
 
 Decomposition of Ethyl Acetate. Into a half-litre 
 flask put about 20 ccm. of ethyl acetate and 50 grams 
 of potassium hydroxide dissolved in 200 ccm. of water. 
 Connect the flask with a reflux condenser and boil gently 
 for an hour or so. Now arrange the condenser for dis- 
 tillation and distil off about 50-60 ccm. Examine dis- 
 tillate for alcohol. Acidify the contents of the flask 
 with dilute sulphuric acid and again distil. What 
 now passes over ? 
 
 Note. The student must thoroughly understand 
 the nature of the decomposition which the fore- 
 going ethereal salt undergoes by treatment with 
 caustic potash. All ethereal salts, or as they are 
 now sometimes called, esters, are decomposed by 
 boiling with caustic alkalies. Nearly all natural fats 
 are ethereal salts, or esters. Now, when these fats are 
 boiled with alkalies they are decomposed in the same 
 way as the ethyl acetate, an alcohol and the salt of 
 a fatty acid being produced. As this decomposition 
 is best known on the large scale in the preparation of 
 soaps, it is commonly called saponification. Hence, to 
 saponify an ester, means to decompose it into the 
 corresponding alcohol and the alkali salt of the acid 
 contained in it. 
 
PRACTICAL WORK IN ORGANIC CHEMISTRY. 95 
 
 Saponification of a Natural Fat. Preparation of 
 Stearie Acid. Cut up about ^ Ib. of mutton or beef 
 suet, and throw the pieces into a little boiling water 
 contained in a basin ; the fat soon melts, and can be 
 squeezed out from the animal membrane, the latter 
 being thrown away. Put the fat into a large iron 
 saucepan, add a little water, and then a moderately 
 strong solution of commercial caustic soda, and boil 
 gently for two or three hours, stirring frequently. 
 Water may be added from time to time to replace the 
 loss by evaporation. The boiling must be continued 
 until the fat is decomposed. 
 
 After cooling, add a strong solution of sodium 
 chloride. The soap will separate out and rise to the 
 top of the solution, where it will form a curd. Collect 
 and wash with a little cold water. 
 
 When suet is boiled with a solution of a caustic 
 alkali, its component ethereal salts, stearin (CnH 35 
 COO) 3 .C 3 H 5 ; palmitin (C 15 H 31 COO)3.C 3 H 5 ; and olein 
 (C 1 7H 33 COO)3 . C 3 H 5 , are decomposed according to the 
 following scheme : 
 
 C 3 H 5 '"(Ol) 3 + SNaOH = C 3 H 5 '"(OH) 3 + 3NaOA. 
 
 A sodium or potassium salt, or " soap " of the fatty 
 acid, is produced, together with glycerol. 
 
 Note to Student. Write out in detail the equations 
 representing the saponification of stearin, palmitin, 
 and olein by caustic potash. 
 
 Most of the glycerol C 3 H 5 "' (OH) 3 in the experiment, 
 
96 PRACTICAL WORK IN ORGANIC CHEMISTRY. 
 
 remains in solution in the brine, from which however it 
 cannot be economically separated. 
 
 For the preparation of stearic acid, take about half 
 the soap formed as above, dissolve in hot water and 
 filter if necessary. To the hot solution add a slight 
 excess of moderately strong hydrochloric acid. The 
 soap is decomposed, and an oil rises to the surface 
 which solidifies in cooling. This mass, consisting of a 
 mixture of stearic, palmitic, and oleic acids [Note to 
 Student. Write out the reaction here brought about by 
 the decomposition of the foregoing soap by hydrochloric 
 acid] is collected, and washed by stirring up with hot 
 water once or twice. It is now separated from the 
 aqueous portion and digested with a small quantity 
 (about an equal bulk) of hot methylated spirit, allowed 
 to cool, well drained on the filter-pump and washed 
 with a little cold spirit. This operation is to be re- 
 peated, the object being to remove oleic acid, which is 
 much more soluble in alcohol than stearic or palmitic 
 acid. Now remove the mass from the funnel and press 
 thoroughly between folds of blotting paper. The well 
 pressed acids are now dissolved up completely in hot 
 methylated spirit (employ for this purpose a flask 
 attached to a reflux condenser, see " Operations," p. 4), 
 and allowed to crystallise. Collect the crystalline 
 deposit, drain well on the filter-pump and press 
 between blotting-paper. The degree of purity effected 
 by the successive crystallisations should be ascertained 
 by determining the melting-point of the different 
 
PRACTICAL WORK IN ORGANIC CHEMISTRY. 97 
 
 fractions. (See p. 7.) The well pressed mass is now 
 dissolved up in a large excess of spirit, and to this is 
 added, while hot, a boiling alcoholic solution of magne- 
 sium acetate. The latter salt is added in the propor- 
 tion of one part of the acetate to four parts of the mixed 
 acids. By this treatment a precipitate of almost pure 
 magnesium stearate is obtained ; most of the magnesium 
 palmitate, being more soluble, remains in solution. The 
 precipitate is collected when cold, well drained, pressed, 
 and decomposed by boiling for some time with dilute 
 hydrochloric acid. After cooling and filtering, the 
 stearic acid is again crystallised from alcohol, and the 
 melting-point determined. Pure stearic acid melts at 
 69 ' 2. If the sample of stearic acid has a much lower 
 melting-point, recrystallise until pure. When pure, 
 determine carbon and hydrogen. 
 
 The foregoing separation of stearic from palmitic 
 acid is an example of fractional precipitation. An 
 alcoholic solution of other salts can be employed instead 
 of magnesium. In general, the acid richest in carbon 
 is thrown down first, if care be taken only to add suffi- 
 cient to precipitate a small proportion of the acids 
 present. The filtrate is again treated with more of the 
 alcoholic solution of the salt, and so on. The various pre- 
 cipitates are decomposed, examined, and the process of 
 fractional precipitation repeated. The acids obtained 
 are crystallised until a pure substance is obtained, this 
 being ascertained by a determination of melting-point 
 and other characteristics. 
 
98 PRACTICAL WORK IN ORGANIC CHEMISTRY. 
 
 Experiments with Stearic Acid. Preparation of 
 Potassium Salt. To a hot alcoholic solution of stearic 
 acid add alcoholic potash until neutral, this point being 
 ascertained by using phenol-phthalem as an indicator. 
 On concentrating the solution and allowing it to cool, 
 the potassium salt separates out in shining needles or 
 thin plates. Or the salt may be obtained by dissolving 
 one part of stearic acid in ten parts of water containing 
 one part of caustic potash. The resulting mass may 
 now be dissolved up in hot alcohol and allowed to 
 crystallise. Determine the potassium in a sample of 
 the salt. 
 
 Dissolve one part of potassium stearate in ten parts 
 of water, heat until clear and largely dilute with cold 
 water, when an acid stearate will separate out, having 
 the composition C 17 H 35 COOK, C 17 H 35 COOH (determine 
 the potassium in a sample), which crystallises in white 
 pearly laminae, while the solution becomes more or less 
 alkaline. (Test it.) This hydrolysis of the salt of a 
 higher fatty acid is important, and has an intimate 
 relation to the detergent properties of soap. (See paper 
 by Wright and Thompson, Jour. Soc. Chem. Ind., iv. 630.) 
 
 Preparation of Lead Stearate. Dissolve some potas- 
 sium stearate in water, and add a clear solution of lead 
 acetate. Collect the precipitate on a filter, and wash 
 with cold water; dry at 100 and estimate lead. Test 
 solubility of lead salt in alcohol, ether, and petroleum. 
 Determine the melting-point of a sample of the salt. 
 
 Action of Bromine and Iodine on Stearic Acid. To 
 
PKACTICAL WORK IN OEGANIC CHEMISTRY. 99 
 
 an aqueous solution of the salt add a few drops of 
 bromine water drop by drop, and note what happens. 
 Kepeat this experiment, substituting an aqueous solu- 
 tion of iodine for the bromine. Dissolve a little of 
 the pure steario acid in carbon tetrachloride or ether, 
 and add the foregoing reagents also dissolved in tetra- 
 chloride or etlier. (See p. 10(1) 
 
 Titration of Stearic Acid with Standard Alkali. 
 Weigh off about one gram of pure stearic acid into 
 a stoppered ^-litre flask, and wash down with about 
 50 ccm. of neutralised methylated spirit.* Immerse 
 the flask in hot water, and effect as complete solution 
 of the acid as possible by agitating thoroughly. Add 
 a few drops of phenol-phthalei'n solution, and titrate 
 with a semi-normal solution of sodium hydroxide 
 (=20-0 NaOH per litre). The addition of the alkali 
 is continued, with vigorous shaking, until a permanent 
 pink coloration is obtained : 
 
 C 17 H 35 COOH + NaOH = C 17 H 35 COO^a + H 2 0. 
 
 Calculate the percentage of pure stearic acid. 
 
 Saponification of Olive Oil. Isolation of Glyeerol. 
 Into a porcelain basin put about 100 grams of pure 
 olive oil (which consists largely of the glyceride olein 
 gHs), together with about three times 
 
 * Some of the purified methylated spirit prepared in accordance 
 with the directions given on p. 72 is treated with a few drops of an 
 alcoholic solution of phenol-phthalei'n, and then dilute sodium hy- 
 droxide added drop by drop until the solution retains a faint pink tint 
 after shaking. 
 
 H 2 
 
100 PRACTICAL WORK IN ORGANIC CHEMISTRY. 
 
 the volume of water. Heat on a water-bath, stir 
 in gradually 50 grams of finely powdered litharge 
 (PbO), and continue to heat for several hours, adding 
 water from time to time to replace loss by evaporation. 
 A pasty mass is finally obtained (this is lead oleate; 
 the principal constituent of the "lead plaster" of 
 pharmacy). 
 
 Pour off the aqueous portion which contains the 
 glycerol, wash the residue in the dish with hot water, 
 and pass sulphuretted hydrogen to remove any lead in 
 solution ; filter, and evaporate to a small bulk on the 
 water-bath. A sweet syrupy liquid is left, which is 
 glycerol or glycerine. The lead soap obtained should 
 be preserved ; it is useful for the preparation of oleic 
 acid. (See p. 104.) 
 
 Note to Student. Express in the form of an equation 
 the decomposition of the olein contained in olive oil, 
 by lead hydroxide. 
 
 Fig. 32 
 
 Experiments with Glycerol (a) Heat a little of the 
 glycerol quickly in a small test-tube, and note the 
 acrid tear-exciting odour produced. This is due to 
 
PRACTICAL WORK IN ORGANIC CHEMISTRY. 101 
 
 the formation of acrolein, and constitutes a test for 
 glycerol. 
 
 (b) Put 20 ccm. of glycerol into a flask with 200 ccm. 
 of water, connect with a condenser and boil briskly, 
 passing in a current of steam. Prove that glycerol 
 passes over with the water vapour. Into a 4-oz. Wurtz 
 flask connected air-tight to a similar flask by means of 
 a glass tube (see Fig. 32 ) put 30 grams of glycerol. 
 Exhaust by means of an air-pump, and distil over in 
 vacua half the glycerol. From the appearance and 
 odour of the distillate, what conclusions do you draw ? 
 
 Determination of Carbon and Hydrogen in Glycerol. 
 Heat some glycerol nearly to its boiling-point, to 
 render it anhydrous, and allow it to cool in a small 
 desiccator over sulphuric acid. Weigh out into a 
 porcelain or platinum boat 0'2 to 0*3 gram glycerol, 
 and determine carbon and hydrogen by combustion. 
 
 Note. The weighing-out of the glycerol must be 
 done with expedition, as it is very hygroscopic. 
 
 Determination of Glycerol ly Oxidation with Alkaline 
 Permanganate. When glycerol is treated with per- 
 manganate in the presence of excess of caustic alkali, 
 it is converted into oxalic acid, carbon dioxide, and 
 water, in accordance with the following equation : 
 
 C 3 H 8 3 + 30 2 = C 2 HA + C0 2 + H 2 0. 
 
 From this equation it will be seen that one molecule 
 of oxalic acid corresponds to one of glycerol. 
 
