=596. Fermented and Unfermented Tobacco.=—Samples of tobacco may
reach the analyst either in the fermented or unfermented state. As a
basis for comparison, it is advisable in all cases to determine the
constituents of the sample before fermentation sets in. The analysis,
after fermentation is complete, will then show the changes of a
chemical nature which it has undergone during the process of curing and
sweating. Only tobacco which has undergone fermentation is found to be
in a suitable condition for consumption. In addition to the natural
constituents of tobacco, it may contain, in the manufactured state,
flavoring ingredients such as licorice and sugar, coloring matters and
in some instances, it is said, opium or other stimulating drugs. It
is believed, however, that opium is not often found in manufactured
tobacco, and it has never been found in this laboratory in cigarettes,
although all the standard brands have been examined for it.[614]
In researches made at the Connecticut Station it is shown that
fermentation produces but little change in the relative quantities
of nitric acid, ammonia, fiber and starch in the leaves, while those
of nicotin, albuminoids and amids are diminished. This is not in
harmony with the generally accepted theory that starch is inverted and
fermented during the process.[615]
The nature of the ferments which are active in producing the changes
which tobacco undergoes in curing, is not definitely understood. Some
of the organic constituents of the tobacco undergo a considerable
change during the process. Any sugar which is found in the freshly
cured leaves disappears wholly or in part. As products of fermentation
may also be found succinic, fumaric, formic, acetic, propionic and
butyric acids.
=597. Acid and Basic Constituents of Tobacco.=—In unfermented and
fermented tobacco are found certain organic acids, among the most
important of which are citric, malic, oxalic, pectic and tannic. Of
the inorganic acids the chief which are found are nitric, sulfuric
and hydrochloric. Among the bases ammonia and nicotin are the most
important. Ammonia is found in the unfermented tobacco in only small
quantities, but in the fermented product it may sometimes reach as high
as half a per cent. The presence of these two nitrogenous bases in
tobacco renders the estimation of the proteid matter contained therein
somewhat tedious and difficult.
=598. Composition of Tobacco Ash.=—The mineral constituents of tobacco
are highly important from a commercial point of view. The burning
properties of tobacco depend largely upon the nature of its mineral
constituents. A sample containing a large quantity of chlorids
burns much less freely than one in which the sulfates and nitrates
predominate. For this reason, the use of potash fertilizers containing
large amounts of chlorin is injudicious in tobacco culture, the
carbonates and sulfates of potash being preferred. The leaves of the
tobacco plant contain a much larger percentage of mineral constituents
than the stems, their respective contents of pure ash, that is ash free
from carbon dioxid, carbon and sand, being about seventeen and seven.
The pure ash of the leaves has the following mean composition: Potash
29.1 per cent, soda 3.2 per cent, lime 36.0 per cent, magnesia 7.4 per
cent, iron oxid 2.0 per cent, phosphoric acid 4.7 per cent, sulfuric
acid 6.0 per cent, silica 5.8 per cent, and chlorin 6.7 per cent.[616]
=599. Composition of Tobacco.=—The mean composition of some of the more
important varieties of water-free tobacco is shown in the following
table:[617]
Havana, Sumatra, Kentucky, Java,
per cent. per cent. per cent. per cent.
Nicotin 3.98 2.38 4.59 3.30
Malic acid 12.11 11.11 11.57 6.04
Citric acid 2.05 2.53 3.40 3.30
Oxalic acid 1.53 2.97 2.03 3.38
Acetic acid 0.42 0.29 0.43 0.22
Tannic acid 1.13 0.98 1.48 0.51
Nitric acid 1.32 0.60 1.88 0.23
Pectic acid 11.36 11.88 8.22 10.13
Cellulose 15.76 10.59 12.48 11.82
Ammonia 0.49 0.06 0.19 0.23
Soluble nitrogenous matter 7.74 8.84 13.90 10.39
Insoluble ” ” 9.75 7.97 8.10 9.53
Residue and chlorophyll 5.15 8.63 1.99 6.45
Oil 1.03 1.26 2.28 0.81
Ash 17.50 17.03 14.36 18.46
Undetermined 8.68 12.88 13.10 15.20
Among the undetermined matters are included those of a gummy or
resinous composition not extracted by ether, the exact nature of
which is not well understood, and the starches, sugars, pentosans and
galactan.
