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George Willard Benton.

A laboratory guide for a twenty weeks course in general chemistry : containing detailed illustrations for the successful performance of over 150 experiments in general inorganic chemistry and useful tables of reference for pupil and teacher online

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SCIENCE TEXT-BOOK,



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^QENERAL CHEMISTRY



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LABORATORY GUIDE



TWENTY WEEKS COURSE



GENERAL CHEMISTRY

CONTAINING

DETAILED INSTRUCTIONS FOR THE SUCCESSFUL PERFORMANCE
OF OVER 15O EXPERIMENTS IN GENERAL INORGANIC
CHEMISTRY, AND USEFUL TABLES OF REF-
ERENCE FOR PUPIL AND TEACHER.



BY

GEORGE WILLARD BENTON, A.M.

INSTRUCTOR IN CHEMISTRY, HIGH SCHOOL, AND CHEMIST FOR THE CITY OF
INDIANAPOLIS, IND.




BOSTON, U.S.A.:

D. C. HEATH & CO., PUBLISHERS.
1893.






tf



COPYRIGHT, 1893,
BY GEO. W. BENTON.




PREFACE.



THE LABORATORY METHOD of teaching chemistry is
thoroughly established. Its superiority over the old
lecture methods has been and is being constantly
demonstrated, in the increased use of text-books and
manuals introducing chemical principles in simple form,
and in the encouragement of teachers who see in the
Laboratory the means of high development on approved
pedagogical grounds.

This method implies the adaptation of the chemical
course to the capacity of the average pupil, not only as
to apparatus and chemicals, but in the far more impor-
tant matter of the comprehension of results and the
development of great principles. Simplicity in the for-
mer respect is attained by the use of materials whose
handling is least involved and complex. Success in
reaching results and conclusions lies in the correct use
of the facts observed.

In the course, of which these experiments are a part,
little use is made of the lecture-room experiment and
only an occasional lecture is introduced as a rounding-up
or development step, following the work in laboratory
and quiz. The experiments themselves are simple, but
reasonable. The book is not a compilation, except in so
far as all books on the elements of chemistry are, of

3



4 PREFACE.

necessity, compilations. Again, it is not a book for the
teacher, but eminently one for the pupil. A good
teacher will be able to furnish a bright pupil with any
amount of supplementary work. The teacher's busi-
ness in the laboratory is to direct, the pupil's, to do the
work. It is believed that contact with the thing itself
is essential for the best development ; and it is equally
essential that the sequence of fact and conclusion should
be attained by the natural process of observation fol-
lowed by discussion. In this belief the pupil is led to
discover, as far as practicable by purely inductive pro-
cesses, the main truths of the science, the question
marks occurring at intervals inviting to the making of
many of his own questions. Experimentation is fol-
lowed by quiz and discussion, with a sprinkling of reci-
tation from the text, not omitting references to reliable
authorities.

In this way the pupil not only is unconsciously led
to adopt methods of logical thinking, and to come into
touch with chemical principles and methods of deter-
mining them, but, on the other hand, is saved the dis-
tasteful task of repeating experiments which have been
already seen and discussed in the lecture-room. Such
repetition would necessarily lack the enthusiasm and
zest of originality ; the ingenuity of the pupil would
constantly suffer from dearth of action, and the whole
work become mechanical.

The use of the note-book should be confined to the,
laboratory, that its statements, right or wrong, may be
free from "bookish" phrases, and represent the pupil's
own work. The form of the notes must necessarily
vary with the experiment and the individuality of pupil



PREFA CE. 5

and teacher. Neat, concise, logical, and complete notes
should be insisted upon from the start, and will soon
become the habit of the careful student.

The favorable criticisms of many officers and teachers
in high Schools throughout this and other States, have
induced the writer of these experiments to put them in
permanent form, in the hope that their use may be ex-
tended, and their influence upon elementary chemical
education may be marked and of a high order.