 The details are as follows ; Weigh off about 5 gram 
 
102 PRACTICAL WORK IN ORGANIC CHEMISTRY. 
 
 of the anhydrous glycerol, prepared as above, transfer to 
 a porcelain basin, and dilute with cold water to about 
 300 com. Then a strong solution of caustic potash, 
 containing at least 12 grains of potash, is added : now 
 pour in a saturated solution of potassium permanganate, 
 until the solution is no longer green, but blackish. The 
 liquid is then heated to the boiling-point for an hour or 
 so ; a strong solution of sodium sulphite is then added 
 to the hot liquid until all greenish colour is destroyed. 
 The liquid containing the precipitated oxide of man- 
 ganese is then poured into a 500 ccm. flask : the basin is 
 washed out with hot water. The liquor and washings 
 in the flask are made up to 15 ccm. above the 500 ccm. 
 mark, the excess being an allowance for the volume 
 of the precipitate and hot liquid. The solution is 
 passed through a dry filter, and when cold 400 ccm. of 
 the filtrate are measured off, acidified with acetic 
 acid, and the oxalic acid precipitated with calcium 
 chloride. 
 
 The solution must be kept in a warm place for two 
 or three hours, in order to insure complete precipita- 
 tion of the oxalate. The precipitate, which consists of 
 calcium oxalate and sulphate, is well washed. After 
 was4iing, the filter is pierced and the precipitate rinsed 
 into a beaker, the filter-paper well washed with hot dilute 
 sulphuric acid (which of course is added to the contents 
 of the beaker), the liquid diluted to 200 ccm., warmed 
 up to 60, and titrated with standard permanganate. 
 It' decinormal permanganate be employed, each ccm. 
 
PRACTICAL WORK IN ORGANIC CHEMISTRY. 103 
 
 corresponds to *0045 oxalic acid, or *0046 gram 
 glycerol. 
 
 Preparation of Allyl Alcohol, CH 2 : CH.CH 2 .OH. 
 Into a retort of about 500 ccm. capacity, provided with 
 a condenser and arranged for distillation, introduce 50 
 grams of oxalic acid and about 200 ccm. of glycerol. 
 Pass a thermometer through the cork of the retort, 
 and let the bulb dip well under the liquid. If com- 
 mercial oxalic acid is employed, it is necessary to add 
 to the contents of the retort about a half per cent, of 
 sodium chloride and a quarter per cent, of ammonium 
 chloride. 
 
 When the temperature has reached 130, much carbon 
 dioxide gas is evolved and a little formic acid distils 
 over ; continue to heat gradually up to 200, when more 
 gas is evolved. At 200-210, oily streaks are observed 
 to run down the neck of the retort and a peculiar, 
 somewhat irritating, but highly characteristic odour is 
 perceptible; at this stage the receiver is changed. By 
 gently heating the contents of the retort, a temperature 
 of about 220-230 is maintained for some time, and 
 when it has finally risen to 260 the distillation is 
 stopped. Excess of glycerol remains behind in the 
 retort, and may be used again by repeating the opera- 
 tion with a smaller quantity of oxalic acid (20-30 
 grams). The whole of the allyl alcohol, together with 
 a small quantity of formic acid and acrolein, is obtained 
 by submitting the distillate to rectification. The dis- 
 tillation is this time continued until, on treating the 
 
104 PRACTICAL WORK IN ORGANIC CHEMISTRY. 
 
 last portions, coming over at about 105, with potassium 
 carbonate, no oily layer separates. Now add to the 
 distillate solid potassium carbonate, when the allyl 
 alcohol separates out as an oil. This is separated from 
 the aqueous portion and allowed to stand for 24 hours 
 in contact with 5 to 10 per cent, of powdered potassium 
 hydroxide ; the liquid loses the smell of acrolein, and at 
 the same time assumes a brown colour. (Compare the 
 purification of ethyl alcohol from acetaldehyde, p. 72.) 
 The liquid is decanted off and distilled. In order to 
 abstract the last traces of water, which are obstinately 
 retained, the alcohol is left in contact with anhydrous 
 baryta and then distilled. 
 
 C 2 H 2 4 + C 3 H 5 (OH) 3 = C 3 H & (OH) 2 -0-CHO 
 
 Oxalic acid. GlyeeroL Monoformin. 
 
 + H 2 + CO* 
 C 3 H 6 (OH) 2 -0-CHO = C a H & OH + H 2 O -f CO* 
 
 Allyl alcohol. 
 
 Allyl alcohol, when pure, is a colourless liquid 
 boiling at 96 ; sp. gr. 0'858 at 0. 
 
 The foregoing preparation is an example of the eon- 
 version of a trihydric alcohol (glycerol) into a mono- 
 hydric alcohol. 
 
 Preparation of Oleic Acid, CnHaaCOOH. Introduce 
 some of the lead oleate (free from water) obtained in 
 the preparation of glycerol, into a flask, and agitate 
 repeatedly with petroleum spirit, which dissolves the 
 lead oleate and free oleic acid, leaving the palmitate 
 
PRACTICAL WORK IN ORGANIC CHEMISTRY. 105 
 
 and stearate of lead unchanged. (Note this fact care- 
 fully.) The solution is separated from insoluble salts 
 and thoroughly shaken with an excess of hydrochloric 
 acid. The aqueous portion now contains chloride of 
 lead, while the spirit will retain the oleic acid. It is 
 separated from the acid aqueous liquid, washed by 
 agitation with water, carefully separated, and the spirit 
 distilled off rapidly and at as low a temperature as 
 possible. The oily residue is dissolved in moderately 
 strong ammonia, solution of barium chloride added, the 
 precipitate of barium oleate collected, washed with 
 water and crystallised from alcohol. (Determine the 
 barium in a sample of the salt). 
 
 The barium oleate is finally decomposed by boiling 
 with a strong solution of tartaric acid, the oleic acid 
 extracted with ether, and the ether distilled off as 
 quickly as possible. The residual oleic acid may be 
 further purified by allowing to crystallise from alcohol, 
 or by cooling down to about 7 C., when it solidifies to 
 a crystalline mass, which is quickly pressed between 
 folds of filter paper, or drained on a vacuum-filter, 
 (see p. 21) ; by repeatedly melting, cooling, and press- 
 ing the crystalline portion, and finally crystallising 
 from alcohol, the impurities are completely removed. 
 
 Oleic acid crystallises from alcohol in brilliant white 
 needles melting at 14 C. 
 
106 PRACTICAL WORK IN ORGANIC CHEMISTRY.. 
 
 Action of Reagents on Oleic Acid. 
 
 Action of Bromine. Dissolve a little oleic acid in 
 ether or chloroform, and add drop by drop a dilute 
 solution of bromine dissolved in the same solvent. 
 Note what happens. 
 
 The foregoing reaction can be made approximately 
 quantitative, and is of great technical importance. 
 Iodine can be used instead of bromine. The iodine 
 absorption of an oil has been thoroughly studied by 
 Baron Hubl.* 
 
 On p. 99 it was found that pure stearic acid does 
 not readily combine with bromine ; this was because 
 the acid is a u saturated compound," inasmuch as it is 
 a higher homologue of acetic acid, the general formula 
 of the acids of this series being CJET^jCOOH. Oleic 
 acid belongs to the series C.H^^COOH. 
 
 Oleic acid, C 18 H 34 2 , forms C 18 ll3 4 Br 2 2 , and 
 C)8H 3 J 2 2 . 
 
 From the foregoing considerations we can approxi- 
 mately estimate oleic acid from the amount of halogen 
 assimilated. About 1-0 2 gram of pure anhydrous 
 oleic acid is placed in a stoppered bottle of about 
 100 ccm. capacity, and dissolved in 50 ccm. of carbon 
 tetrachloride previously dried by calcium chloride. 
 
 N 
 An approximately ~ solution of (8 grams per litre) 
 
 * Dingl. Polyt. Jour., ccliii., 281, Jour. Soc. Chem. Ind., iii. 641 
 See also Allen's 'Commercial Organic Analysis/ vol. ii., page 48. 
 
PRACTICAL WORK IN ORGANIC CHEMISTRY. 107 
 
 bromine in dry carbon tetrachloride, having an exactly 
 known strength, is then gradually added to the solu- 
 tion, until after standing a few minutes it is no longer 
 decolourised. The excess of bromine is then estimated 
 by adding an aqueous solution of potassium iodide and 
 starch, and titrating back with a standard solution of 
 sodium thiosulphate. Kepeat the above, substituting 
 pure olive oil for the oleic acid. Express the results 
 in percentages of bromine assimilated. 
 
 Action of Nitrous Acid on Oleie Acid. Pass, for a few 
 minutes only, a gentle current of the nitrous fumes 
 generated by the action of nitric acid on sugar or 
 arsenious oxide (see Fig. 34, p. 129), into about 
 10 grams of well-cooled oleic acid ; after some time a 
 crystalline mass separates out, called elaidic acid (which 
 is considered an isomer of oleic acid). The acid may 
 be purified by washing with hot water, and crystallisa- 
 tion from alcohol. From this solvent it crystallises in 
 fine pearly laminaa, melting at 45. It has strongly 
 acid characters, forming well-defined salts. (Prepare the 
 sodium and potassium salts by dissolving in alcohol and 
 adding the necessary quantity of alkaline hydroxides.) 
 
 The property of forming an isomer of higher melting 
 point under the influence of nitrous acid is not peculiar 
 to oleic acid, but is exhibited by its homologues. The 
 glyceride triolein also, when similarly treated, gives a 
 solid modification termed Elaidin. Experiment : Pass 
 a current of nitrous acid through some 
 olive oil, and allow to stand fur some time. 
 
108 PRACTICAL WORK IN ORGANIC CHEMISTRY. 
 
 Note. The drying oils, which consist chiefly of 
 linolein and its homologues, are not visibly affected by 
 treatment with nitrous acid. Upon this property is 
 based the important " Elaidm test," described in works 
 treating of the analysis of fats and oils. 
 
 Determination ofOleic Acid by Standard -^ Sodium 
 
 2t 
 
 Hydroxide. 
 
 This operation is carried out as in the titration of 
 stearic acid. (See p. 99.) 
 
 C 17 H 34 COOH + NaOH = C 17 H 34 COONa + H 2 0. 
 
 Determination of the Percentage of Caustic Potash 
 required for Saponification of an Oil. 
 
 Before commencing this operation, the following 
 standard solutions must be prepared : 
 
 (a) Dissolve 14 grams of good stick potash in 500 
 ccm. of good rectified methylated spirit (distilled from 
 potash), and allow the liquid to stand till clear. This 
 solution will be approximately seminormal. 
 
 (I) A standard solution of hydrochloric or sulphuric 
 acid of approximately seminormal strength. 
 
 About 2 grams of pure olive oil are accurately 
 weighed into a flask fitted to a reflux condenser. 
 25 ccm. of the prepared alcoholic potash are added, 
 and the flask is heated on a water-bath, with frequent 
 rotatory agitation for about half an hour, or until 
 
PKACTICAL WORK IN ORGANIC CHEMISTRY. 109 
 
 saponification is judged to be complete. After cooling, 
 about 1 ccm. of an alcoholic solution of phenol 
 phthalein is added, and the liquid is titrated with the 
 seminormal hydrochloric or sulphuric acid. 25 ccm. 
 of the same alcoholic solution of potash, without the 
 fat, should then be carefully titrated with the standard 
 acid. The difference between the volumes of standard 
 acid used in the two titrations gives the number of 
 ccm. corresponding to the alkali neutralised in saponi- 
 fying the oil. 
 
 1 ccm. of ^ acid = 0' 02805 of KOH. 
 
 Calculate the percentage of KOH required to saponify 
 100 parts of the oil. 
 
 C 3 H 5 (OF) 3 + 3KOH = C 3 H 5 (OH) 3 + 3K(OF), 
 
 From the foregoing general equation it appears that 
 one molecule of glyceride requires three molecules of 
 potassium hydroxide for its saponification. The amount 
 of glyceride saponified by one molecule of potash will 
 therefore be one-third of the molecular weight (in the 
 case of a monohydric alcohol the number will be 
 identical with the molecular weight). 
 
 The number of grams of any oil saponified by one 
 litre of any normal alkali is designated the " saponifica- 
 tion-equivalent," and it is found by dividing the per- 
 centage of alkali required for saponification into 5610 
 for KOH and into 400 for NaOH. (See Allen's 
 ' Commercial Organic Analysis/ vol. ii. p. 40.) 
 
110 PRACTICAL WORK IN ORGANIC CHEMISTRY. 
 
 PEOGKAMME IV. 
 
 COAL-TAR AND COAL-TAR PRODUCTS. 
 
 Distillation of Coal-tar. Into a tubulated glass 
 retort of about 1J litre capacity, introduce about 
 500 com. of good gas-tar (to be obtained from any gas- 
 works). Close the tubulure with a cork fitted with a 
 thermometer. The retort is supported on a cup-shaped 
 piece of wire-gauze, placed in an aperture cut in a plate 
 of sheet-iron, conveniently supported in position by 
 four bricks. Over the retort is placed a dome of thin 
 sheet-iron, so cut as to allow the neck of the retort to 
 pass through. (See Fig. 33.) 
 