Tobacco grown in more northern latitudes has less nicotin than the
samples given in the foregoing table.
The following table shows the composition of tobacco grown in
Connecticut:[618]
(A)= Unfermented,
(B)= Fermented,
Upper leaves. Short seconds. First wrappers.
(A) (B) (A) (B) (A) (B)
% % % % % %
Water 23.50 23.40 27.40 21.10 27.50 24.90
Pure ash 14.89 15.27 22.85 25.25 15.84 16.22
Nicotin 2.50 1.79 0.77 0.50 1.26 1.44
Nitric acid 1.89 1.97 2.39 2.82 2.59 2.35
Ammonia 0.67 0.71 0.16 0.16 0.33 0.47
Proteids 12.19 13.31 6.69 6.81 11.31 11.62
Fiber 7.90 8.78 7.89 8.95 9.92 10.42
Starch 3.20 3.36 2.62 3.01 2.89 3.08
Oil and fat 3.87 3.42 2.95 3.04 2.84 2.92
Undeterm’d 29.39 27.99 26.28 28.36 25.52 26.88
=600. Estimation of Water.=—In the estimation of water in vegetable
substances, as has already been noted, it is usual to dry them in
the air or partial vacuum, or in an inert gas, at a temperature of
100° until a constant weight is reached. By this process, not only
the water, but all substances volatile at the temperature and in the
conditions mentioned are expelled. The quantity of these volatile
substances in vegetable matter, as a rule, is insignificant and hence
the total loss may be estimated as water. In the case of tobacco a
far different condition is presented, inasmuch as the nicotin, which
sometimes amounts to five per cent of the weight of the sample, is also
volatile under the conditions mentioned. It is advisable, therefore, to
dry the sample of tobacco at a temperature not above fifty degrees and
in a vacuum as complete as possible. Tobacco is also extremely rich in
its content of crystallized mineral salts, containing often water of
crystallization, and there is danger of this crystal water being lost
when the sample is dried at 100°. The desiccation is conveniently made
in the apparatus described on page 22. If a high vacuum be employed,
_viz._, about twenty-five inches of mercury, it is better not to allow
the temperature to go above 40° or 45°. A rather rapid current of dry
air should be allowed to pass through the apparatus for the more speedy
removal of the moisture and a dish containing sulfuric acid may also be
placed inside of the drying apparatus. It is possible by proceeding in
this way to secure constant weight in the sample after a few hours.
=601. Estimation of Nitric Acid.=—The nitric acid in a sample of
tobacco is most easily estimated by the ferrous chlorid process.[619]
The sample is best prepared by making an alcoholic extract which is
accomplished by exhausting about twenty-five grams of the fine tobacco
powder with 200 cubic centimeters for forty per cent alcohol made
slightly alkaline by soda lye. The mixture is boiled in a flask with
a reflux condenser for about an hour. After cooling, the volume is
completed to a definite quantity, and, after filtering, an aliquot
part is used for the analytical process. It is evident that the nitric
acid cannot be estimated in this case after previous reduction to
ammonia by zinc or iron on account of the presence of ammonia in the
sample itself. If, however, the amount of ammonia be determined in a
separate portion of the sample, the nitric acid may be reduced in the
usual way, by zinc or iron, the total quantity of ammonia determined by
distillation, the quantity originally present in the sample deducted
and the residual ammonia calculated to nitric acid.
=602. Sulfuric and Hydrochloric Acids.=—These two acids are determined
in the ash of the sample by the usual methods. The sulfuric acid thus
found represents the original sulfuric acid in combination with the
bases in the mineral parts of the plant, together with that produced
by the oxidation of the organic sulfur during combustion. In order to
avoid all loss of sulfur during the combustion, the precautions already
given should be observed. The separation of the sulfur pre-existing as
sulfates from that converted into sulfates during the combustion is
accomplished as previously directed.[620] For ordinary purposes, this
separation is not necessary.
To avoid loss of chlorin from volatilization during incineration the
temperature should be kept at the lowest possible point until the mass
is charred, the soluble salts extracted from the charred mass and the
incineration completed as usual.
