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Full text of "Elementary applied chemistry"

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LIBRARY OF THE 
NEW YORK STATE COLLEGE 
OF HOME ECONOMICS 

CORNELL UNIVERSITY 
ITHACA, NEW YORK 




Cornell University Library 
TP 146.A6 



Elementary applied chemistry, 




3 1924 003 619 032 



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ALBERT R. MANN LIBRARY 

ITHACA, N. Y. 




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ELEMENTARY 
APPLIED CHEMISTRY 



BY 



LEWIS B. ALLYN 

DEPAKTMENT OF CHEMISTRY, STATE NORMAL SCHOOL 
WESTPIELD, MASSACHUSETTS 



' For the world was built in order 
And the atoms march in tune." 
— Emerson 



GINN AND COMPANY 

BOSTON • NEW YORK ■ CHICAGO • LONDON 



COPYRIGHT, 1912, BT 

LEWIS B. ALLYN 



ALL RIGHTS RESERVED 
912.6 



gbe attenaum grea* 

CINN AND COMPANY • PRO- 
PRIETORS • BOSTOIf ■ U.S.A. 



PREFATORY NOTE 

The object of the exercises in this book is to create and 
to foster a real love for and interest in the great science of 
chemistry, to give the pupil a broader outlook on life, 
and to cause him to feel that he is a factor in the busy, 
living world. 

These experiments and tests have been of personal value 
to hundreds of earnest students ; possibly they may be of 
value to you. If you know of some one who would profit 
by the information you may receive, pass it on. 



CONTENTS 

SECTION PAGE 

I. Filtration . . . . . •. . 1 

II. Acids and Alkalis 5 

III. Alkalis in Textile Analysis ... 7 

IV. Acids and Alkalis in the Qualitative Analysis or 

Soils . . . . . ... . 9 

V. Detection or some of the Compounds present in 

Plants . . . . 13 

VI. Exercises with Standard Solutions . . . 16 

VII. Sanitary' Analysis or Water . 28 

VIII. Examination of Baking Powder . 3-5 

IX. Analysis of Milk . . .41 

X. Examination of Ice Cream, Cheese, and Condensed 

Milk ... 52 

XI. Distillation Experiments 54 

XII. Detection of Coal-Tar Dye . . 76 

XIII. Identification of Vegetable Colors 79 

XIV. Raffia Dyeing . ... 81 
XV. Chemistry of Stains . . . 88 

XVI. Food Preservatives ... 90 

XVII. Examination of Tooth Powders ... . 95 

XVIII. Experiments with Glucose .... . . 97 

XIX. Examination of Headache Powders . . . 102 

XX. Tests for Arsenic ... 105 

XXI. Method for testing Paint and Oils . ... 109 

XXII. Determination of Food Values 113 

XXIII. Testing Urine . 118 

XXIV. Selected Exercises . ... 120 

INDEX 125 



SUGGESTIONS TO TEACHER AND PUPIL 

Be sure that the work done is correct, and then certify it. 

The use of blanks similar to the one on page x gives a 
suggestion of importance to the task performed and is con- 
ducive to honest, accurate work, and, best of all, to a regard 
for the truth. 

Much time will be saved by making counterpoises with 
stoppered vials and fine shot for beakers, crucibles, evap- 
orating dishes and specific-gravity flasks. Test the accuracy 
of these tares occasionally. 

If you are not sure of a reaction, -work with a sample 
which is known to contain the substance in question. For 
example, if the odor of phenylcarbamine is unkrtown, heat 
a few drops of commercial anilin with 5 cc. of stock solution 
of KOH. Add a cubic centimeter of chloroform, agitate 
gently, cool, and note the odor. 

Form the habit of using a pipette instead of a graduate 
whenever special accuracy is desired. 

Distilled water should be used for dilutions and solu- 
tions, especially for solutions of precision. 

Many semifluid substances may be ashed by allowing 
the flame to strike the surface of the material, meanwhile 
applying a gentle heat to the bottom of the crucible. 

Save products and samples. Bottle and label them. A 
collection is an inspiration and an incentive. 

Notebooks should be illustrated by mounted samples, 
cuts, and clippings from newspapers and magazines. 



ELEMENTARY APPLIED CHEMISTRY 
REPORT OF CHEMICAL ANALYSIS 



Sample. 



Obtained froni_ 



Manufactured by_ 



Reaction . . . 

Test 

Coal-tar dye 

Vegetable colors . . . . 

f ethyl 
AlcohoH 

L methyl . . . 

Jlineral matter or metals . 

Organic compounds (iniscellaneou.s) . 

Bases . ... . . . 

Radicals .... . . 

Essential oils 

Preservatives 

Glucose . 

Acetanilid or phenacetin 

Equation . . . . 

C fraudulent . . . 
Adulteration-; 

l^ injurious 

Quality 



KEMARKS 



I hereby certify that the above is coi-rect to the best of my knowledge. 

Name 

Date 19 



SUGGESTIONS TO TEACHER AND PUPIL xi 

Much collateral reading should be encouraged. The 
following books and pamphlets are valuable : 

Leach, A. E. Food Inspection and Analysis. John Wiley & Sons. 

Wiley, H. W. Foods and their Adulteration. Blakiston. 

Blyth, a. W. Foods, their Composition and Analysis. D. Van 
Nostrand Company. 

Pearson. Jensen's Milk Hygiene. J. B. Lippincott. 

Olsen, J. C. Pure Foods. Ginn and Company. 

Olsen, J. C. Quantitative Chemical Analysis. D. Van Nostrand 
Company. 

Snyder. Human Foods. The Macmillan Company. 

Allen, A. H. Commercial Organic Analysis. D. Van Nostrand 
Company. 

CoHN. Tests and Reagents. John Wiley & Sons. 

Bulletin No. 107, Bureau of Chemistry, United States Department 
of Agriculture. 



ELEMEI^TARY APPLIED 
CHEMISTRY 



SECTION I 
FILTRATION 

Application to Qualitative and Quantitative Analysis (2-Part 
CQmpound). A very satisfactory remedy for tonsillitis is a 
mixture consisting of equal parts of sulfur and powdered 
sugar. This is a recognized specific, and at one time was 
sold as a patent medicine at fifty cents per ounce. The 
instructor should prepare a quantity of the specific, varying 
the proportions slightly. Pass the mixture several times 
|ihrough a fine sieve. 

(a) Qualitative Work. Place a spoonful of the powder in 
a beaker. Add 50 cc. of water, boil, and filter. Test both 
filtrate and residue in any way you choose. Of what is the 
powder composed ? How do you know ? 

Copy and sign the following statement: 

I hereby certify that a mixture called Tonsillitis Specific and 
examined by me contains 

Name 

Date 



(V) Quantitative Work. Weigh as exactly as possible 
3 to 5 g. of the specific upon a carefully balanced filter 
paper. Adjust to a funnel and wash with repeated portions 
of hot water until the filtrate ceases to darken when a few 

1 



2 ELEMENTARY APPLIED CHEMISTRY 

drops are heated with strong H^SO^ ; or until a drop leaves 
no dark-colored residue when evaporated upon a piece of 
platinum foil. 

Dry the residue over a water bath ; remove and cool. 

Place the duplicate filter paper in the opposite scale pan 
and weigh the sulfur directly. Determine the weight of 
the sugar by difference. 

Copy and sign the following, or use a printed blank : 

The sample of Tonsillitis Specific as analyzed by me contains 

per cent sulfur, per cent sugar. 

I hereby certify that the above is correct to the best of my 

knowledge. 

Name . 



Application to the Analysis of a 3-Part Compound, (a) In- 
troduce a definite amount of gunpowder (2 to 3 g.) into a 
balanced filter paper. Wash with repeated portions of hot 
water. Test the filtrate for residue with the platinum foil as 
before, using only a drop or so for the test. Collect the filtrate 
and evaporate it to dryness in a tared evaporating dish. 

(by Dry the residue remaining in the filter paper. Ex- 
tinguish *aH flame in the vicinity, and wash the residue with 
tlu-ee or four 10-cc. portions of CS^. Collect filtrate No. 2 
in a small beaker. Blow on it gently through a pointed 
tube until evaporation is complete, or allow it to evaporate 
spontaneously. What remains ? 

Dry the black residue over a water bath and weigh with 
the counterpoised filter. 

Record and certify your results. 

Character and per cent of the white .salt . . . 

Character and per cent of the black residue . . 

Character and per cent of the yellow substance 

Read on the history and composition of gunpowder. 



FILTRATION 3 

Application to Quantitative Analysis of Soil. Thoroughly 
dry about 5 g. of soil procured by the pupil. Weigh 
exactly upon a balanced and folded filter paper. Place in 
a funnel and wash with successive poi'tions of hot water 
until the filtrate does not darken when heated with an 
equal volume of concentrated H^SO^. Dry the filter paper 
and contents at 100° C. Reweigh and calculate the loss of 
weight as soluble matter. Transfer the dried residue to a 
counterpoised porcelain or quartz crucible and determine 
its exact weight. Gently heat to full redness with occa- 
sional stirring, being careful not to lose any of the material. 
Continue heating until all of the organic matter is burned 
away. Cool the crucible in a desiccator and weigh the resi- 
due. Calculate the loss as insoluble organic matter. 

Tabulate as follows : 

Soluble matter . . .... % 

Insoluble organic matter % 

Mineral matter . % 

Total . 100% 

How have you seen filtration employed outside of school ? 

What is another name for the process ? 

What kind of substances may be separated by filtration ? 

Make a list of mixtures containing such substances. 

Application to Commercial Analysis of Tea. The approxi- 
mate value of tea may be determined by calculating the per 
cent of matter which is not soluble in hot water. The in- 
soluble matter should not be in excess of 60 per cent. If 
over this amount, the presence of spent or exhausted leaves 
is indicated. 

Place exactly 2 g. of the finely powdered tea in a balanced 
and folded filter paper. Extract with successive portions of 
boiling water until the filtrate runs clear. Dry the residue 



4 ELEMENTARY APPLIED CHEMISTRY 

at 100° C. Cool and reweigh. Calculate by difference in 
weight the per cent of water-soluble matter. 

Test samples of tea of various prices, and answer the 
question, Does the- price indicate the quality of tea based 
upon matter insoluble in boiling water ? 

What per cent of insoluble matter has the tea which is 
used at your home ? 

To isolate Theine, the Alkaloid of Tea. Extract a spoon- 
ful of high-grade tea in 50 cc. of boiling water. Filter the 
liquid and add 10 cc. of chloroform. Transfer the mixture 
to a separatory funnel, shake the contents vigorously for a 
minute, and allow the chloroform to settle. Draw it off 
into a clean, dry watch glass and allow it to evaporate at 
room temperature. Note the white, silky crystals and the 
pleasant odor of the theine. 

Repeat the above experiment, substituting coffee for 
tea. The alkaloid of coffee is called what ? It is identicar 
with that of tea. Its chemical symbol is CgHj^N^O^ + H^O. 
What per cent of nitrogen does it contain ? 

Application to a Domestic Analysis of Oysters. The de- 
termination of the amount of water added to shucked oys- 
ters is important from the viewpoint of the consumer. The 
per cent of water that may be separated by means of a' 
strainer or sieve should not exceed 15 per cent.i Weigh' 
on a trip balance about a pint of the samplte as purchased. 
Place in a flat-bottomed sieve and allow to drain into a 
weighed dish for twenty minutes, stirring gently from time 
to time. Determine the weight and per cent of the exterior 
liquor. Determine the weight and per cent of the drained 
oysters by difference. 

1 Merck's RepoH, July, 1910, p. 189. 



SECTION II, 
ACIDS AND ALKALIS 

Detection in Everyday Compounds. The instructor will 
show samples of acids in solid, liquid, and gaseous form, to 
do away with the impression that all acids are liquids. 

Show samples of the common alkalis. 

Discover the effect of acids and alkalis upon the vari- 
ous indicators — phenolphthalein, methyl orange, cochineal, 
carmine, and litmus. 

Take home some litmus paper cut into small strips. Test 
different articles — foods at the table, substances in the 
kitchen, laundry, etc. Be sure that the substance tested, if 
a solid, is either dissolved in water or well moistened. 

One pupil tested the following : cream of tartar, ashes, 
salt, milk, apple juice, borax, sugar, baking soda, washing 
soda, soap, vinegar, tea, kerosene, tooth powder, coffee, 
butter, stomach bitters. 

Arrange your results in three columns, thus : 

Acid Alkaline Neutral 

Give the chemical names and symbols of as many of the 
above list as possible. What per cent of the foods eaten 
during the day were acid ? alkaline ? neutral ? 

Determine the reaction of the soil from your lawn or 
garden. What advantage is it to know this reaction ? 

Thoroughly moisten 20 to 50 g. of the soil and in- 
sert two pieces of litmus paper, one red, the other blue. 



6 ELEMENTARY APPLIED CHEMISTEY 

Allow them to remain undisturbed for an hour or even 
overnight. 

What would you suggest as a suitable dressing for an 
aciel or " sour " soil ? for an alkaline one ? 

What plants have a distinctly acid reaction ? Do you 
know of any fruits which are not acid ? Find out the name 
of the acid which imparts the sour taste to the common 
sheep sorrel (^Rumex acetosella), apples, oranges, grapes, 
rhubarb, etc. What acid is found in the membranous cov- 
ering of nuts ? Mention some of the alkalis which are 
found in nature. 



SECTION III 



ALKALIS IN TEXTILE AMAL^'SIS 



Determination of the Per Cent of Wool and Cotton in 
Fabrics. Wool is soluble in a solution of NaUlI or lv(.)Il. 
C'otton is insoluble! in this reagent. 

Qualitative Work. Place a small piece of the sample in 
a test tube or crucible. Cover with 20 per cent K()1I 





Fig. 1. Mixed goods heated with K<!)H, .sliowing cotton ix'widue 

and boil for two or three minutes. If the sample en- 
tirely dissolves, what is the per cent of wool ? Suppose it 
partially dissolves, what is indicated ? Experiment with 
bits of cotton, wool, and mixed goods until you are 
familiar with the action of the caustic solution upon these 
substances. 

Caution. Take great care that none of the hot alkali 
comes in contact with the flesh or clothing. If this does 
hapjpen, apply dilute HCl at once. 



8 ELEMENTARY APPLIED CHEMISTRY 

Quantitative Work. If a portion of the cloth dissolves, cut 
a second sample about 8 cm. square. Determine the exact 
weight. Place in a beaker or large evaporating dish and 
cover with the caustic potash. Boil for three minutes, or 
until the wool is dissolved. Remove the cotton residue, tak- 
ing care not to lose any detached threads. Rinse thoroughly. 
Add a drop of phenolphthalein and sufficient HCl to make 
slightly acid. Wash, dry at 100° C, and reweigh. Calcu- 
late the per cent of wool and cotton. Devise a method for 
testing silk. 



SECTION IV 

ACIDS AND ALKALIS IN THE QUALITATIVE 
ANALYSIS OF SOILS 

The appended list comprises the more important plant 
foods, and the majority of them can be easily detected in 
common soil. 

Water Sulfuric acid as sulfates 

Lime (CaCOg) Hydrochloric acid as chlorids 

Carbon dioxid Nitric acid as nitrates 

Ferric oxid (Fe^Gj) Magnesia (MgO) 

Soda (Na^O) " Sand (SiOj) 
Potash (KgO) 

Calcium Carbonate. Place 10 g. of the soil in a test 
tube and add 2 cc. of HCl. An effervescence indicates the 
presence of a carbonate. This effervescence may frequently 
be heard when the action is only faintly visible, by placing 
the ear near the mouth of the test tube. 

Add enough water to make a thin paste and boil for about 
two minutes. Make alkaline with ammonia, and filter. Test 
the clear filtrate with an equal volume of (Jl^H^')JOfi^. A 
cloudiness or flocculent precipitate, which forms on standing, 
indicates the presence of calcium. 

CaCO, + 2 HCl = ? 
CaCl, + (NHJ,Cp,= ? 

Ferric Oxid. First Test. Boil 4 g. of the soil with 10 cc. 
of HCl (5 parts of acid and an equal volume of water). 
Filter and test half of the filtrate with ammonia added in 



10 ELEMENTAEY APPLIED CHEMISTRY 

excess. A reddish-brown, flocculent precipitate assures the 
presence of iron in the sample of soil. 

Second Test. To the other half of the filtrate add a few 
drops of potassium sulfo-cyanide (KCNS). A blood-red 
color is seen if ferric oxid is present in the original soil. 
Test further by adding a little HgCl^ to a cubic centimeter 
of the red liquid. The color should be destroyed. Write the 
reactions which take place in the first and second tests. 

Soda and Potash. Boil 50 g. of the soil in an equal 
volume of water, stirring constantly. Allow the undis- 
solved matter to settle and decant the clear liquid. Evapo- 
rate this, preferably over a water bath, to about 5 cc. Clean 
a platinum wire by heating until it gives no color to the 
blue Bunsen flame. Dip the wire into the concentrated 
filtrate and place immediately in the outer flame. A yellow 
coloration indicates soda. A lilac or violet color, best seen 
through a piece of cobalt-blue glass, indicates potash. 

Sulfuric Acid as Sulfates. To a little BaCl^ solution add 
a few drops of the filtrate left from the soda and potash 
experiment. Boil. A precipitate insoluble in acids indi- 
cates the presence of sulfates. Write the reaction between 
sodium sulfate and barium chlorid. 

Hydrochloric Acid as Chlorids. To two or three cubic 
centimeters of the soda filtrate add a few drops of AgNOg. 
Churn the contents of the test tube. A white, curdy precipi- 
tate soluble in ammonia indicates the presence of chlorids 
in the soil. 

Since other substances are lUtely to precipitate the silver 
solution, decant or filter off the ammoniacal solution and add 
an excess of HCl. If a second precipitate is seen or a decided 
milkiness is evident, the presence of chlorids is assured. 
NaCl -f- AgNO, = ? 



A(;ir)S AND ALKALIS 



11 



Nitric Acid as Nitrates. To one volume of Uiu soda- 
potash filtrate add two volume.s of .strong H,S(J^ free l'r<jni 
nitrates. Allow the mixture to cool. Incline the test tube 
and cautiously add a few drops of a cijncentrated solution 
of FeSO^, so that the li(iuids will not mix. A brownish 
ring at the junction of the two 
solutions assures the presence 
of nitrates. 

Phosphoric Acid as Phos- 
phates. T<j 5 ec. of the soda- 
potash liltrate add a few drops 
of annu(]uuim nK.ilytjdate in 
I1N(J^. Warm the evaporating 
dish gently. The presence of 
phosphates is indicated by a 
lemon-yellow color, or, if there 
is a considerable quantity pres- 
ent, b}' a yellow precipitate. 

Magnesia (MgO). 15oil 25 g. 
of the soil in 50 cc. of \\'ater and 
10 cc. of IK'l. Filter and evap- 
orate the liltrate to aljout 5 cc. 
Add a few drops of NH^C'l and 

an equal volume of NlipH. j,,,, 2. Soil before and afturboil- 
If a precipitate forms, filter and in^ in stvoiii;- HCl. Tlie i-esidue 
test the filtrate with HNa^PO^. '" "'""'^ 

A white crystalline precipitate of ^IgNH^PO^, soluble in 
acids, assures the presence of magnesium in the soil. 




Sand. W 



10 



"■. o: 



f the soil in a 250-cc. beaker with 



a small stream of water, stirring constantly until all the 
humus is washed out. Boil the residue in strong HCU 
for five minutes. Sand is the princi^jal substance left. 



12 ELEMENTARY APPLIED CHEMISTRY 

Examine with a magnifying glass. What material do you 
recognize? Can you suggest what some of the original 
rock might have been ? How could you make this experi- 
ment quantitative ? 

Another important constituent of soils is organic nitro- 
gen. Its detection and determination should be omitted 
until the pupil is familiar with the Gunning method for 
nitrogen, q.v. 



SECTION V 

DETECTION OF SOME OF THE COMPOUNDS 
PRESENT IN PLANTS 

By far the greater part of the growing plant is carbon 
and water. How could you prove this ? 

This list comprises other compounds present in plants 
and vegetable matter. 



Organic nitrogen 

Chlorophyl 

Starch 


Phosphates 

Sulfates 

Chlorids 


Potash and soda 


Iron 


Manganese (infrequently) 


Silica 



Organic Nitrogen. Grind a small handful of grass or 
hay through a meat chopper. Mix with an equal weight 
of soda lime or with strong KOH, and heat gently in an 
Erlenmeyer flask, in the mouth of which is suspended a 
strip of moist red litmus paper. The ammonia given off 
will turn the test paper blue and prove the presence of 
organic nitrogen. 

Chlorophyl. Chlorophyl is the green coloring matter 
common to growing plants. 

Grind a handful of grass or green leaves, or scrape the 
green layer from any woody stem. Triturate in a mortar 
with enough alcohol to cover the mass. Decant or filter 
the green liquid. Allow the alcohol to evaporate spon- 
taneously. The chlorophyl remains as an intensely green 

substance. 

13 



14 ELEMENTARY APPLIED CHEMISTRY 

When extracted from suitable kinds of leaves, as spinach, 
parsley, etc., the chlorophyl is sometimes used for color- 
ing confections; jellies, and beverages. Of what use is 
chlorophyl to plants? 

Starch. Grind a few kernels of corn or any kind of 
grain ; scrape a potato, or bruise any kind of root. Boil 
with 10 cc. of water. Cool the contents of the tube and 
add a few drops of iodin. A distinct blue coloration is 
proof of the presence of starch. 

Potash and Soda. First Test. Place a handful of dried 
grass in a white enameled pan or upon a porcelain tile. 
Light it with a blazing splint.. When it has stopped burn- 
ing collect the residue in a porcelain crucible. Repeat the 
experiment several times until the crucible is half full. 
Heat until the contents are thoroughly ashed. Sometimes 
the ash will be greenish, due to the presence Of manganese, 
but more frequently it will be white or light brown. Care 
must be exercised lest the ash fuse to the crucible. 

Wash the ash into a beaker and boil in 25 cc. of water. 
Allow the undissolved material to settle, and reserve. Ex- 
amine the clear liquid directly for potash and soda by the 
flame test, as directed for the analysis of soils. If the results 
are not positive, evaporate 10 cc. of the liquid to dryness 
and repeat the test. Is the liquid acid or alkaline ? 

Second Test. Cut the bottom from a quart bottle or use 
a glass percolator. Loosely plug the neck of the percolator 
with absorbent cotton. Fill about two thirds full of sifted 
wood ashes, through which allow half a liter of warm water 
to pass. Collect the filtrate in a large evaporating dish or 
enameled pan. Evaporate to dryness, but do not char. The 
grayish-white substance is potash and soda, or the " lye " 
used in the early settlements for making soft soap. Dissolve 



COMPOUNDS PRESENT IN PLANTS 15 

in a little water and treat with phenolphthalein, cochineal, 
or litmus. Apply the flame test. 

Phosphates, Sulfates, and Chlorids. Separate the unused 
portion of the liquid obtained in the first or second test 
into three parts and apply the appropriate tests, as directed 
under soil analysis. 

Iron. Boil the residue saved from the undissolved ash 
with a few cubic centimeters of HCl. Decant the liquid 
and test for iron with KCNS. 

Silica. The residue from the iron test is mainly silica. 
Wash with water, allow to settle, decant the liquid, and 
rub the grayish material with the rounded end of a glass 
rod. A distinct scratching sound can usually be heard. 

Tabulate those exercises in which you have used an acid 
or an alkali as a reagent. In which of these tests have you 
found an acid or an alkali ? 



SECTION VI 

EXERCISES WITH STANDAED SOLUTIONS 

Titration and Standard Solutions. The strength of many 
solutions may be determined with great accuracy by adding 
definite volumes of other solutions of known strength, which 
will react chemically with them. The process is known as 
titration, and is of great importance in chemical analysis. 

The added solution is called a standard solution. It is 
made to contain an accurately determined weight of chemical 
substance in a definite volume. 

A standard solution which contains 1 g. of replaceable 
hydrogen per liter is known as a normal solution. Standard 
solutions may be spoken of in terms of normal solutions, as 
1/2, 1/10, 1/50, etc., usually written N/2, N/10, N/50. 

The amount of a given substance to be dissolved in dis- 
tilled water and made up to a liter will vary directly as its 
molecular weight and inversely as the number of replace- 
able hydrogen atoms represented in its molecule. Thus a 
liter of normal HCl must contain 36.5 g. of acid, since its 
molecular weight is 36.5 and only one atom of replaceable 
hydrogen is present. A decinormal solution of this acid 
will contain 3.65 g. per liter, while a cubic centimeter will 
contain 0.00365 g. 

A liter of normal H^SO^ must contain 49 g. of acid, 
since its molecular weight is 98, and 2 atoms of replace- 
able hydrogen are present. N/10 H^SO^ will contain 4.9 g. 
per liter. 

16 



EXERCISES WITH STANDARD SOLUTIONS 17 

A liter of normal oxalic acid (H^C^O^ + 2 H^O) must 
contain 63 g. of acid, since its molecular weight is 126 and 
it contains 2 atoms of replaceable hydrogen. 

To prepare a liter of N/10 oxalic acid, weigh exactly 
6.3 g. of acid of the highest purity, which has not lost its 
water of crystallization, and transfer to a liter measuring 
flask. Add about 500 cc. distilled water and agitate to dis- 
solve the acid. This done, make up to the mark on the 
neck with more distilled water. Turn into a clean, dry 
bottle and mix thoroughly. 

A cubic centimeter of any normal acid will exactly neu- 
tralize a cubic centimeter of any normal allcali. A liter of 
normal NaOH must contain 40 g. of the hydrate, since its 
molecular weight is 40. A liter of normal KOH must con- 
tain 56 g. of the salt because its molecular weight is 56. 

That one may know when enough of a standard solution 
has been added to neutralize or to complete the reaction, it 
is customary to employ a third or neutral substance called 
an indicator. Litmus, phenolphthalein, cochineal, methyl 
orange, potassium chromate, etc. are often used. 

Phenolphthalein is a good general indicator, but must 
not be employed when more than traces of CO^ are present. 
To prepare, dissolve 1 g. of the crystals in 100 cc. of 95 per 
cent alcohol. To use, add two or three drops of the alco- 
holic solution to the acid or to the alkaline solution under 
examination. In acid or in neutral solutions phenolphthal- 
ein is colorless, but the smallest excess of alkali turns it a 
vivid purple-red. 

To prepare a liter of N/10 NaOH, weigh roughly 4 g. 
of the pure hydrate, transfer to a liter flask, and make up 
to the liter mark with distilled water. When the hydrate has 
dissolved, transfer to a large bottle and mix thoroughly. 



18 



ELEMENTARY APPLIED CHEMISTRY 



The solution must now be standardized by the N/10 oxaHc 
acid previously made. 