It is a pleasure at this time to acknowledge the assist-
ance received from Mr. JAMES. H. SHEPARD, author of
" Shepard's Chemistry," from whose admirable book
much of the material has been adapted, and to which
reference is constantly made ; from Mr. HUGH BRYAN,
Assistant in Chemistry, Indianapolis High School, in
the preparation of the manuscript ; and Mr. M. E.
CROWELL, Instructor in Physics, of the same school,
in the criticism of manuscript and proof. The obliga-
tions of the writer are also due Mr. E. F. HOLDEN, of
Melrose, Mass.; Mr. T. PHOENIX, New Britain, Conn.;
Mr. T. W. SMITH, Indianapolis High School No. 2 ; Mr.
W. W. GRANT, Providence, R. I. ; Mr. M. A. BRANNON,
Fort Wayne High School, and many others who have
by their criticisms aided in the presentation of the book
in its present form.

G. W. B.

INDIANAPOLIS, Aug. 10, 1893.



W7ERSITY

oar _,






FOE THE PUPIL.



1. This book must not be taken from the laboratory
without permission. Statements written in it must
represent your own laboratory work and conclusions.

2. Write in ink on the fly-leaf of the book, your name,
division, desk, and drawer in the laboratory.

3. Each pupil is held responsible for the condition of
his desk and apparatus, and is required to leave every-
thing clean and in good order.

4. Each pupil should have a good pencil, a clean
towel, old cloths for cleaning purposes, an apron, a tin
or other metal box with matches, and blank paper for
miscellaneous use.

5. To clean a test-tube, rinse it thoroughly with water
using a brush if necessary. If this does not leave it
clean, use a little cone, hydrochloric or nitric acid, or if
necessary, both at once, and then rinse with plenty of
water. A tube will clean with one-tenth the time and
trouble if not allowed to stand until dry. Brushes
must not be used with acids.

6. Pupils should be, and are, held responsible for all
unnecessary or careless breakage.

7. Glassware should be drained, not wiped, on the
inside. Before heating, tubes and flasks should be dry
on the outside,

7



8 FOR THE PUPIL.

8. In heating test-tubes, hold them in the fingers, using
the test-tube holder only when necessary. Keep the
tube constantly moving. In the case of solids which
may melt or give up water, heat should be applied
gradually, to avoid breaking.

9. Pupils are cautioned not to mix chemicals or to
attempt experiments on their own account.

10. In generating gases, care should be taken to have
all joints tight, and corks in good condition.

11. In using reagent bottles, never lay the stoppers
down. Hold them between the first and second fingers
and replace at once.

12. Tubes to which reagents are to be added, and in
which liquids are to be measured, should be held on a
level with the eye.

13. In applying reagents, especially with work in
metals, add the reagent a drop at a time. Remember
that more may be added, but none taken out of your
mixture.

14. Nothing should be put into reagent bottles, not
even stirring rods or litmus paper. Never pour back a
reagent once removed from its bottle.

15. Reagents found on the side table are for general
use, and must not be taken to individual desks.

16. Only the finer-grained solid matters and liquids
are to be put into the sink. Flush well with water,
especially when acids are tin-own out. Larger solid
refuse, burned matches, etc., must be put into the jars
provided for the purpose.

17. Before beginning the work of an experiment,



FOR THE PUPIL. 9

read the directions through carefully, get the necessary
material at hand, and then follow each step intelligently.
Do not attempt anything you do not understand. Ask
for an explanation.

18. You will have enough to do, without attending to
the work of your neighbor.

19. In experimenting, use your own hands; in ob-
serving, use your own eyes ; in reasoning, use your own
mind and common sense.

20. In making your notes, be original and clear.
Emphasize important facts ; notice minor ones. Use
symbols and formulae wherever possible, in case the
name of a substance appears more than once in the same
experiment.

21. Equations should be expressed in symbols and
formulae, and should not only be completed but bal-
anced. Constant use of the table of elements appended
will aid in equation work.

22. References to text-books should be consulted only
after performing the experiment.

23. Accidents, as burns, etc., should receive prompt
attention from the instructor, to avoid annoying and
perhaps serious consequences.




CONTENTS.



SUBJECTS TREATED BY EXPERIMENTS.

EXPERIMENTS.