=603. Oxalic, Citric and Malic Acids.=—The separation and estimation of
organic acids from vegetable tissues is a matter of great difficulty,
especially when they exist as is usually the case, in very minute
proportions. During incineration, the salts of the inorganic acids
are converted into carbonates and the subsequent examination of the
ash gives no indication of the character of the original acids. In
the case of tobacco, the organic acids of chief importance, from an
analytical point of view, are oxalic, citric and malic. These acids may
be extracted and separated by the following process:[621]
Ten grams of the dry tobacco powder are rubbed up in a mortar with
twelve cubic centimeters of dilute sulfuric acid (one to five) and then
absorbed with coarse pumice stone powder in sufficient quantity to
cause all the liquid to disappear. The mass is placed in an extraction
apparatus of proper size and thoroughly extracted with ether until a
drop of the extract leaves no acid residue on evaporation. Usually
about ten hours are required. The organic acids are thus separated
from the mineral acids. The ether is removed from the extract and
the residue dissolved in hot water, cooled, filtered, if necessary
several times, until the solution is separated from the fat and resin
which have been extracted by the ether. The filtrate is neutralized
with ammonia, slightly acidified with acetic and the oxalic acid
contained therein thrown out by means of a dilute solution of calcium
acetate, which must not be added in excess. The calcium oxalate is
separated by filtration, and determined as lime oxid. To the filtrate
is added drop by drop, with constant stirring, a dilute solution of
lead acetate, prepared by mixing one part of a saturated solution of
lead acetate with four parts of water. When the precipitate formed
has settled, the clear supernatant liquid is tested by adding a drop
of acetic acid and a few drops of the dilute lead acetate. In case a
precipitate be formed, the addition of the lead acetate is continued
until a precipitate is secured which will immediately dissolve in
acetic acid. At this moment the citric acid is almost completely
precipitated. In order to avoid the accumulation of the acetic acid
by reason of the repetition of the process as above described, the
mixture is neutralized each time with dilute ammonia. The precipitated
neutral lead citrate obtained by the above process, is separated by
filtration and, in order to avoid its decomposition when washed with
pure water, it is washed with a very dilute acetic acid solution of
lead acetate. The washing and filtration are accomplished as quickly
as possible, and the final washing is made with alcohol of thirty-six
per cent strength. In the filtrate the residual lead citrate, together
with a little lead malate, are precipitated by the alcohol used as the
wash and this precipitate is also separated by filtration. The filtrate
containing the greater part of the malic acid is evaporated to remove
the alcohol and treated with lead acetate in excess. Afterwards it
is mixed with five times its volume of thirty-six per cent alcohol
containing a half per cent of acetic acid. In these conditions the lead
malate is completely precipitated as neutral salt, and after standing a
few hours, is separated by filtration. The three precipitates, obtained
as above, are dried at 100° and weighed. If the precipitates have
been collected on filter paper they should be removed as completely
as possible, the papers incinerated in the usual way and any reduced
lead converted into nitrate and oxid by treatment with nitric acid and
subsequent ignition. From the quantities of lead oxid obtained, the
weights of the citric and malic acids are computed. The precipitate
which is obtained by the action of alcohol, above noted, is also dried
and ignited and the lead oxid found divided equally between the citric
and malic acids, the respective quantities of which found, are included
in computing their total weights. The weight of the citric acid is
calculated from the formula (C₆H₅O₇)₂Pb₃ + H₂O, and that of the malic
acid from the formula C₄H₄O₅Pb + H₂O.
=604. Acetic Acid.=—For the determination of the volatile acids of the
fatty series existing in tobacco, the following process, also due to
Schlösing, may be followed:[622]
The apparatus employed is shown in Fig. 121. Ten grams of the
pulverized tobacco, moistened with water and mixed with a little
powdered tartaric acid, are placed in the tube _A_. The two ends of
the tube, _A_, are stoppered with asbestos or glass wool. Steam,
generated in the flask, _D_, is passed into _B_. After fifteen minutes,
or as soon as it is certain that the contents of _A_ have reached a
temperature of 100°, the dish, _F_, containing mercury, is placed in
the position shown in the figure. The steam, by this arrangement,
is forced into the lower end of _A_, passes into the condenser _E_,
and the condensed water collected in _C_. The operation should be so
conducted as to avoid any condensation of water in _B_. It is advisable
during the progress of the distillation, which should continue for at
least twenty minutes, to neutralize from time to time the acetic acid
collected in _C_ by a set solution of dilute alkali, or, an excess of
the alkaline solution may be placed in _C_ and the part not neutralized
by the acetic acid determined at the end of the distillation by
titration.