By means of an accurate pipette transfer 10 cc. of the 
NaOH solution to a beaker. Add two or three drops of 
phenolphthalein. Set the beaker on a white 
tile or sheet of white p^per and draw into it 
from a burette just enough N/10 oxalic acid 
so that the last drop destroys the lingering 
trace of 'pink in the alkali. Note carefully 
the amount of acid required. 

Suppose 12 cc. are used; the alkali is too 
strong, for 1 cc. of the acid must neutral- 
ize 1 cc. of the alkali. Add 50 cc. of dis- 
tilled water to the NaOH solution, mix well, 
and again titrate 10 cc. By observing the 
change made by the 50 cc. of water one 
may easily calculate the amount of 
water necessary to bring the alkaline 
solution to the exact tenth-normal 
strength. 

Suppose only 8 cc. of the acid are 
required to neutralize the solution ; 
the NaOH is too weak. Add a drop 
of saturated NaOH solution, mix well, 
and titrate a second 10-cc. portion. 
The requisite amount of alkali to be 
added may be calculated. Thus by 
adding water or alkali as required, an exact balance may 
be secured. Work for perfect standardization.^ 




Fig. 3. A convenient 
type of burette 



1 For those wishing to go more into detail with volumetric solu- 
tions, Olsen's "Quantitative Analysis" (D. Van Nostrand Co.) will be 
helpful. 



EXERCISES WITH STANDARD SOLUTIONS 19 
A cubic centimeter of N/10 NaOH is equal to 



Acetic acid (HC^HgOj) . . 


0.0060 g. 


Boric acid (HgBOj) 


0.0062 g. 


Citric acid (IIjCeHjO,, H^O) 


. .0070 g. 


Lactic acid (HCgHjOg) . . . 


0.0090 g. 


Malic acid (C^HeOj) . 


. . 0.0067 g. 


Oxalic acid (H^CgO^, 2 H^O) 


0.0063 g. 


Sulfuric acid (H2SO4) .... 


. 0.0049 g. 


Tartaric acid (H^C^H^O J 


. 0.0188 g. 



Determine the Acidity of Oranges or Lemons calculated 
as Citric Acid. Weigh or counterpoise a small, clean, dry 
evaporating dish. In this place 2 to 3 g. of orange juice 
free from pulp. If lemon juice is used, 1.5 to 2 g. is suffi- 
cient. Add two or three drops of phenolphthalein (^plie- 
nolphtJtalein, 1 g.; alcohol, 100 cc.'). Fill a burette to the zero 
mark with N/10 NaOH or talce any other convenient mark 
as zero. Allow this standard solution to drop slowly into 
the fruit juice until the first permanent trace of pmk appears 
in the well-mixed solution. If, after standing for a minute, 
the pinlc color disappears, add another drop of the alkali. 
The fruit juice has been titrated with N/10 alkali. 

Calculation 
1 cc. of N/10 NaOH is equivalent to 0.007 g. of citric acid. 

Suppose the weight of the orange juice and evaporating 

dish is ... . 15.82 g. 

Suppose the weight of the evaporating dish is . 13.30 

Weight of the orange juice is . 2.52 g. 

Suppose at the end of the reaction the burette reads . 13.80 cc. 

Suppose the zero point was .... 10.50 

Number of cubic centimeters of N/10 NaOH used 3.3 cc. 

3.3 X .007 = .0231 g. of citric acid in the 2.52 g. of juice. There- 
fore citric acid is present to the extent of 0.916 per cent. 



20 ELEMENTARY APPLIED CHEMISTRY 

Test the acidity of commercial lime and lemon juices. 
The U.S.P. requires about 7 per cent of citric acid. 

Determine the Purity of Cream of Tartar. Place exactly 
half a gram of the sample in a clean beaker and dissolve 
in boiling water. Add the phenolphthalein solution as in the 
preceding experiment and titrate with decinormal NaOH. 
After the first pink color appears, heat nearly to boiling. 
If the color disappears, add another drop of the alkali. 
Half a gram of pure cream of tartar requires approximately 
26.6 cc. (26.595) of N/10 NaOH to neutralize it. 

If your balance is suiSciently accurate, weigh exactly 
0.188 g. Dissolve in hot water and titrate, using phenol- 
phthalein. If pure, it will require 10 cc. of the N/10 alkali. 

Determine the Purity of Baking Soda. Every cubic cen- 
timeter of N/10 baking soda must contain .0084 g. of 
HNaCOg. Why? 

Titrate exactly half a gram of the sample with N/10 HCl, 
using methyl orange as an indicator. 

How many cubic centimeters were required ? Suppose the 
sample were absolutely pure, how many cubic centimeters 
of the N/10 acid would be required to neutralize it ? 

What is the per cent of purity ? Write the reaction 
between HCl and HNaCO^. 

Determine the Per Cent of Lactic Acid in Milk. Fresh 
milk should not contain over .2 per cent of acid. Cream 
for the best butter should coiitaui from .5 to .65 per cent. 

Into a clean white evaporating dish or teacup place 9 cc. 
of milk or cream, being sure to rinse the graduate into 
the cup. Titrate with N/10 NaOH, using phenolphthalein 
as an indicator. Stir the contents of the cup frequently 
with a glass rod. The rod must not be taken from the 
dish lest some of the contents be lost. Neither must alkali 



EXERCISES WITH STANDARD SOLUTIONS 21 



from the burette spatter upon it. The first permanent tint 
of pink in the milk indicates the end of the operation. The 
color should remain pink after one minute. 

The number of cubic centimeters of the standard alkali 
used, indicates directly in tenths of one per cent the amount 
of acid present. Thus : 

6 cc. of the alkali = .6 per cent of acid. 
9.3 cc. of alkali = .93 per cent of acid. 

An Exercise in testing Vinegar. " Vinegar is formed by the 
action of an organism found in the 'mother' of vinegar upon 
weak alcoholic solutions. 
This organism serves in 
some way to carry the 
oxygen of the air to the 
alcohol. The sour taste is 
largely due to acetic acid " 
(^RemseTi). 

The following equations 
illustrate the process of so- 
called acetic fermentation : 
CJ-I„0+0=C,Hp+Hp. 

alcohol 

C,H,0+0 = HC,H30, 

acetic acid 

The physical and chemi- 
cal examination of vinegar 
is full of interest. Examine a few drops under a low- 
power microscope and see if you can find any of the so- 
called " vinegar eels." They are best seen after allowing 
a large test tube of vinegar to remain undisturbed for 
several hours. The eels are usually near the surface of 
the liquid. 




Fig. 4. "' Vinegar eels." (Magnified) 
(Wilson) 



22 ELEMENTAKY APPLIED CHEMISTEY 

Total Acidity. Introduce exactly 6 cc. of the sample into 
a clean beaker and set upon a white paper or tile in a good 
light. Titrate with N/10 NaOH, using phenolphthalein as 
an indicator. 

The number of cubic centimeters of the decinormal alkali 
used, divided by 10, represents the per cent of acetic acid. 

Calculation 

Suppose 34.3 cc. of the standard alkali are required to neutralize 

34.3 
6 cc. of the vinegar ; then — — = 8.43 per cent of acetic acid. 

Proof. 1 cc. of N/10 NaOH neutralizes 0.006 g. of acetic acid. 

34.3 X .006 = 0.2053 g. of acetic acid. 

Therefore 6 g. (or 6 cc.)of vinegar contain 3.43 per cent of acetic acid. 

The acidity of pure cider vinegar should not be less 
than 4.5 per cent. 

Total Solids. Weigh exactly 10 g. of the vinegar into a 
tared crucible or evaporating dish and evaporate to dryness 
for two hours. Cool in a desiccator, weigh, and calculate 
the per cent of the residue. The total solids should not fall 
below 2 per cent by weight if the sample is cider vinegar. 

Ash. Place the vessel containing the total solids on a 
suitable triangle and burn to ash at a low red heat. Cool 
and weigh. 

The ash should not be less than 0.25 per cent. Its reac- 
tion to litmus should be distinctly alkaline. If it is not, 
it contains some mineral acid which must be determined. 
Gather some of the ash on the loop of a clean platinum 
wire and apply the flame test. View through the cobalt- 
blue glass if necessary. What base is present ? 

Add a few drops of 10 per cent HCl. What radical 
is evident? In the ash of pure cider vinegar potassium 
carbonate is prominent. 



EXERCISES WITH STANDAED SOLUTIONS 23 

Ashby's Test for Mineral Acids. Prepare a solution of log- 
wood by dissolving 0.5 g. of the extract in 100 cc. of boiling 
water. Place one drop of this solution on the bottom of an 
evaporating dish and dry over a water bath. To the dried 
residue add a drop of vinegar and dry again. Pure vinegar 
gives a yellow stain. Free mineral acids color the residue red. 

To be sure of the Ashby reaction, it is well to add a 
little H,SO^ to vinegar of known purity and compare the 
result with the residue under examination. 

To detect Sulfuric Acid in the Presence of Natural Sulfates 
of the Vinegar. Evaporate 100 cc. of the sample to one tenth 
of its volume, and when cold add 50 cc. of alcohol. Sulfuric 
acid remains in solution while the natural sulfates are pre- 
cipitated. Dilute the solution and precipitate the H^SO^ 
with BaClg. Write the reaction. 

Detection of Caramel. Caramel, or burned sugar, is some- 
times used to make the vinegar seem stronger than it really 
is, or to make it resemble cider vinegar. Shake 5 cc. of the 
sample with twice its volume of amyl alcohol. If caramel 
is present, the supernatant layer will be wholly or par- 
tially decolorized. The under layer will be a deep brown, 
depending upon the amount of caramel present. 

Detection of Coal-Tar Dye. Use the double-dyeing process 
of Sostegni and Carpentieri, q.v. 

To distinguish Cider Vinegar from Other Vinegars. Lyth- 
goe's Method. Prepare lead subacetate solution by dissolv- 
ing 180 g. of lead acetate in half a liter of water. A'dd 
110 g. of PbO and make up to 1000 g. with water. Agitate 
often and filter. 

To 25 cc. of the vinegar add 2.5 co. of the subacetate 
solution. Shake the contents of the tube. The precipitate 
should be copious and settle out in a few minutes. 



24 



ele:mextaey applied chemistey 



For comparative results, centrifuge in a graduated tube 
and read the volume of the precipitate. The amount 
piresent, in part at least, indicates the value of the vinegar. 
Unless a precipitate is formed the 
sample is not cider vinegar. 

Determination of the Approximate 
Acidity or Alkalinity of Soils. Boil 
exactly 10 g. of thoroughly dried 
soil m 30 cc. of water. Filter and 
wash the residue several times with 
small portions of liot water. Add the 
washings to the filtrate with two or 
three drops of phenolphthalem. If 
the reaction is alkaline, titrate with 
N/10 oxalic acid until the pink color 
is destroyed by addition of the last 
di-op. 

If the reaction is acid, titrate with 
N/lONaOH until the irrst tmge of 
pink appears. 

In either case express the result 
as the number of cubic centimeters of 
the N/10 solution required to neu- 
tralize the filtrate. 

Approximation of the Purity of 
Cocoa. The purity of cocoa can, m 
part at least, be determined by cal- 
culating the per cent of its ash, \\liich in pure samples 
seldom exceeds 5..5 per cent; and under ordinary condi- 
tions the ash from each gram of the sample will require 
not more than 3.7 cc. of N/10 oxalic acid to neutralize it. 
If possible, test samples from your home. 



Fig. 5. True and artifi- 
cial vinegar treated with 
lead subacetate 

The artiticial vinegar, on 

the right, sliows little or 

no effect 



EXERCISES WITH STANDARD SOLUTIONS 25 

Burn 2 g. of the sample to a carbon-free ash at the 
lowest possible heat. Cool the crucible and calculate the 
per cent of ash. Boil the contents of the crucible in 50 cc. 
of water, being sure to rinse it well and save the washings. 
Titrate with N/10 oxalic acid, using phenolphthalein as 
an indicator. 

Analysis of Soap. Insoluble Matter. Dissolve 5 g. of the 
sample in 75 cc- of water, heating if necessary. If there 
are more than mere traces of residue, filter on a tared filter 
paper, wash with hot water until the filtrate is neutral, dry 
at 105° C, and calculate the per cent. 

Test various " hand " and scouring soaps for insoluble 
matter. 

Alkali may exist in soap in at least three forms, — free, 
combmed, and as alkaline carbonates, borates, etc. 

Detection of Free Alkali. Treat the freshly cut surface 
of the soap with a few drops of the alcoholic solution of 
phenolphthalein. If no red color appears, it may be assumed 
that free alkali is absent. Take great care that no water 
comes in contact with the soap, otherwise the results may 
be misleading. 

When testmg washing powders for free alkali, dissolve a 
small quantity in alcohol and add the phenolphthalein. 

Combined Alkali. If free alkali, alkaline carbonates, bo- 
rates, etc. are absent, dissolve a gram of the soap in 20 cc. 
of hot water. Treat with phenolphthalein. A red color is 
immediately seen. Why ? 

Titrate with N/10 oxalic acid. Allow the acid to drop 
slowly from the burette until the last drop added destroys the 
pink color. Shake or stir the solution frequently during the 
operation and be sure to waste none. If after a minute 
the pink color reappears, add another di'op of the acid. 



26 ELEMENTARY APPLIED CHEMISTKY 

Free alkali may also be estimated by dissolving it 
from 1 g. of the soap by means of alcohol. Filter, wash 
with alcohol, and titrate as for combined alkali. Calcu- 
late as NaOH. 

Calculation fob Free or Combined Alkali 

1 cc. of N/10 oxalic acid neutralizes Ice. of N/10 NaOH, or 0.004 g. 
of NaOH. Suppose the number of cubic centimeters of acid required 
is 4.75 ; then the per cent of alkali present is 4.75 x .004 = .019, 
or 1.9 per cent. 

Write the reaction between oxalic acid and sodium 
hydrate. 

Total Alkali. If the soap is free from sand and other 
mineral matters, burn 2 g. to ash in a porcelain or quartz 
crucible. Cool and wash the contents into 50 cc. of water. 
Boil and titrate with N/10 oxalic acid, using two drops 
of methyl orange as an indicator. (^Dissolve 1 g. of methyl 
orange in 1 liter of water.') 

Express the result as the acid number ; that is, the num- 
ber of cubic centimeters of decinormal acid necessary to 
neutralize the alkali in 1 g. of the soap. 

Alkaline Carbonates. Place 5 g. of the soap in an Erlen- 
meyer flask and add 20 cc. of alcohol. Set a funnel in the 
neck of the flask to act as a reflux condenser, and heat on a 
water bath for ten minutes. Alkaline carbonates will be in 
the residue. Place a bit of this residue on a clean platinum 
wire and apply the flame test for sodium and potassium 
(see under Soil Analysis). Filter the alcohol and dis- 
solve the residue in warm water. Add a few drops of 
dilute HCl. A marked effervescence indicates the presence 
of carbonates ; whether Na^COg (washuig soda) or K CO 
(potash) will be indicated by the flame test. 



EXEKCISES WITH STANDARD SOLUTIONS 27 

Borates. Place 5cc. of turmeric tincture in a watch 
glass. Add a few drops of the soap dissolved in water, and 
acidify slightly with dilute HCl. Evaporate to dryness over 
a water bath. The presence of borates is indicated by the 
pronounced reddening of the dried residue. 

Record the results of your analysis in this form : 



Sa.iu'le 



Pek Cext 

Insoluble 

Matter 



Per Cent 
Free Alkali 



Per Cent 

Combined 

Alkali 



Carbonates 



SECTION VII 

SANITARY AJSTALYSIS OF WATER 

The importance of wholesome water cannot be overesti- 
mated. Do the barns, the sinks, the outbuildings, contami- 
nate the supply ? Does the water dissolve poisonous metals 
from the pipes or other sources ? Is the water hard or soft ? 
All these questions we shall be able to answer. 

Clear, sparkling, odorless water may be totally unfit for 
domestic purposes, while a suspicious-looking or peculiar- 
smellmg sample may be quite harmless. A simple chemical 
analysis is often of great value, except in the detection 
of specific disease germs, when an intelligent bacteriologi- 
cal examination is necessary. The analysis in this case, 
however, may throw much light upon the source of the 
contamination. 

Keep carefully tabulated results of your analyses. You 
can then see at a glance how the water varies from the 
normal. 

Sediment. Allow a test tube or conical glass full of the 
water to stand overnight, or centrifuge 10 cc. in a pointed 
tube. If any sediment falls, decant the liquid and exam- 
ine the deposit under a microscope. This deposit may be 
divided into two classes, harmless and suspicious matter: 
harmless matter, sand, clay, alga, diatoms; suspicious matter, 
hair, epithelial scales, bits of wool and cotton, muscle fibers, etc. 

Filter the remainder of the original sample before making 
further tests. 

28 



SANITAKY AIv^ALVSlS OF WATER 



29 



Color. Fill a clean test tube, the longer tlie better, with 
the water, or use a Nessler tube. Stand it on a while 
paper or tile, facing a good light. Cover the back of the 
tube, except an inch at the Ijottoni, ^v•ith a piece of white 
paper. On looking clown through the tube the water should 
lie perfectly transparent, or show only a faint bluish tinge. 
Pollution is indicated by tints 
of green, yellow, or brown. 

Odor. Warm about 250 cc. 
of tlie water to 3S° C. in a 
corked flask. Shake, remove 
the stopper, and smell the con- 
tents. Pure water is free from 
cidor. The udor may be classi- 
Ked as earthy, vegetable, alka- 
line, putrid, etc. 

^V putrid iidor indicates de- 
composing animal or vegetable 
matter. Jf nuicli polluted by 
fresh sew age, the odor of urine 
is )i(it infre(pient. One should 
note that many waters unfit to 
drink liave ikj odor. A positive 
odor teaches volumes ; a nega- 
tive result is of little value. 

Total Solids. These C(aisist 
for the most part of Oat'O^,, ]MgS(.)^, CaSO^ with their 
chlorids and nitrates, NaC'l, Si(J„, and organic matter. 

Evaporate 70 ce. of the water t<> dryness in a thin, 
counterpoised evaporating dish over a water or steam bath. 
Dry, cool in a desiccator, and weigh as milligrams. Every 
milligram of solids per 70 cc. represents (.me grain per gallon 




Fig. 6. A convenient rack for 
Nessler tubes 

The mu\'aljle mirror showy at an 
an^le 



30 



ELEMEXTAEY APPLIED CHEMISTRY 



in the oi'iguial sample. Total solids in good water may be 
as liigii as 30 grains per gallon. 

Save the residue and examine for phosphates. The resi- 
due from pure water is almost white. Iron gives a yellow 

or coppeiy luster to the sides 
of the dish. 

Evaporate about 50 cc. of 
the sample in a porcelain 
evaporating dish and heat 
gently at first. Charring de- 
notes the piresenee of organic 
matter. 

Determination of Chlorin. 
Pleasure 50 cc. of the M-ater 
with a }iipcttc into eacli of 
two small llasks nr fieakers. 
Add three or four drops 
of potassium chromate solu- 
tion, 10 per cent, as an indi- 
cator, coloring the contents 
of each flask exactly alike. 
Place botli llasks on a wliite 
tile in a good light. Titrate 
the water in one of the flasks 
with a standard silver solu- 
tion. Do not add more than a drop at a time. Continue 
the titration \\ith frequent agitation of the contents until 
tlie water shows the first tinge of red. The first trace is 
Ijest seen Ijy looking at the titrated sample through the 
colored water in the control flask. 

The number of cubic centimeters of tlie silver solution 
re(|uired to produce the red tinge equals the number of 




Fig. 7. Apparatus for the ileteinii 

nation of chlorin in water 

Control tlask on the left 



SANITARY ANALYSIS OF WATER 31 

parts of chlorin in 100,000 parts of water. If the water 
contains more than five parts of chlorin per 100,000, con- 
tamination from human urine or sink drains is to be sus- 
pected, unless the water is taken near the seacoast or from 
some locality where the normal sodium chlorid content 
is above this amount. This information can usually be 
obtained from any state board of health. 

"Write the reaction between silver nitrate and potassium 
chromate. 

The standard silver solution is prepared by dissolving 2.3944 g. of 
pure AgNOg in a liter of distilled water. Keep this solution in a 
yellow or black bottle away from the light. 

Detection of Ammonia. To 25 cc. of the water in a Nessler 
tube, tall test tube, or foot tube, add 5 cc. of Nessler's 
reagent and note the color. A faint yellow tinge only 
should be visible. A deeper color or turbidity indicates 
animal contamination. 

Compare the treated water with an equal volume of the 
untreated sample in a similar tube. 

The experiment may be made quantitative by comparing 
the color of the sample with different Nesslerized samples of 
distilled water which contain known quantities of NH^Cl. 

All natural waters contain a trace of ammonia, but the 
amount present should not be sufficient to cause more than 
a slight coloration with the Nessler solution. An excep- 
tion must be made in the case of rain water, which, although 
relatively pure, contains a considerable amount of ammonia 
dissolved from the atmosphere. Rain water, however, shows 
practically no nitrates or chlorin. 

Nessler's Reagent. Dissolve 62.5 g. of KI in 250 cc. of water. Re- 
serve about 10 cc. of this solution. Run into the remainder a cold, 
saturated solution of HgCl., until a permanent precipitate forms. 



32 ELEMENTARY APPLIED CHEMISTRY 

Redissolve this precipitate by means of the reserve KI solution. 
Very cautiously add more of the mercuric chlorid solution until a 
slight preciijitate remains after agitation. Add 150 g. of KOH in 
water and make up to a liter. 

Allow the precipitate to settle and decant or siphon off the clear 
liquid. This solution improves with age. 

Detection of Nitrites. Into a Nessler tube place a drop of 
HCl, 2 CO. of sulfanilic acid, an equal volume of naphthyl- 
amine hydrochlorid, and 50 cc. of the water under exami- 
nation. If a red color is produced immediately or within 
twenty minutes, the presence of iiitrites is assured. 

As a rule nitrites are never found in good water. 

Sulfanilic Solution. Dissolve 0.8 g. of the acid in 100 ec. of pure 
water, heating if necessary. 

Naphthylamine Hydrochlorid Solution. Dissolve 0.8 g. of the salt 
in 100 cc. of hot water to which 1 cc. of HCl has been added. Filter 
through bone black or add bone black to the solution, and decant as 
needed. Keep from the light. 

Detection of Nitrates. Evaporate 100 cc. of the sample 
to dryness in a white evaporating dish over a water or 
steam bath. Treat with 1 cc. of phenol-sulfonic acid, stir- 
ring thoroughly. Add 10 cc. of distilled water and half 
as much Nil OH. 

4 

In the presence of nitrates the characteristic yellow color 
of the ammonia salt of nitrophenol-sulfonic acid is formed. 

Nitrates are present in almost all natural terrestrial waters. 

Detection of Phosphates. Evaporate 70 cc. of the sample 
to dryness or use the residue from the determination of total 
solids. Add a few drops of ammonia molybdate in nitric 
acid and warm gently. There should be only a slight lemon- 
yellow coloration. A decided yellow coloration indicates 
animal pollution. The degree of intensity is sometimes 
recorded as traces, heavy traces, and very heavy traces. 



SANITARY ANALYSIS OP WATER 33 

Ammonium Molybdate Solution. Dissolve 15 g. of ammonium inolyb- 
date in 100 cc. of water, with the addition of a little ammonia if neces- 
sary. If there is pronounced turbidity, filter the solution and pour with 
constant stirring into a mixture of 50 cc. nitric acid and an equal vol- 
ume of water. Allow the solution to stand in a warm place for several 
days at a temperature of about 80° F. and decant the clear liquid. 

Determination of Absorbed Oxygen. This test gives 
reliable information concerning the amount of organic 
contamination, but does not distinguish between that of 
animal and vegetable origin. 

If more than one grain per gallon is absorbed, the water 
is probably polluted. 

Preliminary Test. Fill two test tubes half full, one with 
distilled water, the other with the sample. To each add a 
drop of strong H^SO^ and sufficient KMnO^ in distilled 
water to color each a very light purple, as nearly alike 
as possible. Boil the contents of each tube. What is the 
action of organic matter on KMnO^ ? 

Regular Test. Prepare a standard solution of KMnO^, 
0.395 g. per liter, and keep in a clean well-stoppered bottle. 

Place exactly 70 cc. of the water to be examined in a 
clean flask and add ten drops of 10 per cent H^SO^. Warm 
gently and add the standard solution from a burette, drop 
by drop, shaking the flask gently after the addition of each 
drop. As soon as the faintest tinge of pink appears, warm 
the flask again and notice whether the color is permanent. 
If not, add another drop. The first permanent tinge of pink 
indicates the end of the operation. 

Limit the test to fifteen minutes. Use an ordinary Bohe- 
mian flask. 

When 70 cc. of water is thus titrated, each cubic centi- 
meter of the permanganate solution represents 0.1 of a grain 
per gallon. Good water absorbs less than a grain per gallon. 



34 ELEMEXTAEY APPLIED CHEMISTRY 

Metallic Compounds. Lead. Evaporate 100 cc. of the 
sample to 20 cc. and add a few drops of K.^Cr^O,. A pre- 
cipitate of chrome yellow assures the presence of lead. 

Iron and Copper. Boil 2 g. of stearic acid for five minutes 
in 30 cc. of the suspected water. Set aside, and when 
cool compare its color with a sample of the acid that has 
been boiled for the same length of time in distilled water. 
Examine before a white background. Iron salts impart a 
yellow color. If traces of copper are present, the acid will 
be colored a bluish green, which can be seen even before 
the acid has solidified. 

Hardness. Titrate 100 cc. of the water with N/10 HCl, 
using methyl orange or erythrosin as an indicator. The 
number of cubic centimeters of the decinormal acid used, 
multiplied by 50, represents the number of parts of CaCOj 
per million parts of water. Calculate the results to parts 
per 100,000. Water is considered "hard" if it contains 
over five parts of CaCO^ per 100,000. 



SECTION VIII 

EXAMINATION OF BAKING POWDER 

All baking powders leave a more or less insoluble resi- 
due in the food which they are used to leaven. What salts 
does one take into his system when he eats cake or biscuit 
made with cream of tartar, with alum, or with phosphate 
baking powder ? The following reactions are of interest : 



KiKD OF Baking 

POWDEK 


Reactions 


Cream of tartar 


HKCJ-I^Oj + HNaCOj = KNaCJI^O^, + CO^ + TT.O 




PotaBemm bitartrate Rochelle saltB 


Alum .... 


KjAl^iSO^)^ + 6 HNaCOg = Al2(0H)5 + 3Na„S(), 




Burnt alum Glauber's salts 




+ K2SO4 + 6 CO, 


Phosphate . . 


