Textile chemistry : an introduction to the chemistry of the cotton industry

Front matter

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Preface

DVANCED manuals on various branches of the textile indus- As are fairly numerous, but often the proper appreciation of

them is considerably impaired by a lack of elementary chemical knowledge on the part of students and workers who are most interested in their contents.

This book is intended to supply this deficiency.

For several years the matter incorporated in this volume has been the basis of instruction introductory to the systematic study of the technical processes of Sizing, Bleaching, Dyeing and Finishing, and the Chemistry of Mill Stores and Materials. It has been put into permanent form only after considerable experiment and experience.

The Syllabus of the Union of Lancashire and Cheshire Institutes in Textile Chemistry is admittedly framed on it and the ground covered includes the subjects of the Syllabus of the City and Guilds of London Institute in “‘ Chemistry as Applied to the Cotton Industry,” Subject -28E in the programme of the Department of Technology ; it is hoped, therefore, that the book will be particularly suitable for classes in Technical Schools conducted under the regulations of these bodies.

But it should appeal also to the young studious cotton operative who desires to increase his technical knowledge, and to those in positions of authority in mills who wish to know something of the nature, preparation, and properties of the materials used in the various processes through which cotton must pass in its journey from fibre to marketable cloth.

The attempt has been made—it is hoped successfully—to produce a manual which shall serve not only as a textbook for a school course which includes lectures and practical work, but also as a complete laboratory manual for those who cannot obtain special practical instruction, and finally as a trustworthy guide for the private student.

The user hardly needs to be reminded that it should be worked through in an experimental manner; every exercise should be performed by, or demonstrated to, the student, and no attempt should be made to “cram up” the information it contains.

Several friends have been good enough to read and criticize the manuscript when ready for the press, of whom I wish to thank

CT a vi TEXTILE CHEMISTRY publicly Mr. Harold Hunter, of the Battersea Polytechnic ; Mr. H. G. Leigh, of this College; and Mr. R. B. Duerden, of Nelson.

Many pieces of apparatus described in this book are new and original and not included in the usual trade catalogues of makers of Scientific Apparatus, but arrangements have been made with

Messrs. Batrp & Tatnock, LTD., 34, Gr. Ducitrn STREET, MANCHESTER, to supply the same, and all communications relating thereto should be addressed to them and not to the publishers or author.

Small cotton hanks and dyes for experimental purposes may be obtained from

Messrs. ‘‘ COMMERCIAL LABORATORIES,”

Finally, I desire to express my gratitude.to Dr. R. H. Pickard, F.R.8., for the opportunities he gave me, when he was Principal here, of developing this scheme of work in the day classes, and for the interest he took in it to make it successful.

F. J. COOPER

BLACKBURN, LANCGs,

SECTION

I

Contents

PAGE CHEMICAL DIAGRAMS. CHEMICAL TooLs and how to use them. Balances; Bunsen Burner; Thermometers ; Hydrometers 1 Guass MANIPULATION ; Cork-boring; Fitting up Simple Pieces of Apparatus : , ‘ ‘ : 15

StmpLE Processes. Solution, Evaporation, Distillation, Crystallization, Filtration, Boiling, Melting. Determination of Melting-points and Specific Gravities. Effects of Heat ; Ignition. Determination of Moisture and Ash : ; :

CLASSIFICATION OF Matter. Identification of Common Substances. Physical and Chemical Changes

Section I

I. HOW TO DRAW DIAGRAMS q oe correct representation of chemical apparatus is a very important preliminary to the study of chemistry. Very few lessons are complete unless accompanied by sketches or

diagrams of the articles used in the various preparations.

In order to reduce to a minimum the time spent in drawing dia-

THE UNIT Fig 1 grams, and to ensure that they shall be fairly uniform, some system should be adopted. The following method will be found to be as satisfactory as any, and more so than most.

2 1

All lines should be drawn first in pencil (where necessary with the aid of a ruler), and then the completed diagram inked in freehand throughout. Every diagram in this book has been produced in this manner. ;

Circles should be drawn by tracing round a halfpenny (Fig. 1), and the diameter of this circle should be considered as a unit of length upon which is based the dimensions of the figures.