[Illustration: FIG. 121.—APPARATUS FOR ACETIC ACID.]
=605. Pectic Acid.=—Under this term are included not only the pectic
acid but all the other bodies of a pectose nature contained in tobacco.
These bodies are of considerable interest, although they do not belong
to the most important constituents. In fresh tobacco leaves are found
three pectin bodies. One pectin is soluble in water, another is an
insoluble pectose and the third is the pectose body forming salts
with the alkalies, _i. e._, true pectic acid. In fermented tobacco
pectic acid is found chiefly in combination with lime in the ribs of
the leaves, serving to give them the necessary stiffness. For the
estimation of the pectin bodies (mucilage) the powdered tobacco is
thoroughly extracted with cold water. An aliquot part of the aqueous
extract is mixed with two volumes of strong alcohol and allowed to
stand in a well closed vessel in a cool place for twenty-four hours.
The precipitate is collected on a filter, washed with sixty-six per
cent alcohol, dried and weighed. The dried residue is incinerated and
the amount of ash determined. In general, vegetable mucilages contain
about five per cent of ash. If more than this be found, it is due to
the solution of the salts of the organic acids contained in the sample.
A dried vegetable mucilage, obtained as above, dissolves in water to
a mucilaginous liquid which does not reduce alkaline copper solution
until it has been hydrolyzed by boiling with a dilute mineral acid.[623]
=606. Tannic Acid.=—This acid is separated and estimated by the
processes given in paragraphs =589-595=.
=607. Starch and Sugar.=—The unfermented leaves of tobacco contain
considerable quantities of carbohydrates in addition to woody fiber,
pentosans, galactan and cellulose. Among these, starch is the most
important. Sugar exists in small quantities in the fresh leaf,
usually not over one per cent. During fermentation, according to some
authorities, the starch is partially converted into sugar and the
latter substance disappears under the action of the alcoholic ferments.
It has been found at the Connecticut Station, however, that the starch
content of the leaf does not decrease during fermentation. The starch
and sugar may be determined in the fresh leaves by the methods already
given.
In the manufacture of certain grades of tobacco it is customary to add
a quantity of sugar. The analyst may thus be called upon to determine
in some cases whether the sugar found in a sample is natural or added.
The occurrence of natural sugars in tobacco has been investigated at
the instance of the British Treasury.[624]
The natural sugars which may be found in sun dried tobaccos usually
disappear entirely during the process of fermentation. It was found by
the Somerset House chemists that the content of sugar in commercial
tobaccos varies from none at all to over fifteen per cent. A remarkable
example of this variation is reported in two samples from this
country, one of which, grown in Kentucky, contained no sugar, and the
other grown in Virginia, 15.2 per cent.
It was noticed that the saccharin matters in the tobaccos examined
were neutral to polarized light. They are determined by their copper
reducing power. The tobacco sugars are therefore to be classed with the
reducing bodies, not optically active, found in the juices of sorghum
and sugar canes.
=608. Ammonia.=—As has already been intimated, ammonia exists only
in minute quantities in fresh tobacco leaves, but in considerable
quantities after fermentation. In the estimation of ammonia, twenty
grams of the tobacco powder are digested with 250 cubic centimeters of
water, acidulated with sulfuric and after an hour enough water added
to make the total quantity 400 cubic centimeters. After filtration, an
aliquot part of the filtrate, about 200 cubic centimeters, is treated
with magnesium oxid in excess and the ammonia and nicotin removed by
distillation in a current of steam. The distillate is collected in
dilute sulfuric acid of known strength. The total amount of the two
bases is determined by titration and the quantity of base representing
the nicotin, which has been determined in a separate sample, subtracted
in order to obtain the weight of the ammonia.[625]
The ammonia in tobacco is determined by Nessler in the following
manner:[626]
The powdered tobacco is mixed with water and magnesium oxid and after
standing for several hours it is distilled in a current of steam, the
distillate received in dilute sulfuric acid and the process continued
until a drop of the distillate gives no reaction for ammonia with the
nessler reagent. The excess of sulfuric acid in the distillate is
neutralized with pure sodium carbonate and the nicotin precipitated
by a neutral solution of mercuric iodid and potassium iodid. The
precipitate is separated by filtration, the filtrate treated with
sodium sulfid, and the ammonia again obtained by distillation with
an alkali, collected in dilute solution of set sulfuric acid and
determined by titration. The difference of the two determinations
represents the ammonia.