 This latter contrivance confines the heat, and so 
 prevents condensation in the upper part of the 
 retort. 
 
 No condensing arrangement is necessary, the neck 
 of the retort acting in this capacity. 
 
 The retort is heated very gently and carefully at 
 first (one of Fletcher's powerful ring burners should be 
 used, as towards the close of the operation it is 
 necessary to maintain the wire-gauze at a red heat). 
 There is usually much frothing, and if great care is not 
 taken, the distillate will be spoilt. 
 
PKACTICAL WORK IN OEGANIC CHEMISTRY. Hi 
 
 The burner being lighted, the ammoniacal liquor 
 and "light oils" are collected together in a graduated 
 cylinder, which is changed when a drop of the distillate 
 
 Fig. 33. 
 
 collected in a test-tube begins to sink. After 
 standing, to allow perfect separation of the ammoniacal 
 liquor and light oils, the volume of each is observed. 
 The strength or amount of ammonia contained in the 
 former, is to be determined by distilling an aliquot 
 portion with caustic alkali and titration of the distillate. 
 (See Fig. 22, p. 59). 
 
 The quantity of light oils (containing benzene, 
 toluene, &c.) is usually too small to admit of further 
 fractionating, but can be preserved as a specimen. 
 
 The next fraction of the distillate (200-240) con- 
 sists of k< creosote oil " ; at first it will contain much 
 naphthalene, and will probably solidify on cooling ; but 
 
112 PRACTICAL WORK IN ORGANIC CHEMISTRY. 
 
 as the distillation proceeds it will become more fluid. 
 When a drop of the distillate received on a cool 
 surface deposits solid matter of a yellow or greenish- 
 yellow colour, the receiver is changed. (The temperature 
 will be about 270. Pull the bulb of the thermometer 
 up into the cork). Measure the fraction, and label it 
 " Creosote oils." 
 
 The next fraction is rich in anthracene, and mostly 
 condenses in the neck of the retort as a yellow 
 waxy substance, which may be melted by the cautious 
 application of a small Bunsen flame. The operation is 
 continued until no more distillate can be obtained, and 
 the pitch intumesces and gives off heavy yellow fumes. 
 This last fraction is measured, cooled thoroughly, and 
 the resulting pasty mass pressed between folds of thick 
 filter paper and weighed. Label it "Anthracene cake," 
 and preserve for future experiments. (See p. 141.) 
 
 When the distillation is complete, the retort is 
 allowed to cool down, and when almost cold, its body is 
 plunged into cold water. This operation causes a rapid 
 surface cooling and shrinking of the pitch from the 
 glass of the retort, which may then be broken by 
 gently tapping, leaving the pitch clean and ready for 
 weighing. Preserve a specimen. 
 
 In this experiment it will be seen that the retort 
 (costing about one shilling) is sacrificed ; it is therefore 
 recommended that the experiment be performed by a 
 group of three or more students. 
 
 The following table will give some idea as to how 
 
PRACTICAL WORK IN ORGANIC CHEMISTRY. 113 
 
 the results of the foregoing operation should appear in 
 the note-book : 
 
 DISTILLATION OF A SAMPLE OF LONDON TAB. 
 
 per cent. 
 
 Ammouiacal water .. .. .. .. 4*5 
 
 Total light oils 3'5 
 
 Carbolic and creosote oils 26*2 
 
 Anthracene oils 14'5 
 
 Pitch (grams per 100 ccm.) .. .. 58-6 
 
 107-3 
 
 The apparent excess is due to the tar having been 
 measured and the pitch weighed. 
 
 Fradionation of Light Oil. Isolation of Benzene 
 and Toluene. Shake up in a capacious flask a measured 
 quantity (say 250 ccm.) of light oil, procured from 
 some tar distillery, with an equal bulk of dilute 
 sulphuric acid (1 of acid to 3 of water), connect 
 flask to condenser, and distil in a current of steam. 
 Collect, and separate oil from aqueous distillate, and 
 repeat foregoing operation, substituting a 20 per 
 cent, solution of caustic soda for the sulphuric acid. 
 The purified oil is separated, dried over calcium 
 chloride, and fractionated. It will be observed that 
 there is a tendency to an accumulation of the distillates 
 in the parts boiling near 80 (B.P. of benzene, 80 '5) 
 and 110 (B.P. of toluene, 110-111). The portion 
 which passes over below 90 C. is digested at 100 in a 
 flask furnished with an upright condenser, with 5 
 per cent, by measure of concentrated sulphuric acid 
 for several hours, in order to separate thiophene and 
 
 I 
 
114 PRACTICAL WORK IN ORGANIC CHEMISTRY. 
 
 hydrocarbons of the C n H 2n _ 2 and CH 2n series. This 
 treatment is continued with successive portions of 
 acid as long as any blackening takes place. The oil is 
 separated as far as possible from acid, and distilled in 
 a current of steam. The oil is separated from water 
 and submitted to a freezing mixture of ice and salt, 
 when the benzene crystallises out, and may be sepa- 
 rated from the more fusible hydrocarbons by draining 
 on a vacuum pump. (See p. 21.) 
 
 Pure benzene melts at 5 C *5, and boils at 80 5. 
 
 The fraction boiling above 90, together with the 
 mother-liquors accumulated during the purification of 
 benzene, are carefully fractionated by means of the 
 bulb apparatus, and the portion which finally comes 
 over at 110-111 is collected. This will be nearly pure 
 toluene. Submit a sample to a powerful refrigerating 
 mixture ; it does not solidify (distinction from benzene). 
 
 Action of Reagents on Benzene and its Derivatives. 
 
 Action of Sulphuric Acid. Preparation of Potassium 
 Benzene-Sulphonate, C 6 H 6 S0 3 K. Into a flask of about 
 J-litre capacity introduce 100 grams pure commercial 
 benzene and 200 grams of concentrated sulphuric 
 acid ; attach a reflux condenser, and keep the mixture 
 gently boiling on a sand-bath for about twenty-four 
 hours. When about four-fifths of the benzene have 
 dissolved, and more prolonged heating produces no 
 further change, distil off any residual benzene, cool, 
 
PKACTICAL WOKK IN OKGANIC CHEMISTRY. 115 
 
 and pour the dark-coloured liquid into about a litre of 
 water contained in an earthenware pan. The acid liquid 
 is now neutralised whilst hot with powdered chalk mixed 
 into a thin cream with water. The mass is filtered 
 through calico (conveniently stretched on a wooden 
 frame), and the residue well washed with water. The 
 brown-coloured filtrate, together with the wash-water, 
 is concentrated over a small flame until a sample with- 
 drawn on the end of a glass rod solidifies on cooling. 
 From the solution the calcium salt of benzenesulphonic 
 acid separates out on cooling, forming an almost solid 
 mass of small white crystals, which, after being well 
 drained from the mother-liquor, are almost pure. 
 Note. Press some of the well-drained crystals between 
 filter-paper, and when dry, determinine the calcium (as 
 sulphate) in a sample. 
 
 In order to prepare the corresponding potassium salt 
 from the calcium compound, dissolve the latter in hot 
 water and add a moderately concentrated solution of 
 potassium carbonate until the calcium is completely 
 precipitated as carbonate. The aqueous solution of the 
 potassium salt is filtered from the calcium carbonate 
 and evaporated down, first over a small flame, and 
 finally on the water-bath, until a sample crystallises 
 on cooling. 
 
 The potassium salt crystallises in the form of colour- 
 less crystalline plates, which, after collecting and 
 draining, may be dried on a porous tile or plate. 
 
 Note to Student. Write out equations explaining all 
 
 i2 
 
115 PRACTICAL WOKK IN ORGANIC CHEMISTRY. 
 
 chemical reactions involved in the preparation of the 
 foregoing compound. Is the action of sulphuric acid 
 on benzene a typical one? How is ethyl-sulphonic 
 acid obtained ? 
 
 Action of Fused Potassium Hydroxide on Potassium 
 Bemene-Sulphonate. Preparation of Phenol, C 6 H 5 OH. 
 In an iron crucible (or small gluepot) melt 40-50 
 grams of potassium hydroxide, after adding a few 
 ccm. of water. Now add gradually, and with constant 
 stirring, 10-15 grams of finely powdered potassium 
 benzene-sulphonate. Do not heat to a very high 
 temperature. Note. A narrow piece of iron tube, 
 closed at one end and containing a little mercury, 
 and sufficiently large in bore to admit of the insertion 
 of a thermometer, is a useful adjunct in conducting 
 fusions with potash; by employing a thermometer, 
 protected as described, the temperature in the present 
 experiment may be maintained at about 290-295. 
 During fusion the mass is first thick and pasty, but 
 soon becomes semi-fluid, and remains in this condition 
 until towards the end of the operation, when it regains 
 its original consistency. 
 
 After the mass has been kept in a state of fusion for 
 about an hour, allow it to cool, and dissolve in about 
 200 ccm. of water; transfer to a porcelain basin and 
 acidify with concentrated hydrochloric acid. (What gas 
 comes off ?) When the liquid has cooled down, shake 
 up with ether in a glass separating-funnel. After 
 separating, distil off the ether ; the residue consists of 
 
PRACTICAL WORK IN ORGANIC CHEMISTRY. 117 
 
 impure phenol, which may be detected by the following 
 reactions, for which a solution in water should be 
 prepared : 
 
 (a) A few drops of ferric chloride give a beautiful 
 violet colour. 
 
 (b) To another portion add some ammonia and then 
 a few drops of a solution of bleaching powder ; a blue 
 colour is produced. 
 
 (c) Bromine water gives a yellowish white precipitate 
 of tribromphenol. 
 
 Now repeat and compare the above reactions with 
 a sample of commercial phenol. 
 
 Separation of Phenol from Coal-tar. Procure about 
 two litres of the fraction from coal-tar boiling at 
 150-200 C. This is transferred to a separating funnel 
 or Winchester quart bottle, and agitated with suc- 
 cessive quantities of caustic potash solution (25 per 
 cent). The aqueous portion is now drawn off and con- 
 centrated to a small bulk over a sand-bath, allowed to 
 cool completely, separated from any further stratum of 
 oil, and treated with a slight excess of dilute sulphuric 
 acid (one of cone, acid to three of water). The oily 
 layer obtained is separated as completely as possible 
 from the aqueous portion, and distilled from a small 
 Wurtz flask ; the portion coming over at about 182 
 is fairly pure phenol. It may be further purified by 
 freezing, pressing, and redistillation. 
 
 Estimation of Phenol. The reaction which bromine 
 gives with phenol may be utilised in approximately 
 
118 PRACTICAL WORK IN ORGANIC CHEMISTRY. 
 
 determining the amount of the latter in aqueous liquids. 
 The precipitate of tribrorn phenol may be collected on 
 tared filter papers, dried in the desiccator, and weighed ; 
 or the estimation may be effected by adding stan- 
 dardised bromine water in excess, followed by potassium 
 iodide, and then titrating back with a standard solution 
 of sodium thiosulphate. 
 
 C 6 H 5 OH + 3Br 2 = C 6 H 2 Br 3 OH + 3HBr. 
 
 Action of Nitric Acid on Phenol. Preparation o/Ortho 
 and Para-nitrophenol. To a mixture of 80 grams nitric 
 acid, sp. gr. 1 '34, and 164 grams of water, contained in a 
 porcelain basin, and kept cool by standing in a vessel of 
 water, 40 grams of melted phenol are gradually added 
 in small quantities, and the contents of the basin well 
 stirred. On the addition of the phenol the liquid 
 changes to a deep brown or black colour, and a heavy 
 dark brown oil separates out. When all the phenol 
 has been added, the mixture is allowed to stand for 
 about twelve hours. 
 
 The oil, which for the most part collects at the bottom 
 of the vessel, is washed two or three times with water 
 by decantation. The black oily product is now put 
 into a flask and distilled in a current of steam. (See 
 " Operations," p. 12.) Yellow crystals pass over and 
 appear in the receiver. The distillation is continued 
 until the distillate is almost colourless. The volatile 
 substance is ortho-nitrophenol, which can be further 
 purified by crystallisation from dilute alcohol. Deter* 
 
PRACTICAL WORK IN ORGANIC CHEMISTRY. 119 
 
 mine the melting-point of a sample after well pressing 
 and drying between filter-paper. 
 