H^CaCPO^)^ + 2 HNaCOj = HCaPO^ + HNaP(\ 




Calcium acid ^ 2 CO, + 2 II.,0 
phosphate ' 2 ' 2 



Determination of Carbon Dioxid. The value of a baking 
powder, in part at least, depends upon the amount of avail- 
able COj it contains. To determine this, two separate tests 
are necessary. 

Total Carbon Dioxid. This determination consists of lib- 
erating the COj from a weighed amount of the sample, 
passing the gas through caustic potash, and ascertaining 
the increase in weight. Into an Erlenmeyer flask of about 
150 cc. capacity weigh exactly 2 g. of baking powder. 
Fit the flask with a dropping funnel and a delivery tube 
inclined upward at an angle of about 20°. To the free 

35 



36 



ELE.MEXI'AEV APPLIED CHE:MISTRY 



end nf tlie delivery tul:)e attach a drying tnhe filled with 
granulated C'aC'l,, previously saturated with C<;).,. 

Fill a set of Liebig potash Ijulbs two thirds full of a 
solution of 1 part KOH and 2 parts water. Determine 
the exact weiglit of the prepiared Ijulbs l)y suspending from 




Img. 8. Appanitiis for the lU'tenninatii.ii (i{ carbon dioxid 

one arm of the ))a]ance. Tliis done, connect the inlet of the 
bulbs with the free end of tlie drying tube, and the outer 
end with an aspirator. 

Fill the dropping funnel half full of IIC'l (sp. gr. 1.1). 

Place a small drying tube filled with soda lime in the 
mouth of tlie funnel, to prevent any CO,, from the air 



EXAMINATION OF BAKING POWDER 37 

being drawn into the potash bulbs when the aspirator is 
in operation. 

Open the funnel slightly and allow the acid to drop slowly 
upon the sample. Adjust the aspirator so that the gas will 
be drawn through the potash bulbs at the rate of about two 
bubbles per second. When nearly all the acid has been 
added, heat the contents of the generating flask to boiling, 
until the water begins to condense in the delivery tube. 

Aspirate until the potash bulbs are cool ; then discon- 
nect and reweigh. The increased weight is due to total 
carbon dioxid. 

Write the reaction between HCl and baking soda. Is the 
absorption of CO^ by KOH due to physical or chemical 
change ? 

Residual Carbon Dioxid. Thoroughly clean the apparatus 
used in the determination of total carbon dioxid. Intro- 
duce 2 g. of the sample into the generating flask and add 
20 cc. of cold water. Allow it to stand for twenty minutes. 
Then set the flask into a tin can surrounded by boiling 
water for the same length of time. Drive off the last traces 
of gas in the pasty mixture by boiling for one minute. 
Aspirate until the air is thoroughly changed. At this 
point in the experiment connect the apparatus and perform 
the work exactly as for the determination of total carbon 
dioxid. The increase of weight in the potash bulbs is due 
to the residual carbon dioxid. 

Available Carbon Dioxid. From the per cent of total carbon 
dioxid subtract the p^ cent of residual carbon dioxid. 

The average per cent of available carbon dioxid found in 
the three principal kinds of baking powder is as follows : 
cream of tartar, 12.58; phosphate, 12.86 ; alum, 8.10 (^Bulle- 
tin No. 13, United States Bureau of Chemistry'). 



38 ELEMENTARY APPLIED CHEMISTRY 

Tests for Radicals found in Baking Powder. CMorids. 

Shake 2 to 4 g. of the sample with 25 cc. of cold water. 
Filter. This constitutes a cold-water extract. To 5 cc. of 
this extract add a few drops of 10 per cent AgNO^ solu- 
tion. If a precipitate forms, agitate and allow it to settle. 
If it is insoluble in hot water, but dissolves in ammonia, 
the presence of chlorids is indicated. 

AgN03 + XCl = ? AgCl + NH^OH = ? 

Sulfates. Treat a few^ cubic centimeters of the cold-water 
extract with barium chlorid solution. A precipitate insolu- 
ble in acids and m water assures the presence of sulfates. 

XSO^ + BaCl^ = ? 

Tartrates. Dissolve a crystal of silver nitrate in 5 cc. of 
water and add two drops of ammonia. Add 1 cc. of the 
cold-water extract and heat gently. If tartrates are present, 
the silver will be deposited as a beautiful silver mirror on 
the interior of the tube. 

Carbonates. To a gram or so of the dry baking powder 
in a test tube add a few drops of dilute HCl. Hold a gkiss 
rod wet with limewater so that the escaping gas will come 
in contact with it. If the limewater becomes milky, the 
presence of a carbonate is assured. 

Write the reaction between hydi-ochloric acid and bicar- 
bonate of soda. Write the reaction between carbon dioxid 
and limewater. 

Phosphates. Add a few drops of tlie cold-water extract to 
a cubic centimeter of ammonium molvbdate (NH ) MoO^ in 
HNOg. Heat gently. A lemon-yellow precipitate indicates 
the presence of phosphates. 

Phosphoric acid is an important constituent of the body. 
Its presence can be easily demonstrated by experiment. 



EXAMINATION OF BAKING POWDER 39 

Burn a piece of bone in a clear fire until the residue is 
perfectly white. Powder from 2 to 3 g. of this and dissolve 
in HCl. Dilute the solution about one half and add an ex- 
cess of ammonia. A white, gelatinous precipitate of calcium 
and magnesium phosphate forms. Filter, and to the filtrate 
add ammonium oxalate. The characteristic precipitate of 
CaC„0, is evident. 

What other radical was present in the bone ? 

Tests for Bases found in Baking Powder. Calcium. To a 
test tube half full of the extract add a few drops of ammo- 
nium oxalate (J^H^yjufi^. A precipitate insoluble in acetic 
acid, but soluble in hydrochloric acid, shows the presence 
of calcium. 

Write the reaction between ammonium oxalate and cal- 
cium acid phosphate. 

Ammonia. Boil 50 cc. of the extract with 25 cc. of 10 per 
cent NaOH. Test the steam with red litmus jjaper. Avoid 
touching the neck of the flask with the paper. If present, 
the liberated ammonia will turn the test paper blue. 

Write the reaction between ammonium carbonate and 
sodium hydrate. 

Aluminium. ( Thirty-first Report of the Massachusetts State 
Board of Health.') Burn to ash about 2 g. of the baking pow- 
der in a crucible. Extract with boiling water, and filter. 
To the filtrate add sufficient NH^^Cl to give a distinct odor 
of ammonia. A flocculent precipitate indicates the presence 
of aluminium. The lower grades of baking powder often 
contain salts of aluminium or of ammonium. 

Detection of Alum in Pastry as well as in Baking Powder. 
Make a tincture of logwood by digesting 5 g. of the well- 
powdered chips in 100 cc. of alcohol. Prepare a saturated 
solution of (NHJ^CO^. 



40 ELEMENTARY APPLIED CHEMISTEY 

Rub 5 g. of the baking powder, cake, cooky, or biscuit 
in a mortar with 10 cc. of water. Add 2 cc. of the logwood 
mixture and an equal volume of the ammonium carbonate 
solution. 

If alum is present, the color changes to lavender or blue, 
and does not disappear on boiling. If alum is not present, 
the color varies from red to pink. 



SECTION IX 

ANALYSIS OF MILK 

More disease and fraud eiitei' the liome tlirougli the milk 
supply than througli any (jthei' article of food. Chemistry 
is of untold benefit in protecting peo[)le fr(jm these evils. 

What is the quality and condition of the milk which you 
are using at liome? 

Fat. Examine a drop of milk under a half-inch objective 
and note the collection of various-sized fat globules. De- 
scribe their appearance and arrangement. Tlie fat of milk is 



'% %•% 




■% *li -% 


Prom CLEAN MILK 




From DIRTY M ILK 


COTTON PLUGS F 


"om 


FILTERED MILK 



Fi(i. '.) 



one of its most variable constituents, and the determination 
of the amount present is of importance. 

Determination of the Per Cent of Fat by the Babcock 
Method. This method consists in adding strong sulfuric acid 
to the milk to dissolve all of the solids except the fat, which 
is afterwards separated by means of a centrifugal macliine. 

Measure exactly 1 7.6 cc. of tlie milk into a Babc/ock bottle 
by means of a milk pipette. Add exactly 17.5 cc. of H ,SO^, 



41 



42 



elemkxtai;y applied che^iistey 



specific gnnity 1.83 at (i<)° F.. inclining tlic Ijottle so that 
tlie acvl Avill niu in slowly and wash all adhering milk 
from tlie neck. 

Sliake ^yitll a rotary motion so as to thoronghlv mix 
the acid and milk. Avciid getting cnrds into the neck 
of the hottle. 

If the A'iork has been done properly, the mixture •^'ill Ijc 
a dark lirown color and very hot. Place directly into a 
centrifuge, arranging the bottle so that the rotating head 




Fig. 10. Haml and electric centrifujjes for milk analysis or for 
sedimentation 



will lialance properly. If the machine yibrates badly, the 
Ijalance is not correct, and it must be adjusted. 

Centrifuge for five minutes; then set the bottle into a 
pan of hot water and add sufficient hot \\"ater to bring the 
fat up to the neck of the Ijottle. 

Centrifirge for two minutes and add hot water .sufficient 
to bring the fat iippositc the graduated scale. 

Centrifuge for one ininnte and take tlie reading in tenths 
of 1 per cent directly from the srale. 

.V [lair of small di\'iilers is us(.d'ul for determining the 
length of the fat column. This dctermuicd, place one leg of 



ANALYSIS OF MILK 



43 



the dividers upon zcio and take the reading from the oppo- 
site leg. It is eustomar_y to taki; the distanee from the 
bottom of the fat column t<j the top of its meniscus as 
the true length. 

The fat in milk varies from 2.2 per cent to 9.0 per 
cent. The United States standard is 3.25 per cent. What 
is the standard in your 
state ? 

Determination of Acid- 
ity. Test both with red 
and blue litnuis paper. 
1 'erfectly fresh ct )w"s milk 
is generally alkaline. It 
is sometimes amphoteric, 
that is, it exliil)its the 
phenomenon of reacting 
alkaline with red litmus 
and acid with blue. The 
acidity increases as the 
milk sugar is converted 
into lactic acid. 

For quantitative deter- 
mination of lactic acid, 
see page 20. 

Specific Gravity. De- 
termhie with a lactometer, speciirc-gravity flask, or West- 
plial balance. Milk of good standard quality slunild have 
a specific gravity of 1.027-1.033 at 00° F. 

Milk whose specific gravity varies from these limits is 
of a suspicious character. 

Total Solids, by Evaporation. Heat 2 g. of milk to a con- 
stant weight in a counterp(jised dish over a, water bath. 




Fig. 11. Babcock Ijottles for milk and 
cream with dividei'M to f acilitatt; reading 



44: 



ELE-^LEXTAl;Y APPLIED CHE.MISTKY 



The residue cif milk must not Ije heated 
over 100° C, as it will decompose and 
lose weight almost indefinitely. If prop- 
erly heated, the dried residue will be almost 
white. 

Total Solids, by Richmond's Slide Rule. 
This method is Ijy far the more conven- 
ient, and accurate enough for all practical 
purposes. 

Take the temperature of the milk and 
the lactometer reading. Set this reading on 
tile slide opposite the observed temperature. 
The corrected reading will be found oppo- 
site 60 on the scale. Call this reading A. 

Place the arrow at the riglit-haud end of 
tlie slide, o[)posite the per cent "f fat found 
by the Babeock method. Find A on the 
opposite edge of the slide. It will coincide 
with the total solids in tlie milk. 

The results obtained by these two methods 
should agree closely. 

Total solids sliould not be less than 12.50 
pier cent. 

Tests for Foreign Matter, Dirt, Hair, etc. 
Some of the most disagreeable as \\-ell as 
dangerous kinds of foreign matter A\hich 
contaminate the milk supply enter tlu-ough 
the carelessness of the pn'odneer. 

Construct a percolator by cutting the bot- 
tiim from a pint bottle, or use an ordinar\" 
glass percolator employed by a druggist. 
Insert a plug of clean absorbent cotton in 



ANATA'WIS (_>F MILK 



45 



the neclv from the inside, and allow a half pint or more of 
the well-shaken milk to slowly filter through. Remove the 
plug carefully and examine (see p. 41). 

Insoluble matter, if present, can easily be seen. Wash 
the clean end oi the plug gently with cold water. Dry and 
mount on cardboard with an appro- 
priate inscription. 

Tests for Adulterants : Artificial 
Colors. Coloring matter is sorae- 
tiines added to milk to give it a 
rich, creamy apjieaiance. The prac- 
tice, if not absolutely injui'ious, is 
at least reprehensible. Wliy? 

The two most connnonl^y em- 
ployed coloi'S ai-e annatto and coal- 
tar dye. 

Detection of Annatto. Shake 
al)out .5 cc. of the milk «ith t«ice 
its volume of ether in a large test 
tube. When the li(|uid.s have sepa- 
rated, pour off the ether extract. 
Evaporate on a water bath. ]\'Iake 
the residue alkaline with NaOIi 
and pour on a small wet iilter 
paper. The annatto will be ab- 
sorbed by the pores of the paper. 

Wash off the fat gently with slightly warmed water. 
Annatto will trive a decided orange tone, which turns to 
pink when treated with a few drops of stannous chlorid. 

Detection of Coal-Tar Dye. To 10 cc. of the milk add 
an equal volume of IICl and mix thoroughly. A pink 
coloration uulicates the presence of azo orange. 




Fic;. 13. Percolating milk, 

for dirt and other foreign 

matter 



46 ELEMENTARY APPLIED CHEMISTRY 

Tests for Adulterants : Preservatives. The preservatives 
most commonly employed to keep milk sweet for a longer 
time than nature intended are formaldehyde, compounds 
of boron (horax and boric acid'), sodium bicarbonate, and 
calcium sucrate. 

Detection of Formaldehyde (HCHO). This is one of the 
most poisonous of preservatives found in foods, and when 
so used cannot be too strongly condemned. 

Leach's Casein Test. First Part. To 10 cc. of pure milk 
add an equal volume of hydrochloric acid, contaming about 
1 per cent of Fe^Clg. Use an evaporating dish or casserole 
and heat slowly, stkring or shaking the contents constantly 
to break up the curd. When nearly but not quite boiling, 
remove the heat and note the color of the treated milk when 
hot and when cold. 

Second Part. To 50 cc. of water add 1 cc. of HCHO 
and mix the liquids well. Add two drops of this dilute 
formaldehyde to 10 cc. of pure milk and perform the work 
as directed under the first part. 

How is the presence of formaldehyde indicated ? How 
much was in the milk, assuming that the cubic centimeter 
added to the water contamed 40 per cent formaldehyde ? 

The work under the first and second parts is designed to 
make the pupil familiar with the appearance of miUi which 
contains and which does not contain formaldehyde, when 
the samples are treated with hydrochloric acid containing 
a small percentage of ferric chlorid. 

To test any given sample of milk, proceed as directed 
under the first part, and if the results are similar to those 
obtained under the second part, the presence of formalde- 
hyde is indicated. Both this and the following test are 
exceedingly delicate and the results are thoroughly reliable. 



ANALYSIS OF MILK 47 

Detection of HCHO by means of Hehner's Ring. To 25 vol- 
umes of H^SO^ add 1 volume of ferric chlorid solution. 
Place 4 cc. of this reagent in a large test tvibe and carefully 
add 5 ce. of the suspected milk, inclining the tube so that 
the milk shall rest upon the surface of the acid. In the 
presence of formaldehyde a violet rmg is seen at the contact 
of the two liquids. 

Detection of Boron Compounds. First Part. Place 5 cc. . 
of pure milk in a watch glass and acidulate slightly with 
10 per cent HCl. Add five drops of turmeric tincture and 
evaporate to dryness over a water bath. What is the 
appearance of ■ pure milk thus treated ? 

Second Part. To 5 cc. of the milk add a drop of boric acid 
or borax dissolved ui a little water. Transfer to a watch glass 
and proceed as before. Take care that the mixture does not 
char. How is boron mdicated ? The reaction is said to be 
sensitive to 1 part of boric acid in 25,000 parts of milk. The 
red color is proportionate to the amount of boron present. 

Test unknown samples of milk, performmg the work as 
outlined under the first part. If the sample of miUt is very 
rich, or if cream is under examination, dilute with two or 
three volumes of water. 

Turmeric Tincture, U.S. P. Digest any convenient amount of 
ground turmeric root in small quantities of water, discarding the 
liquids. Digest the dried residue with six times its weight of alcohol, 
and filter. 

Detection of Bicarbonate of Soda. The ash of pure milk 
shows no effervescence with HCl. Burn 10 cc. of milk to 
a white ash in a porcelain or. quartz crucible over a low 
flame. Treat the ash with a drop of 10 per cent HCl. An 
effervescence indicates bicarbonate of sodiuin. 

HNaCO, + 2 HCl = ? 



48 ELEMENTAEY APPLIED CHEMISTRY 

Detection of Calcium Sucrate. This substance is used as 
a thickener as well as a preservative, and is more frequently 
found in cream than in milk. It may be readily detected by 
means of the Baier and Neumann test which follows : 

First Part, the Sugar. To 25 cc. of the milk or cream add 
10 cc. of a 5 per cent solution of uranium acetate. Shake 
and allow to stand for five minutes. 

Filter ; if the filtrate is not clear, pour it through again. 
To 10 cc. of the clear filtrate (if the sample is cream, 
use the total filtrate) add 2 cc. of a cold saturated solu- 
tion of ammonium molybdate freshly prepared and 8 cc. of 
dilute HCl (1 part of 25 per cent HCl and 8 parts of 
water). Agitate the mixture well and place the small flask 
containing it in a water bath at 80° C. for ten minutes. 

If the sample is pure, the solution will be a peculiar 
green, resembling nickel sulfate solution ; but if sugar is 
present, it will be a Prussian blue color. 

Second Part, the Calcium. Evaporate 25 cc. of the milk 
or cream to dryness and burn to ash in a muffle. Dissolve 
the ash in 20 cc. of N/10 H^SO^. Boil to expel the CO^ and 
titrate back with N/10 NaOH, using plienolphthalein as 
the indicator. 

Express the results as cubic centimeters of N/10 acid re- 
quired to neutralize 100 g. of milk or cream. Suppose that 
the ash was dissolved in 20 ee. of N/10 acid and that 14 cc. 
N/10 NaOH neutralized the excess. It is evident that 6 cc. of 
the acid was required to neutralize the alkalinity of the ash. 

Detection of Gelatin in Milk, Cream, and Ice Cream. 
This substance is sometimes used in cream, and more 
frequently in ice cream, either as a thickener or to make 
the material stand transportation better. Gelatin is readily 
detected by the Stokes test. 



ANALYSIS OF MILK 



49 



Stokes's Test. To 10 cc. of the sample add an equal 
volume of acid nitrate of mercury solution and 20 cc. of 
cold water. Shake the mixture vigorously and allow it to 
stand for five minutes. Filter; if gelatin is present, the 
filtrate will be opalescent. Confirm by treating the filtrate 
with 1 cc. of a saturated aqueous solution of picric acid. 
The gelatin will be precipitated as a yellow solid, more or 
less flocculent in appearance. 

^Icid Nitrate of Mercury Solution. Dissolve any convenient weight 
of mercliry in twice its weight of concentrated HNOg and dilute this 
solution to 25 times its bulk with water. 

Detection of Milk adulterated by Skimming and by 
Watering. In order to do this work intelligently one must 
become familiar with the principal factors employed in 
calculations of this kind. These factors are: 

Total solids : all the constituents of milk except water. 

Fat. 

Solids not fat : obtained by subtracting the fat content 
from the total solids. 

Proteins: the nitrogenous part of the milk. 

Ash: the mineral constituents. 

Milk sugar and lactose. 

The following table, devised by H. C. Lythgoe, is believed 
to show the limits between which normal milk varies : 





Extreme limits 


Usual limits 


Herd milk 




(per cent) 


(per cent) 


(per cent) 


Total solids 


10.0-17.0 


10.5- 16.0 


11.8-15.0 


Fat 


2.2 - 9.0 


2.8- 7.0 


3.2- 6.0 


Proteins 


2.1- 8.5 


2.5- 4.5 


2.5- 4.0 


Ash 


0.6- 0.9 


0.7- 0.8 


0.7- 0.8 


Solids not fat ... . 


7.5-11.0 


7.7-10.0 


8.0- 9.5 


Milk sugar . . 


4.0- 6.0 


4.2- 5.5 


4.3- 5.3 



50 ELEMENTARY APPLIED CHEMISTRY 

A relation has been found to exist between the fat and 
proteins of milk. If the fat is given, the proteins may be 
approximately calculated by means of Van Slyke's formula : 
0.4 (F.- 3) +2.8 = P. 

Suppose the fat found in a certain sample of milk is 
3.50 per cent. According to the formula, the proteins are 
3.0 per cent. 

A relation also exists between the total solids and 
proteins, which is expressed by Olsen as 
T.S.-T.S/1.34 = P. 

Suppose the solids in the sample mentioned above were 
12.50 per cent. The proteins, by Olsen's formula, are 3.18 
per cent. If the milk is pure, the per cent of proteins calcu- 
lated by the two formulas will agree closely with a variation 
of approximately 0.2 per cent or less. If the milk is adulter- 
ated with water or by skimming, the results will not agree, 
the difference increasing with the amount of adulteration. 

Illustrations. A sample of milk known to be watered contained 
3.4 per cent fat and 10.41 per cent of total solids. 

Proteins calculated from the fat 2.96% 

Proteins calculated from the solids . . . 2.65 % 

Difference . . .... . ^31% 

A sample of milk known to be skimmed contained 2 per cent fat 
and 11.18 per cent of total solids. 

Proteins calculated from the fat . . 2.40% 

Proteins calculated from the solids . . 2.84 % 

Difference ■ -44% 

According to Lythgoe we may use these formulas in the 
indirect calculation of milk sugar, if we assume the average 
ash of milk to be 0.7 per cent. 

T.S. - (F. + [0.4 (F. - 3) + 2.8] + 0.7) = Milk sugar. 
T.S. - (F. + [T.S. -T.S./1.34] + 0.7) = Milk sugar. 



ANALYSIS OP MILK 51 

Detection of Skimmed Milk. If the sample has been 
skimmed, the calculated proteins will exceed the fat, and 
the calculated milk sugar will be too high, exceeding 4.8 
per cent, which is approximately the average milk sugar, 
according to the table. 

If the fat is less than 2.2 per cent and the solids not 
fat are above 8.5 per cent, the milk has probably been 
skimmed. 

Detection of Added Water, Copper Sulfate Method. Since 
there is no chemical test to distinguish between added 
water and the water naturally present in milk, it is cus- 
tomary to precipitate the fat and proteins by means of 
acetic acid, copper sulfate, or by spontaneous souring. This 
leaves the fat and protein in the curd, the milk sugar and 
ash in the whey. 

Dissolve 72.0 grains of pure orystaHized CiiSO^ in a little water 
and dilute to 1 liter. Adjust this to have a specific gravity of 1.0443 
at 20° C. compared with water at 4°C. 

To 1 part of copper solution add 4 parts of sweet milk, 
shake thoroughly, and filter. 

If the speciiic gravity of the clear filtrate is less than 
1.0245 at 20° C, compared with water at 4° C, added water 
is indicated. 

Dry 5 cc. of the copper serum to a constant weight over 
a water bath. Determine the weight of the 5 cc. from the 
specific gravity of the serum and calculate the total solids. 
If the total solids are below 5.28 per cent, added water is 
indicated. 



SECTION X 

EXAMINATION OF ICE CREAM, CHEESE, AND 
CONDENSED MILK 

Determination of the Fat in Ice Cream. Tare a Babcock 
cream bottle and add 10 g. of the well-mixed sample 
together with 5 or 6 cc. of water. Mix thoroughly and 
add just enough suKuric acid to turn the contents dark 
brown. Avoid an excess of acid, as the mixture will char 
badly. Proceed with the regular Babcock test. Multiply 
the scale reading by 18 and divide by 10, to find the per 
cent of fat. 

The per cent of fat m ordinary cream is also found by 
this method. 

Starch. Boil a small quantity of the sample in a test 
tube with 10 cc. of water. Cool, and add a few drops of 
iodin tincture. The well-known blue color will be evident 
if the sample contains starch. 

If starch is present, place a drop of the sample on a 
slide and examine with the microscope to see if you can 
determine the kind. 

Gelatin. Apply Stokes's test. 

Fat in Cheese. Weigh 6g. of the sample in a tared beaker. 
Add 10 cc. of boiling water and a few drops of ammonia. 
Stir gently until a smooth emulsion is formed. Transfer 
the contents to a Babcock cream bottle, cool slightly, and 
add 17.6 cc. of H^SO^, first rinsing out the beaker with the 
acid. Proceed with the regular Babcock test. 

52 



ICE CEEAM, CHEESE, CONDENSED MILK 53 

The fat reading on the scale multiplied by 18 and divided 
by the weight of the sample (6 g.) gives the per cent of 
fat in the cheese. 

How can you distinguish a full-cream cheese from a 
skimmed-milk cheese ? 

Fat in Condensed Milk (Unsweetened). Weigh 6 g. of 
the thoroughly mixed sample into a tared Babcock milk 
bottle and add enough water to make the volume up to 
about 17.6 cc. Mix, and add sufficient H^SO^ to produce the 
deep brown color required by the Babcock method. About 
14 cc. of acid will be needed. Proceed with the regular 
Babcock test. 

Multiply the fat reading by 3, to find the correct per 
cent of fat in the sample. 

Number of Times Condensed and Fat in the Original Milk. 
The average ash of pure milk is .70 per cent. Burn from 
2 to 3 g. of the sample in a crucible and calculate the per 
cent of ash. This per cent divided by . 7 gives approximately 
the number of times the milk has been condensed. 

Divide the fat found by the Babcock method by the 
number of times condensed, to find the fat in the original 
sample. 



SECTION XI 

DISTILLATION EXPERIMENTS 

Prepare a solution of 2 g. of NaCl in 50 cc. of water. 
Taste. Add a few cloves and a little sand, and color with 
red ink or dye. Pour into a retort or distilling Hask. Adjust 
a suitable condenser and distil off about one half. 

Examine both residue and distillate. What substances 
are present in the distillate that were present in the original 
mixture ? What kinds of substances are separated by distil- 
lation ? What physical principle is involved ? What prac- 
tical applications of distillation do you know of ? What is 
fractional distillation ? 

Extraction of Essential Oils. The odor and taste of many 
ve_getable substances is due, in large measure, to the presence 
of a volatile compound known as essential oil. 

What is the difference. between fixed and essential oils? 

Extract the essential oil from wintergreen leaves, sweet 
birch (^Betula lentula), cloves, cinnamon, nutmeg, pepper- 
mint, bay leaves, orange or lemon rind. 