=609. Nicotin.=—In this laboratory McElroy has made a study of some of
the best approved methods for determining nicotin, and finds the most
simple and reliable to be that proposed by Kissling.[627] The finely
powdered tobacco should be dried at a temperature not exceeding 60°, or
it may be partially dried at that temperature before grinding and the
final drying completed afterwards. Twenty grams of the powdered sample
are intimately mixed by means of a pestle with ten cubic centimeters
of dilute alcoholic solution of soda lye, made by dissolving six grams
of sodium hydroxid in forty cubic centimeters of water and completing
the volume to 100 cubic centimeters with ninety-five per cent alcohol.
The mass is transferred to an extraction paper cylinder, placed in
an extraction apparatus and extracted for three hours with ether.
The ether is nearly all removed by careful distillation, the residue
mixed with fifty cubic centimeters of a very dilute soda lye solution
(4 to 100) and subjected to distillation in a current of steam. The
flask containing the nicotin extract should be connected with the
condensing apparatus by a safety bulb as is usual in the distillation
of substances containing fixed alkali. The distillation should be
conducted rapidly and in such a manner that when 200 cubic centimeters
of the distillate have been collected, not more than fifteen cubic
centimeters of the liquid remain in the distillation flask. In
the distillate, the nicotin is determined by titration with a set
solution of dilute sulfuric acid, using rosolic acid or phenacetolin
as indicator. It is advisable to titrate each fifty cubic centimeters
of the distillate as it is received and the distillation is continued
until the last fifty cubic centimeters give no appreciable quantity
of the alkaloid. In the calculations one molecule of sulfuric acid is
equivalent to two molecules of nicotin according to the equation
H₂SO₄ = (C₁₀H₁₄N₂)₂.
98 324
_Polarization Method._—Popovici has based a method of detecting the
quantity of nicotin in tobacco on its property of rotating the plane
of polarized light.[628] The gyrodynat of pure nicotin is expressed by
the formula [_a_]_{D} = -161°.6. When ten parts of nicotin are mixed
with ninety parts of water, this value becomes -74°.1. By reason of
this great depression in gyrodynatic value Popovici determined the
relation which exists between the dilute solutions of nicotin and the
number of minutes of angular rotation produced on polarization in a
200 millimeter tube. In a solution in which two grams of nicotin are
contained in fifty cubic centimeters, each minute of angular rotation
is found to correspond to 6.5 milligrams of nicotin. For one gram in
solution in the same volume one minute of angular rotation corresponds
to 5.9 milligrams and for a half gram in solution to 5.7 milligrams.
The nicotin is prepared for polarization by extracting with ether, as
indicated in the previous paragraph, and the ethereal solution from
twenty grams of tobacco is shaken with a concentrated solution of
sodium phosphotungstate in nitric acid by means of which nicotin and
ammonia are precipitated and rapidly settle. The supernatant liquid
is carefully poured off and the residue made up to a volume of fifty
cubic centimeters with distilled water and the nicotin freed from any
of its compounds by the addition of eight grams of finely powdered
barium hydroxid. In order to promote the decomposition of the nicotin
compounds the mixture should be shaken at intervals for several hours.
The at first blue precipitate changes into blue green and finally into
yellow. It is separated by filtration and the somewhat yellow colored
filtrate placed in an observation tube, polarized, the polarization
calculated to minutes of angular rotation and the number of minutes
thus found multiplied by the nearest factor given above.
The analyst will find a description of other methods of estimating
nicotin in tobacco in the periodical literature of analytical
chemistry.[629]
=610. Estimation of Amid Nitrogen.=—For the estimation of amid
nitrogen ten grams of the powdered tobacco are digested with 100
cubic centimeters of forty per cent alcohol, the extract separated by
filtration, acidified with sulfuric and the albumin, peptone, nicotin
and ammonia precipitated with as little phosphotungstic acid as
possible. The precipitate is separated by filtration and seventy-five
cubic centimeters of the filtrate evaporated in a thin glass or tin
foil capsule after the addition of a little barium chlorid and the
nitrogen determined in the residue. The nitrogen thus obtained is that
which was present in an amid state. The nitrogen present as amids,
ammonia and nicotin subtracted from the total nitrogen leaves that
present as protein.