 The residue in the flask contains the other isomer, 
 the non-volatile para-nitrophenol, which can be ex- 
 tracted from the black, pitchy, contaminating substance 
 by repeatedly exhausting with boiling water. The 
 united portions of the aqueous extract are boiled with 
 animal charcoal and filtered, the filtrate concentrated 
 to a small bulk and allowed to crystallise, further puri- 
 fication being effected by recrystallisation from hot 
 dilute alcohol. 
 
 After pressing and drying the crystals between filter- 
 paper, determine the melting-point, and also point out 
 any further distinguishing properties by which the 
 compound is distinguished from its isomer. 
 
 Action of Phosphorus Pentaehloride on Potassium 
 Benzene- Sulplionate. In a dry evaporating dish mix 
 15 to 20 grams potassium benzene-sulphonate and an 
 equal weight of phosphorus pentachloride, by means of 
 a dry pestle. The mass beomes hot and semi-liquid, 
 and hydrochloric acid is given off. Hence the opera- 
 tion should be performed under a hood or out of doors. 
 The reaction which takes place is represented by the 
 equation : 
 
 C 6 H 5 S0 2 OK + PC1 5 = C 6 H 5 S0 2 C1 + POC1 3 + KCL 
 
 When the action is over and the mass has cooled 
 down to the ordinary temperature, add about a litre 
 of cold water. Everything will dissolve except ihe 
 
120 PEACTICAL WOKK IN OKGANIC CHEMISTRY. 
 
 sulphon-chloride, C 6 H 5 S0 2 C1, which will remain as 
 a heavy oil at the bottom of the basin. Pour off the 
 greater part of the water, and add 30-40 grams of 
 powdered ammonium carbonate. The chloride is 
 thus converted into the corresponding sulphon-amide, 
 thus : 
 
 C 6 H B S0 2 C1 + 2NH 3 = C e H 5 S0 2 NH 2 -f NH 4 C1. 
 
 After cooling, filter off the sulphon-amide ; wash well 
 with cold water and crystallise from water. The com- 
 pound crystallises in needles, melting at 153. 
 
 Note to Student. Kefer to the manufacture of sae- 
 charin, and compare its mode of formation with the 
 foregoing. 
 
 Action of Potassium Cyanide on Potassium Benzene- 
 Sulphonate. Mix 20 grams of dry potassium benzene 
 sulphonate with an equal weight of potassium cyanide 
 (or, preferably, dry ferrocyanide), and distil from a 
 small retort. The distillate is impure phenyl cyanide, 
 C 6 H 5 CN. 
 
 C 6 H 6 SO a OK -f- KCN = C 6 H 5 GN + K a SOa. 
 
 Put the phenyl cyanide into a flask of 250 ccm. to 
 300 ccm. capacity, and add 150 ccm. of a moderately 
 strong solution of potassium hydroxide. Connect with 
 an inverted condenser and boil for two or three hours. 
 What is given off? After cooling, acidify with 
 hydrochloric acid. A solid substance is precipitated, 
 Filter off, wash slightly, and crystallise from water, 
 
PEACTICAL WOKK IN OKGANIC CHEMISTRY. 121 
 
 or sublime between watch-glasses. This substance is 
 benzoic acid. 
 
 Write out the reactions showing its formation from 
 the phenyl cyanide. (See also p. 134, on the application 
 of Sandmeyer's reaction.) 
 
 Action of Nitric Acid on Benzene. Preparation of 
 Nitrobenzene. 
 
 Into a flask of about J-litre capacity containing 
 50 grams of benzene introduce a well-cooled mixture 
 of 100 grams concentrated nitric acid and 150 grams 
 strong sulphuric acid. The acid must be very slowly 
 added from a tap-funnel and the contents of the flask 
 well shaken. Nitrous fumes are evolved and a consider- 
 able amount of heat developed. Care must be taken 
 that the temperature does not exceed 40-50, by im- 
 mersing the flask in cold water. The nitrobenzene 
 separates out as a brown, oily layer on the surface of 
 the acid. When all the acid has been added an 
 operation which should last about half-an-hour heat 
 the mixture for half-an-hour to 60 on the water-bath 
 with frequent agitation ; then pour slowly into about a 
 litre of cold water. The nitrobenzene will sink to the 
 bottom as a yellow oil. Pour off the acid and wash three 
 or four times with water, then add a dilute solution of 
 sodium carbonate, and distil in a current of steam. The 
 nitrobenzene, separated as carefully as possible from 
 water, is allowed to stand over a little granulated 
 
122 PRACTICAL WORK IN ORGANIC CHEMISTRY. 
 
 calcium chloride and shaken occasionally until the 
 liquid is perfectly clear. The yellow liquid is now 
 decanted from the calcium chloride and distilled from 
 a dry distilling-flask, noting the temperature. Nitro- 
 benzene has the formula C 6 H 5 N0 2 , and distils at 
 205-207 C. 
 
 Show by means of an equation the reaction which 
 has taken place in its formation from benzene and 
 nitric acid. Why is sulphuric added to the nitric 
 acid ? 
 
 Action of Nitric Acid on a Mixture of Benzene and 
 Petroleum. To a mixture of 10 ccm. benzene and 
 5 ccm. of petroleum contained in a small flask fitted 
 with an inverted condenser, add twice its measure of 
 fuming nitric acid of 1 "50 sp. gr. If a vigorous action 
 occur, no extraneous heat need be applied, but if the 
 reaction be sluggish the liquid should be well agitated 
 and moderately heated for a few minutes. Cool the 
 flask, transfer the contents to a tapped funnel, and run 
 off the bottom layer into water, when nitrobenzene 
 will be seen to have formed. The top layer in the 
 funnel will be found to be unaltered paraffin. This 
 experiment is to demonstrate the difference in behaviour 
 towards reagents, between hydrocarbons of the benzene 
 series and those of the paraffin series. Its application 
 to technical purposes will readily appear. 
 
PRACTICAL WORK IN ORGANIC CHEMISTRY. 123 
 
 Action of Reducing Agents on Nitrobenzene. 
 
 Preparation of Aniline, C 6 H 5 NH 2 . (1.) Sixty grams 
 nitrobenzene and 100 grams granulated tin are placed 
 in a flask of about 1 litre capacity connected with a 
 reversed condenser; 360 grams of strong commercial 
 hydrochloric acid are gradually added in small quan- 
 tities, the amount being regulated by the reaction, 
 which should proceed steadily. Should the contents of 
 the flask boil up violently, the flask is cooled in water 
 until the reaction has somewhat slackened ; towards 
 the conclusion of the operation the flask is gently 
 heated for about an hour. When nearly the whole 
 of the tin has dissolved, the contents of the flask 
 (which solidify on cooling to a crystalline mass con- 
 sisting of a double salt of stannic chloride and aniline 
 hydrochloride) are submitted to distillation in a cur- 
 rent of steam (see " Operations," p. 12), so long as 
 any unaltered nitrobenzene comes over. The contents 
 of the flask are now cooled and neutralised with quick- 
 lime ground into a thin paste with water, a small 
 quantity of sodium hydroxide solution being added 
 until slightly alkaline. The contents of the flask are 
 again distilled in a current of steam. Aniline and 
 water collect in the receiver, the former as an almost 
 colourless oil. When no further condensation of oil is 
 observed, the operation is discontinued and the oil 
 separated from the aqueous distillate by means of the 
 separating funnel. The aqueous portion of the distil- 
 
124 PRACTICAL WORK IN ORGANIC CHEMISTRY. 
 
 late contains aniline in suspension and in solution. 
 The latter may be extracted with ether, the ethereal 
 solution separated as far as possible from water, and the 
 ether distilled off.* The residue in the flask, together 
 with the oil in the separating-funnel, is dehydrated over 
 solid caustic potash, decanted, and distilled. Aniline, 
 when pure, distils at 181-182, and has usually a faint 
 amber colour. 
 
 (2.) Dissolve a further quantity of nitrobenzene in 
 alcoholic ammonia, and saturate the solution with 
 hydrogen sulphide, keeping it slightly warm. On the 
 water-bath distil off the excess of ammonium sulphide 
 and some of the alcohol. (Operation to be conducted 
 in fume cupboard.) To the residue add dilute hydro- 
 chloric acid. This will combine with and dissolve the 
 aniline, but leave any unchanged nitrobenzene undis- 
 solved. Separate the latter ; evaporate to dryness on 
 the water-bath, mix with a little lime and soda solu- 
 tion, and distil as in process No. 1. Aniline will pass 
 over. 
 
 Experiments with Aniline. To an aqueous solution 
 of a little of the aniline in a test tube add a clear 
 solution of bleaching powder. A beautiful purple 
 colour is produced. 
 
 Heat a few drops of the base with a little alcoholic 
 
 * An alternative method for recovering the aniline from its aqueous 
 solution is to evaporate the latter, rendered slightly acid by the addi- 
 tion of dilute hydrochloric acid, nearly to dryness on the water-bath. 
 Aniline hydrocbloride is formed, which may be collected and used for 
 subsequent experiments. 
 
PRACTICAL WORK IN ORGANIC CHEMISTRY. 125 
 
 potash and a drop or two of chloroform in a test tube. 
 Phenylcarbamine is produced, a substance possessing 
 a most unpleasant odour. (Hofmann's reaction for 
 primary amines.) 
 
 Salts of Aniline. Put a few ccm. of aniline into a 
 test-tube containing an equal bulk of water, and add 
 hydrochloric acid. Note that the aniline slowly dis- 
 appears on shaking the liquid ; the solution contains 
 aniline hydrochloride, C 6 H 5 NH 2 HC1, which can be ob- 
 tained as a solid by evaporating the solution. Kepeat 
 with dilute sulphuric and nitric acids. 
 
 Note. It is necessary to point out here that aniline 
 is by no means the sole product of the reduction of 
 nitrobenzene, and that intermediate compounds are 
 known, one of which, azolenzene, is next described. 
 The manner in which these compounds are related to 
 nitrobenzene and aniline must be fully explained by 
 the teacher, or by reference to a good text-book. 
 
 Preparation of Azobenzene, C 6 H 5 . N 2 . C 6 H 5 . Dis- 
 solve 16 grams of powdered sodium hydroxide in 100 
 ccm. of boiling methylated spirit, contained in a flask 
 of about half-litre capacity connected to an inverted 
 condenser, and add gradually to the hot solution 20 
 grams of nitrobenzene (can be introduced down the con- 
 denser). Heat for two to three hours. Now add, in 
 small portions, 8 grams of zinc dust, and continue the 
 heating for one or two days. Distil off the alcohol, 
 add water, and filter ; wash the residue with a little 
 water and boil up with hydrochloric acid and alcohol ; 
 
126 PRACTICAL WORK IN ORGANIC CHEMISTRY. 
 
 filter hot. Azobenzene crystallises out on cooling in 
 large red crystals melting at 67. Determine the 
 nitrogen in a sample of the azobenzene. 
 
 Preparation of Acetanilide, C 6 H 5 NH . COCH 3 . Equal 
 weights of aniline and glacial acetic acid are mixed in 
 a flask of about 250 ccm. capacity connected with a 
 reversed condenser, and gently boiled for about twelve 
 hours. The liquid on cooling solidifies. The contents 
 while warm are therefore at once distilled until excess 
 of acetic acid has been expelled, and the liquid which 
 passes over begins to solidify. The contents of the 
 flask are allowed to cool somewhat and then poured 
 into some cold water. The crystals are collected on a 
 filter, washed with a little water, and crystallised from 
 boiling water. The compound forms colourless tabular 
 crystals, melting when pure at 114, and the purity of 
 the preparation under consideration must be ascer- 
 tained by pressing a sample between filter-paper, drying 
 in the water-oven, and carefully observing the melting- 
 point. When pure, determine percentage of carbon, 
 hydrogen, and nitrogen. 
 
 Acetanilide is an important compound. The aromatic 
 amido-com pounds are readily acted on by glacial acetic 
 acid or acetic anhydride, and form acetyl derivatives 
 or acid amides. The introduction of the acid radicle 
 into the NH 2 group confers stability on the compound ; 
 for instance, aniline cannot be readily nitrated with- 
 out undergoing decomposition, acetanilide is easily 
 nitrated. The acetyl group can afterwards be removed 
 
PEACTICAL WOKK IN ORGANIC CHEMISTRY. 127 
 
 by heating with hydrochloric or sulphuric acid, or 
 with caustic alkalies (saponification or hydrolysis). 
 
 K-NHC 2 H 3 + H 2 = KNH 2 + C 2 H 4 2 . 
 
 Action of the Halogens on Benzene. 
 