To obtain the greatest amount of oil from any of these 
substances, grind tlu'ough a meat chopper, add water to 
make an extremely thin paste, and distil. At first the dis- 
tillate will be of a milky appearance, due to the suspended 
oil. Set aside until the liquid clears. 

A second method for the extraction of essential oils, 
which gives even better results than the first and removes 
the liability of breaking the retort through the heavy 

54 



DISTILLATION EXPERIMENTS 55 

material sticking to the bottom, is to place the finely ground 
mass in a dry flask fitted with a two-hole stopper and con- 
nected with a condenser. Steam from a generating flask is 
blown in through a long bent glass delivery tube, which 
extends nearly to the bottom of the flask. 

What is the use of essential oils ? What is the meaning 
of " essence," " extract," and " tincture " ? How may essen- 
tial oils be extracted except by distillation ? (See Harpers' 
Monthly for November, 1906. ) 

Experiments with Alcohol. Few substances are of greater 
industrial value than alcohol. Make a list of the uses of 
alcohol, either ethyl (C^H^H) or methyl (CHpH), or 
both. What is denatured alcohol ? 

Usually from 5 to 8 per cent of grain alcohol is sufficient 
to preserve the extractive principles of medicine. How do 
you account for such high amounts as 28. to 44 per cent 
sometimes present ? 

Make a medicine tester. Cut a piece of quarter-inch 
glass tubing 8 in. long. Smooth the ends. Push one end 
through a one-hole rubber stopper. To the free end fit an 
ordinary Welsbach burner and mantle. 

Place two tablespoonfuls of the liquid under examina- 
tion in a Bohemian flask and insert the stopper and tube. 
Heat the flask gently, and if alcohol is present in amounts 
of over 12 per cent, it will cause the mantle to glow brightly 
when ignited. 

To get the best effect, inclt)se the mantle in a glass or 
mica chimney. Some brands of "bitters," "tonics," "cures," 
"specifics," etc. contain enough alcohol to keep up the 
incandescence for five or six minutes. 

Instead of the Bohemian flask one may substitute a cop- 
per can fitted with a small screw stopper. Into the top of 



66 



ele:\iextai;y applied chemistry 



the can solder a piece of gas pipe about 8 in. long and fit 
with a Ijurner. Be sure that all connections are well made. 




Fig. 14. Testing apparatus to demonstrate the presence of alcohol hi 
medicine and beverages 

Preparation of Alcohol (C^H^OH). Dissolve 30 g. of cane 
sugar in 7o cc. of water, add a chop of HC'l, and boil one 



DISTILLATION EXPERIMENTS 57 

minute. If grape sugar or 20 cc. of molasses is used instead 
of cane sugar, the boiling and acid may be omitted. 

Dissolve half a cake of yeast in the same volume of water 
not above 50° C. Cool the sugar solution to about the same 
temperature and mix with the yeast. Allow to remain in a 
warm place for two or three days, and observe from time to 
time any visible changes. 

Decant the liquid into a retort and distil off about one 
half. Wash the retort, pour in the distillate, and distil off 
10 cc. Test the second distillate as follows: 

Determine its odor and taste. In it test the solubility 
of a bit of camphor or the oil from a piece of orange or 
lemon peel. Burn a little in an evaporating dish. To 
equal quantities of the distillate and acetic acid add a few 
drops of H^SO^, taking care that the contents of the tube 
do not spatter in your face. Heat gently. Notice the 
ethereal, fruitlike odor of ethyl acetate, or acetic ether, a 
substance much used in the preparation of artificial flavor- 
ing compounds. 

If the experiment has been conducted properly, the fer- 
mented liquid will contain about 4.5 per cent of alcohol 
by volume. 

Cane sugar does not ferment. Treated properly with 
acid the reaction probably takes place as follows: 

C,.H,p„ -f HP = C,H,p, + Gfl,p,. 

cane sugar glucose fructose 

CAA = 2C,HpH + ? 

The instructor or one of the pupils should prepare a 
flask of the sugar-yeast mixture. Fit a delivery tube so 
that its free end dips below the surface of a few cubic cen- 
timeters of limewater contained in a small, narrow-necked 



58 ELEMENTAKY APPLIED CHEMISTRY 

bottle. The presence of CO^, given off during the process 
of fermentation, is thus easily demonstrated.^ 

Determination of the Per Cent of Alcohol by Distillation. 
The chemical and physical characteristics of alcohol are so 
apparent that a qualitative analysis is seldom necessary. It 
is highly important, however, to know how much of this 
substance enters into the composition of various medicines 
and articles intended for internal use. To comply with the 
Food and Drugs Act, the amount of alcohol must be plainly 
stated upon the label. How does your analysis agree with 
the statement ? 

Introduce exactly 100 cc. of sweet cider, beer, wine, medi- 
cine, root-beer extracts, or any of the various " tonics " and 
" blood purifiers," into a retort and distil off about one half, 
being sure that the free end of the condenser dips deeply 
into the receiving flask. Make up the distillate to exactly 
100 cc. by adding distilled water. Determine the specific 
gravity of the thoroughly mixed distillate, and from this 
determine the per cent of alcohol by volume by means of 
the tables (pp. 66-75). 

Repeat the experiment by weighing exactly 100 g. of 
the sample in a tared flask or beaker. Transfer to a retort 
and distil as before. 

Make the distillate up to 100 g. with distilled water. 
Take the specific gravity. From this determine, by means 

1 The student will find helpful references to alcohol in the following 
publications : 

Popular Science Monthly: "History of Alcohol," Vol. LI, p. 231; 
"Physiology of Alcohol," Vol. L, p. 796; "Natural Production of Alco- 
hol," Vol. XIX, p. 238; "Discovery and Distillation of Alcohol," Vol. 
XLIII, p. 85; "Use of Alcohol in Medicine," Vol. XXXVIII, p. 86; 
"Vinous Superstitions," Vol. XXIV, p. 234; "Pigs as Wine Bibbers," 
Vol. XXIV, p. 426. 

Farmers^ Bulletin No. S68, United States Department of Agriculture. 



DISTILLATION EXPERIMENTS 



59 



01 the la))le.s, the per cent of alcohol hy weight. Discover 
any mathematical sequence in the alcoliol tal)les(pp. (l(i-75). 

Suggestions. Always carefnlly rinse the vessel contain- 
ing the measured amount of the sample int(j the retort, 
using al)out half its 
volume of water. 

Determine the tem- 
perature of the dis- 
tillate at wliich yon 
take the specific 
gra\'ity and correct 
to 60° F. or 15° t'. 
Fr)r all temperatures 
ahove these stand- 
ards sul)tract .OOOSO 
for each Centigrade 
degree or .0OUL4 for 
eacli Fahrenheit de- 
gree. For all temper- 
atures l)elow these 
standards tlie cor-' 
rection is ad<litive. 

If, fur this work, 
pupils are encour- 
aged to bring sam- 
ples from home, the 
results will often l)e 
a revelation not only to themselves but also to their parents. 

Determination of the Per Cent of Alcohol by Difference in 
Specific Gravity. Tliis method, suggested hy Ijcacli, gives 
approximate results. Use the preceding method whenever 
possible. 




Fif:. 15. Apparatus for dutorminiiii,' the 
per I't'iit of alcoliiil 



60 ELEMEXTAEY APPLIED CHEMISTRY 

Determine the specific gravity of the original sample. 
Evaporate 50 cc. over a water bath to one fourth its 
bulk. Make up to its original volume with distilled water. 
Determine the specific gravity of this dealcoholized por- 
tion. Add 1 to the original specific gravity and subtract the 
second. The difference corresponds to the alcohol in the 
original sample. 

Consult the tables (pp. 66-75) as before and read the 
per cent of alcohol by volume. 

Methyl or Wood Alcohol (CH3OH). . It is difficult to find a 
more dangerous liquid used to cheapen food products and 
medicinal preparations than methyl alcohol. It is responsi- 
ble for many cases of death and blindness. It apparently 
makes little difference whether it is taken internally in 
medicines and beverages, rubbed on the skin as a liniment, 
or its vapor inhaled; death, severe illness, or blindness 
may result.^ 

In more instances than one this poison has been found, 
in its deodorized form, in Jamaica ginger, lemon extract, 
peppermint and cinnamon, "hot drops," liniments, bitters, 
toilet waters, bay rum, witch hazel, spirits of camphor, 
paregoric, whisky. 

Detection of Methyl Alcohol. Except where a refractom- 
eter is used, the presence of wood alcohol is proved indi- 
rectly, usually by oxidizing it into formaldehyde. 

Cut a piece of No. 14 copper wire 90 cm. long. At a 
point 20 cm. from one end wind the wire neatly around a 
pencil into a close spiral until about 20 cm. from the oppo- 
site end. Push the first end through the coil and twist 
both together to form a handle. 

1 For instances of methyl alcohol poisoning, see Journal of the Ameri- 
can Medical Association, October 1-29, 1904. 



DISTILLATION EXPEEIMENTS 61 

Prepare a solution of 1 part CHgOH and 6 parts water. 
Mix, and pour 10 cc. into a 5-in. test tube whose inside 
diameter is a little greater than the diameter of the spiral. 
Stand the tube in a bottle of cold water, to cool the contents 
during the oxidizing process. 

Heat the coil to a dull red in the upper Bunsen flame 
and plunge immediately into the dilute alcohol. Withdraw 
in a second and dip into water. Repeat the operation from 
three to six times. This treatment will change all or a 
part of the alcohol into formaldehyde. 

CHpH - 2 H = HCHO. 

CuO + 2 H = ? 

What reaction takes place when the copper spiral is 
heated in the upper Bunsen flame ? 

Decant the oxidized liquid and divide into two portions. 
Add one portion to a little milk and apply the tests for 
formaldehyde. 

To the other portion add 1 drop of 1 per cent resorcin 
solution and mix well. Pour this mixture carefully clown 
the side of a wide test tube which contains a half inch of 
concentrated H^SO^. A red ring (not brown) will form 
between the two liquids. If much formaldehyde is present, 
a precipitate may be seen. This is known as Hehner's 
resorcin test. 

Test witch hazel, lemon extract, cheap vanilla, etc. 
by oxidizing 10 cc. as indicated. In the case of vanilla 
it is advisable to distil off about 10 cc. and oxidize the 
distillate. 

Caution. One must always be sure that the original 
sample does not contain formaldehyde before testing for 
methyl alcohol, otherwise the results might be misleading. 



62 



ELE.MEXTAEY APPLIED CHEMISTEY 



If there is a question, adil a few drops of the original 
sample to 5 ec. of milk ami apply the Hehiier test. 

jVll aldehydes may be removed by distilling 50 cc. of the 
sample with 10 g. of sodium bisulfite and alknvhig the mix- 
ture to stand for two hours. Distil a second time, and make 

distinctly alkaline 
withXaOH. Oxidize 
this distillate and 
test for methyl alco- 
hol (Rvjhirt JIiis.s((- 
cJiusetts State BoanJ 
of Health, moo, 
p. 401). 

Use of Alcohol in 
the Preparation of 
Vanilla Extract. The 
preparation of fla- 
^■oring extracts from 
pure and high-grade 
materials is a \alu- 
able ex[)erience for 
students of chcm- 
istrv. The work ean 
be done in the lab- 
oratory or at home. 




Fn:. 10. Copper .■spiral ami water-cooleil test 

tube for the oxiilation of methyl aleohol into 

fonnaUlehvde 



A'anilla extract is the flavtiring extract prepared from 
vanilla beans, wdth or ^^dthcait sugar or glycerin, and con- 
tains in 100 ce. the soluble matters from not less than 
10 g. of the beans (f. S. »fa)i,]ard). 

r reparatiun (United States FJiarmaeopeeia). Cut 100 g. 
(if Aanilla licans in a meat chopper, -wliieh must be clean 
and free from foreign odors. Weigh 2()0 g. of coarse 



DISTILLATION EXPERIMENTS 63 

granulated sugar; mix 650 cc. of alcohol with 350 cc. of 
water. 

Macerate the vanilla in 500 cc. of this dilute alcohol 
for twelve hours ; then drain off the liquid and set it aside. 
Transfer the vanilla to a mortar and beat it with the sugar. 
Pack the mass into a "percolator, the neck of which has 
been plugged with a piece of absorbent cotton from within, 
and pour on the reserved dilute alcohol. When this has 
disappeared from the surface, gradually pour on the men- 
struum and continue percolation until 1000 cc. have been 
obtained. E-epercolajte several times. 

Vanilla extract improves with age. If the alcoholic mix- 
ture remains on the beans for several months, the flavor of 
the extract will be improved. 

To distinguish between True and Artificial Vanilla Extract. 
Many of the so-called vanilla extracts contain little or no 
vanilla, but are composed of a dilute alcoholic solution of 
vanillin, or coumarin, prepared from coal tar. Sometimes 
true coumarin, the aromatic principle of the tonka or 
" snuff " bean, is added to make the flavor more pronounced 
and lasting. Such extracts are often colored with caramel 
or with coal-tar dye. 

Some experience is necessary to distinguish between true 
and artificial extracts by a sense of smell or taste alone, but 
there are several chemical tests which will definitely settle 
the matter. 

By the Lead Acetate Precipitate. To 40 cc. of the sample 
add an equal volume of normal lead acetate solution pre- 
pared by dissolving 189.5 g. of Fh(Cfip;)^+Sllfl in 
water and diluting to 1 liter. 

The absence of a precipitate is conclusive evidence that 
the extract is artificial. Pure vanilla thus treated yields a 



64 ELEMENTARY APPLIED CHEMISTRY 

heavy precipitate wliich should settle in a few minutes, 
leaving a clear, partially decolorized liquid (LeacK). 

By Examination of the Resins Present. Evaporate the alco- 
hol from 50 cc. of the extract over a water bath and 
make up to the original volume with water. If an alkali 
(usually KjCOg) has not been used in the manufacture of 
the extract, the resins will appear as a flocculent red to 
brown residue. Acidify with acetic acid, allow to stand for 
a few mmutes, and collect the resins on a filter paper. 
Wash the residue twice with slightly warmed water. 

Tear off a portion of the filter p9,per with the resins 
attached, and place it in a few cubic centimeters of dilute 
KOH. If the vanilla is pure, this resm will dissolve, making 
a deep red solution. 

Dissolve the rest of the resin in alcohol and divide the 
solution into three parts: 

(a) Add a few drops of ferric chlorid. There will be no 
particular change if the vanilla is pure. 

(V) Add a few drops of dilute HCl. If the vanilla is 
pure, there will be no particular color change. 

(c) Add a few drops of lead subaeetate solution. If 
the vanilla is pure, the precipitate will be so bulky as to 
almost solidify. Its filtrate will be almost colorless (^Bulletin 
No. 107, revised). 

Use of Alcohol in the Preparation of Lemon Extract. 
Lemon extract is the flavoring extract prepared from the oil 
of lemon or from lemon peel, or both, and contains not less 
than 5 per cent by volume of lemon oil ( U. S. standard). 

An extract of fair quality, but which does not contain the 
legal amount of lemon oil, may be prepared by grating the 
yellow rind from six lemons and macerating in 40 per cent 
alcohol for a few days. It can then be filtered and used. 



DISTILLATION EXPERIMENTS 65 

A legal extract can be prepared by dissolving 1 oz. of 
lemon oil in 19 oz. of alcohol. This extract can then be 
colored, if desired, by the addition of some of the bright 
yellow solution prepared from the lemon peel. 

Approximate Test for Strength and Purity. To 50 cc. of 
cold water add 2 cc. of the lemon extract. The oil will be 
thrown out of solution, giving the top of the water column a 
decided milky appearance. The depth of the milkiness, in a 
measure, enables one to judge of the strength of the extract. 
Absence of the milky color is conclusive proof that the 
extract is artificial. If it is of a decided yellow color, test 
for artificial color as directed under Coal-Tar Dye. 

Per Cent of Lemon Oil. Mitchell's Test. Place 20 cc. of 
the extract in a Babcock milk bottle. Add 1 cc. dilute HCl 
(1 to 1) and about 28 cc. of warm water at 60° C. Mix 
and allow the bottle to stand in warm water at the same 
temperature for five minutes. Centrifuge for five minutes. 
Add warm water to bring the oil into the graduated neck. 
Centrifuge for two minutes more and stand the bottle in 
water at 60° C. up to the top of the oil column for a few 
minutes, and read the per cent of oil by volume. 

If more than 2 per cent of oil is present, add 0.4 per 
cent to correct for the oil retained in solution. If between 
1 and 2 per cent, add 0.3 per cent for correction. 



66 



ELEMENTARY APPLIED CHEMISTRY 



TABLE FOR DETERMIXATIOX OF ALCOHOL PER- 
CENTAGES 1 

By Squibb, Drinkwater, and Gilpin 





Alcohol 


Specific 
Gravity 

AT|goF. 


Alcohol i 


Specific 
Gravity 

AT|g°F. 


Alcohol 


Specific 

UUAVITY 
AT|§OF. 


Per 
cent 
by vol- 
ume 


Per 

cent 

by 

weigbt 


Per 

cent 
by vol- 
ume 


Per 
cent 
by 

weight 


Per 
cent 
by vol- 
ume 


Per 
cent 

by 
weight 


1.00000 


0.00 


0.00 


0.99775 


1..50 


1.19 


0.99557 


3.00 


2.39 


0.99992 


0.05 


0.04 


.99768 


1.55 


1.23 


.99550 


3.05 


2.43 


.99984 


0.10 


0.08 


.99760 


1.60 


1.27 


.99543 


3.10 


2.47 


.99976 


0.15 


0.12 


.997.53 


1.65 


1.31 


.99.536 


3.15 


2..51 


.99968 


0.20 


0.16 


.99745 


1.70 


1.35 


.99529 


3.20 


2.55 


.99961 


0.25 


0.20 


.99738 


1.75 


1.39 


.99522 


3.25 


2.59 


.99953 


0.30 


0.24 


.99731 


1.80 


1.43 


.99515 


3.30 


2.64 


.99945 


0.35 


0.28 


.99723 


1.85 


1.47 


.99508 


3.35 


2.68 


.99937 


0.40 


0.32 


.99716 


1.90 


1..51 


.99501 


3.40 


2.72 


.99930 


0.45 


0.36 


.99708 


1.95 


1.55 


.99494 


3.45 


2.76 


.9992.3 


0.-50 


0.40 


.99701 


2.00 


1.59 


.99487 


3..50 


2.80 


.99915 


0.55 


0.44 


.99604 


2.05 


1.63 


.99480 


3.55 


2.84 


.99907 


0.60 


0.48 


.99687 


2.10 


1.67 


.99473 


3.60 


2.88 


.99900 


0.05 


0..52 


.99679 


2.15 


1.71 


.99466 


3.65 


2.92 


.99892 


0.70 


0.56 


.99672 


2.20 


1.75 


.99459 


3.70 


2.96 


.99884 


0.75 


0.60 


.99665 


2.25 


1.79 


.99452 


3.75 


3.00 


.99877 


0.80 


0.64 


.99658 


2.30 


1.83 


.99445 


3.80 


3.04 


.99869 


0.85 


0.67 


.99651 


2.35 


1.87 


.99438 


3.85 


3.08 


.99861 


0.90 


0.71 


.99643 


2.40 


1.91 


.99431 


3.90 


3.12 


.99854 


0.95 


0.75 


.99636 


2.45 


1.95 


.99424 


3.95 


3.16 


.99849 


1.00 


0.79 


.99629 


2.50 


1.99 


.99417 


4.00 


3.20 


.99842 


1.05 


0.83 


.99622 


2.55 


2.03 


.99410 


4.05 


3.24 


.99834 


1.10 


0.87 


.99615 


2.60 


2.07 


.99403 


4.10. 


3.28 


.99827 


1.15 


0.91 


.99607 


2.65 


2.11 


.99397 


4.15 


3.32 


.99819 


1.20 


0.95 


.99600 


2.70 


2.15 


.99390 


4.20 


3.36 


.99812 


1.25 


0.99 


.99593 


2.75 


2.19 


.99383 


4.25 


3.40 


.99805 


1..30 


1.03 


.99586 


2.80 


2.23 


.99376 


4.30 


3.44 


.99797 


1.35 


1.07 


.99579 


2.85 


2.27 


.99369 


4.35 


3.48 


.99790 


1.40 


1.11 


.99571 


2.90 


2.31 


.99363 


4.40 


3.52 


.99782 


1.45 


1.15 


.9956^ 


2.95 


2.. 35 


.99356 


4.45 


3.56 



1 From BuUetin No. 107, United States Department of Agriculture. 



PERCENTAGE OF ALCOHOL 



67 



PERCENTAGE OF ALCOHOL (Continued) 





Alcohol 


Specific 
Gravity 

AT|8°F. 


Alcohol 


Specific 
Gravity 
AT IgoF. 


Alcohol 


Specific 
Gravity 

ATggoF. 


Per 

cent 

by rol- 

unie 


P.er 

cent 

by 

■weiglit 


Per 
cent 
by vol- 
ume 


Per 

cent 

by 

weight 


Per 
cent 
by vol- 
ume 


Per 

cent 

by 

weight 


0.99349 


4.50 


3.60 


0.99117 


6.25 


5.00 


0.98897 


8.00 


6.42 


.99342 


4.55 


3.64 


.99111 


6.30 


5.05 


.98891 


8.05 


6.46 


.99335 


4.60 


3.68 


.99104 


6.35 


5.09 


.98885 


8.10 


6.50 


.99329 


4.65 


3.72 


.99098 


6.40 


5.13 


-.98879 


8.15 


6.54 


.99322 


4.70 


3.76 


.99091 


6.45 


5.17 


.98873 


8.20 


6.58 


.99315 


4.75 


3.80 


.99085 


6.50 


5.21 


.98867 


8.25 


6.62 


.99308 


4.80 


3.84 


.99079 


6.55 


5.25 


.98861 


8.30 


6.67 


.99301 


4.85 


3.88 


.99072 


6.60 


5.29 


.98855 


8.35 


6.71 


.99295 


4.90 


3.92 


.99066 


6.65 


5.33 


.98849 


8.40 


6.75 


.99288 


4.95 


3.96 


.99059 


6.70 


5.37 


.98843 


8.45 


6.79 


.09281 


5.00 


4.00 


.99053 


6.75 


5.41 


.98837 


8.50 


0.83 


.99274 


5.05 


4.04 


.99047 


6.80 


5.45 


.98831 


8.55 


6.87 


.99268 


5.10 


4.08 


.99040 


6.85 


5.49 


.98825 


8.60 


6.91 


.99261 


5.15 


4.12 


.99034 


6.90 


5.53 


.98819 


8.65 


6.95 


.99255 


5.20 


4.16 


.99027 


6.95 


5.57 


.98813 


8.70 


6.99 


.99248 


5.25 


4.20 


.99021 


7.00 


5.61 


.98807 


8.75 


7.03 


.99241 


5.30 


4.24 


.99015 


7.05 


5.65 


.98801 


8.80 


7.07 


.99235 


5.35 


4.28 


.99009 


7.10 


5.69 


.98795 


8.85 


7.11 


.99228 


5.40 


4.32 


.99002 


7.15 


5.73 


.98789 


8.90 


7.15 


.99222 


5.45 


4.36 


.98996 


7.20 


5.77 


.98783 


8.95 


7.19 


.99215 


5.50 


4.40 


.98990 


7.25 


5.81 


.98777 


9.00 


7.23 


.99208 


5.55 


4.44 


.98984 


7.30 


5.86 


.98771 


9.05 


7.27 


.99202 


5.60 


4.48 


.98978 


7.35 


5.90 


.98765 


9.10 


7.31 


.99195 


5.65 


4.52 


.98971 


7.40 


5.94 


.98759 


9.15 


7.35 


.99189 


5.70 


4.56 


.98965 


7.45 


5.98 


.98754 


9.20 


7.39 


.99182 


5.75 


4.60 


.98959 


7.50 


6.02 


.98748 


9.25 


7.43 


.99175 


5.80 


4.64 


.98953 


7.55 


6.06 


.98742 


9.30 


7.48 


.99169 


5.85 


4.68 


.98947 


7.60 


6.10 


.98736 


9.35 


7.52 


.99162 


5.90 


4.72 


.98940 


7.65 


6.14 


.98730 


9.40 


7.56 


.99156 


5.95 


4.76 


.98934 


7.70 


6.18 


.98724 


9.45 


7.60 


.99149 


6.00 


4.80 


.98928 


7.75 


6.22 


.98719 


9.50 


7.64 


.99143 


6.05 


4.84 


.98922 


7.80 


6.26 


.98713 


9.55 


7.68 


.99136 


6.10 


4.88 


.98916' 


7.85 


6.30 


.98707 


9.60 


7.72 


.99130 


6.15 


4.92 


.98909 


7.90 


6.34 


.98701 


9.65 


7.76 


.99123 


6.20 


4.96 


.98903 


7.95 


6.38 


.98695 


9.70 


7.80 



68 



ELEMENTARY APPLIED CHEMISTRY 



PERCENTAGE OF ALCOHOL (Continded) 





Alcohol 


Specific 
Gravity 

AT §g°F. 


Alcohol 


Specific 
Gravity 
ATggoF. 


Alcohol 


Specific 
Gravity 

ATggoF. 