=611. Fractional Extraction of Tobacco.=—To determine the character of
the soluble constituents of tobacco it is advisable to subject it to
a fractional extraction with different reagents. The reagents usually
employed in the order mentioned are petroleum ether, ether, absolute
alcohol, water, dilute soda lye and dilute hydrochloric acid. The
extract obtained by petroleum ether contains vegetable wax, chlorophyll
and its alteration products, fat, ethereal oils, and resin bodies.
The extract with ether may be divided into water soluble and alcohol
soluble bodies. Among the first are small quantities of glucosids and
nicotin while in the alcoholic solution resin predominates.
The alcoholic extract is also divided into water soluble and alcohol
soluble parts. The first contains the nicotin, which is insoluble in
ether, in combination with acids, together with tannic acid and allied
bodies and also the sugar. The part insoluble in water consists chiefly
of resin.
The aqueous solution contains the vegetable mucilages (pectin) soluble
carbohydrates, soluble proteids and organic acids.
The dilute soda lye solution contains chiefly proteids.
The dilute hydrochloric acid solution contains the starch and the
oxalic acid originally combined with lime. The extractions with dilute
soda lye and dilute hydrochloric acid should be made at a boiling
temperature. The residual matter consists of a mixture of carbohydrate
bodies to which the term crude fiber is usually applied.
=612. Burning Qualities.=—When tobacco is to be used for the
manufacture of cigars, or cigarettes, or for smoking in pipes, its
ability to keep burning is a matter of great importance. The tobacco,
when once ignited, should burn for some time and form, a fluffy ash,
free of fused mineral particles. A tobacco with good burning properties
is one containing nitrates in considerable quantity, not too much sugar
and starch, a porous cellular structure and comparatively free of
chlorin. In determining comparative burning properties the tests may
be applied to the single leaf or the tobacco may be first rolled into
a cigar form and burned in an artificial smoker.
[Illustration: FIG. 122. APPARATUS FOR SMOKING.]
In applying the test to the leaf it is important that the ignition
be made with a fuse without flame, which maintains a uniform burning
power. Any good slow burning fuse may be used and it is applied to the
leaf in such a way that a hole may be burned in it, leaving its edges
uniformly ignited. The number of seconds elapsing before the last spark
is extinguished is noted. At the Connecticut Experiment Station a
lighter, proposed by Nessler, is employed. It is prepared by digesting
eighty grams of gum arabic in 120 cubic centimeters, and forty grams of
gum tragacanth in a quarter of a liter of water for two days, mixing
the mucilaginous masses and adding ten grams of potassium nitrate and
about 350 grams of pulverized charcoal. The mixture is rolled, on a
plate sprinkled with charcoal, into sticks a few inches in length and
of the diameter of a cigar and dried at a gentle heat. These fuses
burn slowly and without smoke and are well suited for lighting tobacco
leaves. Several tests, at least six, should be made with each leaf.
Leaves having a uniform burning power should be used as comparators and
the number of seconds they burn be designated by 100. It is important
that all the samples to be tested be exposed for a day or two to the
same atmosphere in order that they may have, as nearly as possible,
the same content of moisture. The burning tests, when possible, should
be made both before and after fermentation. As a rule fermentation
improves the burning quality of second rate leaves, but has little
effect on leaves of the first quality.
=613. Artificial Smoker.=—For the purpose of comparing the burning
properties of cigars, or of leaves rolled into cigar form, the
artificial smoking apparatus devised by Penfield and modified in this
laboratory is employed.[630] The construction of the apparatus is shown
in the accompanying figure.
The lighted cigar is set in the tube at the left, so that air entering
the test-tube must pass through the cigar. The test-tube contains
enough water to seal the end of the tube carrying the cigar, and is
connected with the aspirator on the right by the =T= tube, as shown. An
arm of the =T= dips just beneath the surface of the liquid in the cup
in the center. Water flows in a slow stream into the aspirator through
the tube at the extreme right, forcing the air out through the arm
of the =T= until the siphon begins to act. While the water is voided
through the long arm of the siphon, air enters through the cigar, the
liquid rising in the =T=. The action of the apparatus is automatic and
intermittent. When the cigar is about one-third burned, it is removed
without disturbing the ash cone, and the latter examined and compared
with other samples as a standard. The sealing liquid of the long arm of
the =T= may be mercury or water. In case mercury be used, care must be
taken not to immerse the open end of the =T= more than one millimeter
therein.