The flask is drawn, as shown in Fig. 2, by making the circle, drawing a vertical diameter, and continuing it one unit. Parallel lines are drawn on each side of this, the width between being equal to } of the © unit length. Shoulders are put on where they meet the circle, the —

CHEMICAL DIAGRAMS 3 bottom is formed by cutting a segment at the base, and the flange is formed by drawing short straight lines at right-angles.

The method for drawing a retort is shown in Fig. 3.

The triangular flask is evolved from an equilateral triangle of sides 14 units long (Fig. 4).

Corks should be drawn with lines which are continuations of the neck of the flask, etc. (Fig. 5). Figs. 6 and 7 show (much enlarged) how holes should be represented in diagrams of corks.

Glass tubing and glass bends should be drawn as two parallel lines, the corners being rounded off, the outside one last, as shown in Figs. 8, 9, 10. Fig. 11 gives the construction lines necessary for drawing the tubes in a laboratory wash bottle.

The beaker (Fig. 12), gas jar (Fig. 13), test tube (Fig. 14), and tripod (Fig. 15) are all very easily drawn.

Rectangles form the skeletons for the aspirator (Fig. 16), bell jar (Fig. 17), and Woulf bottle (Fig. 18).

CHEMICAL DIAGRAMS 5

Displace- - ment Collection

Fig 19

Durette

Parallel lines form the basis upon which are constructed the following: gas jar collecting a gas by displacement, pipette, burette, Liebig condenser, and retort stand (Figs. 19 to 23).

Fig. 24 illustrates the correct way to represent the bunsen burner.

The arrangement when heating a crucible supported by a pipeclay triangle resting on a tripod is given in Fig. 25. The combination shown in Fig. 26 represents an evaporating dish placed on a sand bath being heated by a bunsen burner provided with a rose.

Liebig Condenser

Fig.26 Frade

If a gas is being collected by displacement of water in a pneumatic trough, the diagram is drawn as shown in Fig. 27. A gas

CHEMICAL DIAGRAMS 4 jar is standing on a beehive shelf. Liquid is always represented as a continuous straight line for the surface, with dotted lines under it.

Other diagrams frequently required are:—Wuriz or distillation

Distillation Flask flask (Fig. 28), acid or thisile funnel (Fig. 29), drying tower (Fig. 30), U tube (Fig. 31), retort stand and clamp supporting boiling-tubes, etc. (Fig. 32).

The method of construction of a potash bulb is shown in three stages in Fig. 33 (1, 2, 3).

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II. CHEMICAL TOOLS

Every trade has its tools. In chemistry we call them apparatus. Those described in the following pages are of very general use and necessary for the work which follows.

1. The Balance. This is the most important piece of apparatus a chemist possesses ; without it he can do nothing: in fact chemistry ftash Bulb Fiadd was not a science till its workers used a balance. Good and accurate balances are now easily obtainable. form of. student’s balance is shown in Fig. 34.

Adjust.

Screw

CHEMICAL TOOLS 9

A box of weights containing grams and fractions of a gram must always be provided for use with a balance. Figs. 35 and 38 show in section the usual shape of brass gram weights, which are arranged in a box as shown in plan in Fig. 36. Note that the 20’s and 2’s are duplicated. A groove is cut in front for the tweezers (Fig. 37) with which weights are always moved.

Fractions of a gram are often kept in a separate box or a separate compartment. They are usually numbered in milligrams and range from 500 to 10.

SSS

SSS

SSS

Fig. 36

They are made of platinum, German silver, or aluminium in the form of foil (Fig. 39) or wire bent into various shapes. Fig. 40 is a new and very good form in which the wire is so bent that the weight in milligrams is seen at a glance.

If it is required to weigh more accurately than to 10 mg. a rider is used on the beam. This article (Fig. 41) is a stirrup of aluminium wire which weighs exactly 10 mg., and if placed in the pan of the balance acts as a weight of 10 mg. But if it be placed on the beam it only weighs that amount if placed at the end.

If the beam be divided into 10 equal spaces between the knifeedge and the pan, as in Fig. 42, and the rider is placed on one of these divisions, it will weigh less thanl0 mg. If on division 1, it will weigh I mg.; on division 2, 2 mg.; on division 3, 3 mg., etc.

THE PRocESS OF WEIGHING WITH A BALANCE

1. Test the balance to see if it is accurate—that is so when the pointer swings an equal distance on each side of the zero mark.