Per 

cent 
by vol- 
ume 


Pel- 
cent 

weight 


Per 

cent 
by vol- 
ume 


Per 
cent 

by 

■weight 


Per 

cent 
by vol- 
ume 


Per 

cent 

by 

weight 


0.98689 


9.75 


7.84 


0.98491 


11.50 


9.27 


0.98299 


13.25 


10.69 


.98683 


9.80 


7.88 


.98485 


11.55 


9.31 


.98294 


13.30 


10.74 


.98678 


9.85 


7.92 


.98479 


11.60 


9.35 


.98289 


13.35 


10.78 


.98672 


9.90 


7.96 


.98474 


11.65 


9.39 


.98283 


13.40 


10.82 


.98666 


9.95 


8.00 


.98468 


11.70 


9.43 


.98278 


13.45 


10.86 


.98660 


10.00 


8.04 


.98463 


11.75 


9.47 


.98273 


13.50 


10.90 


.98654 


10.05 


8.08 


.98457 


11.80 


9.51 


.98267 


13.55 


10.94 


.98649 


10.10 


8.12 


.98452 


11.85 


9.55 


.98262 


13.60 


10.98 


.98643 


10.15 


8.16 


.98446 


11.90 


9.59 


.98256 


13.65 


11.02 


.98637 


10.20 


8.20 


.98441 


11.95 


9.63 


.98251 


13.70 


11.06 


.98632 


10.25 


8.24 


.98435 


12.00 


9.67 


.98246 


13.75 


11.11 


.98626 


10.30 


8.29 


.98430 


12.05 


9.71 


.98240 


13.80 


11.15 


.98620 


10.35 


8.33 


.98424 


12.10 


9.75 


.98235 


13.85 


11.19 


.98614 


10.40 


8.37 


.98419 


12.15 


9.79 


.98230 


13.90 


11.23 


.98609 


10.45 


8.41 


.98413 


12.20 


9.83 


.98224- 


13.95 


11.27 


.98603 


10.50 


8.45 


.98408 


12.25 


9.87 


.98219 


14.00 


11.31 


.98597 


10.55 


8.49 


.98402 


12.30 


9.92 


.98214 


14.05 


11.35 


.98592 


10.60 


8.53 


.98397 


12.35 


9.96 


.98209 


14.10 


11.39 


.98586 


10.65 


8.57 


.98391 


12.40 


10.00 


.98203 


14.15 


11.43 


.98580 


10.70 


8.61 


.98386 


12.45 


10.04 


.98198 


.14.20 


11.47 


.98575 


10.75 


8.65 


.98381 


12.50 


10.08 


.98193 


14.25 


11.52 


.98569 


10.80 


8.70 


.98375 


12.55 


10.12 


.98188 


14.30 


11.56 


.98563 


10.85 


8.74 


.98370 


12.60 


10.16 


.98182 


14.35 


11.60 


.98557 


10.90 


8.78 


.98364 


12.65 


10.20 


.98177 


14.40 


11.64 


.98552 


10.95 


8.82 


.98359 


12.70 


10.24 


.98172 


14.45 


11.68 


..98546 


11.00 


8.86 


.98353 


12.75 


10.28 


.98167 


14.50 


11.72 


.98540 


11.05 


8.90 


.98348 


12.80 


10.33 


.98161 


14.55 


11.76 


.98535 


11.10 


8.94 


.98342 


12.85 


10.37 


.98156 


14.60 


11.80 


.98529 


11.15 


8.98 


.98337 


12.90 


10.41 


.98151 


14.65 


11.84 


.98524 


11.20 


9.02 


.98331 


12.95 


10.45 


.98146 


14.70 


11.88 


.98518 


11.25 


9.07 


.98326 


13.00 


10.49 


.98140 


14.75 


11.93 


.98513 


11.30 


9.11 


.98321 


13.05 


10.53 


.98135 


14.80 


11.97 


.98507 


11.35 


9.15 


.98315 


13.10 


10.57 


.98130 


14.85 


12.01 


.98502 


11.40 


9.19 


.98310 


13.15 


10.61 


.98125 


14.90 


12.05 


.98496 


11.45 


9.23 


.98305 


13.20 


10.65 


.98119 


14.95 


12.09 



PERCENTAGE OF ALCOHOL 



69 



PERCENTAGE OF ALCOHOL (Continued) 





Alcohol 


Specific 
Gravity 

AT88°F. 


Alcohol 


Specific 
Gravity 
AT ggop. 


Alcohol 


Specific 
Gravity 

ATggoF. 


Per 

cent 
by vol- 
ume 


Per 

cent 

by 

weight 


Per 

cent 
by vol- 
ume 


Per 

cent 

weight 


Per 

cent 
by vol- 
ume 


Per 

cent 

by 

weight 


0.98114 


15.00 


12.13 


0.97935 


16.75 


13.57 


0.97758 


18.50 


15.02 


.98108 


15.05 


12.17 


.97929 


16.80 


13.62 


.97753 


18.55 


15.06 


.98104 


15.10 


12.21 


.97924 


16.85 


13.66 


.97748 


18.60 


15.10 


.98099 


15.15 


12.25 


.97919 


16.90 


13.70 


.97743 


18.65 


15.14 


.98093 


15.20 


12.29 


.97914 


16.95 


13.74 


.97738 


18.70 


15.18 


.98088 


15.25 


12.33 


.97909 


17.00 


13.78 


.97733 


18.75 


15.22 


.98083. 


15.30 


12.38 


.97904 


17.05 


13.82 


.97728 


18.80 


15.27 


.98078 


15.35 


12.42 


.97899 


17.10 


13.86 


.97723 


18.85 


15.31 


.98073 


15.40 


12.46 


.97894 


17.15 


13.90 


.97718 


18.90 


15.38 


.98068 


15.45 


12.50 


.97889 


17.20 


13.94 


.97713 


18.95 


15.39 


.98063 


15.50 


12.54 


.97884 


17.25 


13.98 


.97708 


19.00 


15.43 


.98057 


15.55 


12.58 


.97879 


17.30 


14.03 


.97703 


19.05 


15.47 


.98052 


15.60 


12.62 


.97874 


17.35 


14.07 


.97698 


19.10 


15.51 


.98047 


15.65 


12.66 


.97869 


17.40 


14.11 


.97693 


19.15 


15.55 


.98042 


15.70 


12.70 


.97864 


17.45 


14.15 


.97688 


19.20 


15.59 


.98037 


15.75 


12.75 


.97859 


17.50 


14.19 


.97683 


19.25 


15.63 


.980.32 


15.80 


12.79 


.97853 


17.55 


14.23 


.97678 


19.30 


15.68 


.98026 


15.85 


12.83 


.97848 


17.60 


14.27 


.97673 


19.35 


15.72 


.98021 


15.90 


12.87 


.97843 


17.65 


14.31 


.97668 


19.40 


15.76 


.98016 


15.95 


12.91 


.97838 


17.70 


14.35 


.97663 


19.45 


15.80 


.98011 


16.00 


12.95 


.97833 


17.75 


14.40 


.97658 


19.50 


15.84 


.98005 


16.05 


12.99 


.97828 


17.80 


14.44 


.97653 


19.55 


15.88 


.98001 


16.10 


13.03 


.97823 


17.85 


14.48 


.97648 


19.60 


15.93 


.97996 


16.15 


13.08 


.97818 


17.90 


14.52 


.97643 


19.65 


15.97 


.97991 


16.20 


13.12 


.97813 


17.95 


14.56 


.97638 


19.70 


16.01 


.97986 


16.25 


13.16 


.97808 


18.00 


14.60 


.97633 


19.75 


16.05 


.97980 


16.30 


13.20 


.97803 


18.05 


14.64 


.97628 


19.80 


16.09 


.97975 


16.35 


13.24 


.97798 


18.10 


14.68 


.97623 


19.85 


16.14 


.97970 


16.40 


13.29 


.97793 


18.15 


14.73 


.97618 


19.90 


16.18 


.97965 


16.45 


13.33 


.97788 


18.20 


14.77 


.97613 


19.95 


16.22 


.97960 


16.50 


13.37 


.97783 


18.25 


14.81 


.97608 


20.00 


16.26 


.97955 


16.55 


13.41 


.97778 


18.30 


14.85 


.97603 


20.05 


16.30 


.97950 


16.60 


13.45 


.97773 


18.35 


14.89 


.97598 


20.10 


16.34 


.97945 


16.65 


13.49 


.97768 


18.40 


14.94 


.97593 


20.15 


16.38 


.97940 


16.70 


13.58 


.97763 


18.45 


14.98 


.97588 


20.20 


16.42 



70 



ELEMENTARY APPLIED CHEMISTRY 



PERCENTAGE OF ALCOHOL (Continued) 





Alcohol 


Specific 
Gravity 


Alcohol 


Specific 
Gravity 


Alcohol 


SPEcrFic 
Gravity 


Per 


Per 


Per 


Per 


Per 


Per 


AT IgoF. 


cent 
by vol- 


cent 

ty 


ATlgoF. 


cent 
by vol- 


cent 

by 


AT|8°F. 


cent 
by vol- 


cent 
by 




ume 


weight 




ume 


weight 




ume 


weight 


0.97583 


20.25 


16.46 


0.97406 


22.00 


17.92 


0.97227 


23.75 


19.38 


.97578 


20.30 


16.51 


.97401 


22.05 


17.96 


.97222 


23.80 


19.42 


.97573 


20.35 


16.58 


.97396 


22.10 


18.00 


.97216 


23.85 


19.40 


.97568 


20.40 


16.59 


.97391 


22.15 


18.05 


.97211 


23.90 


19.51 


.97563 


20.45 


16.63 


.97386 


22.20 


18.09 


.97206 


23.95 


19.55 


.97558 


20.50 


16.67 


.97381 


22.25 


18.13 


.97201 


24.00 


19.59 


.97.5.52 


20.55 


16.71 


.97375 


22.30 


18.17 


.97196 


24.05 


19.63 


.97547 


20.60 


16.75 


.97370 


22.35 


18.21 


.97191 


24.10 


19.67 


.97542 


20.65 


16.80 


.97365 


22.40 


18.26 


.97185 


24.15 


19.72 


.97537 


20.70 


16.84 


.97360 


22.45 


18.30 


.97180 


24.20 


19.70 


.97532 


20.75 


16.88 


.97355 


22.50 


18.34 


.97175 


24.25 


19.80 


.97527 


20.80 


16.92 


.97350 


22.55 


18.38 


.97170 


24.30 


19.84 


.97.522 


20.85 


16.96 


.97345 


22.60 


18.42 


.97165 


24.35 


19.88 


.97.517 


20.90 


17.01 


.97340 


22.65 


18.47 


.97159 


24.40 


19.93 


.97512 


20.95 


17.05 


.97335 


22.70 


18.51 


.97154 


24.45 


19.97 


.97507 


21.00 


17.09 


.97330 


22.75 


18.55 


.97149 


24.50 


20.01 


.97502 


21.05 


17.13 


.97324 


22.80 


18.59 


.97144 


24.55 


20.05 


.97497 


21.10 


17.17 


.97319 


22.85 


18.63 


.97139 


24.60 


20.09 


.97492 


21.15 


17.22 


.97314 


22.90 


18.68 


.97133 


24.65 


20.14 


.97487 


21.20 


17.26 


.97309 


22.95 


18.72 


.97128 


24.70 


20.18 


.97482 


21.25 


17.30 


.97304 


23.00 


18.76 


.97123 


24.75 


20.22 


.97477 


21.30 


17.34 


.97299 


23.05 


18.80 


.97118 


24.80 


20.26 


.97472 


21.35 


17.38 


.97294 


23.10 


18.84 


.97113 


24.85 


20.30 


.97467 


21.40 


17.43 


.97289 


23.15 


18.88 


.97107 


24.90 


20.35 


.97462 


21.45 


17.47 


.97283 


23.20 


18.92 


.97102 


24.95 


20.39 


.97457 


21.50 


17.51 


.97278 


23.25 


18.96 


.97097 


25.00 


20.43 


.97451 


21.55 


17.55 


.97273 


23.30 


19.01 


.97092 


25.05 


20.47 


.97446 


21.60 


17..59 


.97268 


23.35 


19.05 


.97086 


25.10 


20.51 


.97441 


21.65 


17.63 


.97263 


23.40 


19.09 


.97081 


25.15 


20.56 


.97436 


21.70 


17.67 


.97258 


23.45 


19.13 


.97076 


25.20 


20.60 


.97431 


21.75 


17.71 


.97253 


23.50 


19.17 


.97071 


25.25 


20.64 


.97426 


21.80 


17.76 


.97247 


23.55 


19.21 


.97065 


25.30 


20.68 


.97421 


21.85 


17.80 


.97242 


23.60 


19.25 


.97060 


25.35 


20.72 


.97416 


21.90 


17.84 


.97237 


23.65 


19.30 


.97055 


25.40 


20.77 


.97411 


21.95 


17.88 


.97232 


23.70 


19.34 


.97049 


25.45 


20.81 



PEECENTAGE OF ALCOHOL 



71 



PERCENTAGE OF ALCOHOL (Continued) 





Alcohol 


Specific 
Gkavity 

ATggoF. 


Alcohol 


Specific 
Gravity 

ATlg"!". 


Alcohol 


Specific 
Gkavitv 

ATig°F- 


Per 

cent 
by vol- 
ume 


Per 
cent 

by 

weight 


Per 
cent 
by vol- 
ume 


Per 

cent 

by 

weight 


Per 

cent 
by vol- 
ume 


Per 

cent 

by 

weight 


0.97044 


25.50 


20.85 


0.96855 


27.25 


22.33 


0.96658 


29.00 


23.81 


.97039 


25.55 


20.89 


.96850 


27.30 


22.37 


.96652 


29.05 


23.85 


.97033 


25.60 


20.93 


.96844 


27.35 


22.41 


.96646 


29.10 


23.89 


.97028 


25.65 


20.98 


.96839 


27.40 


22.45 


.96640 


29.15 


23.94 


.97023 


25.70 


21.02 


.96833 


27.45 


22.50 


.96635 


29.20 


23.98 


.97018 


25.75 


21.06 


.96828 


27.50 


22.54 


.96629 


29.25 


24.02 


.97012 


25.80 


21.10 


.96822 


27.55 


22.58 


.96623 


29.30 


24.06 


.97007 


25.85 


21.14 


.96816 


27.60 


22.62 


.96617 


29.35 


24.10 


.97001 


25.90 


21.19 


.96811 


27.65 


22.67 


.96611 


29.40 


24.15 


.96996 


25.95 


21.23 


.96805 


27.70 


22.71 


.96605 


29.45 


24.19 


.96991 


26.00 


21.27 


.96800 


27.75 


22.75 


.96600 


29.50 


24.23 


.96986 


26.05 


21.31 


.96794 


27.80 


22.79 


.96594 


29.55 


24.27 


.96980 


26.10 


21.35 


.96789 


27.85 


22.83 


.96587 


29.60 


24.32 


.96975 


26.15 


21.40 


.96783 


27.90 


22.88 


.96582 


29.65 


24.36 


.96969 


26.20 


21.44 


.96778 


27.95 


22.92 


.96576 


29.70 


24.40 


.96964 


26.25 


21.48 


.96772 


28.00 


22.96 


.96570 


29.75 


24.45 


.96959 


26.30 


21.52 


.96766 


28.05 


23.00 


.96564 


29.80 


24.49 


.96953 


26.35 


21.56 


.96761 


28.10 


23.04 


.96559 


29.85 


24.53 


.96949 


26.40 


21.61 


.96755 


28.15 


23.09 


.96553 


29.90 


24.57 


.96942 


26.45 


21.65 


.96749 


28.20 


23.13 


.96547 


29.95 


24.62 


.96937 


26.50 


21.69 


.96744 


28.25 


23.17 


.96541 


30.00 


24.66 


.96932 


26.55 


21.73 


.96738 


28.30 


23.21 


.96535 


30.05 


24.70 


.96926 


26.60 


21.77 


.96732 


28.35 


23.25 


.96529 


30.10 


24.74 


.96921 


26.65 


21.82 


.96726 


28.40 


23.30 


.96523 


30.15 


24.79 


.96915 


26.70 


21.86 


.96721 


28.45 


23.34 


.96517 


30.20 


24.83 


.96910 


26.75 


21.90 


.96715 


28.50 


23.38 


.96511 


30.25 


24.87 


.96905 


26.80 


21.94 


.96709 


28.55 


23.42 


.96505 


30.30 


24.91 


.96899 


26.85 


21.98 


.96704 


28.60 


23.47 


.96499 


30.35 


24.95 


.96894 


26.90 


22.03 


.96698 


28.65 


23.51 


.96493 


30.40 


25.00 


.96888 


26.95 


22.07 


.96692 


28.70 


23.55 


.96487 


30.45 


25.04 


.96883 


27.00 


22.11 


.96687 


28.75 


23.60 


.96481 


30.50 


25.08 


.96877 


27.05 


22.15 


.96681 


28.80 


23.64 


.96475 


30.55 


25.12 


.96872 


27.10 


22.20 


.96675 


28.85 


23.68 


.96469 


30.60 


25.17 


.96866 


27.15 


22.24 


.96669 


28.90 


23.72 


.96463 


30.65 


25.21 


.96861 


27.20 


22.28 


.96664 


28.95 


23.77 


.96457 


30.70 


25.25 



72 



ELEMENTARY APPLIED CHEMISTRY 



PERCENTAGE OF ALCOHOL (Continued) 





Alcohol 


Specific 
Gravity 

AT|goF. 


Alcohol 


Specific 
Gravity 

AT|8°F. 


Alcohol 


Specific 
Gravity 

ATfgOF. 


Per 
cent 
by vol- 
ume 


Per 

cent 

by 

weight 


Per 
cent 
by vol- 
ume 


Per 

cent 

by 

weight 


Per 
cent 
by vol- 
ume 


Per 

cent 

by 

weight 


0.96451 


30.75 


25.30 


0.96235 


32.50 


26.80 


0.96010 


34.25 


28.31 


.96445 


30.80 


25.34 


.96229 


32.55 


26.84 


.96003 


34.30 


28.35 


.96439 


30.85 


25.38 


.96222 


32.60 


26.89 


.95996 


34.35 


28.39 


.96433 


30.90 


25.42 


.96216 


32.65 


26.93 


.95990 


34.40 


28.43 


.96427 


30.95 


25.47 


.96210 


32.70 


26.97 


.95983 


34.45 


28.48 


.96421 


31.00 


25.51 


.96204 


32.75 


27.02 


.9.5977 


34.50 


28.52 


.96415 


31.05 


25.55 


.96197 


32.80 


27.06 


.95970 


34.55 


28.56 


.96409 


31.10 


25.60 


.96191 


32.85 


27.10 


.95963 


34.60 


28.61 


.96403 


31.15 


25.64 


.96185 


32.90 


27.14 


.95957 


34.65 


28.65 


.96396 


31.20 


25.68 


.96178 


32.95 


27.19 


.95950 


34.70 


28.70 


.96390 


31.25 


25.73 


.96172 


33.00 


27.23 


.95943 


34.75 


28.74 


.96384 


31.30 


25.77 


.96166 


33.05 


27.27 


.95937 


34.80 


28.78 


.96378 


31.35 


25.81 


.96159 


33.10 


27.32 


.9.5930 


34.85 


28.83 


.96372 


81.40 


25.85 


.96153 


33.15 


27.36 


.9.5923 


84.90 


28.87 


.96366 


31.45 


25.90 


.96146 


33.20 


27.40 


.95917 


84.95 


28.92 


.96360 


31.50 


25.94 


.96140 


33.25 


27.45 


.95910 


35.00 


28.96 


.96353 


31.55 


25.98 


.96133 


33.30 


27.49 


.95908 


35.05 


29.00 


.96347 


31.60 


26.03 


.96127 


33.35 


27.53 


.95896 


35.10 


29.05 


.96341 


31.65 


26.07 


.96120 


33.40 


27.57 


.95889 


35.15 


29.09 


.96335 


31.70 


26.11 


.96114 


33.45 


27.62 


.95883 


85.20 


29.13 


.96329 


31.75 


26.16 


.96108 


33.50 


27.66 


.95876 


35.25 


29.18 


.96323 


31.80 


26.20 


.96101 


33.65 


27.70 


.95869 


85.30 


29.22 


.96316 


31.85 


26.24 


.96095 


33.60 


27.75 


.95862 


85.35 


29.26 


.96310 


31.90 


26.28 


.96088 


33.65 


27.79 


.95855 


35.40 


29.30 


.96304 


31.95 


26.33 


.96082 


33.70 


27.83 


.95848 


35.45 


29.35 


.96298 


32.00 


26.37 


.96075 


33.75 


27.88 


.95842 


85.50 


29.30 


.96292 


32.05 


26.41 


.96069 


33.80 


27.92 


.95885 


35.55 


29.43 


.96285 


32.10 


26.46 


.96062 


33.85 


27.96 


.95828 


35.60 


29.48 


.96279 


32.15 


26.50 


.96056 


83.90 


28.00 


.95821 


35.65 


29.52 


.96273 


32.20 


26.54 


.96049 


33.95 


28.05 


.95814 


35.70 


29.57 


.96267 


32.25 


26.59 


.96043 


84.00 


28.09 


.95807 


35.75 


29.61 


.96260 


32.30 


26.63 


.96036 


34.05 


28.13 


.95800 


35.80 


29.65 


.96254 


32.35 


26.67 


.96030 


34.10 


28.18 


.95794 


35.85 


29.70 


.96248 


32.40 


26.71 


.96023 


34.15 


28.22 


.95787 


35.90 


29.74 


.96241 


32.45 


26.76 


.96016 


34.20 


28.26 


.95780 


35.95 


29.79 



PERCENTAGE OF ALCOHOL 



73 



PERCENTAGE OF ALCOHOL (CosTiNnED) 





Alcohol 


Specific 
Gkavity 
AT JgoF. 


Alcohol 


Specific 
Gravity 

ATggoP. 


Alcohol 


Specific 
Gravity 

ATgJOF. 


Per 
cent 
by vol- 
ume 


Per 

cent 

by 

weight 


Per 

cent 
by vol- 
ume 


Per 
cent 

ty 

weight 


Per 

cent 
by vol- 
ume 


Per 

cent 

by 

weight 


0.95773 


36.00 


29.83 


0.95523 


37.75 


31.36 


0.95262 


39.50 


32.90 


.95766 


36.05 


29.87 


.95516 


37.80 


31.40 


.95254 


39.55 


32.95 


.95759 


36.10 


29.92 


.95509 


37.85 


31.45 


.95246 


39.60 


32.99 


.95752 


36.15 


29.96 


.95502 


37.90 


31.49 


.95239 


39.65 


33.04 


.95745 


36.20 


30.00 


.95494 


37.95 


31.54 


.95231 


39.70 


33.08 


.95738 


36.25 


30.05 


.95487 


38.00 


31.58 


.95223 


39.75 


33.13 


.95731 


36.30 


30.09 


.95480 


38.05 


31.63 


.95216 


39.80 


33.17 


.95724 


36.35 


30.13 


.95472 


38.10 


31.07 


.95208 


39.85 


33.22 


.95717 


36.40 


30.17 


.95465 


38.15 


31.72 


.95200 


39.90 


33.27 


.95710 


36.45 


30.22 


.95457 


38.20 


31.76 


.95193 


39.95 


33.31 


.95703 


36.50 


30.26 


.95450 


38.25 


31.81 


.95185 


40.00 


33.35 


.95695 


36.55 


30.30 


.95442 


38.30 


31.85 


.9.5177 


40.05 


33.39 


.95688 


36.60 


30.35 


.95485 


38.35 


31.90 


.95169 


40.10 


33.44 


.95681 


36.65 


30.39 


.95427 


38r40 


31.94 


.95161 


40.15 


.33.48 


.95674 


36.70 


30.44 


.95420 


38.45 


31.99 


.95154 


40.20 


33.53 


.95667 


36.75 


30.48 


.95413 


38.50 


32.03 


.95146 


40.25 


33.57 


.95660 


36.80 


30.52 


.95405 


38.55 


32.07 


.95138 


40.30 


33.61 


.95653 


36.85 


30.57 


.95398 


38.60 


32.12 


.95130 


40.35 


33.66 


.95646 


36.90 


30.61 


.95390 


38.65 


32.16 


.95122 


40.40 


33.70 


.95639 


36.95 


30.66 


.95383 


38.70 


32.20 


.95114 


40.45 


33.75 


.95632 


37.00 


30.70 


.95375 


38.75 


32.25 


.95107 


40.50 


33.79 


.95625 


37.05 


30.74 


.95368 


38.80 


32.29 


.95099 


40.55 


33.84 


.95618 


37.10 


30.79 


.95360 


38.85 


32.33 


.9.5091 


40.60 


33.88 


.95610 


37.15 


30.83 


.95353 


38.90 


32.37 


.95083 


40.65 


33.93 


.95603 


37.20 


30.88 


.95345 


38.95 


32.42 


.95075 


40.70 


33.97 


.95596 


37.25 


30.92 


.95338 


39.00 


32.46 


.95067 


40.75 


34.02 


.95589 


37.30 


30.96 


.95330 


39.05 


32.50 


;95059 


40.80 


34.06 


.95581 


37.35 


31.01 


.95323 


39.10 


32.55 


.95052 


40.85 


34.11 


.95574 


37.40 


31.05 


.95315 


39.15 


32.59 


.95044 


40.90 


34.15 


.95567 


37.45 


31.10 


.95307 


39.20 


32.64 


.95036 


40.95 


34.20 


.95560 


37.50 


'31.14 


.95300 


39.25 


32.68 


.95028 


41.00 


34.24 


.955.52 


37.55 


31.18 


.95292 


39.30 


32.72 


.95020 


41.05 


34.28 


.95545 


37.60 


31.23 


.95284 


39.35 


32.77 


.95012 


41.10 


34.33 


.95.538 


37.65 


31.27 


.95277 


39.40 


32.81 


.95004 


41.15 


34.37 


.95531 


37.70 


31.32 


.95269 


39.45 


32.86 


.94996 


41.20 


34.42 



74 



ELEMENTARY APPLIED CHEMISTEY 



PERCENTAGE OF ALCOHOL (CoNTiunED) 





Alcohol 


Specific 
Gravity 

ATjgoF. 


Alcohol 


Specific 
Gravity 
ATigoF. 


Alcohol 


Specific 
Gbavity 

ATgg°F. 