1. Measurements, 1-2

2. Comparison of Physical and Chemical Change, ... 3-6

3. Methods of Producing Chemical Change, 7-9

4. Chemical Processes, 10- 15

5. Comparison of Elements and Compounds, .... 16- 18

6. Mechanical Mixtures, 19-20

7. To Produce a Chemical Compound from a Mechani-

cal Mixture, 21

8. Oxygen, 22-29

9. Phenomena of Combustion, 30- 36

10. The Blowpipe Oxidizing and Reducing Flames, . . 37- 39

11. Kindling Temperature, 40- 44

12. Ozone, 45-46

13. Chemistry of the air, 47-48

14. Hydrogen, . 49- 55

15. Water, 56-58

16. Nitrogen, 59-60

17. Ammonia, 61- 64

18. Neutralizing an Acid with a Base, 65

19. Nitrogen and Oxygen Compounds, 66- 70

20. Nitric Acid and the Nitrates, 71-78

21. Chlorine and Chlorides, 79-83

22. Bromine and Bromides, 84- 88

23. Iodine and Iodides, 89-94

24. Hydrofluoric Acid, 95

25. Carbon, 96

26. Carbon and Hydrogen, 97- 98

27. Destructive Distillation, Coal and Wood, Coal Gas, . 99-102

11



12 CONTENTS.

EXPERIMENTS.

28. Carbon Monoxide, 103

29. Carbon Dioxide, 104-107

30. Carbonates, 108

31. Cyanides, 109

32. Sulphur, 110-112

33. Hydrogen Sulphide, 113-114

34. Sulphur 'Dioxide, 115-116

35. Sulphates, 117

36. Phosphine, 118

37. Tests for Common Acids, 119

38. Metals. Group I. Amalgams, 120

39. " " " Lead, 121-123

40. " " " Silver, 124-126

41. " " " Mercury, 127-128

42. " " " Separation, ' 129

43. " " II. Arsenic, 130-131

44. " " " Tin, 132-133

45. " " " Copper, 134-137

46. " " III. Iron, 138

47. " " " Chromium, 139-140

48. " " "|^ Aluminum, 141

49. " " "^Separation of Iron, Chromium,

and Aluminum, 142

50. " " " Nickel, 143-144

51. " " " Cobalt, 145-146

52. " " 'VZinc, < 147

53. " " IV. i, Barium, rT 148-149

54. " " " ^Strontium,< 150

55. Colored Fire, 151

56. Metals. Group IV. ^Calcium, ~ 152

57. " " V. ^Potassium, .w 153-154

58. " " " ^Sodium, 155-156



THE APPENDIX.

1. Table of References by Experiments.

2. Table of Weights and Measures.

3. Table of Principal Elements.

4. List of Chemicals and Apparatus for the Course.



HIM




n N - MEASUREMENTS.



1. Capacity of a Test-Tube. Draw in your
note-took two vertical parallel lines, 15 cm (about 6 in.)
long, and l^ cm (about in.) apart.

Connect the upper ends by a straight line, the lower
by a curved line. This figure represents the outline of
a common test-tube.

Draw a line 10 cm from the bottom, and parallel to the
top. Mark this 20 cc .

From this data show by measurement the part of
the tube filled by 10 cc , 5 cc , and 1 cc of a liquid.

Would you measure from the extreme bottom of the
curve in estimating capacity? Give reason for your
answer.

Experiment 2. To approximate Quantities of a Liquid.
Compare a test-tube from your rack with the diagram
traced in Exp. 1. Pour water into the tube, noting the
quantity required to reach the l cc , 5 CC , 10 cc , and 20 cc
marks in succession, measuring the depth and compar-
ing with the diagram.

Repeat the experiment until you are able to measure
quantities with reasonable accuracy.

Do you find all the tubes of the same diameter? If
not, what allowance must be made for these variations ?

14



16 LABORATORY GUIDE IN CHEMISTRY.

Note the curved surface of the liquid in the tube.
It is called the meniscus. (?)

It is customary in measuring liquids to measure from
the lower surface of the meniscus.

PHYSICAL AND CHEMICAL CHANGES.

Experiment 3. Place in a test-tube 10 cc of H 2 O, and
holding over the flame of the Bunsen burner, boil until
only 5 c c remain. (?)

Note the liquid condensed on the sides of the tube.
What is it?

Have the changes just noted resulted from chemical
or physical action ?

Experiment^. Place a crystal of iodine in a test-
tube and heat it moderately as long as a violet vapor
arises from the bottom of the tube. Let the tube cool.