 Preparation of Monobrom- and Dibrombenzene. Into 
 a flask of about 300 ccm. capacity pour 50 grams of 
 benzene, then measure out 28 ccm. of bromine. (Bromine 
 is more readily measured than weighed : the operation 
 must be conducted in a good draught-chamber.) The 
 quantities given are in the proportion of nearly two 
 atoms of bromine for one molecule of benzene. Place 
 the flask in cold water and gradually add the bromine 
 to the benzene. What gas is given off? Note that 
 the mixture remains highly coloured by the bromine. 
 (Kefer to the action of bromine on ethylene.) Now 
 connect the flask, by means of an asbestos stopper * well 
 luted with plaster of Paris, to an upright condenser, 
 and heat the contents of the flask over wire gauze, with 
 a small flame, until the evolution of hydrobromic acid 
 fumes from the top of the condenser have nearly ceased.t 
 
 The product, which has a deep red colour, is poured 
 into water containing a little caustic potash ; the liquid 
 
 * A strip of thin sheet asbestos-board, rendered pliable by moisten- 
 ing with water, and wrapped round the condensing-tube until of 
 sufficient thickness to form a tightly-fitting stopper. 
 
 t By attaching a glass tube to the top of the condenser, the hydro- 
 bromic acid may be absorbed in a little weak caustic potash; on 
 evaporating to dryness, igniting, and subsequent crystallisation, the 
 bromine may be recovered as potassium bromide. 
 
128 PRACTICAL WOEK IN ORGANIC CHEMISTRY. 
 
 monobrombenzene settles to the bottom of the vessel 
 as a heavy oil. On shaking in a stoppered funnel with 
 a little weak caustic potash, the liquid gradually loses 
 its red colour. Separate the oil from the aqueous 
 liquid, place in a flask connected with a condenser, and 
 distil in a current of steam. 
 
 The oil quickly passes over with the steam and is col- 
 lected in a receiver. Separate the oil from the aqueous 
 distillate as carefully as possible by means of the 
 separating funnel, and dehydrate over a few pieces of 
 fused calcium chloride. 
 
 The clear liquid decanted from the calcium chloride 
 is distilled over wire gauze from a Wurtz flask provided 
 with a thermometer. A small quantity of benzene 
 first passes over and the temperature then rises rapidly, 
 the chief portion which comes over between 150-155, 
 being separately collected. The colourless distillate is 
 nearly pure monobrombenzene. 
 
 A small quantity of a crystalline residue remains in 
 he flask ; this is para-dibrombenzene. This compound 
 may be submitted to steam distillation, when it will 
 solidify in the condenser in prismatic crystals, melting 
 at 89. Collect a sample, and after well pressing 
 between filter paper and allowing to remain for a few 
 hours in the desiccator, determine percentage of bromine. 
 
 Now express in the form of an equation the action 
 of bromine on benzene. What is the general action of 
 the halogens on the hydrocarbons of the aromatic 
 series ? 
 
PRACTICAL WORK IN ORGANIC CHEMISTRY. 129 
 
 ACTION OF NITROUS ACID ON ANILINE (A STUDY 
 OF THE DIAZO-KEACTION). 
 
 Preparation of Diazobenzene Nitrate. Prepare some 
 aniline nitrate by mixing 15 grams of aniline with 
 16 grams strong nitric acid previously diluted with 
 about 20 ccm. of water. Drain the crystalline mass of 
 nitrate from the acid liquid, and wash once or twice 
 with a little cold water. Introduce into each of the 
 
 FIG. 34. 
 
 flasks C and D an equal quantity of the nitrate, and 
 sufficient water to form a stiff paste. Now pass a 
 current of the oxides of nitrogen, generated from 
 nitric acid (60 ccm.) and arsenic trioxide (60 grams) 
 until the material in the flasks dissolves. Special care 
 must be taken that the temperature of the liquid does 
 
 K 
 
130 PKACTICAL WORK IN ORGANIC CHEMISTRY. 
 
 not exceed 10 C. To this end the flasks are kept in 
 ice water, and the current of gas is cooled by passing 
 through the empty cylinder B surrounded by ice 
 water. 
 
 Filter, if necessary, and add to the filtrate an equal 
 volume of strong alcohol, previously cooled to C., 
 and then a little cold ether. If the operation has 
 been properly carried out, a copious precipitate of 
 crystals of diazobenzene nitrate is formed. Filter off 
 with the aid of a filter pump, and proceed without 
 delay to study the properties of the compound. 
 
 (a) Dissolve a little in cold water and allow the 
 solution to stand. Decomposition, indicated by change 
 of colour, will take place. 
 
 (b) Boil a little with water in a small flask, and 
 notice the odour of phenol. Connect flask to con- 
 denser, and distil over a few ccm. Test distillate with 
 bromine water. 
 
 (e) Boil a few grams with strong alcohol in a small 
 flask attached to a reversed condenser, and notice the 
 odour of aldehyde. After boiling for some time add 
 excess of water, and notice the light, nearly colourless 
 oil, having the odour of benzene, at the top of the 
 liquid. The oil can be separated by means of a sepa- 
 rating funnel, and distilled with a little water, when it 
 will be obtained quite colourless, and can be shown to 
 be benzene. 
 
 (d) Boil a few grams with strong hydrochloric acid 
 in a small flask attached to a reversed condenser. Add 
 
PRACTICAL WOKK IX ORGANIC CHEMISTRY. 131 
 
 water, when an oil will sink to the bottom of the flask ; 
 this is chlorbenzene. Note. If hydrobromic acid is 
 used instead of hydrochloric, brombenzene will be 
 formed. 
 
 (e) Dissolve about a gram in a little cold water, 
 and add either aqueous hydriodic acid, or an aqueous 
 solution of potassium iodide. The diazo-compound is 
 rapidly decomposed, and iodobenzene separates from 
 the aqueous solution as a heavy oil, which can be puri- 
 fied by distilling with steam. It is obtained as a 
 colourless liquid, which soon turns red on standing. 
 (B.P. 188, sp.gr. 1-69.) 
 
 (/) If to another portion dissolved in a little cold 
 water, a little bromine, dissolved in potassium bromide, 
 be added, a brown oil separates out, which, after 
 pouring off the water and adding ether, solidifies ; 
 this is diazo-benzene perbromide. This compound, 
 boiled with alcohol or glacial acetic acid, furnishes 
 brombenzene. 
 
 (g) In all the foregoing experiments a gas is given 
 off when the diazo-compound is decomposed ; this 
 gas can be shown to be nitrogen. Boil a little of the 
 diazo salt with water in a test-tube, and collect some 
 of the gas ; show that it does not support combus- 
 tion. 
 
 (h) Place a very small quantity of the compound, 
 carefully dried by pressing between filter paper, on an 
 anvil, and strike it sharply with a hammer. It 
 explodes. 
 
 K 2 
 
132 PEACTICAL WOKK IN OEGANIC CHEMISTRY. 
 
 Now write out equations for the above experiments, 
 and show how, having a nitro-compound, we can convert 
 it into an amido-derivative ; and, by employing the diazo 
 reaction, convert the latter into (1) the corresponding 
 hydroxyl derivative ; (2) into the corresponding chlo- 
 rine, bromine, or iodine derivative ; (3) and finally how 
 the amido-group can be eliminated and replaced by 
 hydrogen. 
 
 Sandmeyer's Modification of the Diazo Reaction for the 
 substitution of Chlorine, Bromine, and Cyanogen in 
 Aromatic Compounds. 
 
 Traugott Sandmeyer has found * that diazo-com- 
 pounds are very readily decomposed in the presence of 
 cuprous salts, giving rise to corresponding chlorine, 
 bromine, or cyanogen derivatives, according to the 
 salt of copper employed. In this modification the 
 diazo-compound is not isolated, as will be seen in the 
 following preparations. 
 
 Preparation of Monochlorbenzene from Aniline. 
 Prepare a solution of diazobenzene-chloride by dissolv- 
 ing 30 grams aniline in 67 grams strong acid diluted 
 with 200 grams water ; thoroughly cool in ice water, 
 and add very slowly 23 grams sodium nitrite dissolved 
 in 60 grams of water. Now, into a flask of about a 
 litre capacity connected to an upright condenser, place 
 
 * Berichte der Deutschen Chemischen Geeellschaft Jahrg., xvii., 
 1633. 
 
PRACTICAL WORK IN ORGANIC CHEMISTRY. 133 
 
 150 grams of a 10 per cent, solution of cuprous chloride,* 
 heat to the boiling-point, and allow the diazobenzene 
 chloride to flow from a separatiug-funnel, drop by 
 drop, down the condenser, the flask meanwhile being 
 kept well shaken. Each drop of the diazobenzene 
 solution, as it meets the copper solution, produces a 
 yellow precipitate, which, however, at once decomposes 
 with evolution of nitrogen into an oil. When all the 
 diazo-solution has been added, arrange the apparatus 
 for distillation, and distil over the chlorbenzene, 
 separate the oil from the aqueous distillate, dry over 
 calcium chloride, and fractionate from a small flask. 
 The chlorbenzene should distil over at about 130. 
 
 Preparation of Brombenzene from Aniline. 25 grams 
 of crystallised copper sulphate and 72 grams potas- 
 sium bromide are dissolved in 160 grams of water ; 24 
 grams of strong sulphuric acid and 40 grams of copper 
 turnings are now added, and the whole boiled up in a 
 flask furnished with a reversed condenser until the 
 solution is almost decolourised; cool down, and add 
 
 * The cuprous chloride solution is prepared as follows : 25 parts 
 (by weight) of crystallised copper sulphate and 12 parts sodium 
 chloride are boiled together in a flask, with 50 parts water, until 
 decomposition is complete, i. e. until sodium sulphate crystallises out. 
 100 parts of concentrated hydrochloric acid and 13 parts of copper 
 turnings are now added, and the whole gently boiled until all colour 
 is discharged, the flask meanwhile being loosely stoppered. Now, so 
 much concentrated hydrochloric acid is added as is sufficient to make 
 up the total solution to 203*6 parts. Of the copper added only 
 6-4 parts go into solution, so that we have 197 parts of a solution 
 which contains 19 -7 parts, that is one-tenth of the molecular weight, 
 of anhydrous cuprous chloride. 
 
134 PRACTICAL WORK IN ORGANIC CHEMISTRY. 
 
 19 grams of aniline ; heat again to the boiling-point, 
 and add from a dropping-fimnel a solution of 14 grams 
 sodium nitrite dissolved in 80 grams of water. The 
 solution must be added drop by drop down the con- 
 denser, the flask in the meanwhile being kept well 
 agitated. When all the nitrite has been added, arrange 
 the apparatus for distillation. Separate the aqueous 
 portion of distillate, and wash the oil with a little weak 
 sodium hydroxide solution, then once or twice with 
 water; extract with ether, carefully distil off the 
 ether from a water-bath, dry the residue over a little 
 calcium chloride, and proceed to carefully fractionate. 
 The monobrombenzene should distil over at about 
 150-152. 
 
 Preparation of Phenyl-cyanide from Aniline (replace- 
 ment of the Amido-group ~by Cyanogen). 50 grams of 
 copper sulphate are dissolved in 150 grams of hot water 
 contained in a flask, and to the hot solution 56 grams 
 of 9 per cent, potassium cyanide solution are added. 
 The precipitate which at first forms quickly dissolves, 
 a quantity of prussic acid being generated (for this 
 reason the operation must be carried out in a fume 
 cupboard or in the open air). When all the cyanide 
 has been added, the flask is attached to a reversed 
 condenser, the contents heated to about 90 C., and a 
 solution of diazobenzene-chloride slowly added drop 
 by drop down the condenser, the flask being kept well 
 agitated. The diazobenzene-chloride solution is pre- 
 pared as follows : 19 grams of aniline are dissolved in 
 
PRACTICAL WOEK IN ORGANIC CHEMISTRY. 135 
 
 200 ccm. of dilute hydrochloric acid (160 grams 
 water and 40 grams strong hydrochloric acid), to this 
 solution 14 grams of sodium nitrite dissolved in 40 
 grams of water are slowly added, care being taken to 
 keep the mixture quite cold. 
 