Per 

cent 
by vol- 
ume 


Per 
cent 

by 

weight 


Per 
cent 
by vol- 
ume 


Per 
cent 

ty 

■weight 


Per 

cent 
by vol- 
ume 


Per 
cent 

by 

weight 


0.94988 


41.25 


34.46 


0.94704 


43.00 


36.03 


0.94407 


44.75 


37.62 


.94980 


41.30 


34.50 


.94696 


43.05 


36.08 


.94398 


44.80 


37.66 


.94972 


41.35 


34.55 


.94687 


43.10 


36.12 


.94390 


44.85 


37.71 


.94964 


41.40 


34.59 


.94679 


43.15 


36.17 


.94381 


44.90 


37.76 


.94956 


41.45 


34.64 


.94670 


43.20 


36.21 


.94373 


44.95 


37.80 


.94948 


41.50 


34.68 


.94662 


43.25 


36.23 


.94364 


45.00 


37.84 


.94940 


41.55 


34.73 


.94654 


43.30 


36.30 


.94355 


45.05 


37.89 


.94932 


41.60 


34.77 


.94645 


43.35 


36.35 


.94346 


45.10 


37.93 


.04924 


41.65 


34.82 


.94637 


43.40 


36.39 


.94338 


45.15 


37.98 


.94916 


41.70 


34.86 


.94628 


43.45 


36.44 


.94329 


45.20 


38.02 


.94908 


41.75 


34.91 


.94620 


43.50 


36.48 


.94320 


45.25 


38.07 


.94900 


41.80 


34.95 


.94612 


43.55 


36.53 


.94311 


45.30 


38.12 


.94892 


41.85 


35.00 


.94603 


43.60 


36.57 


.94302 


45.35 


38.16 


.94884 


41.90 


35.04 


.94595 


43.65 


36.62 


.94294 


45.40 


38.21 


.94876 


41.95 


35.09 


.94586 


43.70 


36.66 


.94285 


45.45 


38.25 


.94868 


42.00 


35.13 


.94578 


43.75 


36.71 


.94270 


45.50 


38.30 


.94860 


42.05 


35.18 


.94570 


43.80 


36.75 


.94267 


45.55 


38.35 


.94852 


42.10 


35.22 


.94561 


43.85 


36.80 


.94258 


45.60 


38.39 


.9484.3 


42.15 


35.27 


.94553 


43.90 


36.84 


.94250 


45.65 


38.44 


.94835 


42.20 


35.31 


.94544 


43.95 


36.89 


.94241 


45.70 


38.48 


.94827 


42.25 


35.36 


.94536 


44.00 


36.93 


.94232 


45.75 


38.53 


.94810 


42.30 


35.40 


.94527 


44.05 


36.98 


.94223 


45.80 


38.57 


.94811 


42.35 


35.45 


.94519 


44.10 


37.02 


.94214 


45.85 


38.62 


.94802 


42.40 


35.49 


.94510 


44.15 


37.07 


.94206 


45.90 


38.66 


.94794 


42.45 


35.54 


.94502 


44.20 


37.11 


.94197 


45.95 


38.71 


.94786 


42.50 


35.58 


.94493 


44.25 


37.16 


.94188 


46.00 


38.75 


.94778 


42.55 


35.63 


.94484 


44.30 


37.21 


.94179 


46.05 


38.80 


.94770 


42.60 


35.67 


.94476 


44.35 


37.25 


.94170 


46.10 


38.84 


.94761 


42.65 


35.72 


.94467 


44.40 


37.30 


.94161 


46.15 


38.89 


.94753 


42.70 


35.76 


.94459 


44.45 


37.34 


.94152 


46.20 


38.93 


.94745 


42.75 


35.81 


.94450 


44.50 


37.39 


.94143 


46.25 


38.98 


.94737 


42.80 


35.85 


.94441 


44.55 


37.44 


.94134 


46.30 


39.03 


.94729 


42.85 


35.90 


.94433 


44.60 


37.48 


.94125 


46.35 


39.07 


.94720 


42.90 


35.94 


.94424 


44.65 


37.53 


.94116 


46.40 


39.12 


.94712 


42.95 


35.99 


.94416 


44.70 


37.57 


.94107 


46.45 


39.16 



PERCENTAGE OF ALCOHOL 



75 



PERCENTAGE OE ALCOHOL (Concluded) 





Alcohol 


Specific 
Gravity 
AT 18° F. 


Alcohol 


Specific 
Gravity 

ATggoF. 


Alcohol 


Specific 
Gravity 

ATg8°F. 


Per 
cent 
by vol- 
ume 


Per 
cent 

ty 

weight 


Per 
cent 
by vol- 
ume 


Per 

cent 

by 

weight 


Per 

cent 
by vol- 
ume 


Per 

cent 

by 

weight 


0.94098 


46.50 


39.21 


0.93870 


47.75 


40.37 


0.93636 


49.00 


41.52 


.94089 


46.55 


39.26 


.93861 


47.80 


40.41 


.93626 


49.05 


41.57 


.94080 


46.60 


39.30 


.93852 


47.85 


40.46 


.93617 


49.10 


41.61 


.94071 


46.65 


39.35 


.93842 


47.90 


40.51 


.93607 


49.15 


41.66 


.94062 


46.70 


39.39 


.93833 


47.95 


40.55 


.93598 


49.20 


41.71 


.940-53 


46.75 


39.44 


.93824 


48.00 


40.60 


.93.588 


49.25 


41.78 


.94044 


46.80 


39.49^ 


.93815 


48.05 


40.65 


.93578 


49.30 


41.80 


.94035 


46.85 


39.53 


.93805 


48.10 


40.69 


.93569 


49.35 


41.85 


.94020 


46.90 


39.58 


.93796 


48.15 


40.74 


.93559 


49.40 


41.90 


.94017 


46.95 


39.62 


.93786 


48.20 


40.78 


.93550 


49.45 


41.94 


.94008 


47.00 


39.67 


.93777 


48.25 


40.83 


.93540 


49.50 


41.99 


.93999 


47.05 


39.72 


.93768 


48.30 


40.88 


.93530 


49.55 


42.04 


.93990 


47.10 


39.76 


.93758 


48.35 


40.92 


.93521 


49.60 


42.08 


.93980 


47.15 


39.81 


.93749 


48.40 


40.97 


.93511 


49.65 


42.13 


.93971 


47.20 


39.85 


.93739 


48.45 


41.01 


.93502 


49.70 


42.18 


.93962 


47.25 


39.90 


.93730 


48.50 


41.06 


.93492 


49.75 


42.23 


.93953 


47.30 


39.95 


.93721 


48.55 


41.11 


.93482 


49.80 


42.27 


.93944 


47..35 


39.99 


.93711 


48.60 


41.15 


.93473 


49.85 


42.32 


.93934 


47.40 


40.04 


.93702 


48.65 


41.20 


.93463 


49.90 


42.37 


.93925 


47.45 


40.08 


.93692 


48.70 


41.24 


.93454 


49.95 


42.41 


.93916 


47.50 


40.13 


.93683 


48.75 


41.29 








.93906 


47.55 


40.18 


.93679 


48.80 


41.34 








.93898 


47.60 


40.22 


.93664 


48.85 


41.38 








.93888 


47.65 


40.27 


.93655 


48.90 


41.43 








.93879 


47.70 


40.32 


.93645 


48.95 


41.47 









SECTION XII 
DETECTION OF COAL-TAR DYE 

The use of coal-tar dyes in food and drink, while very 
general, is quite unnecessary, and frequently constitutes 
fraudulent adulteration. These dyes can usually he de- 
tected by the following methods: 

Double-Dyeing Process. Sostegni and Carpentieri. If a 
solid or semisolid, dissolve 10 to 20 g. of the sample in 
100 cc. of water. If a liquid, use from 50 to 100 cc, depend- 
ing upon the intensity of the color. Acidify with 2 to 4 cc. 
of 10 per cent HCl. Boil nun's veiling or other white 
woolen cloth in very dilute KOH or strong soapsuds and 
wash thoroughly. Boil a piece about 10 cm. square in the 
dissolved- sample until it has been well colored. This usually 
takes from five to ten minutes. 

Remove the cloth, wash in cold water, and boil in 2 per 
cent HCl. After thorough rinsing dissolve the color in hot 
dilute NH^OH (1 to 50). Remove the cloth and throw 
it away. 

Add a slight excess of HCl to the ammonia solution. Im- 
merse in this a second and smaller piece of cloth (2x3 cm.) 
and boil. 

If the dye is of vegetable origin, the second piece of wool 

will be practically uncolored in the ammonia solution; if 

it is of coal-tar origin, it will take a decided tone, — red, 

pink, yellow, green, etc., — depending upon the color of 

the sample tested. 

76 



DETECTION OF COAL-TAR DYE 77 

Arata's Method. Dissolve 20 to 30 g. of the sample in 
100 cc. of water and 10 cc. of a 10 per cent solution of 
HKSO^. In this mixture boil a small piece of cloth which 
has been previously boiled in dilute NaOH and thoroughly 
washed in water. Remove, wash in water, and dry between 
filter or blotting papers. 

•If the coloring matter is entirely of vegetable origin, the 
wool will be uncolored or will take a faint pink or brown, 
which is changed to green or yellow by ammonia and not 
restored by washing. 

In addition, double dye, as indicated in the previous 
method. If the wool is still uncolored, the dye is of vege- 
table origm. 

Nun's veiling is a very suitable cloth for these experi- 
ments. In removing the natural wool fat many students 
make the mistake of boiling it in too strong caustic. A 
1 per cent solution is sufficiently strong. 

Cochineal and some vegetable colors dye wool directly, 
hence the necessity of double dyeing. 

Common substances which furnish excellent material for 
coal-tar-dye testing are candy, soft drinks, wine, tablets, jam, 
jelly, catsup, colored sugars, dessert powders, gelatin, etc. 

Well-mounted pieces of wool dyed with these materials 
and placed in the notebook give it a living interest. 

Detection of Coal-Tar Dye in Butter. Melt a quantity of 
butter the size of a marble in a test tube, being careful not 
to scorch it. Add an equal volume of Low's reagent and 
shake vigorously. Heat nearly to boiling and set aside. 
After the acid has settled it will be wine red in the pres- 
ence of azo colors. Pure butter fat gives only a faint bluish 
tinge, (iow's test.') 

Low's Reagent. HC^HgOg, 4 parts ; HjSO^, 1 part. Mix. 



78 ELEMENTARY APPLIED CHEMISTRY 

Martin's Test. Shake 5 g. of the butter in a test tube 
with 20 CO. of Martin's reagent. Let the mixture stand 
until the fat has settled to the bottom of the tube. The 
dye, if present, will color the supernatant liquid yellow. 

Martin's Reagent. CSj, 4 cc. ; C^HjOH, 30 cc. Mix. 

Acid and Alkali Test. Melt about 20 g. of the butter in 
an evaporating dish and set on a water bath until the curd 
and contained water have entirely separated. Pour off the 
clear, supernatant fat and filter it through a dry filter paper 
in a hot-water funnel or in an oven at 60° C. If the fat is 
not clear, it must be filtered again. 

Pour into each of two test tubes 2 g. of this filtered 
fat dissolved in ether. Into one of the tubes pour 1 cc. of 
HCl and into the other the same volume of 10 per cent 
KOH. Shake the tubes well and allow to stand. In the 
presence of azo dye the test tube to which the acid has been 
added will show a pink to wine-red coloration, while the 
alkaline solution in the other tube will show no color. If 
annatto or other vegetable color has been used, the potash 
solution will be colored yellow (^Bulletin No. lOT). 

Coal-Tar Dye in Lemon Extract. Lythgoe's Test. To the 
original sample add two or three drops of strong HCl. 

No change indicates natural color, turmeric, or naphthol 
colors. 

Pink indicates tropaeolin or methyl orange. 

Partial decoloration indicates Martin's yellow. 

Complete decoloration indicates dinitro-cresols. 

Evaporate 10 to 20 cc. of the sample to dryness, dissolve 
the residue in water, and employ the test of Sostegni and 
Carpentieri. 

Why are flavoring extracts often artificially colored ? 



SECTION XIII 
IDENTIFICATION OF VEGETABLE COLOES 

Caramel. Amthor's Test. Place 10 cc. of the suspected 
solution in a Nessler tube or narrow clear-glass bottle. Add 
from 30 to 50 cc. of paraldehyde, the latter volume if the 
color is very dark. To make the solutions mix, introduce a 
few cubic centimeters of absolute alcohol. 

If caramel is present, a yellow to dark-brown precipitate 
will fall to the bottom of the tube. 

Fuller' srEarth Method. Shake 50 cc. of the solution with 
25 g. of fuller's earth. Allow the mixture to stand in a 
corked bottle of about 2 in. diameter for an hour at room 
temperature. 

The caramel will be absorbed by the earth, and the super- 
natant liquid will appear more or less clear, depending upon 
the amount of the absorption. 

As some fuller's earth absorbs color more readily than 
others, it is advisable to experiment with different samples 
upon solutions known to contain caramel. 

Amyl-Alcohol Method. Shake 5 cc. of the solution with 
10 cc. of amyl alcohol in a small vial for a minute or so. 
Allow the liquids to separate. 

If caramel is present, the upper layer will be decolorized 
to a greater or less extent. The lower layer will be colored 
in proportion to the amount of caramel in the solution. 

Test vanilla extract, whisky, ginger ale, soft drinks, and 

the like for caramel. 

79 



80 



ele:mextaey appeied chemistry 



Cochineal. Girard and Ihipre's Metliod. If the sample is 
catsup, canned fruit, or of this nature, triturate in a mortar 
with water until it is reduced to a 
very thin paste. Filter, acidulate 
with HCl, and shake with amvl 
alcohol. If cochineal is present, the 
alcohol will be colored yellow or 
orange. Separate the amyl alcohol 
and wash it with water until neutral. 
Add, drop Ijy drop, a very dilute 
solution of uranium acetate. In the 
presence of cocliineal a beautiful 
emerald-green color is produced. 

Turmeric. Extract the color with 
alcohol. Saturate a filter paper \\ith 
the extract and dry at 10iJ° ('. Dip 
•ial whisky treated with the paper in a dilute solution of 
ainyl alcohol boric acid to which a few drops 

Caiainel shows in the hot- ^f ;^() pgj. ^^y^^ \\Q\ ]mye been 
toiiniltlie right-hand bottle. , , , t^ r,, 

Tiie supernatant liquid is added. Dry the paper, lurmeric 
deeoiorized j^. injieated by a distinct cherry-red 

coloration. Add a drop of alkali and olive-green will de- 
velop (Bulletin M. 51, Unifed Sfati'S Bxreau of (Jliemhlnj, 
p. lol). 



Fio. 17. True and artifi- 
cii 



SECTION XIV 
EAFFIA DYEING- 

Raffia is the cuticle of the leafstalks of the Madagascar 
palm QRaffia ruffia). Its tissue is cellulose for the most 
part, so the method of dyeing must necessarily differ from 
the method followed in dyeing wool, silk, or other animal 
fabrics. 

A mordant is a substance to "set" a color; that is, to 
make the pigment unite chemically, or in some cases physi- 
cally, or both, with the material dyed. The principal mor- 
dants used in raffia dyeing are alum and other aluminium 
salts, and certain salts of iron, tin, and copper. 

Raffia is soaked in the mordant solution until thoroughly 
impregnated, and then boiled in a solution of the dye, which 
forms with the mordant a metallic colored substance known 
as a " lake." A lake is relatively insoluble and cannot be 
easily washed out. 

General Principles. Alum should be used as a mordant 
unless otherwise specified. Dissolve 1/4 lb. in 10 qt. of 
water. Let the raffia stand in this solution until it has 
become thoroughly saturated. From six to twenty-four 
hours is generally sufficient. Always untie the bundles 
and do them up loosely. 

Raffia should not be dry when placed.in the dye. Either 

take it directly from the mordant or wet it thoroughly 

with water. Let the dye be boiling when the raffia is 

placed in it. 

81 



82 ELEMENTARY APPLIED CHEMISTRY 

Alum spots, grayish patches on the finished product, are 
not generally disadvantageous. Most autumn foliage has 
a white fungus which, in general appearance, these spots 
resemble. A dip in warm water will remove them. Colors 
obtained as herein directed will compare favorably with the 
bright, soft colors of autumn or the fresh tints of spring. 

Do not dye too dark. Lighter tints are more pleasing in 
woven and braided work. Dye slightly darker than desired, 
as the raffia is lighter when dried. Test pieces may be 
quickly dried by holding them against the side of the hot 
dye pan. This saves time and affords a convenient means 
of judging color value. 

Strong dye and short boiling makes soft, flexible, tough 
raffia. Weak dye and long boiling makes harsh, brittle 
raffia. Some of the coal-tar dyes leave the material glossy, 
harsh, and brittle. Fifteen minutes should be the maximum 
time of boiling. 

Vegetable dyes, in general, give soft, pleasmg tones. 
Coal-tar dyes give bright, glossy colors. 

Rinse before putting into a dye of another color. DuU, 
passive colors may be brightened by boiling in fresh or 
stronger dye. Weak dye is of little value. Keep the rafiBa 
well covered with dye, and turn frequently. 

Dyes extracted from bark, leaves, fruit, roots, vegetables, 
wood, and the like should be carefully strained before using. 

Save the waste dye, as many beautiful effects may be pro- 
duced from it. It is not only economical to use this dye, 
but interesting to discover the different colors that may be 
obtained. 

Time directions are only approximate, as much depends 
upon the quality and strength of the dye and on the kind 
and amount of mordant absorbed. 



EAFFIA DYEING 83 

The outer side of the raffia will take a brighter tone than 
the inner side. This is especially noticeable in green and 
orange tones. 

Do not place the full amount of raffia in the pan at 
once. Dye a small piece and see if the color suits you. Do 
not throw away the material which is displeasing in color, 
as it may easily be dyed black or brown. 

Experiment by mixing small quantities of various dyes 
and mordants in cups and test tubes. You will doubtless 
discover some new and pleasing combination. 

Material will absorb only a certain amount of the dye. 
This amount absorbed, the pigment point is reached. Do 
not expect to pour a quart of water at once into a pint cup. 

Dye pans should be large enough for the work at hand. 
The four-quart or eight-quart size is convenient. The best 
results are obtained by using enamel ware. 

Preparation of Dyes and Mordants. Dyes and mordants 
should be prepared in the following manner : 

Butternut. Fill a four-quart pan half full of the husks ; 
green ones give the softest tones ; the shells are not objec- 
tionable. Cover with water and boil for fifteen minutes. 

Cardinal Red. Dissolve a mass the size of a cranberry in 
a gallon of water. 

Copper Sulfate. Two ounces to a quart of water. 

Elderberries. Berries, 1 part ; water, 3 parts. 

Fustic Chips. A teacupful to 4 qt. of water. Boil ten 
minutes. 

Fustic Extract. Dissolve a piece the size of a walnut in a 
gallon of water. 

Iron Sulfate. Two ounces to a quart of water. Always 
use this solution in an old dish, as it will soon ruin a 
new one. 



84 ELEMENTARY APPLIED CHEMISTEY 

Indigo. Use indigo paste (sulfate of indigo). Dissolve a 
mass the size of two shoe buttons in 4 qt. of water. 

Logwood Chips. See Fustic Chips. 

Logwood Extract. See Fustic Extract. 

Leaves. Fill a four-quart pan full of the shredded leaves 
well pressed down. Cover with water, and boil. Replenish 
the water from time to time until the dye appears highly 
colored. The usual time is about fifteen minutes. 

Onion Skins. The outer skins from half a dozen medium- 
sized onions will furnish yellow dye for half a pound of 
raffia. Boil until the color is extracted. The time requu-ed 
is about ten minutes. 

Potassium Ferri-cyanide (Red Prussiate of Potash). Two 
ounces to a quart of water. 

Potassium Bichromate. Dissolve 1 oz. in a quart of water. 
This solution used with red dulls it and gives an orange 
tone. 

Sumac. Three quarts of the broken cones. Keep well 
covered with water and boil for twenty minutes. 

Walnut. See Butternut. 

Specific Directions for obtaining the Following Colors : 

Black. 1. Dye heavily with logwood and place imme- 
diately, without rinsing, into a strong, hot FeSO^ solution. 

2. Dye as above, substituting oak leaves for the logwood. 

Blue. Dye unmordanted raffia m indigo solution to which 
two or three drops of H^SO^ have been added. Dry in 
direct sunlight. The brighter the light, the bluer the color. 
Many tones can be produced by dyeing for different lengths 
of time in this solution. 

Blue-Green. 1. Boil mordanted raffia in plain indigo solu- 
tion and dry away from the sunlight. Raffia dyed with indigo 
must be thoroughly rinsed to remove all traces of acid. 



RAFFIA DYEING 85 

2. Dye in potassium ferri-cyanide to which a few drops 
of H^SO^ have been added and mixed thoroughly. 

S. Dye as in 2, and place directly into hot iron sulfate. 

Brown. 1. Boil in dye from maple leaves until thoroughly 
colored. Remove, rinse, and wring out the superfluous 
liquid. Then boil in a dye prepared as follows: Strong 
butternut dye to which has been added 1/2 pt. of K Cr O 
solution and an equal amount of cardinal-red solution. 

2. First dye in redwood solution and immerse for about 
three minutes in hot, strong logwood. 

Light Brown. 1. Boil in clear butternut dye. 

2. Boil in clear maple dye. 

3. Dye green with fustic and indigo, q.v., and then boil 
in a solution of CuSO,. 

GJiocolate-Broivn. Dye in sumac and treat with FeSO . 

Dark-Brown. Boil in butternut and then in K^Cr^O . 

Q-ray-Brown. Equal amounts of sumac, maple, and oak 
leaves make a green-brown dye. Since red is the comple- 
ment of green, and combined with it makes gray, add 
sufficient logwood to brmg to the desired shade. 

Olive-Brown. Boil for six minutes in dye from walnut 
husks. 

Red-Brown. 1. Add a teaspoOnful of alum to walnut 
dye and boil in the resulting solution for ten minutes. 

2. Dye with cardinal and then with logwood. 

3. (a) Dye in redwood solution. 

(i) Then dye in a solution made from fustic chips, 3 parts, 
and logwood chips, 1 part. 

Yellow-Brotvn. Boil first in a dye from maple leaves and 
then in Kfirfi^. 

Green. Bright Cfreen. Dye yellow with fustic and onion 
skins. Place immediately in a strong, hot solution of 



86 ELEMENTAEY APPLIED CHEMISTRY 

indigo. Dull with iron sulfate to the desired shade. Nearly 
all tones can be produced by this method. 

Bull Green. Dye with black birch leaves. 

Barh Green. Dye with the birch and dip into FeSO . 

Gray- Green. Add sufficient ammonia to elderberry juice 
to turn it a pronounced green. Boil the raffia in this solu- 
tion until the desired shade is produced. The time required 
is about eight minutes. 

Olive-Green. See Dark Green. Boil longer in the iron 
sulfate solution. If left too long, the raffia acquires a heavy 
olive tone not pleasing to the eye. 

Yellow- Green. Color with fustic or onion skins and very 
slightly with indigo. 

Gray. For these effects in general, boil in dye from 
sumac cones with the stems. A dip in iron sulfate will 
produce a pleasant neutral effect. 

Old Rose. Dye with sumac berries, discarding all stems. 
Substitute elderberries for the sumac. 

Orange. 1. Dye in fustic and then in strong, hot redwood 
infusion. 

2. Boil in butternut for about six minutes. Rinse and 
dip into cardinal solution. 

To produce a peculiar but pleasing effect, dye first in 
fustic and then in cardinal. One side will be brown yellow, 
the other a dark red. 

Red. With infusions of redwood it is possible to get an 
almost complete color scale, from a deep, rich, dark red to 
a pale orange. These colors can be dulled with FeSO^, 
thus producing an infinite variety of tints and shades. 

For a deep red a very strong solution is needed, and only 
a small quantity of material can be colored at a time. As 
the strength is reduced the color tends toward orange. 



EAFFIA DYEING 87 

The lighter tints of orange can be dulled with iron sul- 
fate to give a pleasing light brown, practically identical 
with that produced from sumac. 

Bright Red. Dye in sumac and strengthen in cardinal, 
or dye directly in the cardinal. 

Bark Red. 1. Dye a bright red and dip in iron sulfate. 
The longer it remains the darker it becomes, until the limit 
is reached. 

2. Dye brown with waste dye and then boil in cardinal. 

Indian Red. 1. Dye orange red and boil in CuSO for 
two minutes. 

2. Dye light brown and boil first in cardinal solution 
and then in potassium dichromate. 

3. To butternut dye add half as much cardinal solution, 
one eighth as much KgCr^O,, one fourth teaspoonful of 
indigo paste, 2 oz. of logwood chips. Boil and strain, and 
dye the raffia in the clear liquid. 

4. To produce a pale shade, dye in an extra strong solu- 
tion from the sumac berries after discarding the stems. 

Purple-Red. Dye in cardinal and then in indigo, or dye 
alum-mordanted raffia in logwood. 

Yellow. Any of the yellow tones may be intensified by 
longer boiling. 

Lemon Yellow. 1. Boil in dye from pear leaves to which a 
spoonful of alum has been added. Alum intensifies the color. 

2. Boil for one minute in fustic, or for the same length 
of time in onion skins. 

Any of the colors herein described can be duplicated, 
provided the experimenter becomes familiar with the special 
dye at hand. 

Raffia dyemg is not merely a mechanical process ; it is 
an art learned best by the patient and orderly worker. 



SECTION XV 
CHEMISTRY OF STAINS 

A stain may be caused by the union, chemical or physi- 
cal, or both, of some substance with a suitable medium, as 
paper, cloth, skin, and the like. The subject is a very deep 
and intricate one. 

When a stain is purely physical, as, for example, a spot 
of grease on cloth, physical means of removing it are best ; 
that is, some simple process of absorption or solution. 

When the stain is of a chemical nature and certain oxids 
are formed, — take, for example, the stain of apple juice on 
cloth, — chemical means must be employed to reduce or 
" bleach " the oxid. 

When a stain is of both a chemical and physical nature, 
both physical and chemical means should be employed to 
remove it. A stain of this character may be illustrated by 
an mk spot on cloth. 

A good general bleaching reagent consists of a double 
solution kept in separate bottles. 

No. 1. Acetic or tartaric acid solution, 20 per' cent. 
No. 2. Five grains of bleaching powder (CaClOj). Boil in 100 cc. 
of water until a pink color appears. Filter and add 50 cc. of cold water. 

This combination is sometimes called " ink eradicator." It 
must not be applied to silk or to fabrics of deUcate color. 

To remove stains of ink, coffee, tea, fruit, and dye, wet 
the spot thoroughly with No. 1. Absorb the superfluous 
liquid with a blotter and apply No. 2. Rinse and repeat, 

88 



CHEMISTRY OF STAINS 



89 



if necessary. If a persistent, yellowish spot remains, as is 
often the- case when woolen goods have been treated, 
remove all traces of the reagents and saturate with fresh 
H^O^. Common stains may be removed by treating as 
shown in the following table: 



Stain 


Removjed by 


Acids 


Cold water, Nos. 1 and 2 


Grass and fruit . . . 


Cold water, alcohol, Nos. 1 and 2 


Grease 


Gasoline, carbon tetrachlorid, chloroform, 




ether, carbon bisulfid, ammonia, soapsuds. 




warm fuller's earth (cover with a blotter 




and apply a warm flatiron) 


Dyes, coal-tar or of vege- 




table origin . . . 


Nos. 1 and 2, ammonia 


Mildew . .... 


Nos. 1 and 2, sunlight 


Inks 


Nos. 1 and 2 


Inks, indelible (silver) . 


Potassium cyanide, 10 per cent. Use great 




caution, intensely poisonous. Sodium hypo- 




sulflte, 20 per cent 


lodin 


Methyl alcohol, potassium iodid solution, 




10 per cent 


Iron rust 


"Warm oxalic or citric acid, 10 per cent. If in 




silk, let it alone 


Paint, varnish .... 


Turpentine, benzine, carbon tetrachlorid. Use 




no turpentine on silk 


Tar, wagon grease . . 