Examine the small crystals collected near the top of
the tube. Compare with the original crystal. (?)

Heat them a little. (?) Let the tube cool. (?)
Heat the crystals again. (?)

Are you convinced that the small crystals are of the
same composition as the original crystal ?

Does this show chemical or physical action ?

Experiment 5. Examine a fragment of marble,
CaCO 3 . (?) Note taste, odor, etc., if any. (?)

Place the marble in a tube and heat it. (?)

When the tube has cooled, add about 5 CC of H 2 O,
and boil. (?)

Now add three or four drops of concentrated HC1.
(?) Insert a lighted match into the mouth of the
tube. (?)



18 LABORATORY GUIDE IN CHEMISTRY.

Place in a test-tube 5 cc of calcium hydroxide solu-
tion, Ca(OH) 2 , and by means of a delivery tube and
cork pass some of the gas evolved from the marble
through the Ca(OH) 2 solution. ( ? )

Were the changes noted due to chemical change?
Give reason.

Experiment 6. Place a small piece of sheet copper
in a tube and add about 5 cc of dilute nitric acid, HNO 3 .
(?) Note the color of the liquid. (?)

Take two drops of the liquid 011 a piece of glass and
warm gently, holding the glass in the hand over the
flame. (?)

Compare the product with the original copper. (?)

Indicate which process is chemical and which is
physical.

VARIOUS WAYS OF INDUCING CHEMICAL CHANGE.

Experiment 7. Contact of Chemical Substances. Mix
about .2 gram each of powdered potassium chlorate,
KClOa, and sugar in an evaporating dish.

Drop into the mixture 4 or 5 drops of concentrated
H 2 S0 4 . (?)

Would the first step of Exp. 6 illustrate the same
principle ?

Experiment 8. Change produced by Heat. Hold a strip
of magnesium in your nippers. Bring the end into the
flame until it becomes ignited. (?) Hold the ribbon
while burning over a piece of paper.

Examine the product. (?)

Compare the product with the original magnesium. (?)



20 LABORATORY GUIDE IN CHEMISTRY.

Experiment 9. Change produced by Solution. Mix in
a dry evaporating dish a small quantity of anhydrous
(?) ferrous sulphate, FeSO 4 , and an equal quantity
of potassium ferrocyanide, K 4 FeCy 6 .

Now moisten the mixture with water. (?)

Compare with the dry mixture. (?)

Dissolve in separate tubes a small quantity O A the
two original powders, using about 10 cc of water in
each. (?)

Pour the solutions together. (?)

Note that it is the contact of the substances in water
which causes the change.

SOME PROCESSES EMPLOYED IN CHEMISTRY.

Experiment 10. Mechanical Solution. Place in a tube
about .1 gram of common salt, NaCl. This will fill
the curved part of the tube.

Add 10 cc of H 2 O. Examine carefully and note any
change.

Holding the tube in a good light, shake it gently. (?)
Finally shake vigorously. (?)

Is the disappearance of the salt due to a physical or
chemical change ?

Problem. If l cc of H 2 O weighs 1 gram, what per
cent of NaCl is contained in the above solution ?

Experiment 11. Evaporation. Pour a few drops of
the salt solution upon a glass plate ; hold over the flame
and warm gently until the residue is dry. (?) Do not
let the liquid boil.

What has become of the water ?

Examine the residue with a magnifying glass. (?)
Note the taste. (?) Is it still salt ?



22 LABORATORY GUIDE IN CHEMISTRY.

Is your answer to the last question In Exp. 10 con-
firmed ?

Experiment 12. Chemical Solution. Pour l cc of di-
lute H 2 SO 4 on a small piece of zinc in a tube. (?)
Heat gently. (?) Compare Exp. 10.

After action ceases, evaporate a few drops of the so-
lution nearly to dryness. (?) Compare Exp. 11.

Examine the remaining substance with a magnifying
glass. (?) Compare with the original zinc. (?)

Distinguish between ordinary or mechanical solution
and chemical solution.

Experiment 13. Precipitation. To 1 c c of the salt solu-
tion obtained in Exp. 10, add 10 cc of H 2 O.

Hold the tube in a good light and add about 5 drops
of a solution of silver nitrate, AgNO 3 , a drop at a time,
and note the effects. (?) The white curdy precipitate
is silver chloride, AgCl.