 After all the solution of diazobenzene-chloride has 
 been added to the copper solution, the apparatus is 
 arranged for distillation. The oil which distils over 
 with the water is separated as far as possible by means 
 of a small separating-fuimel, and the aqueous portion 
 carefully extracted with ether. The latter is distilled off 
 over the water-bath, and the residue mixed with the 
 portion separated by means of the funnel. The whole of 
 the oil is now dissolved in about four times its volume 
 of ether, and the ethereal solution washed by agitation, 
 first with a dilute solution of sodium hydroxide, then 
 once or twice with water, and finally with a little dilute 
 sulphuric acid. The ethereal liquid is carefully sepa- 
 rated and allowed to stand some time over fused calcium 
 chloride. The ether is distilled off over the water-bath, 
 and the residue carefully distilled, noting the tempera- 
 ture. It should boil near 184. Experiment. Into a 
 small flask provided with a cork and a long tube to act 
 as a condenser, place about 2 ccm. of the phenyl cyanide 
 and a little alcoholic potash. Digest at a gentle heat 
 for some time, and notice the odour of the gas which is 
 given off. After heating for about an hour, evaporate off 
 the alcohol on a water-bath ; to the residue add a little 
 dilute hydrochloric acid, collect the 'precipitate on a 
 
136 PRACTICAL WOKE IN ORGANIC CHEMISTRY. 
 
 filter, wash with a little cold water, dry by pressing 
 between filter paper, and sublime between watch-glasses. 
 On determining the melting-point of the sublimate, it 
 will be found to be that of benzoic acid. Confirm by 
 the ordinary reagents. 
 
 Appendix to Diazo-Reaction. Lndwig Gattermann 
 has lately published (Ber. d. Deut. Chem. Ges. 1890, 
 p. 1218), a modification of the diazo-reaction for the 
 replacement of NH 2 by other radicles. The amido 
 compound is diazotised in the usual way, and mixed 
 with the salt whose acid radicle is to be substituted. 
 Finely divided copper is then added, which brings about 
 decomposition of the diazo-compound and the forma- 
 tion of the desired compound, which is isolated in an 
 appropriate manner. 
 
 The application of this method to the preparation of 
 Phenylisocyanate, C 6 H 5 -N = CO, from aniline will next 
 be considered. 10 grams of aniline are dissolved in a 
 mixture of 100 grams water and 20 grams concentrated 
 sulphuric acid. To this solution 7*5 grams of sodium 
 nitrite are added, in small portions at a time, and with 
 all necessary precautions. The diazotised solution is 
 then poured into a porcelain dish and mixed with a 
 concentrated aqueous solution of 9 grams of pure 
 potassium cyanate.* 
 
 * Preparation of pure Potassittin Cyanate (Chichester, A. Bell, Chem. 
 flews, 32, 99). 100 grams of dehydrated and finely-powdered potas- 
 sium ferrocyanitle are intimately mixe 1 with 75 grams of finely- 
 powdered and anhydrous potassium bichromate. This mixture is 
 slowly, and in portions of 3-5 grams, introduced into a large iron crucible 
 
PRACTICAL WORK IN ORGANIC CHEMISTRY. 137 
 
 Now add, with vigorous stirring, about 5 grams of 
 copper powder.* An energetic reaction takes place, 
 nitrogen is evolved, and the well-known pungent smell 
 of the isocyanates is perceptible. (Note. The opera- 
 tion must be conducted in a fume closet). When 
 
 (or glue pot) which is heated nearly to low redness over a large Bunsen 
 gas-burner. As the mixture is introduced it becomes black, and care must 
 be taken not to heat to fusion. During the introduction of the mixture, 
 an operation that should occupy about fifteen minutes, the contents of 
 the crucible are kept well stirred by means of an iron spatula. The 
 product of the reaction should present a loose porous appearance. 
 After cooling, it is powdered and boiled up with five times its volume 
 of 80 per cent, alcohol (dry methylated spirit). The alcoholic solution 
 can be poured off quite clear from the heavy residue. In order to 
 separate the potassium cyanate from its alcoholic solution, the con- 
 taining vessel is placed in cold water and the contents vigorously 
 stirred with a glass rod. The heavy white precipitate is collected on 
 a filter, and the alcoholic filtrate employed again for extracting a 
 further quantity of the cyanate. This is repeated until nothing fur- 
 ther separates from the alcohol. On distilling off the alcohol an 
 additional quantity of cyanate may be obtained. The various portions 
 of cyanate are collected on the same filter, washed with a little absolute 
 alcohol, well drained on the filter-pump, and finally washed with a 
 little ether. The dry salt is preserved in a stoppered bottle. 
 
 * Preparation of Copper-powder. To a cold saturated solution of 
 copper sulphate, contained in a capacious porcelain basin, dust in, by 
 the aid of a fine sieve, some recently-prepared zinc dust, and keep the 
 solution well stirred throughout the operation. The addition of zinc 
 is discontinued when only a faint blue colour remains. By this means 
 we avoid a large excess of zinc. The hot supernatant liquid is 
 allowed to cool down and then removed by decantation, the heavy 
 precipitate of finely divided copper is then repeatedly washed with 
 cold water. In order to remove a trace of zinc, tue precipitate is 
 treated with some very dilute hydrochloric acid until no further evolu- 
 tion of hydrogen is observed. The acid liquid is removed, the metallic 
 precipitate collected on the filter-pump, well washed with water, and 
 whilst in a moist state transferred to a stoppered bottle. It cannot be 
 dried in the air without oxidising. 
 
138 PRACTICAL WORK IN ORGANIC CHEMISTRY. 
 
 the reaction has somewhat moderated, add a further 
 quantity of 5 grams copper powder. The oily layer 
 which rises to the surface, consisting of phenyl- 
 isocyanate, is removed as far as possible, by means of 
 a glass spoon, from the decomposing action of the 
 aqueous solution, and dissolved in ether. The addition 
 of copper powder is continued until there is no 
 further evolution of nitrogen. The whole of the 
 ethereal solution is then filtered through cotton wool, 
 carefully separated from aqueous liquid by means of a 
 separating funnel, and dried over anhydrous potassium 
 carbonate. The residue left after distilling off the 
 ether is submitted to distillation over a small flame, 
 and that portion coming over at about 163 C. collected. 
 It is nearly pure phenylisocyanate. 
 
 ACTION OF OXIDISING AGENTS UPON AROMATIC 
 COMPOUNDS. 
 
 Preparation of Benzoquinone (Quinone), C 6 H 4 2 . 
 Fifty grams of commercial aniline are dissolved in a 
 mixture of 400 grams strong sulphuric acid and 
 1500 grams water, contained in a large flask of about 
 4 litres capacity. To the well-cooled solution of 
 aniline sulphate, 175 grams of finely-powdered potas- 
 sium bichromate are slowly added in small portions at 
 a time. After each addition of the bichromate the 
 flask must be well shaken, and care must be taken 
 that the temperature of the mixture does not rise above 
 
PEACTICAL WOKK IN OEGANIC CHEMISTRY. 139 
 
 the ordinary atmospheric temperature. The mixture 
 changes from dark green to violet-black. When all 
 the bichromate has been added the mixture is heated 
 for a short time to 35 C. on the water-bath, and, after 
 well cooling, extracted with small quantities of ether. 
 
 On distilling off the ether, quinone remains in the 
 form of yellow needle-shaped crystals, which are usually 
 discoloured by the presence of a substance called 
 quinhydrone. The quinone may be further purified 
 by distilling in a current of steam and extracting the 
 distillate with ether, or by crystallisation from 
 petroleum spirit. 
 
 Note. The formation of quinone from aniline shows 
 that the reaction consists in the elimination of the 
 amido group and an atom of hydrogen, and the simul- 
 taneous substitution of two atoms of oxygen. The 
 nitrogen is removed in the form of ammonia. The 
 changes taking place cannot well be expressed in the 
 form of an equation. 
 
 Quinone, when pure, melts at 116 C. It readily 
 dissolves in ether and alcohol, sublimes on heating, and 
 volatilises at the ordinary temperatures. 
 
 OOOTT 
 
 Preparation of PTitlialic Acid, C 6 H 4 <C QQQTI > from 
 
 Naphthalene. Mix 40 grams powdered naphthalene 
 with 80 grams of powdered potassium chlorate and 
 add this mixture gradually to 400 grams concen- 
 trated hydrochloric acid. Naphthalene tetrachloride, 
 C 10 H 8 C1 4 , is formed in this reaction. Wash with water. 
 
140 PRACTICAL WORK IN ORGANIC CHEMISTRY. 
 
 Now add gradually 400 grams of concentrated nitric 
 acid (sp. gr. 1 45), and boil in a flask connected to an 
 inverted condenser. When all is dissolved, distil off 
 the excess of nitric acid, pour into a porcelain basin, 
 add water, and continue evaporation in order to expel 
 nitric acid ; finally distil the residue. Phthalic anhy- 
 dride passes over. Kecrystallise from water. Determine 
 melting-point. Sublime some of the phthalic acid, 
 
 and determine the melting* point of the phthalic 
 
 PO 
 anhydride formed (C 6 H 4 <J>0). 
 
 Phthalic anhydride reacts with phenols, giving rise 
 to compounds known as phthaleins. 
 
 Phenol-phthalein, C 2 oH 14 04. This interesting sub- 
 stance, now so extensively used as a substitute for 
 litmus in alkalimetry, is prepared in the following 
 manner: Ten grams phthalic anhydride, 20 grams 
 phenol, and 8 grams cone, sulphuric acid (dehydrating 
 agent), are heated together in a small flask to 115- 
 120 C. in an oil-bath for ten hours. The dark red and 
 semi-fluid mass is poured into water and boiled until 
 the smell of phenol has disappeared. When cool the 
 yellow granular precipitate is separated by filtration, 
 and washed with water. It is then dissolved in dilute 
 sodium hydroxide solution, filtered from undissolved 
 residue, and the filtrate acidulated with acetic acid and 
 a few drops of hydrochloric acid. The solution, after 
 standing a few hours, deposits phenol-phthalein as a 
 light yellow crystalline powder. It is further purified 
 
PRACTICAL WORK IN ORGANIC CHEMISTRY. 141 
 
 by dissolving in dry methylated spirit, adding about 
 half its weight of freshly ignited animal charcoal, 
 and digesting in a flask fitted to an inverted condenser 
 on the water-bath for about an hour. The solution is 
 filtered hot, the charcoal washed with a little hot 
 alcohol, and the filtrate concentrated to about two- 
 thirds of its bulk by evaporation or distillation. To 
 the cooled solution water is added until it becomes 
 turbid (about eight times the quantity of water will 
 be required). The liquid is stirred and filtered to 
 separate it from the resinous matter, and the filtrate 
 evaporated down on the water-bath to expel alcohol. 
 Phenol-phthalien will separate out as a white 
 crystalline powder. 
 
 Determine the melting-point of a sample, and 
 examine its behaviour with pure sodium carbonate, 
 sodium and potassium hydroxide, and with ammonium 
 hydroxide. 
 
 Explain fully the following equation : 
 
 ro C=(C 6 H 4 OH) 2 
 
 2C 6 H 6 OH + C 6 H.<Xn>0=C 6 H 4 < >0 +H 2 O 
 
 CO 
 
 Special Note for Student. Phenol-phthalein has been 
 shown to be a derivative of triphenylmethane. The 
 manner in which this relationship has been established 
 forms a nice exercise for the earnest student. 
 
 Preparation of Anthraquinone. Estimation of An- 
 thracene. The most satisfactory method of assaying 
 
 /far 0? TH* ^ 
 
142 PRACTICAL WORK IN ORGANIC CHEMISTRY. 
 
 crude anthracene is based on the conversion of the 
 hydrocarbon into anthraquinone by the action of oxidis- 
 ing agents. The operation is carried out as follows : 
 1 gram of the carefully sampled specimen is placed 
 in a flask of about 500 ccm. capacity connected to an 
 inverted condenser. 45 ccm. of glacial acetic acid are 
 then added, and the contents of the flask 
 FIG. 35. brought to the boiling-point, and while boil- 
 ing a solution of chromic acid is added to it 
 gradually, drop by drop, see Fig. 35. The 
 chromic acid solution is prepared by dissolving 
 15 grams of the pure acid in 10 ccm. water 
 and 10 ccm. glacial acetic acid. The addi- 
 tion of the chromic acid should occupy about 
 two hours, and the contents of the flask 
 should be kept gently boiling for two hours 
 longer, four hours in all, this being neces- 
 sary to insure complete oxidation of the 
 impurities. The flask is then allowed to re- 
 main at rest for twelve hours, after which the 
 contents are diluted with 400 ccm. of cold 
 water and again left at rest for another three 
 hours. The precipitated anthraquinone is 
 now filtered off and well washed with cold water. 
 It is next washed on the filter with a boiling hot 
 solution of dilute caustic soda (1 part of soda to 100 
 parts water), and finally thoroughly washed with 
 hot water until the filtrate exhibits no alkaline 
 reaction. The precipitate is now washed from the 
 
PRACTICAL WORK IN ORGANIC CHEMISTRY. 143 
 
 filter by means of a jet of water into a tared 
 platinum dish, the water evaporated off at 100, and 
 the residue weighed. The weight of anthraquinone 
 thus obtained ought not to be regarded as representing 
 pure quinone, as it usually contains a certain proportion 
 of inorganic impurities. Hence, the dish should be 
 gradually heated, so as to completely sublime the 
 anthraquinone, and the residue obtained deducted from 
 the weight previously found. Note. If a funnel be 
 placed over the dish during sublimation, the anthra- 
 quinone will condense on the glass ; the sublimate can 
 be collected and preserved as a specimen. Its melting- 
 point should be determined. 
 