Soap and oil, turpentine 



SECTION XYI 



FOOD PRESERVATIVES 



Detection of Sulfurous Acid. Weigh about 25 g. of the 
sample into a 200-cc. Erlenmeyer flask. Add water, if nec- 
essary, to form a thin paste 
and about 5 g. of sulfur-free 
zinc. Introduce 10-20 cc. 
chemically pure HCl. Over 
the mouth of the flask place 
a small filter paper which 
has been wet with a strong 
solution of Pb (N0,)„. Heat 
gently. The blackening of 
the filter paper indicates the 
presence of sulfites. Why ? 
A mere browning of the filter 
paper sliould not be accepted 
as evidence of the inten- 
tional addition of SO^, either 
as a preservative or as a 
bleaching agent ; it must be 
distinctly black. (^Bulletin 
No. 107, ]). 187:) 

Distillation Method. Leach. 
Reduce 100-200 g. of the 
sample to paste as before, 
and acidif}' with .5 cc. of 

90 




Fig. 18. Apparatus arranged for 

the detection of sulfurou.s acid by 

tile distillation method 



FOOD PKESEEVATIVES 91 

20 per cent phosphoric acid. Transfer to a boiling flask and 
distil. Arrange the apparatus so that the outlet of the con- 
denser will dip below the surface of a little water, about 20 cc. 

Distil off 20 to 30 cc. Treat the distillate with 5 to 10 cc. 
of bromin water and boil for a minute or so. 

Without waiting for the distillate to cool, add a little 
BaClj. A white precipitate indicates sulfurous acid. 

What is this precipitate ? Test its solubility. Of what 
use is the bromin water ? 

Test molasses, lime juice, mushrooms, Hamburg steak, 
sausage, etc. for sulfurous acid. 

Determination of Sulfurous Acid by Direct Titration. Care 
must be taken in applying this method to other products 
than wine to determine whether the iodin is decolorized by 
any substance that may naturally be present. 

Macerate 25 g. of the sample, if a solid or semisolid, with 
sulificient water to form a thin paste. Place in a 200-cc. Erlen- 
meyer flask. Add 25 cc. of normal KOH, mix thoroughly, 
and allow it to stand for fifteen minutes, shaking from time 
to time. Add 10 cc. of dilute sulfuric acid (1 to 3) and 5 cc. 
of freshly prepared starch solution. Rapidly titrate the mix- 
ture with N/50 iodin solution until a blue color is perma- 
nent for several minutes. 

One cubic centimeter of N/50 iodin solution is equivalent 
to 0.00064 gram of sulfur dioxid. 

From the per cent of SO^ calculate the per cent of sulfur- 
ous acid in the original sample (^Bulletin No. 107, p. 188). 

Detection of Boron Compounds — Borax or Boric Acids. It 
is not uncommon to find this forbidden preservative in 
cheese, ice-cream cones, fancy crackers and biscuits. It was 
formerly used in canned meats, but the practice has greatly 
declined of late. 



92 ELEMENTARY APPLIED CHEMISTRY 

" The common symptoms observed after long-continued 
doses of borax or boric acid in food are headaches, sensations 
of fulhiess in the head, uneasiness and nausea in the stomach, 
and disturbances of the digestion and appetite" (^Wiley). 

Discover the Effects of H3BO3 upon Turmeric Paper and 
Turmeric Tincture. Break about 10 g. of saltines or other 
crackers into a crucible. Add a pinch of boric acid or borax, 
and ash. Acidulate the ash with a drop or so of HCl and 
dissolve in as little water as possible. 

(a) Dip a strip of turmeric paper in the solution and 
allow it to dry. Result ? 

(5) Mix the remainder of the ash solution with a cubic 
centimeter of turmeric tincture in a watch glass and evapo- 
rate over a water bath. Result ? 

Confirm both (a) and (6) by placing a drop of dilute 
alkali upon the paper or on the contents of the glass. An 
olive-green color should appear. 

After becoming familiar with the reaction between boric 
acid and turmeric, test crackers or biscuits, butter, cheese, 
canned meat, and shrimps for boron compounds. 

Method. Ash about 10 g. of the sample, first adding 
enough limewater to make an alkaline reaction. Acidulate 
the ash with a drop or two of HCl. Dissolve in a few 
drops of water. Test with the turmeric paper and with the 
turmeric tincture, as outlined. 

If the turmeric is reddened by the solution of the ash 
and turned olive-green by dilute alkali, boric acid, free or 
combined, is present in the sample. 

Boron Compounds in Butter. Melt 25 g. of the sample 
on a water bath and allow the aqueous solution to settle. 
Decant this solution and acidulate with a drop or so of dilute 
HCl. From this point apply the regular turmeric test. 



FOOD PRESERVATIVES 



93 



Detection of Salicylic Acid (HC,H503). This compoiuul 
has lieen used i'dr thu preservation of catsup, jams and 
other fruit products, and beer. Ileduce tlie sample to a 
tliin paste with water, if it is not 
already a licpiid. Acidify sliglitly 
with dilute II SO,. Shake with an 
equal volume of chloroform in a 
closed flask or separatory funnel. 
Separate the chloroform and allow 
it to evaporate spontaneously. 

Firtit Tvat. To a part of the 
dry lesidue add a drop of ferric 
chlorid and an ecpial volume of 
water. A pronoruiced violet or 
jiurple color indicates the pres- 
ence of salicylic acid. 

Scriind Ti:i<t. Heat the remainder 
of the residue gently with a few 
drops of 2(.) per cent II,S(J^ and 
a cubic centimeter of methyl 
alcohol. 

If salicylic acid is present, 
a pronounced odor of "winter- 
green," or methyl salicylate, will 
be apparent. 

Detection of Benzoic Acid 
(HC^HjOJ. Benzoic acid is used 
for much the same purpose as 
salicylic acid, and is more often found in food products. 

Extract tlie sample as for salicylic acid and evaporate 
the chloroform. Dissolve a i)art of the dried residue in 
ammonia and evaporate to drj-ness o\'er a water Ijath. 




Fig. 19. Sep;iratiiry funnel 

t'(ir extr;icting salicyliu or 

benzoic acid with etlier or 

clilorofin'Tu 

Siililimcil crystals of benzoic 

at-id slH.tA\' un tile A\'atc]i glass. 

See Fig-. liO 



94 



ELE^IEXTAEY APPLIED CHE.^IISTRY 



Firf't Test. Dissolve in a few drops of water, heating 
genth- to effect the sohitioii. Filter into a small test tube 
and add a drop of ferric chlorid. A flesh-colored precipi- 
tate of ferric lienzoate assures the presence of benzoic acid. 

Second Test. Dissolve the 
remainder of the chloroform 
extract in ammonia and evap- 
orate to dryness in a tA'\-o-incli 
watch glass. In^•ert a second 
watch glass over the first. 
Jjctween these insert a fil- 
ter paper from the center of 
which has been cut a lialf- 
inch circle. Clamp the watch 
glasses closely together and 
lieat at a \n\y temperature 
on a sand bath. If l)enzoic 
acid is present, needlelike 
crystals Avill sublime on the 
upper watch glass. Examine 
them witli a low-power lens. 
Dissohe and treat them with 
a drop of ferric chlorid, as 
in the preceding test. 
Detection of Saccharin. Prepare the sample as for the 
salicylic acid test. Extract with ether and allow the latter 
to evaporate at room temperature. A distinctly sweet taste 
mdicates the presence of saccharin. 

Add a small piece of NaOH and heat gently. The sac- 
charin \\\\\ be converted into salicylic acid and can be 
detected by the ferric chlorid test. 




Fk:. 20. Saiul bath, lilter iiaper, 

and double watch glass arranged tu 

sublime benzoic acid 



SECTION XVII 

EXAMINATION OF TOOTH POWDERS 

The usual ingredients of these dentifrices are soap pow- 
der, precipitated challi (CaCOg), sugar, orris root, and other 
flavoring materials. 

Sometimes powdered pumice stone and cuttlefish bone are 
substituted for the chalk. Since these substitutes scratch 
the enamel, they are injurious and should be avoided. They 
may be detected as follows : 

Shake up 1 to 2 g. of the powder with 10 cc. of dilute 
alcohol. To the residue add about 4 cc. of HCl and an 
equal volume of water. Note any effervescence. Boil. 
Allow any undissolved matter to settle and decant the 
solution. Insoluble matter indicates pumice stone. Con- 
firm by placing a little on a glass plate and rubbing gently 
with a glass rod. If pumice is present, a scratching sound 
will be heard. 

Divide the decanted solution into two parts. 

The First Part. Evaporate to dryness and test with 
ammonium molybdate for the PO^ radical. If present, 
cuttlefish bone is indicated. 

The Second Part. Test for calcium with (SYi^pp^. 
Its presence is indicated by a flocculent white precipitate. 
This further bears out the suggestion of the presence of 
powdered bone. 



96 



96 ELEMENTARY APPLIED. CHEMISTRY 

TABLE OF INDICATIONS 



Effe rvescence 


Residue Insol- 
uble IN Ha 


Calcium 


PO4 


Indication 


Yes 


No 


Yes 


No 


Chalk 


Yes 


No 


Yes 


Yes 


Cuttlefish bone 


No 


Yes 


No 


No 


Pumice 


Yes 


Yes 


Yes 


No 


Chalk and pumice 


Yes 


Yes 


Yes 


Yes 


Cuttlefish bone 
and pumice 



What are the indications for chalk and cuttlefish bone ? 
In addition to the above tests, determine the free and 
combined allcali and the alkaline carbonates. 



SECTION XVIII 

EXPEKIMENTS WITH GLUCOSE 

Glucose is widely distributed in the vegetable kingdom. 
It occurs naturally in many fruits and vegetables, in honey, 
in the blood, liver, and urine. In the disease diabetes mel- 
litus the quantity present in the urine is sometimes as high 
as 10 per cent. 

It is artificially prepared on a large scale by treating 
corn or potato starch with dilute sulfuric acid. Its sweet- 
ness to that of sugar is as 3 to 5. Large quantities are 
annually consumed in the manufacture of leather, candy, 
table sirups, jams, jellies, and the like. 

Conversion of Starch into Glucose. Boil 5 to 10 g. of 
sawdust, filter paper, cotton rags, or cornstarch, with a 
10 per cent solution of H^SO^ in an Erlenmeyer flask, in 
the neck of which is a funnel to act as a reflux condenser. 
Continue boiling until the liquid becomes a decided yellow 
or brown. Neutralize with powdered chalk and filter. 
Evaporate the filtrate to a thick sirup. 

Suggestions. Pour the acid into the water. 

Flasks will break if the starch is allowed to stick to 
the bottom. For the first attempt use corn or potato 
starch. 

Replenish the water as it boils away. If the acid becomes 
too strong, it will carbonize the starch. 

Neutralize by adding the chalk well powdered. Test 
often with litmus. Filter. If the filtrate is still acid, add 

97 



98 ELEMENTAEY APPLIED CHEMISTRY 

more of the carbonate. A relatively large quantity will 
probably be required. 

Add plenty of water to the filter to wash the glucose 
from the spent carbonate. 

Great care must be taken during the process of evapora- 
tion or the liquid will blacken. Stir constantly and finish 
over a water bath. 

Reactions. Notice the interesting exhibition of catalysis in 
the following reaction : 

starch • glucose 

C^H^P^ and H^S0, + CaC03 = ? 

Name the contents of the filter paper. Dry it. It will 
keep its form. Why ? Which of the changes in the above 
experiment are physical, and which are chemical ? 

Test for Glucose by the Reduction of a Copper Salt. Dis- 
solve a little glucose in water. Add 2 cc. Fehling's solu- 
tion, 1 cc. each of No. 1 and No. 2. Heat nearly to boiling. 
The result is characteristic. 

Repeat, substituting cane sugar for the glucose. Result ? 

Fehling's Solution, No. 1 : CuSO^, 34.6 g. ; water, 500 ec. 
Fehling's Solution, No. 2 : Rochelle salts, 173 g. ; NaOH, 50 g. ; 
water, 500 cc. Keep in separate bottles. 

Test for Glucose by the Precipitation of Dextrine. Dis- 
solve a little glucose in water. To two or three cubic centi- 
meters add a large excess of methyl alcohol. Agitate. The 
glucose is precipitated as dextrine. 

Repeat, substituting cane sugar for glucose. Result ? 

Inversion of Cane Sugar. Make a solution of cane sugar 
as before. Add one drop of HCl and boil vigorously. Test 
with Fehling's solution. 

C..H,p„ + H,0 = C,H,,0, + Q^l\p, 

cane eugar glucose fructose 



EXPERIMENTS WITH GLUCOSE 99 

The mixture of glucose and fructose is called invert 
sugar. Notice how the inversion is brought about by hydrol- 
ysis. Before cane sugar is digested it must pass through 
the process of inversion. 

Test honey, confectionery, maple sirup, molasses, jam, 
jelly, the contents of pies and cake fillers for invert sugar 
by the Fehling method. 

Test the same for glucose by the precipitation of dextrine. 
It is instructive to treat a sample of homemade jelly and 
any one of the cheap varieties by this method. A decided 
milkiness in the alcohol indicates commercial glucose. 

Many soft candies, waxes, taffies, a large proportion of 
stick candy, caramels, and the like are made with glu- 
cose. Sometimes a little cane sugar is added to give it a 
sweeter taste. 

Considerable glucose is used in the manufacture of table 
sirups. These are sent to the market under euphonious 
names, as "Maple Drip," "Bon Ton," "Golden Drip," 
" White-Loaf Drip," etc. 

Detection of Glucose in Honey. Dissolve one part of honey 
in an equal volume of water. Cool and add 5 to 8 drops of 
a dilute solution of iodin in KI. 

If the honey solution remains a pale yellow, commer- 
cial glucose is probably absent. If decolorized, glucose is 
indicated. 

If starch is present, the characteristic blue-to-purple 
coloration will appear (Beckmmis tesf). 

Anilin-Acetate Test for Artificial Invert Sugar in Honey. 
The reagent must be freshly prepared. Shake 5 cc. of 
chemically pure anilin with 5 cc. of water, and add 2 cc. of 
glacial acetic acid. The milky emulsion of anilin and water 
should clear up perfectly upon the addition of the acid. 



100 ELEMENTARY APPLIED CHEMISTEY 

Dissolve about 5 cc. of honey in a test tube with an equal 
volume of water, and pour a little of the anilin solution 
down the sides of the tube so as to form a thin layer upon the 
surface of the liquid. If artificial invert sugar is present, a 
red ring will form beneath this layer, and on gently agitat- 
ing the tube all of the acetate will be tinged this color. 

If the honey is pure and has not been overheated, no 
trace of the red will be found. 

Sugar in Vegetables and Fruits. Grind a quarter of a 
turnip or half an apple through a food cutter. Place the 
pulp in a piece of cheesecloth and squeeze the juice into a 
beaker. Taste the juice. Pour about 5 ce. into a test tube 
and dilute with three or four times its volume of water. 
Test with Fehling's solution. 

Test beets, carrots, parsnips, etc., for sugar. How does 
the sugar from the beet differ from that of the apple ? 

Conversion of Starch to Invert Sugar by the Process of 
Mastication. Grind a few grams of soda or milk crackers in 
a mortar with enough water to form a thin paste. Transfer 
to a test tube and test with Fehling's solution. Result? 

Thoroughly chew about 5 g. of the cracker for about 
one minute. Test as before. How do you account for the 
change ? Could the food be chewed too much ? Why ? 

Detection of Adulteration in Maple Sirup. Coloring Matter. 
Shake 15 cc. of the sirup with 3 cc. of amyl alcohol and 
1 cc. of Hj^PO^ (20 per cent). Allow to settle. The amyl- 
alcohol layer should be a decided brown. Adulterated 
samples give a straw-to-light-brown color. 

Foam Test. Mix 5 cc. of the sirup and 10 cc. of water in 
a graduated tube and shake vigorously for half a minute. 
Allow to stand ten minutes. The foam should not measure 
less than 3 cc. Adulterated samples give less foam. 



EXPERIMENTS WITH GLUCOSE 101 

Precipitate Test. Mix 5 ec. of the sirup with 30 cc. of 
water in a 50-cc. cylinder. Add 2 cc. of lead subacetate 
solution. Mix well and allow to stand for twenty hours. 
The precipitate should not measure less than 3 cc. (^Bulletin 
of Pharmacy, December, 1908.') 

When maple sugar is to be tested, dissolve 15 g. in 
enough water to make 15 cc. of sirup. 



SECTION XIX 
EXAMINATION OF HEADACHE POWDEES 

A great deal of injury is done each year by the in- 
discriminate use of headache powders, " cures," " stops," 
tablets for car sickness, anti-pam tablets and pills, cold 
" cures," and the like. 

Many of these contain a coal-tar derivative commonly 
known as acetanilid, or antifebrin. This is the acetyl de- 
rivative of anilin, and is therefore called phenylacetamid 
by the chemist. This substance is a dangerous heart de- 
pressant and should never be used except by the intelligent 
advice of a physician. 

Another substance frequently used in cheap powders of 
the above description is phenacetin, known to the chemist 
as oxyethylacetanilid. If one values his health, he should 
avoid the common use of such pernicious drugs. 

Detection of Acetanilid in Headache Cures, Cold and Grippe 
Powders, and like Nostrums. Strobel's Test. Place about 
0.2 g. of the sample in a 5-in. test tube and add about 
the same volume of ZnCl^. Heat gently, meanwhile hold- 
ing a wood shaving or splint down the mouth of the tube. 
White fumes soon appear. Continue heating ; the mixture 
melts, turns light yellow and finally black. Observe the 
shaving from time to time. If it is stained yellow, acet- 
anilid is undoubtedly present. Note the peculiar odor of 
the fumes. Varnish or shellac the splint and mount it in 
the notebook with the label from the package. 

102 



EXAMINATION OF HEADACHE POWDEES 103 



Ritsert's Test, lioil 1 g. of the sample in a small l)eaker 
for two or three minutes \\'ith alx.iut 3 ce. strong HC'l. Cool 
and di^'ide into three portions and test in small tul)es. 

1. Add carefully 1 to 3 drops of a solution of bleaching 
powder (CaClOJ, 1 to 200, in sueh a manner that the two 
liquids do not mix. A beautiful blue eoloi' is seen at the 
junction of the two li(puds 
if acetanilid is present. 

This is known as the in- 
dophenol reaeti(in, and it le- 
sponds to anilin compounds 
generally. 

2. To another purtion add 
a small drop of KAIn() . ^V 
clear green color is formed 
if an appreciable amount of 
acetanilid is present. 

3. ]Mix the third portion 
with a 3 per cent chi'c imic acid 
solution. Acetanilid gives a 
green color, changing to a 
dai'k green in a few minutes, 
and forms a dark blue precipitate on the addition of a drop 
or two of NaOH solution. 

In the case of powders containing A'egetaljle matter or 
sugar of milk, both of which will turn brown on heating with 
HC'l, it is advisable to first boil the sample in 5 t(_i 10 cc. of 
water. Filter, cool the liltrate, and agitate. If acetanilid is 
present, it will crystallize out and settle. ^V centrifuge may 
be used t(.) advantage to separate the crystals from the licjirid. 
This latter which still contains some acetanilid in solution 
may be discarded and the crystals tested as indicated. 




Fh.,. 21. Showing iiu'tliod of Iiold- 
iiig .splint for tlio Strobel test 



104 ELEMENTARY APPLIED CHEMISTRY 

The blue color of the bleaching powder solution is prob- 
ably due to the presence of anilin hydrochlorid. 

Test headache powders for the bromin radical by gently 
heating with equal parts of MnO^ and H^SO^. 

Isonitril Reaction. Heat about a gram of the powder with 
10 cc. of a 10 per cent NaOH solution. Remove from the 
flame and cautiously add a few drops of chloroform. Set 
aside for a few minutes. If acetanilid is present, the greasy, 
disgusting odor of phenylcarbamine will be apparent. 

This last test is perhaps the best of all, and is especially 
applicable to a liquid or solid whose color might interfere 
with the Ritsert test. 

To determine the Per Cent of Acetanilid present. Dis- 
solve a definite weight of the powder, about 1 g., in hot 
water. Boil and filter. To the filtrate add bromin water 
until the yellow color persists. The acetanilid is precipitated 
as p-bromacetanilid. Dissolve the precipitate in benzol. 
Filter and evaporate the benzol over a water bath. Dry at a 
temperature not exceeding 100° F. Weigh the residue. 

Caution. Keep the benzol from all flame, as it is exceed- 
ingly inflammable. 

Pure acetanilid melts at 113° C. Determine the melting 
point of your sample. 

If vinfamiliar with any of the above tests, work with a 
known sample. Do not give up until you are familiar with 
them. You may save the life of some one. 



SECTION XX 

TESTS FOR ARSENIC 

Arsenic is one of the most widely distributed elements. 
Unless care is taken by the manufacturer, it may contami- 
nate our foods, articles of clothing, wall papers, paint, and 
the like. In testing any such substance for arsenic it is 
advisable to partially destroy the organic matter with a 
mixture of sulfuric and nitric acids. This treatment oxi- 
dizes the arsenic into arsenic acid, which may be completely 
removed with boiluig water. The method advised is that 
of Chittenden and Donaldson (^Bulletin No. 86, Bureau of 
Chemistry, United States Department of Agriculture'). 

To successfully perform tests for arsenic, it is absolutely 
necessary that all of the reagents are themselves free from 
it. Assure yourself of this first of all. Save time by putting 
a few scraps of arsenic-free zinc into four different flasks : 

No. 1 containing 10 per cent HCl. 

No. 2 containing 10 per cent H^SO^. 

No. 3 containing 10 per cent nitro-sulfuric acid. 

No. 4 containing 10 per cent HCl and a few drops of 
10 per cent CuCl^. 

Over the mouth of each flask place a piece of filter 
paper, which has been wet with a few drops of concen- 
trated solution of mercuric chlorid. There should be a 
brisk evolution of gas. 

If after half an hour the filter paper shows no discolor- 
ation, the reagents are suitable for use. 

105 



lUIJ 



ELE.MEXTAEY APELIED CHE:\riSTET 



Preparation of the Sample. Wall Paper, Cloth, etc. Place 
al;)ont 25 sq. cm. cif the sample cut into small pieces in an 
evaporating dish. Treat with 1 to 5 cc. of a mixtttre of con- 
centrated sulfuric and nitric acids, 30 to 1, both of which 
have been jjroved free from arsenic. Add a few drops of 




Fig. 22. Gutzeit apparatus for the detection of arsenic 
Showing wash hottle witli fuitlet capped with preiiareil filter i>aper 



water and allow the action to proceed for hve minute.s. 
Heat with a low flame until all of the acid is dri\-en off, 
or until the residue lias granulated and tlie fumes have 
nearly disappeared. Break up tlie charred mass, add a little 
water, and boil to get rid of the 11 SO^. Filter througii a 
small Alter and -wash to about 40 cc. 



TEST.S FOR AESEXKJ 



107 



Preparation of the Sample. Jlrats, IW/rtahlcs, et<: Meat in 
a i:)nrceliiin dish about 100 g. of tlie sample ^A-itli 23 ec. of 
HNOg, stii-ring occasionally with a glass roil. When the 
substance has become a deep yellow or orange color, remove 
from the heat and add 3 cc. of H„SO,. Stu- the contents of 
the dish while the nitrous 
fumes are gi^'en off. Care 
should be taken to pro- 
tect the hands from these 
fumes. 

1 1 eat gently and add 
while hot, drop by drop, 
8 cc. of UNO , stirring the 
mass constantly. Heat 
more strongly until acid 
fumes come off and a 
charred mixture remains. 
Break this up, extract 
with boiling -water, and 
filter as in the case of 
wall paper. 

Note. Always conduct 
these prelimbiary proc- 
esses under a gas hood 
or out of doors. 

The Gutzeit Test. Into a clean Erlenmeyer flask of about 
200 cc. capacity, fitted with a thistle tube and a right- 
angled delivery tube, place a few pieces of arsenic-free 
zinc. Slide the zinc gently uito the flask to avoid breakage. 
Pour in the filtrate from the prepared sample and about 
5 cc. of the tested HCU, containmg lialf a cubic centimeter 
of a 10 per cent solution of CuCl, of known purity. 




Fn;.23. 



Siuqili' form of Gutzeit 
apparatus 



rtliowiug till' prepared tilter paper held 
over the mouth of the flask 



108 ELEMENTARY APPLIED CHEMISTEY 

Allow the escaping gas to pass tlirougli a few cubic 
centimeters of lead acetate solution contaiQed in a small 
wash bottle or potash bulb, and impinge upon ai piece of 
Swedish filter paper which has been wet with a drop or so 
of a concentrated solution of mercuric chlorid. 

If after haK an hour the paper shows a stain yellow 
to deep orange, arsenic is present. The color varies with 
the amount. Very large quantities produce a yellowish- 
brown stain. 

Write the reaction between free hydrogen and arsenic. 
What compound causes the yellow color on the filter paper ? 
If the filter paper remains white, freedom from arsenic is 
assured. 

Place a little chemically pure 10 per cent HCl upon per- 
fectly pure zinc. Result ? Then add a few drops of CuCl^ 
solution. How do you explam the effect ? Why was the 
copper chlorid solution added to the origmal sample ? 

iNIake arsenic tests upon the following : wrapping paper, 
samples of cloth, candy wrappings, wall paper, etc. Liquids 
can usually be tested without subjecting them to the pre- 
vious preparation. 



SECTION XXI 
METHOD FOR TESTING PAINT AND OILS 

If one desires to paint his building with a lead and zinc 
paint and pays the price, he should get lead and zinc, not 
sand, lime, and barium sulfate or barytes. On the other hand, 
if he pays a sand-and-lime price, he should not expect to get 
a metallic article. Which kind have you seen used ? 

Extraction of the Oil. Place about 5 g. of the paint in 
a small flask or beaker and wash with successive portions 
of warm petroleum ether, or benzine. Heat this in a water 
bath, away from any flame. Continue the washing until a 
few drops leave no residue on evaporation. 

It is more convenient to conduct the extraction with a 
Soxhlet apparatus, placiiag the paint in an extraction shell 
the weight of which must be previously determined. Dry 
the undissolved residue at 100° C. and calculate the per 
cent of the oil. 

To test the Purity of the Oil. Evaporate the ether extract 
from the previous experiment. Warm 2 cc. of the oil so 
obtained in a test tube and add an equal volume of glacial 
acetic acid. Cool in running water and add one drop of con- 
centrated H^SO^. Pure linseed oil turns sea-green, the color 
deepening on standing. A fugitive violet color indicates 
rosin oil. 

Heat a little of the oil in a test tube to about 100° C. 
Cool and rub on the back of the hand. If present, fish oil 
will be detected by the characteristic fishy odor. 

109 



110 ELEMENTARY APPLIED CHEMISTRY 

To test the Body of the Paint. 1. Boil a portion of the 
residue with strong acetic acid. A residue indicates BaSO^ 
or sand (SiO^), or both. Save the filtrate. 

2. To a second portion add an equal volume of Na^COg, 
then mix and fuse with a blowpipe on charcoal. If lead is 
present, a small metallic globule will fuse out. Lead in 
paint is usually present iu the form of basic lead carbonate, 
2PbC03-Pb(OHX. 

3. Moisten a third portion with a solution of Co (NOg)^. 
Heat strongly as before. A green color indicates zinc. 
Probably ZnO is in the original paint. 