2. Substances must always be placed on a watch glass or other receptacle—never on the bare pan.

3. Weights should be placed on the right-hand pan. Commence with the largest ; remove it if it is too heavy, allow it to remain if too light ; and add in descending order, missing none.

ig 41

4. Do not put anything on or remove anything from the pans whilst the balance is swinging—always bring it to rest first.

5. When a correct balance is obtained count up, first the number of whole grams, then the number of milligrams, and write down with a decimal point between, e.g. 25 grams 830 mg. = 25-830 grams.

If the mg. had amounted to 83 only, a cipher would have been entered in the hundred column, e.g. 25-083.

1. Find the weight of a crucible and lid.

2. Weigh a beaker or an evaporating dish.

3. Perform a “ difference weighing,” i.e. :—

Weigh a tube containing some sand, empty some out, and reweigh the tube. Calculate how much sand was removed.

CHEMICAL TOOLS Il

4. Check the accuracy of exercise 3 by first weighing a watch glass alone, adding the expelled sand, and weighing again.

Borda devised a method for correctly weighing a substance on an incorrect balance. ‘The substance is put on one pan of the balance, and a counterpoise on the other. This counterpoise is made of a pill-box and shot and sand. - Shot is added to the empty pill-box one at a time until just too heavy ; the last shot is then taken out, and grains of sand added a few at a time, until the pointer of the balance is at zero on the scale.

The substance is now removed from the pan and weights are put in its place until the counterpoise is properly balanced. ‘Then this weight is the same as that of the original substance.

2. The Joly Balance. This instrument consists of a delicate spring suspended from a support. At the end of the spring hangs a pointer and a pan; and when required, a glass bob (Fig. 43).

The pointer moves in front of a scale attached to which is a mirror so that its position can be correctly read.

From Hooke’s law we know that the elongation of the spring is (within limits) proportional to the stretching force. Therefore if a substance is put on the pan, and the reading taken, the substance removed from the pan, and weights added until the same reading is obtained, the weight of the substance is thereby obtained. When taking a reading, the pointer should exactly hide its own F; 4 image in the mirror. te ‘4

JORODOO OO VED

1. Find the elongation of the spring for a load of 1 gram.

2. Find the elongation produced by adding the glass float, and hence calculate its weight.

3. Weigh a watch glass with it and compare result with that obtained with an ordinary balance.

4. Find the apparent loss in weight when the glass float is weighed in water and—if possible—other liquids, e.g. alcohol, sulphuric acid, glycerine, ammonia solution, zinc chloride solution.

3. The Bunsen Burner. The heating apparatus for general use in the laboratory is the bunsen burner (Fig. 44), which is capable of giving two distinct flames, known as the luminous and non-luminous according to whether the air-hole at the base is closed or open. For ordinary purposes the non-luminous flame is used.

The figure shows the correct method of heating ; the hot blue zone of the flame should just reach the bottom of the substance to be heated.

4. Thermometers are used for registering temperature. A good thermometer is a necessity ; ordinary boxwood and paper-backed patterns are of no use for scientific work.

They must be treated very carefully. The instruments are graduated in degrees Fahrenheit or Centigrade, the latter being generally used by scientists. As a rule the degrees are numbered at each 10

Figd4

(Fig. 45), one figure being on each side of the graduation mark. The 5 line is longer than the others.

The relationship between the degree Fah. and the degree Cent. is shown in Fig. 46, from which it can be seen that a degree Fah. is $ of a degree C.

5. Hydrometers are old-fashioned, inaccurate, and non-scientific pieces of apparatus; there are several modifications and empirical scales. They are however still frequently used in trade, although it is time they gave place to better apparatus.

Their construction is based on the principle of buoyancy or flotation. Ifa solid, heavier at one end than the other, and lighter on the whole than a liquid, be placed in that liquid, it will tend to float in the liquid so that the heavier end is underneath (Fig. 47).

CHEMICAL TOOLS 13

The heavier this end is made, the deeper the solid sinks in the liquid ; and the denser the liquid, the higher a given solid floats in it.

A body of this kind, when made in a long thin form, is called a hydrometer (Fig. 48). In the top part is a paper scale of degrees, which are quite empirical. Scientific data for relative densities are always given as Specific Gravity—not in degrees.