Reaction : NaCl + AgNO 3 = AgCl + NaNO,.

The silver of the AgNO 3 has united with the chlorine
of the NaCl to form the insoluble solid AgCl, thus
removing the chlorine from the salt solution, and the
silver from the silver nitrate solution.

What is the object of precipitation ? Would evapora-
tion answer the same purpose ?

Define precipitation; precipitate.

The liquid remaining after precipitation is called the
menstruum.

Preserve the contents of the tube for Exp. 14.

Problem. What per cent of salt was contained in the
salt solution to which the AgNO 3 was added ?



24 LABORATORY GUIDE IN CHEMISTRY.

Experiment 14. Filtration. Fold a filter, place in a
funnel, and moisten with clear water. Support the
funnel over a clean tube.

Shake the tube containing the precipitate prepared in
the last experiment, and holding a glass rod vertically
over the funnel and near the filter, pour the contents of
the tube against the rod. Of what advantage is the
rod ?

Examine the liquid which passes through the filter.
(?) What has been accomplished ? The clear liquid
is called the filtrate. Would it be possible to remove
all the silver from a solution of silver nitrate by treat-
ing it as in Exps. 13 and 14 ? Give reasons for answer.

Experiment 15. Decantation. Treat 5 c c of the salt
solution with about 5 drops of AgNO 3 solution as be-
fore. (?) Compare Exp. 13.

Shake vigorously and allow to stand a few moments.
The precipitate settles.

Now pour off the clear liquid leaving the precipitate
in the tube. This process is called decantation. Com-
pare Exp. 14.

Which takes the less time and which is the more
accurate ?

Now take in a clean tube 1 c c of barium chloride
solution, BaCl 2 ; dilute to 5 CC with H 2 O and add two
drops of dil. H 2 SO 4 . (?) *

Shake vigorously and let stand as before. (?)

Could decanting always take the place of filtering ?
Why?



26 LABORATORY GUIDE IN CHEMISTRY.

COMPARISON OF ELEMENTS AND COMPOUNDS.

Experiment 16. The Element. Examine a piece of
platinum wire. Hold the wire in the non-luminous, or
hot flame. (?) Remove from the flame and examine.
Is the wire changed by heating?

Place another piece of the wire in a test-tube. Add
2 cc of cone. HNO 3 . (?) Heat to the boiling point. (?)

Wash the wire well by filling the tube twice with
water and pouring off again slowly, in order not to wash
away the wire.

Add as before, 2 CC of cone. HC1. (?) Heat until
near the boiling point. ( HC1 should not be boiled, as
it drives off the acid.) (?)

Have you succeeded in reducing the platinum to
simpler substances ? Define an element.

Experiment 17. The Compound. Take in a clean dry
test-tube a piece of match stick about 1 in. long.

Heat gradually and evenly, rolling the tube in the
fingers until the stick ceases to undergo change. (?)

Note the liquid produced, also the smoke and other
products. (?)

Have you succeeded in producing simpler substances
out of the pine stick ?

Remove and examine a piece of the charred" product.
(?) Note its weight.

Place the charcoal thus prepared on a piece of plati-
num foil, and holding with your nippers, subject it to
the heat of the Bunsen flame until no further change is
noted. (?)

Compare results in this experiment with the result in
Exp. 16. (?)



28 LABORATORY GUIDE IN CHEMISTRY.

Experiment 18. The Compound. Place in an evaporat-
ing dish a few grains of granulated sugar, C 12 H 22 O n .

Drop on the sugar two or three drops of strong sul-
phuric acid, H 2 SO 4 . ( ? ) Warm gently. ( ? )

What is the black substance produced?

Note the increased quantity of liquid. What is it ?

Reaction :

Ci 2 H w O u + H 2 S0 4 = 12 C + 11 H 2 + H 2 SO 4 .
Explain the equation. Define a compound.

MECHANICAL MIXTURES.

Experiment 19. Mix intimately about equal parts of
fine iron filings and flowers of sulphur. Compare the
mixture with the two ingredients. (?)

Try to separate the iron and sulphur by means of a
magnet. (?)

Cover a small quantity of the mixture with carbon
disulphide, CS 2 , on a watch-glass.