 Preparation of Alizarin. Weigh out 50 grams of 
 fuming sulphuric acid (45 per cent, anhydride) into a 
 small dry flask, and introduce in small portions an equal 
 weight of finely divided anthraquinone. Keep the 
 contents of the flask at about 160 for 3-4 hours. 
 Dissolve the product in about 1J litre of water, and 
 neutralise with finely powdered chalk made into a thin 
 cream with water ; filter. To the filtrate add a solution 
 of sodium carbonate until no further precipitate is pro- 
 duced, filter, and evaporate to dryness. The salt 
 thus obtained is impure sodium anthraquinone sul- 
 phonate. In an iron crucible (a glue-pot will answer 
 as well) prepare a strong syrupy solution of caustic 
 potash ; heat up to about 200 C. (see p. 116), and add 
 in small portions about 20 grams of the sulphonate. 
 
 The heating is continued for some hours, and care 
 
144 PRACTICAL WORK IN ORGANIC CHEMISTRY. 
 
 must be taken not to exceed a temperature of 260 C. 
 If the crucible is heated in an oil-bath there is less 
 risk of exceeding this temperature, and the operation 
 is more under control. 
 
 The formation of alizarin during the fusion of the 
 salt with caustic potash is shown by the dark purple 
 colour of the mass. When a little of this is dissolved 
 in water it should form a beautiful purple-red solution. 
 Continue the fusion until the mass acts in this way. 
 Dissolve in a litre of water and acidify ; alizarin is 
 thrown down in brown amorphous flocks. Filter off, 
 dry, and sublime between watch-glasses. 
 
 Note. On a commercial scale the sulphonate is 
 heated with strong potash solution under pressure. 
 The fusion requires a long time, and is conducted at a 
 lower temperature. 
 
 Preparation of Cinnamic Acid, C 6 H 5 CH : CH . C0 2 H, 
 from Liquid Storax. Into a capacious flask connected 
 with a condenser introduce about 30 grams of liquid 
 storax, along with 15 grams of ordinary crystallised 
 sodium carbonate and 250 ccm. of water. Heat to 
 boiling and pass in a rapid current of steam. When 
 about 200 ccm. have been collected, the operation is 
 discontinued. The distillate contains some oily drops 
 of styrene (what is its formula?) which can be 
 separated and preserved. The residual liquid in the 
 retort is poured off from the resinous residue.* 
 
 * This residue contains an oily substance named " styracin," which 
 is cinnyl cinnamate, C 6 H 3 -CH = CH-COOC 8 H 9 . If then the whole 
 
PRACTICAL WORK IN ORGANIC CHEMISTRY. 145 
 
 The filtrate is mixed at first with just so much 
 dilute sulphuric acid that a very small quantity of 
 cinnamic acid is precipitated along with dissolved 
 resin, and the liquid filtered from this precipitate is 
 treated with excess of sulphuric acid, which precipitates 
 cinnamic acid of a tolerably white colour. It is 
 further purified by dissolving in a largo quantity of 
 water with as little sodium carbonate as possible, and 
 again precipitating, first with a little sulphuric acid, 
 and then, after filtration, with an excess of acid, by 
 which treatment a white precipitate is obtained. 
 Collect and wash with a little water and crystallise 
 from alcohol. Pure cinnamic acid melts at 133 C. 
 Determine melting-point of sample obtained as above. 
 
 Reactions of Cinnamic Acid. (1) Dissolve a little 
 of the acid in water with the aid of ammonia, boil off 
 the excess of the latter so as to obtain a solution of 
 neutral ammonium cinnamate, and add a few drops of 
 ferric chloride to the solution. A buff coloured precipi- 
 tate is obtained very like that produced by a benzoate ; 
 the two acids are, however, sufficiently distinguished 
 by many other reactions, e. g. manganous chloride 
 
 material in the flask be distilled with a strong solution of caustic potash 
 or soda, the ethereal salt is saponified and cinnylic alcohol passes over. 
 The milky distillate is saturated with common salt, in whose solution 
 the alcohol is less soluble than in pure water ; an oily layer is formed 
 which afterwards solidifies. Cinnylic alcohol crystallises from water in 
 soft silky crystals, having a sweet taste and an agreeable odour of 
 hyacinths, melting at 33 C., and when carefully oxidised affords first 
 the aldehyde and then cinnamic acid. 
 
146 PRACTICAL WORK IN OEGANIC CHEMISTEY. 
 
 produces a whitish precipitate with a cinnamate, but 
 not with a benzoate. (Try it.) 
 
 (2) A solution of cinnamic acid boiled with peroxide 
 of lead or chromic acid gives the odour of cinnamon 
 and bitter almond oil (benzoic aldehyde). 
 
 Synthesis of Cinnamic Acid. A knowledge of the 
 fact that cinnamic acid affords benzoic aldehyde on 
 decomposition enabled Dr. W. II . Perkin to success- 
 fully employ this substance in conjunction with acetic- 
 anhydride and sodium acetate in the synthesis of cinna- 
 mic acid. This method, which is known as " Perkin's 
 reaction," is applicable to substituted aromatic alde- 
 hydes on the one hand and a large number of fatty 
 acids on the other. 
 
 12 '5 grams benzaldehyde, 6*5 grains sodium 
 acetate previously fused and powdered, and 19 grams 
 acetic anhydride, are mixed together in a small flask 
 fitted to a reversed condenser and kept at a gentle 
 boil for about eight hours. After cooling add water 
 and a slight excess of sodium carbonate and distil off 
 any unchanged benzaldehyde. After removing resinous 
 by-products by filtration add at first a small quantity 
 of dilute sulphuric acid, filter, and treat the filtrate 
 with excess of acid, and proceed exactly as in the 
 purification of cinnamic acid from liquid storax. 
 
 Compare the acid prepared above with that obtained 
 from storax. 
 
 The manufacture of cinnamic acid has being 
 considerably simplified by Dr. Caro, of Mannheim. 
 
PRACTICAL WORK IN ORGANIC CHEMISTRY. 141 
 
 Toluene is converted into benzylene dickloride by the 
 action of chlorine on the boiling hydrocarbon, and this 
 is heated directly with sodium acetate, when the 
 following reaction takes place 
 
 C 6 H 5 .CHC1 2 + CH 3 -CO-ONa = C 6 H 5 CH = CH-COOH 
 + NaCl + HOI. 
 
 The cinnamic acid thus obtained is the starting 
 point for the production of artificial indigo. 
 
 Preparation of Indigotin, C 8 H 5 NO, from Commercial 
 Indigo. (Operation to be made rouglily quantitative.) 
 About five grams of finely powdered indigo are well 
 mixed in a mortar with an equal weight of pure recently- 
 slaked lime. The mixture is transferred to a stoppered 
 bottle of known capacity (about one litre), the mortar 
 being well rinsed with water which is added to the 
 contents of the bottle. The latter is now heated in a 
 water-bath for some hours and a quantity of powdered 
 ferrous sulphate is added; the bottle is now filled 
 up with hot water, the stopper inserted, and after the 
 contents have been well shaken the whole is left at 
 rest for about 12 hours, till the indigo is reduced and 
 the sediment has sunk to the bottom. A portion of 
 the clear liquor is then drawn off with a siphon, 
 and the quantity of liquid having been accurately 
 measured (say 250 ccm.), it is mixed with an excess 
 of hydrochloric acid and oxidised by forcing a gentle 
 current of air through the solution ; the precipitate 
 is collected on a tared filter and washed with water. 
 
148 PKACTICAL WORK IN ORGANIC CHEMISTRY. 
 
 It is then dried in the water-oven and weighed, and 
 the quantity of indigotin obtained calculated on the 
 total quantity of indigo employed. 
 
 Experiments with Indigo. The yellow supernatant 
 liquid obtained in the reduction of indigo represents 
 the " cold vat " of the dyer. 
 
 (1) Take a small piece of white calico, and having 
 cleansed thoroughly in boiling water, soak it in the 
 clear liquid left in the bottle, and then remove into 
 the air. It soon acquires a blue colour. 
 
 Note. Explain the changes brought about in the 
 foregoing experiments. 
 
 (2) Drop a little of the pure iudigotiu obtained as 
 above on a piece of heated platinum foil ; notice that it 
 volatilises in purple vapours, leaving little or no residue. 
 Eepeat, using commercial indigo, and notice residue 
 left, 
 
 (3) Stir up a little indigotin with water into a thin 
 paste and test separate portions with (a) chlorine water, 
 (b) bromine water, and (c) nitric acid, strong and 
 dilute. 
 
 (4) Treat separate portions of indigotin with strong 
 sulphuric acid and with fuming acid. 
 
 Preparation of Isatin, C 8 H 5 N0 2 , from Indigo. 250 
 grams of finely powdered good commercial indigo are 
 stirred up in a large dish to a thin paste with water ; 
 the mixture is then placed over a water-bath and 
 heated up to 90-95 C. Commercial nitric acid is 
 now added in successive portions of about 10 ecru., 
 
PKACTICAL WORK IN ORGANIC CHEMISTRY. 149 
 
 until the blue colour has disappeared (from 150 to 
 180 grams of acid will be required). After each 
 addition of nitric acid it is necessary to wait until the 
 effervescence which is produced is over before adding 
 more acid. If no effervescence takes place, in conse- 
 quence of the indigo being mixed with too much water 
 or not sufficiently heated, and the addition of nitric 
 acid is continued, a violent reaction suddenly ensues 
 when the solution has reached a certain concentration, 
 the mass overflowing the vessel. The operation must 
 not therefore be hurried, and the contents of the dish 
 must be kept well stirred. Hot water must also be 
 added from time to time, to replace that lost by 
 evaporation. 
 
 When the necessary amount of nitric acid has been 
 added, the solution is mixed with about four times its 
 volume of hot water, and the whole boiled up and 
 filtered as rapidly as possible ; after standing 12 hours 
 the isatin separates in reddish crystalline nodules. 
 The mother-liquor is again boiled up with the un dis- 
 solved residue and filtered, the operation being two or 
 three times repeated. The mother-liquor yields more 
 isatin on evaporation. 
 
 In order to purify the crude isatin it is neccessary 
 to moisten the crystals with water containing a little 
 ammonia (to remove resinous matter); then wash 
 with a little cold water and crystallise from hot 
 alcohol. Another method of purification, when the 
 isatin is contaminated with much resinous matter, is as 
 
 L 3 
 
150 PRACTICAL WORK IN ORGANIC CHEMISTRY. 
 
 follows : The crude isatin is dissolved in moderately 
 strong caustic potash, and dilute hydrochloric acid 
 added to the solution as long as it forms a black or 
 brown precipitate ; when a portion on filtering is of a 
 pure yellow coliur, and gives a highly red precipitate 
 with hydrochloric acid, the whole solution is filtered off 
 and the precipitation completed by the further addition 
 of hydrochloric acid. The precipitate is collected, 
 washed with water, and crystallised, if necessary, from 
 alcohol. 
 
 Properties of Isatin. Tsatin does not unite with acids, 
 but plays the part of an acid, exchanging an atom of 
 hydrogen for an equivalent of metal. Of the salts of 
 isatin we may prepare that of silver, which is obtained 
 as a wine-red crystalline precipitate by mixing silver 
 nitrate with an alcoholic solution of isatin. Collect 
 and wash with a little alcohol, and allow to dry in the 
 desiccator. When dry determine percentage of silver. 
 
 Isatin dissolves in strong sulphuric acid, and this 
 solution is used as a test for thiophene in benzene. 
 
 Experiment. Agitate a few ccm. of commercial 
 benzene with the solution of isatin in strong sulphuric 
 acid : a deep blue colouration is produced, due to the 
 formation of indoplienin, 
 
 C 8 H 5 N0 2 + C 4 H 4 S = C 12 H 7 NSO + H 2 0. 
 
INDEX. 
 
 A. 
 