Rule to convert degrees 7'waddell to sp. gr. Multiply by 5, add 1,000, divide the number thus obtained by 1,000.

E.g. convert 38° Tw. to sp. gr.

To convert sp. grs., reverse the process, ie. multiply by 1,000, subtract 1,000, then divide by 5.

E.g. convert a sp. gr. of 1-76 to ° Tw.

Beaume’s Hydrometer Scales. (a) Lighter than water.

144 Say ee Sp. gr. = Bo 134 and ° B. = anaes 134.

.(b) Heavier than water.

Note.—‘‘ Twaddell”’ hydrometers cannot be used for liquids lighter than water. Of the many distinct Beaume scales, the above are the two best known.

Section II

I. GLASS MANIPULATION

(a) O cut glass tubing. Place the tube flat on the bench, make one cut with a triangular file ; take in both hands (Fig. 49), the nick in front, and give a “ pull bend.” (6) To bend glass tubing. Heat in the yellow portion of a bat’swing or fish-tail flame (Fig. 50), holding the tube with both hands, gently rotating it all the time. The elbows should rest on the bench and the hand be held as shown in Fig. 51, which is a side view. When the glass is quite soft it should be removed from the flame and bent into the required shape, and held fast until it sets.

Fig. 52 shows the appearance of good glass bends. Fig. 53 shows faulty ones, due to overheating, careless bending, using wrong flame, etc.

As an exercise make bends of the shape and dimensions given in Fig. 54 A to F.

(c) To smooth glass ends. Use the non-luminous flame ; hold as shown in Fig. 55, rotating all the time, till the glass just melts.

(d) To make a jet. Heat tube in a bunsen flame, remove, draw out in both directions. Cut off as shown by the dotted lines (Fig. 56), and smooth both ends.

(e) To make a closed tube or bulb tube. (.

First make a jet, then close the end by \ holding it in the bunsen flame (Fig. 55). Vs Gently blow down the open end, holding the tube vertical (Fig. 57). If the tube is to be closed only, and no bulb blown on it, \ ( the thickness should be uniform, neither sharp \

or ‘‘ blobbed ” (Fig. 58).

ee Fig 561 Fig 57

Note.——Always allow hot glass to cool on an asbestos mat, and smooth all cut ends.

II. CORK-BORING

Select a cork slightly too large for tube, flask, etc., and roll it with gentle pressure under the foot to make it soft. Select a cork-borer — slightly smaller than the tubing being used.

Hold the cork in the left hand, cork-borer in the right (Fig. 59), and bore with a screw motion, without excessive pushing. Get nearly through and then place the cork against a hard surface to finish, in

GLASS MANIPULATION 17 order to obtain a clean cut. Withdraw the borer by screwing in the reverse direction.

Fig. 60 shows plan and section of corks bored with one and two holes respectively. The test for a well-bored cork is the appearance of the boring—removed by pushing out with a smaller borer. This should be a perfect cylinder.

Tig 58

Fig 59

Practice on waste corks until proficiency is attained.

To insert glass tubing in a cork, first wet the tube and then screw it in with both hands close together. If pushed or forced in, the glass will break and a serious cut may result.

II. FITTING UP APPARATUS

The following diagrams represent apparatus commonly used in laboratory practice, and the student is advised to set up each one in order to acquire manipulative dexterity.

Fig 64

Minsik L

GLASS MANIPULATION 19

Fig. 61 is of the laboratory wash bottle which contains distilled water.

Fig. 62 is a simple melting-point apparatus that will be used later. Fig. 63 represents a test tube provided with a gas leading tube, clamped on a retort stand. The evolved gas is often collected over water. Fig. 64 shows how this is done in a pneumatic trough with a beehive shelf and gas jars.

Fig. 65 is a diagram of a simple condensing arrangement for preparation of a small quantity of distilled water.

Section III

SIMPLE PROCESSES I. SOLUTION

ATER is a solvent, i.e. a liquid which is capable of dissolving substances. When a substance dissolves in a

\ \ liquid, it disappears to sight as a separate substance— it may however impart a colour. The substance itself is said to be soluble in the solvent and the liquid thereby produced is called a solution.

Water is not a universal solvent, but it will dissolve more substances than any other known liquid. A few substances which are insoluble, i.e. not soluble in water, are silver chloride, barium sulphate, most fats and oils. Sulphonated oils, such as Turkey red oil, are soluble in water.