Drain the liquid onto a glass plate and let it evapo-
rate. (?) Examine the remaining substance. (?)

' Add to a very small quantity of flowers of sulphur
enough CS 2 to dissolve the sulphur. Place the solu-
tion on a glass plate and allow to evaporate. (?)

Compare with the previous product of evapora-
tion. (?)

Have you succeeded in separating the iron and sul-
phur by both processes ?

Were they physical or chemical processes ?

Experiment 20. Mix equal parts of flowers of sul-
phur, potassium chlorate, KC1O 3 , and charcoal. Corn-



30 LABORATORY GUIDE IN CHEMISTRY.

pare the mixture with the original substances. (?) Is
it possible to still distinguish the particles of each ?

Place a filter in a funnel, put a small quantity of the
mixture on the filter and wash with about 2 CC of water.
Catch the filtrate in a clean tube.

Pour three or four drops upon a glass plate and
evaporate with a low heat. (?)

Taste the substance. Taste some KC1O 3 . (?)

What remains on the filter ?

Wash the residue on the filter with about cc of
CS 2 . Collect the filtrate on a glass plate and evaporate
without heat. (?) Compare Exp. 19. (?) What
remains on the filter ?

Have the three substances been separated by chemi-
cal or by mechanical means ?

Define a mechanical mixture.



To PRODUCE A CHEMICAL COMPOUND FROM A
MECHANICAL MIXTURE.

Experiment 21. Place in a tin-box cover about a tea-
spoonful of the mixture of iron and sulphur prepared
in Exp. 19.

Hold the cover in your nippers and heat persistently in
the hot flame (under the hood) until a glow has passed
over the mixture. Some of the sulphur burns with a
blue flame (S -f- O 2 = SO 2 . Note the odor), while the
remainder combines with the iron.

Reaction : Fe -f S = FeS. Some of the iron may
remain uncombined.

Examine and compare the cooled product with the
original mixture. (?) Try it with a magnet. (?)



32 LABORATORY GUIDE IN- CHEMISTRY.

Moisten with one or two drops of H 2 SO 4 . (?) Note
the odor.

When H 2 SO 4 is brought into contact with FeS the
odor of hydrogen sulphide is noticed. (?)

Have we evidence that the iron and sulphur com-
bined?

PREPARATION AND PROPERTIES OF OXYGEN.

Experiment 22. Preparation from Mercuric Oxide, HgO.
Take about .5 in. of mercuric oxide, HgO, in a tube.

Heat the tube gradually and evenly, rolling it in the
ringers. Care must be taken not to melt the tube, but
it must be highly heated.

When hot, and continually held in the flame, plunge
into the tube, without touching the contents, a glowing
splinter of pine. (?)

Have you any evidence of chemical change taking
place ?

Examine the sides of the tube. (?) Is mercury col-
lected there ?

Reaction : HgO = Hg -f- ^ Explain the effect on
the glowing pine.

Is oxygen solid, liquid, or gaseous ?

Experiment 23. Preparation from KC10 3 . Place in a
test-tube a few crystals of potassium chlorate, KC1O 3 .

Heat carefully. The crystals soon melt, and the
liquid appears to boil. In fact, oxygen is being evolved.

Drop into the tube a piece of match stick, and con-
tinue to heat the tube enough to keep up the evolution
of the gas. (?)

How does the action compare with that of Exp. 17 ?

What evidence have you that oxygen has been pre-
pared ?



34 LABORATORY GUIDE IN CHEMISTRY.

Experiment 24. To collect a Gas over Water. Fill the
pneumatic trough with water until the shelf is sub-
merged. Fill a wide-mouth bottle with water, cover
with a glass plate, and holding the cover firmly, invert
the bottle and place on the shelf over the opening.

Why does the water remain in the bottle ?

Hold the end of a delivery tube beneath the opening
in the shelf and bfow gently through the tube. Bubbles
of air will rise through the opening and gradually fill
the bottle. Explain the change.


1 3 4 5 6

Online LibraryGeorge Willard BentonA laboratory guide for a twenty weeks course in general chemistry : containing detailed illustrations for the successful performance of over 150 experiments in general inorganic chemistry and useful tables of reference for pupil and teacher → online text (page 1 of 6)