 ACETANILIDE, 126 
 
 , hydrolysis of, 127 
 
 Acetic acid, 88 
 
 , as solvent, 3 
 
 Acrolein, 101 
 
 Alcohol, " absolute," 72, 73 
 
 , detection of, 70 
 
 , estimation of, 75, 88 
 
 , preparation of ethyl, 08 
 
 , purification of, 71 
 
 Aldehyde, 87 
 
 resin, 88 
 
 Aldehyde-ammonia, 87 
 
 Alizarin, 143 
 
 Allyl alcohol, 103 
 
 Ammonia, action of, on aldehyde,87 
 
 , , on benzene sulphon- 
 
 chloride, 120 
 
 , , on ethyl oxalate, 63 
 
 , estimation of, 35, 59 
 
 Ammonium oxalate, 58 
 
 Analysis, organic, 22 
 
 Aniline, 123 
 
 , reactions of, 124 
 
 , salts of, 125 
 
 Anthracene, cake, 112 
 
 , estimation of, 141 
 
 Anthraquinone, 141 
 
 sulphonate, 143 
 
 Asbestos stoppers, 127 
 
 Azobenzene, 125 
 
 B. 
 
 BARIUM oleate, 105 
 Barium oxide, use of, 73 
 Beer, estimation of alcohol in, 75 
 Benzene, 113 
 
 , action of reagents on, 114, 
 
 121, 127 
 
 , action of nitric acid on 
 
 mixture of benzene and petro- 
 leum, 122 
 
 , purification of, 113 
 
 Benzenesulphonic acid, 114 
 
 calcium salt, 115 
 
 potassium salt, 115 
 
 Benzenesnlphon-amide, 120 
 
 chloride, 119 
 
 Benzoquinone, 138 
 Boiling-point, determination of, 
 
 11 
 
 Brombenzene, 133 
 Bromine, absorption by oils, 106 
 , action of, on benzene, 127 
 
 , , on ethylene, 80 
 
 Briihl's refrigerating-funnel, 114 
 
 C. 
 
 CALCIUM benzenesulphonate, 115 
 Calculation of vapour density, 49, 
 
 53 
 of results of analysis, 33 
 
152 
 
 INDEX. 
 
 Carbon, determination of, 24 
 Carbon dioxide, preparation of, for 
 
 analysis, 36 
 Carius's method for halogens, &c., 
 
 46 
 Charcoal, use of, 4 
 
 , purification of, 5 
 
 Chloral, 89 
 
 , hydrate, 90 
 
 Chlorine, action of, on alcohol, 89 
 
 , preparation of, 89 
 
 Chlorobenzene, 132 
 Chloroform, 91 
 
 . , reactions of, 91 
 
 Cinnamic acid, 144 
 
 . , reactions of, 145 
 
 , synthesis of, 146 
 
 Cinnyl cinnamate, 144 
 Cinnylic alcohol, 145 
 Coal oil, 3 
 
 Coal-tar, composition of, 113 
 
 , distillation of, 110 
 
 Collection and drying of organic 
 preparations, 17 
 
 Combustion tube, 25, 39 
 
 Copper formate, 66 
 
 oxide, 26, 39 
 
 powder, 137 
 
 Creosote oils, 112 
 
 Crystallisation, determination ol 
 
 water of, 57 
 
 . -, fractional, 1 
 
 Cuprous chloride, preparation o f , 
 
 133 
 
 Cyanogen, preparation of, 61 
 t conversion into oxamide, 
 
 61 
 
 D. 
 
 DEHYDRATING agents, selection 
 
 of, 73 
 
 Dextrine, 68 
 Diastase, 68 
 Diazobenzene nitrate, 130 
 
 perbromide, 131 
 
 Diazo-reaction, 130 
 
 , Gattermann's modification, 
 
 136 
 
 , Sandmeyer's modification, 
 
 122 
 
 Dibrombenzene, 127 
 Dibromstearic acid, 106 
 Diethyl oxalate, 
 Distillation, 7 
 , fractional, 7 
 iu steam, 11 
 
 in vacuo, 100 
 
 - of coal-tar, 110 
 Drying and non-drying oils, 108 
 
 E. 
 
 ELAIDIC acid, 107 
 Elaidin test, 1C8 
 Erlenmeyer's combustion furnace, 
 
 25 
 
 Ether, 78 
 Ethereal salts, 94 
 . , action of ammonia on, 
 
 63 
 . , saponification of, 94 
 
 Ethyl acetate, 93 
 
 bromide, 85 
 
 chloride, 82 
 
 oxalate, 63, 64 
 
 Ethylene dibromide, 80 
 
INDEX. 
 
 153 
 
 F. 
 
 FEIILINU'S solution, 69 
 Fermentation, alcjholic, 69 
 Filtration, 17 
 
 in vacuo, 1 7 
 
 Fractional crystallisation, 1 
 distillation, 7 
 
 precipitation, 97 
 Freezing-point, determination of, 
 
 53 
 Funnel, refrigerating, 20 
 
 , separating, 19 
 Fusions with potash, 116, 143 
 
 G, 
 
 GATTERMANN'S reaction, 136 
 Geissler bulbs, 27 
 Glycerol, distillation of, 101 
 
 , estimation of, 101 
 
 , isolation of, 99 
 
 , test for, 100 
 
 Glycerol monoformin, 65 
 Gravity bottle, specific, 14 
 
 H. 
 
 HALOGENS, action of, on benzene, 
 
 127 
 
 , detection of, 23 
 
 , estimation of, 43 
 
 Hempel's fractionating column, 8 
 HofT s, Van't, equation, 51 
 Hydrobromic acid, action of, on 
 
 alcohol, 85 
 Hydrochloric acid, action of, on 
 
 alcohol, 82 
 
 Hydrogen, estimation of, 24 
 Hydrolysis, 98, 127 
 
 INDIGO, action of reagents on, 148 
 
 , artificial, 147 
 
 , reduction of, 147 
 
 , sublimation of, 148 
 
 , valuation of, 147 
 
 Indigotin, 147 
 
 Indophenin, 150 
 
 Iodine, absorption by fats and 
 
 oils, 106 
 , estimation of, in organic 
 
 compounds, 44 
 lodobe^zene, 131 
 lodoform, 71 
 loJcstearic acid, 106 
 Isatin, 148 
 , properties of, 150 
 
 LEAD chromate, use of, in organic 
 analysis, 35 
 
 oleate, 104 
 
 plaster, 100 
 
 stearate, 98 
 
 Light oil, fractionation of, 113 
 Liquid storax, 144 
 
 M. 
 
 MALT, alcohol from, 68 
 Maltose, e8 
 
 , fermentation of, 69 
 Mashing, operation of, 68 
 Melting-point apparatus, 7 
 
 , determination of, 7 
 
 Methylated spirit, purification of, 
 
 72 
 
154 
 
 INDEX. 
 
 Meyer's, Victor, apparatus, 47 
 Molecular weight, determination 
 of, 47 
 
 , method of V.Meyer, 47 
 
 , of Eaou.lt, 50 
 
 , by analysis, 49 
 
 NAPHTHALENE, action of oxidising 
 
 agents on, 139 
 Nitrobenzene, 121 
 , action of reducing agents 
 
 on, 123 
 Nitrogen, detection of, 23 
 
 , estimation of, 35, 39 
 
 Nitrophenol, ortho-, 118 
 
 , para-, 118 
 Nitrous acid, action of, on aniline, 
 
 129 
 , , on fats and oils, 
 
 107 
 , preparation of, 129 
 
 O. 
 
 OILS and fats, composition of, 94 
 
 , drying and non-drying, 108 
 
 , saponification of, 94, 99 
 
 Oleic acid, action of reagents on, 
 106 
 
 , preparation of, 104 
 
 , titration of, 108 
 
 Olei'n, composition of, 95 
 
 Olive oil, action of reagents on, 107 
 
 , saponification of, 99 
 Orthonitrophenol, 118 
 Oxalic acid, from sugar, 55 
 , reactions of, 56 
 
 Oxalic acid, salts of, 57, 58 
 , sublimation of, 56 
 
 , titration of, by potas- 
 sium permanganate, 60 
 
 Oxalic ether, 63 
 
 , action of ammonia on, 
 
 63 
 
 Oxamide, from cyanogen, 61 
 
 , conversion into cyanogen, 64 
 
 , into oxalic acid, 62 
 
 Oxidising agents, action of, on 
 alcohol, 85 
 
 , , on aniline, 138 
 
 , , on anthracene, 
 
 141 
 
 , , on naphthalene, 
 
 139 
 
 P. 
 
 PALMITIC acid, separation of, from 
 
 stearic acid, 97 
 Palmitin, composition of, 95 
 Para-nitrophenol, 118 
 Parchment cone, use of, in filter- 
 ing, 17 
 
 Perkin's reaction, 146 
 modification of Sprengel 
 
 tub', 16 
 Petroleum, action of nitric acid on, 
 
 122 
 
 light oil, 3 
 
 Phenol, estimation of, 117 
 
 , formation of, from aniline, 
 
 130 
 , , from benzene sul phonic 
 
 acid, 116 
 
 , reactions of, 117 
 
 , separation of, from coal-tar, 
 
 117 
 
INDEX. 
 
 155 
 
 Phenol-phthalei'n, 140 
 
 , constitution of, 141 
 
 Phenyl cyanide, from aniline, 
 
 134 
 , from benzene-sul phonic 
 
 acid, 120 
 
 Phenylisocyanate, 136 
 Phenylsulphon-amide, 120 
 
 chloride, 119 " 
 
 Phenylsulphonic acid, salts of, 
 
 114 
 Phosphorus, detection of, 24 
 
 , estimation of, 24 
 
 pentachloride, action of, on 
 
 potassium benzene sulphonate, 
 
 119 
 
 pentoxide, action of, on 
 oxamide, 64 
 
 Phthalic acid, 139 
 
 Pitch, estimation of, in tar, 112 
 
 Potassium benzenesulphonate, 114 
 
 cyanate, 136 
 
 , estimation of, 58 
 
 ethylsulphate, 76 
 
 oxalate, 58 
 
 stearate, 98 
 Precipitation, fractional, 97 
 Pumice, " prepared," 27 
 
 , silvered, 34 
 
 Purification of alcohol, 71 
 
 of benzene, 113 
 
 of methylated spirit, 72 
 
 of organic compounds, 1 
 
 Q. 
 
 QUINHYDEONE, 139 
 
 Quinone, 138 
 
 R. 
 
 RAOULT'S method for determina- 
 tion of molecular weight, 50 
 
 Reducing agents, action of, on 
 nitrobenzene, 123 
 
 Refrigerating funnel, 20 
 
 S. 
 
 SANDMEYEE'S reaction, 132 
 Saponification " equivalent," 109 
 
 , nature of, 94 
 
 Soap, detergent properties of, 98 
 
 Sodium ethylate, 76 
 
 Solvents, selection and application 
 
 of, 2 
 Specific gravity, determination of, 
 
 14 
 
 Stearic acid, 95 
 , reaction of, 98 
 
 , titration of, 99 
 
 Stoppers, asbestos, 127 
 
 Storax, preparation of cinnamic, 
 
 from, 144 
 Stryacin, 144 
 SuMimation of organic compounds, 
 
 13 
 
 Subliming-point, 14 
 Sulphur, detection of, 24 
 
 , estimation of, 45 
 
 Sulphuric acid, action of, on 
 
 alcohol, 76, 78, 80 
 
 , , on benzene, 114 
 
 , , on indigo, 148 
 
 , on isatin, 150 
 
156 
 
 INDEX. 
 
 Synthesis of cinnamic acid, 146 
 
 of indigo, 147 
 
 of oxalic acid, 61 
 
 T. 
 
 THIOPHENE, detection of, in ben- 
 zene, 150 
 
 Toluene, separation from benzene, 
 113 
 
 Tribromphenol, 117 
 
 V. 
 
 VAPOUR density, determination of, 
 by V. Meyer's method, 47 
 
 W. 
 
 WATER of crystallisation, deter- 
 mination of, 57 
 
 Weight, determination of mole- 
 cular, 47 
 
 Triphenylmethane, relation of, to j Wine, determination of alcohol 
 
 phthalic acid, 141 
 
 in, 74 
 
 LONDON : PRINTED BY WILLIAM CLOWES AND SONS, LIMITED, 
 STAMFORD STREET AND CHARJNG CROSS. 
 
THIS BOOK IS DUE ON THE LAST DATE 
 STAMPED BELOW 
 
 AN INITIAL FINE OF 25 CENTS 
 
 WILL BE ASSESSED FOR FAILURE TO RETURN 
 THIS BOOK ON THE DATE DUE. THE PENALTY 
 WILL INCREASE TO 5O CENTS ON THE FOURTH 
 DAY AND TO $1.OO ON THE SEVENTH DAY 
 OVERDUE. 
 
YB 16745 
 
 s