Liquids which are soluble in other liquids are said to be miscible. Alcohol and glycerine are miscible with water; oils are not miscible with water as a general rule.

Gases vary considerably with respect to their solubilities in water. The most soluble gases are ammonia, hydrochloric acid, sulphur dioxide, sulphuretted hydrogen. The least soluble are hydrogen, oxygen, nitrogen, air, and carbon monoxide.

The extreme solubility of ammonia in water can be illustrated by means of the apparatus shown in Figs. 66 and 67.

As a rule the solubility of a solid substance is increased by heating the liquid (an exception is lime). Gases are expelled from solution by boiling the liquid—some completely, some only partially, as with hydrochloric acid.

Next to water the most important solvents are :—

(2) Alcohol and Methylated Spirit, which dissolves shellac, iodine, fats, resins, camphor, etc.

Solutions in alcohol are called tinctures.

(6) Carbon disulphide, which dissolves sulphur, phosphorus, fats, and oils.

(c) Ether—dissolves fats, iodine, india-rubber.

(d) Chloroform—dissolves fats, gums, resins, iodine.

(e) Benzene—dissolves fats, rubber, and many organic substances.

The dissolved solid can be recovered from solution by evaporating off the solvent, and the solvent can also be obtained if the product of evaporation be condensed—the process being known as distillation. The liquid which distils overis known as the distillate. Distillation may be used to prepare a compound—as nitric acid (q¢.v., page 72 et seq.), or to separate two mixed liquids, such as alcohol and water.

The piece of apparatus in which the vapour is cooled is called a condenser. Fig.

22, page 6 , shows a Liebig condenser, and .

Fig. 68 the worm form. An arrangement i Dink

for preparing large quantities of distilled +3

water is shown in Fig. 69. . 2 Solution sometimes raises the température (<eN = of the solvent, e.g. caustic soda in water. - Sometimes the temperature falls, e.g. when

ammonium chloride is dissolved. Sometimes

a soluble substance is mixed with an insoluble N \ one—solution can be used to separate them.

II. SATURATED SOLUTION

If equal quantities of water be mixed with gradually increasing quantities of salt, it will be found that ultimately a point is reached at which the water ceases to dissolve more salt. Similar results are obtained with other liquids and other solids. When this point is reached the solution is said to be saturated.

But if a cold saturated solution be heated, more solid can be dissolved, and if this hot solution be now cooled, the excess is deposited as crystals.

III. CRYSTALS

possess a definite geometric shape but have not a constant size. The size of the angles between the faces is one factor which helps to classify a crystal,.which may be defined as a regular solid of definite form enclosed by four or more faces.

All crystals belong to one or other of seven systems which are distinguished one from the other by the number of planes of symmetry, and the number and inclination of the axes it is possible to obtain from the specimen. A plane of symmetry is produced by cutting a crystal into two equal portions in such a way that one half is symmetrical in shape with the other (Fig. 70).

Crystals exhibit a property known as cleavage, i.e. a tendency to break more easily in one direction than another. Crystals may be obtained by various methods :—

Fig (0 (1) Cooling after Fusion, e.g. prismatic sulphur, granite, and many metals.

(2) Sublimation, e.g. iodine, white arsenic.

(3) Solution and evaporation, e.g. sugar candy; salt.

(4) Cooling a hot saturated solution (see Practical Exercises, page 24). |

IV. PRACTICAL EXERCISES IN SOLUTION, ETC.

(a) T'o determine whether a Solid is soluble or insoluble in Water or other Inguid.

Test the solvent to see what residue it leaves on evaporation to dryness.

1. Place the substance you are experimenting with in the bottom of a test tube, half fill with the solvent, place your thumb over the end and invert several times.

2. If the solid has not disappeared, gently warm over a bunsen flame, and if necessary, boil.

3. To say if the substance has dissolved. If it has disappeared there is no doubt it has dissolved. If some solid remains, the mixture must be filtered.

4. Use apparatus as shown in Fig. 75, page 25. The liquid which passes through the paper into the beaker is called the filtrate. Note that it is clear; if not, pass it through again. The dissolved portion is now present in the filtrate.

5. Evaporate this filtrate to dryness, using a porcelain basin on a sand bath. For more accurate work the apparatus shown in Fig. 71 is used.