4. To the filtrate from 1 add an excess of NHOH 

4 

and then ammonium oxalate. If lime is present, a white 
precipitate of oxalate of lime is formed. 

Suggest a method for determining how much of each 
ingredient is present. 

Test for the Purity of Olive Oil. Shake equal volumes 
(5 cc.) of the oil and HNOg. Pure oil should turn from 
pale to dark green in a few minutes. If it changes to brown, 
red, or orange, the addition of a foreign oil is indicated. 

Heat for five minutes in a water bath at 100° C. It should 
become pale yellow to orange yellow. On standing it will, 
if pure, become a yellow solid. (LeacKs test?) 

Free Fatty Acids in Olive Oil. Weigh exactly 20 g. of 
the sample into a counterpoised Erlenmeyer flask and add 
50 cc. of neutral alcohol. Mix thoroughly and heat the 
contents to 60° F. 

Titrate with tenth-normal sodium hydrate, using phe- 
nolphthalein as an indicator. Shake the mixture often dur- 
ing the titration. The number of cubic centimeters of the 
alltali used to neutralize the acid in 1 g. of the oil is called 
the Acid Xumber. 



METHOD FOE TESTING PAINT AND OILS 111 

Each cubic centimeter of tenth-normal sodium hydrate 
equals 0.0282 g. of oleic acid. Tabulate the results as Acid 
Number and also as Per Cent of Oleic Acid. 

The fresher and better grades of olive oils contain the 
least amount of free fatty acid. 

Neutral Alcohol. Titrate any convenient volume of 95 per cent alco- 
hol with tenth-normal alkali, using phenolphthaleiu as an indicator. 



BACH'S TABLE POR OIL REACTIONS 



Kind of Oil 


After Agitation 

■WITH HNO3 


After Heating 

FOR Five Minutes 

ON Water Bath 


Consistencv 
after standing 

Twelve to 
Eighteen Hour.s 


Olive .... 


Pale green 


(_)range to yellow 


Solid 


Peanut 


Pale rose 


Brownish yellow 


Solid 


Rape . . 


Pale rose 


Orange yellow 


Solid 


Sesame . . 


White 


Brownish yellow 


Liquid 


Sunflower . . 


Dirty white 


Reddish yellow 


Buttery 


Cottonseed . 


Yellowish brown 


Reddish brown 


Buttery 


Castor . . 


Pale rose 


Golden yellow 


Buttery 



Detection of Cottonseed Oil in Olive Oil. Take any con- 
venient volume of C-S,^ m which 1 per cent of sulfur has 
been previously dissolved, and add an equal volume of 
amyl alcohol (fusel oil). 

To 5 cc. of the sample add an equal volume of the re- 
agent. Stop the test tube loosely with cotton and heat for 
fifteen minutes in a bath of saturated boiling brine. 

If cottonseed oil is present, a deep red to orange color is 
developed. Pure olive oil gives little or no color under this 
treatment. (HalpJien tesf) 

This test can also be used for the detection of cottonseed 
oil in lard. The fat from animals fed on cottonseed meal is 
said to give a faint reaction. 



112 ELEMEJSTTAKY APPLIED CHEMISTEY 

If the olive oil containing cottonseed oil has been pre- 
viously heated, the reaction is much less delicate. 

Kapok oil, from the seeds of the Eriodendron anfraetuo- 
sum, and baobab oil give the same reaction. A distinction 
can, however, be made, since the two last oils react without 
heating, while cottonseed oil must be heated. 

To distinguish Renovated from Creamery or Dairy Butter. 
Melt two or three grams of butter in an iron spoon. Pure 
butter melts quietly with the production of much foam. 
Renovated butter and oleomargarine bump and sputter like 
hot grease and produce no foam to speak of. 

Waterhouse Test for Oleomargarine. Thoroughly shake 
50 cc. of sweet milk and heat nearly to boiling. Add from 
2 to 5 g. of the sample and stir with a small wooden stick 
flattened at one end until the fat is entirely melted. 

Place the beaker in a dish of ice water and continue 
stirring until the fat solidifies. 

If the sample is oleomargarine, the fat can be collected 
into a lump. Butter fat cannot be so collected, but is more 
or less emulsified with the milk. 

If the sample is renovated butter, it will tend to collect 
as a film on the surface of the milk when the stu-ring is 
stopped. It does not clot or gather like oleomargarine, but 
usuall}' adheres to the wooden rod. 



SECTION XXII 

DETEEMINATION OF FOOD VALUES 

Total Nitrogen and Proteids of Cereal Products. Gunning's 
Method. This method consists iia decomposing the organic 
matter by prolonged digestion with sulfuric acid and potas- 
sium sulfate. The carbon is driven off as CO^ and the 
hydrogen as water. The nitrogen is converted into am- 
monium sulfate from which the free ammonia is liberated 
by means of an alkali and distilled into a known volume 
of N/10 acid, and the amount calculated by titrating the 
acid remaining. 

It should be observed that foods in their natural state 
seldom if ever contain nitrates. Should this radical be 
present in appreciable amounts, the Gunning method must 
be modified. 

Prove the absence of nitrates by extracting about 5 g. 
of the sample with water. Filter and test the filtrate by 
mixing with a solution of ferrous sulfate. Add concentrated 
sulfuric acid so as to form a layer below the mixed solution. 
In the presence of nitrates a dark brown ring forms at the 
juncture of the two liquids. 

Prove the reliability of this reaction by working with a 
solution known to contain a nitrate. 

In the absence of nitrates proceed with the Gunning 
method as follows : 

Weigh exactly 0.5 g. of the finely powdered sample — 
bread, macaroni, breakfast food, etc. — and transfer to a 

113 



114 



ELH.MEXTAr.Y APPLIED ('IIE:N[ISTRY 



clean, dry Kjcldalil flask of about 250 cc. volume. jVdd 
10 g. of K.,SO^ and from 15 to 25 cc. concentrated H.,SO . 
Incline the flask at an angle of about 75° over a small bare 
flame and licat gently until all foaming stops. 

The mixture is now of a dark brown color. Slip a piece 
of wire gauze under tlie flask and slightly increase tlie heat 

until the gauze is cherry red 
where it comes in contact 
with the Ijottom of the flask. 
Place a funnel in the 
neck of the flask to act as a 
reflux condenser. Continue 
heating until the contents 
are colorless or of a pale 
straw color. Tliis usually 
takes from thirty minutes 
to two hours. Conduct the 
heating in a gas hood. 

^Vlhjw the flask to cool. 
Transfer tlie liquid hito a 
Ijoiling flask of about oOOcc. 
cap)acity, rinsing carefully 
witli 200 cc. of water. 

Add sufficient saturated 
solution of NaOH to make 
the contents strongly alkaline, using phenolphthalein as 
an indicatoi'. 

Place two or three pieces of zuic in the boiluig flask to 
prevent bumping, and distil off at least 150 cc, using a ver- 
tical conden.ser whose outlet dips below the surface of ex- 
actly 50 cc. of N/10 H.,S(,)^ contained in the receiving flask. 
(See apparatus for the detection of sulfurous acid.) 




Fig. ii. Kjclduhl li;isk arraii-t'd lur 
the detenniiialii.iii of iiitropjen 



DETERMINATION OF FOOD VALUES 



115 



It is of the utmost importance to know the exact volume 
of standard acid in the receiving flask. Measure with an 
accurate pipette. 

When all the ammonia has been distilled and absorbed, 
titrate the contents of the receiving flask with N/10 NaOH, 
using cochmeal as an indicator. 

The difference between the original volume of the stand- 
ard acid and the volume of N/10 NaOH required to titrate 
it represents the number of cubic centimeters of N/10 H^SO^^ 




Fig. 25. Digesting shelf for making simultaneous nitrogen determinations 

neutralized by the liberated ammonia. Every cubic centi- 
meter of N/10 sulfuric acid represents .0014 g. of nitrogen. 
The proteids are calculated from the total nitrogen by 
multiplying by the factor 6.25. This factor is the one 
generally adopted in determinations of this kind. 

ExAMPLK. 'Weight of cereal = 0.5 g. 
Volume of N/10 H^SO^ = 50 cc. 
Required 44 cc. of N/10 NaOII to titrate the excess acid. 
Therefore 6 cc. of N/10 H„S()j were neutralized by the liberated 
ammonia. 

1 cc. of N/IO HjSO^ = .0014 g. of nitrogen. 
6 cc. of N/IO H2SO4 = 6 X .0014, or .0084 g. of nitrogen. 
6.25 X .0084 = .0525 g. of proteid. 

.0525/.5 = 10.5 per cent of proteid. 

In such an analysis as the preceding one it is customary 
to state that the Protein = 6.25 x N. 



116 



ELEilEXTAEY APPLIED CHEMISTEY 



Fat of Cereal Products, known as "Ether Extract." 
Weigh from 2 to 3 g. of the sample into a tared extraction 
shell {^Schleirlwr and Sclinll). Dry thoroughly at 212°. 

Place the shell m a Soxhlet or Wiley Extractor and 
extract with water-free ether. Dry the shell and residue to 

constant weight and by differ- 
ence calculate the ether-solul)le 
matter. 

A thorough extraction re- 
Cjuires several liours. (ireat 
caution must lie exercised in 
heating the extracting appara- 
tus lest the ether take lire. 
Use a large water liath and a 
small flame, or, still better, an 
electric stove. 

Water or Moisture in Cereal 
Products. Weigh from 2 to 5 g. 
of the sample into a tared watch 
glass. Spread it evenly over the 
bottom, forming as thin a layer 
as possible. Dry at 100°C.,cool. 
and reweigh. Calculate the per 
cent of water by ilifference. 

Ash or Mineral Content of 
Cereal Products. Transfer the 
dried residue from the water determination to a tared porce- 
lain crucible, taking care that none nf the sample is lost. 
Burn to a white ash at the lowest temperature possiljle. If 
too much heat is employed, i\w ash ^^ill fuse to the bitttom 
(if the ci'uciblc. Cool in a desiccator, reweigh, and calculate 
the per cent. 




Fig. 26. Soxhlet extraction ap- 
paratus properly set up 



DETEEMINATION OF FOOD VALUES 117 

Carbohydrates in Cereal Products. The carbohydrates are 
often expressed by adding the per cent of water, ash, pro- 
teids, and fat, and subtracting the sum from 100. 

Calculation of Fuel Value. This value may be approxi- 
mately determined by means of the Rubner factors, which 
give for each pound of protein or carbohydrate 1860 calories, 
and for each pound of fat 4220 calories. 

Example. Suppose the analysis of a certain cereal product shows : 
protein, 13.4 per cent ; carbohydrates, 74.1 per cent ; fat, 0.9 per cent. 
Then 1860 x (.134 + .741) = 1627.50 calories 

4220 X .009 = 37.98 calories 
Total 1665.48 



SECTION XXIII 

TESTING UELN^Ei 

Determine Reaction. Normal, sliglitly acid ; after a full 
meal may be alkaline. 

Determine Odor. Normal, peculiar, aromatic. 

Determine Color. Normal, pale straw to reddish yellow. 
May be very pale by nervousness or excessive drinking. 

Determine Specific Gravity. Normal, 1.015 to 1.025 at 
60° F. 

Determine Total Solids. Normal, 3.4 per cent to 5.8 per 
cent. Total solids equal (specific gravity — 1) multiplied 
by 2.33. This is equivalent to the number of grams per 
cubic centimeter. 

To detect Albumen and Phosphates. First Method. Fill a 
test tube half full of clear urine. Boil the upper portion 
of the liquid. A turbidity indicates albumen or PO^, or 
both. Add a drop of acetic or nitric acid ; the phosphates 
dissolve, the albumen does not. 

Second- 3Iethod. Place about a cubic centimeter of con- 
centrated HNOg in a test tube, and by means of a pipette 
allow two or three cubic centimeters of the urine to rest 
upon its surface. 

If albumen is present, a white zone or flocculent pre- 
cipitate forms at the ring of contact of the two liquids. 
The extent of turbidity indicates roughly the amount of 
albumen present. 

1 For more complete analysis see Merck's Manual for 1911. 
118 



TESTING URINE 119 

A green turbidity indicates biliary pigments. Reddish 
brown indicates blood. 

Urates or Uric Acid. Murexide Test. Evaporate a few 
drops of urine to dryness on a watch glass. Add a drop or 
two of HNOj and again cautiously evaporate. Then add 
an equal volume of NH^OH. A purple color indicates 
urates, uric acid, or both. 

Invert Sugar. Fehling's Test. Boil 5 cc. of Fehling's 
solution, and if the color does not change, add an equal 
volume (not more) of urine, and boil. In the presence of 
reducing sugars the characteristic red-to-yellow precipitate 
forms. (See tests for glucose.) Use this test only when 
uric acid is absent. 

Haines's Test. Reagents: CuSO^, 2g. ; glycerin, 20 g.; 
KOH, 9g. ; water, 175 g. Boil 4 cc. of the solution and 
add 6 to 10 drops (not more) of the urine and boil again. 
In the presence of reducing sugars the yellow-to-red pre- 
cipitate forms. 

Detection of Sugar in the Presence of Urates or of Uric 
Acid. Heat 1 g. of phenyldrazine hydrochlorate, 2 g. of 
sodium acetate, and 25 cc. of urine, and if the salts do not 
completely dissolve, add a little water, and place in boil- 
ing water. 

Remove after twenty minutes to cold water. If sugar is 
present, characteristic crystals of phenylglucosazone form. 

Chlorids. Add a few drops of nitric acid to the urine 
to prevent the precipitation of the phosphates, and gradu- 
ally add a few drops of AgNO^. A white precipitate solu- 
ble in ammonia indicates chlorids. If present in small 
quantity, a milky color only will be seen. 

Sulfates. Use BaCl^ instead of the silver nitrate. If 
present, the insoluble precipitate of BaSO^ will be seen. 



SECTION XXIV 

SELECTED EXERCISES 

An Experiment with the Albumen of Meat. The most 
important solid constituent of the body of an animal is 
albumen. Place about 20 g. of lean beef finely minced in a 
beaker of cold water and gradually heat to about 130° F. 
Remove, filter the liquid, and test as follows : 

To a portion add HNOj. A white precipitate or a decided 
mUkiness indicates albumen. 

To another portion add a few drops of iodin. A yellow 
or port-wine color indicates the presence of glycogen or 
animal starch. 

Repeat the above experiment by placing the same weight 
of beef in actively boiling water. Leave for a minute and 
test as before. How do you account for the difference? 
What does this show concerning the cooking of meats ? 

Examination of Common Salt. Moisture. Purchase as 
many different brands of table salt as possible ; also several 
samples of " coarse-fine " and rock salt. 

Place exactly 5 g. of the sample in a small tared Erlen- 
meyer flask and heat to a temperature not exceeding 150° C. 
for three hours on a sand bath. Remove from the bath, in- 
sert a funnel in the mouth of the flask, and allow the contents 
to cool. The introduction of the funnel renders the use of a 
desiccator unnecessary for this determination. Reweigh, and 
from the loss of weight calculate the per cent of moisture. 
Reserve the residue for the determination of MgCl^. 

120 



SELECTED EXERCISES 121 

Insoluble Matter. Dissolve 5 g. of the sample in 100 cc. 
of water, heating gently if necessary. Filter the solution 
through a balanced filter paper, washing the residue with 
warm water until the filtrate shows no precipitate with 
AgNOj solution. Dry' and weigh the contents of the filter 
paper and calculate the per cent of insoluble matter. 

Chlorin. Dissolve 5 g. of the undried sample in a little 
water and make up the solution to exactly 500 cc. in a 
measuring flask. Mix thoroughly and withdraw 10 cc. by 
means of a pipette. Place in a clean beaker and add an equal 
volume of distilled water. Titrate with N/10 AgNO^, using 
neutral potassium chromate as an indicator (see p. 30). A 
liter of N/10 silver nitrate contains 17 g. of the pure 
crystallized salt. 

Deduct 0.1 cc. of the silver solution added, as this amount 
is required to produce the permanent red tinge. Every 
cubic centimeter of the N/10 AgNO^ is equivalent to 
0.00355 g. of chlorin. 

The 10 cc. of the titrated salt solution contained, theo- 
retically, how many grams of chlorin ? How many grams 
did you find ? What was the per cent of chlorin ? 

Suggestion. How many grams of salt did yoU dissolve ? 
To what volume did you dilute it ? How many grams of 
salt in 10 cc. of this solution ? 

Calcium Sulfate. First Method. Dissolve 5 g. of the sample 
in 20 cc. of water to which 2 cc. of HCl have been added. 
Boil gently, being careful to lose none of the solution during 
the process. In the case of rock salt it may be necessary to 
continue the treatment for some time in order to dissolve 
all of the CaSO. 

Neutralize the solution with ammonia and precipitate 
the calcium with (l:!m^')JOfi^. Allow it to stand overnight 



122 ELEMENTARY APPLIED CHEMISTRY 

and filter the solution through a fine, ashless filter paper. 
Wash the residue carefully, dry, and ignite it in a weighed 
crucible until the oxalate is converted into CaO. This will 
require about twenty minutes at a white heat. Cool and 
weigh as CaO. One part of CaO is equivalent to 2.4271 
parts of CaSO^. Calculate the per cent of CaSO^ in the 
original sample. 

Second Method. Dissolve 10 g. of salt in warm water 
containing 1 per cent of HCl. Dilute to a liter and draw 
out 250 cc. (2.5 g. of salt). Heat this portion to boiling, 
add 1 cc. of HCl, and immediately pour in about 20 cc. of 
boiling 10 per cent BaCl^. Do not add the barium chlorid 
solution drop by drop, but introduce it all at once. The 
precipitate should settle in half an hour. Decant the clear 
portion through an ashless filter paper. Pour 100 cc. of 
boiling water on the precipitate, agitate, and allow to settle, 
which it should do in about four minutes. Decant agam 
and repeat the operation until the liquid ceases to give 
an acid reaction. Finally wash the precipitate on the filter. 
Dry, ignite at a low heat, and weigh the BaSO^. From this 
calculate the per cent of CaSO^ in the sample. 

, Magnesiilm Chlorid. Into the flask containing the dried 
residue from the moisture determination place 25 cc. of abso- 
lute alcohol. Cork the flask and gently shake the contents 
from time to time for ten minutes. Filter and evaporate 
the a,lcohol, which contains nothing but MgCl . Dissolve the 
residue in water and titrate with N/10 AgNO^. 

From the chlorin found calculate the per cent of MgCl^ 
in the sample. 



WOKKING TABLE OF THE ELEMENTS 123 

SYMBOLS, ATOMIC WEIGHTS, AND VALENCE OF THE 
MORE IMPORTANT ELEMENTS 



Element 


Symbol 


Atomic Weight 


Valence 


Aluminium 


Al 


27.1 


3 


Antimony 






Sb 


120.2 


3,5 


Arsenic . 






As 


75 


3,5 


Barium 








Ba 


137.3 


2 


Bismuth 








Bi 


208 


3, 5 


Boron . 








B 


' 11 


3 


Bromin 








Br 


79.9 


1 


Cadmium 






Cd 


112.4 


2 


Calcium 






Ca 


40 


2 


Carbon 






C 


12 


4 


Chlorin . . 




CI 


35.5 


1 


Chromium . 






Cr 


52.1 


2, 3, 6 


Cobalt . . . 






Co 


58.9 


2 


Copper 






Cu 


63.6 


1,2 


Fluorin . . 






F 


19 


1 


Gold . . ; 






Au 


197.2 


1,3 


Hydrogen 






H 


1 


1 


lodin . . . 






I 


126.9 


1 


Iron . . 






Fe 


55.8 


2,3 


Lead . . . 






Pb 


207.1 


2,4 


Magnesium . 






Mg 


24.3 


2 


Manganese . 






Mn 


54.9 


2,4 


Mercury . . 






Hg 


200 


1, 2 


Nickel . . . 






Ni 


.58.6 


2 


Nitrogen . . 






N 


14 


3,5 


Oxygen . 









16 


2 


Phosphorus . 






P 


31 


3,5 


Platinum . . 






Pt 


195 


4 


Potassium . 






K 


39.1 


1 


Silicon . . 






Si 


28.3 


4 


Silver . . . 






Ag 


107.8 


1 


Sodium . . 






Na 


23 


1 


Strontium 






Sr 


87.6 


2 


Sulfur . . 






S 


32 


2,4,6 


Tin. . . . 






Sn 


119 


2,4 


Zinc . . . 






Zn 


65.3 


2 



INDEX 



Acetanilid, detection of, 102; de- 
termination of, 104 
Acetic acid, per cent of, 22 
Acidity of milk, 20 
Acids and alltalis, 5 
Adulteration of milk, 45 
Albumen, test for, 118 
Alcohol, ethyl, 55; methyl, 60; 

per cent of, 68 ; preparation of, 

56 ; tables, 66 
Alkali, free and combined in soap, 

25 
Alkaline carbonates in soap, 26 
Alum, tests for, 39 
Ammonia in baking powder, 39; 

in water, detection of, 31 
Ammonium molybdate solution, 

33 
Annatto, detection of, 45 
Arsenic, tests for, 107 
Artificial colors in milk, 45 
Ash, of cereal products, 116; of 

vinegar, 22 
Atomic weights, table of, 123 

Bach's table for oil. 111 
Baking-powder analysis, 35 
Baking soda, test for purity, 20; 

in milk, 47 
Barium sulfate in paint, 110 
Bases in baking powder, 39 
Borates in soap, 27 
Boric acid, detection of, 91 
Boron in milk, 47 



Butter, boron compounds in, 92; 
coal-tar dye in, 77 ; renovated, to 
distinguish, 112 

Calcium carbonate in soils, 9 
Calcium sucrate in cream, 48 
Calcium sulfate in salt, 121 
Cane sugar, inversion of, 98 
Caramel, detection of, 79 
Carbohydrates in cereal products, 

117 
Carbon dioxid in baking powders, 35 
Cheese, fat in, 52 
Chlorids in plants, 15 
Chlorin, in salt, 121 ; in water, 

tests for, 30 
Chlorophyl, extraction of, 13 
Cider vinegar, to distinguish, 23 
Citric acjd, per cent of, 19 
Cloth, arsenic in, 106 
Coal-tar dye, detection of, 76 
Cochineal, 80 
Cocoa, purity of, 24 
Condensed milk, fat in, 53 ; times 

condensed, 53 
Cottonseed oil in olive oil. 111 
Cream, determination of fat in, 52 

Dirt in milk, 44 
Distillation experiments, 54 

Equivalents of N/10 NaOH, 19 
Erythrosin as an indicator, 34 
Essential oils, extraction of, 44 



125 



126 



ELEMENTAEY APPLIED CHEMISTRY 



Fabrics, wool and cotton in, 7 
Fat, in cereal products, 116 ; in 

milk by the Babcock test, 41 
Fatty acids in olive oil, 110 
Fehling's solution, 98 
Filtration experiments, 1 
Flame tests, 10 
Food preservatives, 90 
Food values, determination of, 113 
Formaldehyde in milk, 46 
Fuel values, calories, 117 

Gelatin in milk, cream, etc., 48 
Glucose, preparation of, 97 ; tests 

for, 98 
Gunning's method for nitrogen, 

115 
Gunpowder, analysis of, 2 

Hardness of water, 34 
Headache powders, analysis of, 102 
Honey, glucose in, 99 
Hydrochloric acid in soils, 10 

Ice cream, fat in, 52 ; gelatin in, 
48 ; starch in, 52 

Ink eradicator, 88 

Invert sugar, in honey, 99 ; in veg- 
etables, 100 

Iron in plants, 15 

Iron oxid in soils, 9 

Lactic acid, per cent of, 20 

Lead in paint, 110 

Lemon extract, coal-tar dye in, 78 ; 
per cent of oil in, 65; prepara- 
tion of, 64 

Lime in paint, 110 

Litmus, use of, 5 

Magnesium in soils, ll ; chlorid in 
salt, 122 



Maple sirup, tests for purity, 100 

Martin's reagent, 78 

Metallic compounds in water, 34 

Methyl orange as an indicator, 34 

Milk analysis, 41 

Mineral acids in vinegar, 23 

Nessler's reagent, 31 
Nitrate of mercury, acid, 49 
Nitrates and nitrites, detection of, 

in water, 32 
Nitric acid in soils, 11 
Nitrogen, determination of, 115 ; 

in plants, 13 

Oil, extraction of, from paint, 109 ; 

olive, examination of, 110 
Oleomargarine, to detect, 112 
Oxalic acid N/10, 17 
Oxygen absorbed in water, 33 
Oystere, water in, 4 

Paint analysis, 109 
Phenolphthalein as an indicator, 17 
Phosphates in water, 32 
Phosphoric acid, in plants, 15; in 

soils, 11 
Plant analysis, 13 
Potash, in plants, 14 ; In soils, 10 
Potassium sulfo-cyanide test, 10 
Preservatives in milk, 46 
Proteins, determination of, 115 
Pumice stone in tooth powder, 95 

Radicals in baking powder, 38 
Raffia dyeing, 81 

Richmond scale for total solids in 
milk, 44 

Saccharin, detection of, 94 
Salicylic acid, detection of, 93 
Salt analysis, 120 



INDEX 



12T 



Sand in soils, 11 

Sediment in water, 28 

Silica in plants, 15 

Skimmed milk, identification of, 51 

Soap, analysis of, 25; insoluble mat- 
ter in, 25 

Soda, in plants, 14 ; in soils, 10 

Sodium bicarbonate in milk, 47 

Sodium hydrate N/10, 17 

Soil analysis, 9 

Soils, acidity and alkalinity of, 24 

Specific gravity of milk, 43 

Stains, chemistry of, 88 

Standard solutions, 16 ; exercises 
with, 19 

Starch, conversion to invert sugar, 
97 ; effect of mastication on, 
100 ; test for, 14 

Sugar in urine, detection of, 119 

Sulfates, in plants, 15 ; in soils, 10 

Sulfuric acid, in soils, 10; in vine- 
gar, 23 

Sulfurous acid, detection of, 90; 
determination of, 91 

Tartrates, test for, 88 
Tea, soluble matter in, 3 



Theine, extraction of, 4 

Titration, 16 

Tonsillitis Specific, 1 

Tooth powder, examination of, 95 

Total solids, in milk, 43 ; in water, 

29 
Turmeric, tests for, 80 
Turmeric tincture, preparation of, 

47 

Urine analysis, 118 

Vanilla extract, preparation of, 62 ; 

tests for, 63 
Vegetable colors, identification of, 

79 
Vinegar analysis, 21 
Vinegar eels, 21 

Wall paper, arsenic in, 106 

Water, analysis of, 28 ; in cereal 
products, 116; in milk, detec- 
tion of, 51 

Waterhouse test for butter, 112 

Wool in fabrics, 7 

Zinc in paint, detection of, 110 



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