6. If solid substance (other than that yielded by the evaporation of the solvent) be left in the basin the substance was soluble ; if not, it was insoluble. Sometimes it is desirable to weigh the basin before and after evaporation of the filtrate, sufficient information not being obtainable by inspection.

Is sodium carbonate soluble in water? Is it soluble in dilute hydrochloric acid? Is sulphur soluble in water? Is tallow soluble in carbon disulphide ? Is soap soluble in alcohol? Is it soluble in ether ?

Note——tThese last three solvents must not be brought near a flame.

(b) To find of any Change in Weight occurs when a Solid dissolves in Water.

Put a little water in a beaker, and a few crystals of ammonium chloride on a watch glass, and arrange as shown in diagram (Fig. 72). Weigh the set. Carefully tip the solid into the beaker, replace watch glass, and when the crystals have dissolved weigh the set again. What do you find ?

(c) To prepare a cold saturated Solution of a Substance and to determine the Amount of dissolved Substance in a given Volume of Solution,

Also to find the number of parts of Solid dissolved in 100 parts of Water.

A. To make the cold saturated solution (say of nitre). About one-third fill a boiling-tube with water, add a teaspoonful of nitre, and gently warm the liquid. When all the nitre is dissolved, cool under the tap. If crystals are deposited the solution is saturated. If not, more nitre must be added and the process repeated.

B. To find the dissolved solid in 100 c.c. of solution. Weigh a clean dry basin, put in 20 c.c. of solution, measured with a pipette, evaporate to expel the water, and when dry and cool, reweigh. Increase = amount of nitre in 20c.c. Calculate for 100 c.c.

C. To find parts of solid in 100 parts of water. Weigh a dry basin, half fill with solution, and weigh again. Evaporate to dryness, weigh basin and residue. From these weighings find weight of water and weight of solid present. Calculate for 100 grams of water.

How to record weighings— For Exercise B. For Exercise C.

Basin + Residue Basin + Solution

Il. ll

Basin jonlyse ce a, he Basin only Nitre dissolved in Solution = SOSOIG) eae ae Se Basin + Residue. = Basin only = Solid . nae

(d) Crystallization. To prepare Crystals of Nitre and Sal-ammoniac from Solution.

Make a hot saturated solution of the salt. Pour into a watch glass to cool. If a thick deposit is formed, too much solid has been used. Add water and repeat. If it gets cold without forming crystals, add more solid and repeat. When crystals are formed slowly and perfectly, make a sketch of them as shown in Figs. 73 and 74.

(e) Preparation of Standard Solutions.

Standard solutions are solutions which contain a known weight of the dissolved substance in a definite volume of the solution. The usual method adopted for preparing them is to weigh out the solid and then dissolve it in some of the solvent. The solution thus formed is transferred without loss to a measuring vessel, and more solvent added to make up the full volume required. The vessel is stoppered, the liquid thoroughly mixed, and finally transferred to a bottle which is suitably labelled.

EXERCISE

Prepare standard solutions containing 10 per cent. soda ash, 20 per cent. Glauber salt, and 5 per cent. common salt.

Also make a solution of the given dye stuff of such a strength that 1 c.c. of it contains -001 grams of dye.

Carefully label and preserve these standard solutions.

(f) T'o separate the Constituents of a Mixture of soluble and wmsoluble Substances, and to determine the Proportion of each present.

Transfer the mixture to a weighing bottle or test tube fitted with a cork. Weigh and record as shown below.

Empty some of the substance from the bottle into a beaker (or boiling-tube), and weigh bottle again. Enter weighing. :

Add distilled water to the beaker in sufficient Fig oy quantity to dissolve all the soluble portion.

Stir well and warm gently. When solution is considered to be com. plete, filter the liquid to separate the insoluble substance from the solution.

When filtering, remember never to have the paper more than half full, and always to pour down a glass rod (Fig. 75).

Transfer every particle of insoluble substance to the filter paper by washing down with water, or (if possible) use a camel-hair mop.

Wash the substance on the filter paper, collect all washings, add to the original filtrate and evaporate to dryness in a weighed evaporating dish on a sand or, preferably, water bath or steam oven. Record weighing.

Open out the filter paper, place it on another paper from the same packet, and dry in a steam oven. Use the bottom paper to obtain weight of filter paper only.