NBSIR 74-461

The Calibration of Small Volumetric

Laboratory Glassware

Josephine Lembeck

Institute for Basic Standards

National Bureau of Standards

Washington, D. C. 20234

December 1974

Final

Prepared for Optical Physics Division

Institute for Basic Standards

Washington, D. C. 20234

NBSIR 74-461

THE CALIBRATION OF SMALL VOLUMETRIC

LABORATORY GLASSWARE

Josephine Lembeck

Institute for Basic Standards

National Bureau of Standards

Washington, D. C. 20234

December 1974

Final

Prepared for Optical Physics Division

Institute for Basic Standards

Washington, D. C. 20234

U. S. DEPARTMENT OF COMMERCE, Frederick B. Dent, Secretary

NATIONAL BUREAU OF STANDARDS, Richard W. Roberts. Director

The Calibration of Small Volumetric Laboratory Glassware

by

Josephine Lembeck

1. INTRODUCTION ,

This article describes an acceptable procedure for calibrating

burets, pipets and volumetric flasks of the types shown in figure

1. The physical characteristics of these items are indicated in

Interim Federal Specifications NNN-B-00789a (GSA-FSS) , NNN-P00395a (GSA-FSSi NNN-F-00289a (GSA-FSS), and NBS Handbook 105-2.

The general procedure is based upon a determination of the volume

of water either contained in or delivered by the vessel. This

volume of water is based upon knowledge of its measured mass and

its tabulated density. Inasmuch as these calibration volumes,

especially the delivery volume, may be altered by the manner in

which the vessels are used, it is imperative that the user of the

vessel employ the same techniques as those employed during

calibration. The techniques of importance here are:

1. reading and adjusting meniscus

2. filling the vessel

3. draining the vessel. v

These three topics will be covered in detail.

2. CLEANING PROCEDURES

It is important that glassware be thoroughly cleaned before being

tested or used. Apparatus must be sufficiently clean 'to permit

uniform wetting of the surface. When clean, the walls will be

uniformly wetted and the water will adhere to the glass surface

in a continuous film. Imperfect wetting causes irregularities in

capacity by distorting the meniscus and allowing nonuniform

wetting of the interior surfaces to occur.

The liquids usually used for cleaning glassware are sodium

dichromate sulphuric acid cleaning solution (commercially

available from laboratory supply houses), nitric acid, fuming

sulphuric acid, alcohol and water. The choice of cleaning agent

to be used depends on the nature of the contaminant. After

cleaning with the cleaning solution and thoroughly rinsing with

tap water, the vessel should be rinsed with distilled water. If

- 1 -
the vessel is marked "TO CONTAIN'.' it should additionally be

rinsed with ethyl alcohol and dried with clean air at room

temperature, NBS uses bottled breathing air and a drying rack

shown in figure 2. It is not necessary to dry any vessel marked

" TO DELIVER". When cleaning small articles such as pipets, it is

usually easier to fill them with cleaning solution by suction,

vacuum, if available, or a small rubber bulb, but never by mouth.

The solution should be sucked through the pipet several times

until the entire inside surface is evenly coated. Rinse

thoroughly with tap water and then with distilled water.

For cleaning flasks, pour in enough cleaning solution while

rotating so that a film of solution will cover the entire

interior surface. A break in the film indicates a contaminated

area. For filling a buret with cleaning solution, it should be

held in a vertical position and filled by pouring into the top.

Open the stopcock to drain. Regardless of the type of vessel,

always rinse thoroughly, first with tap water and then with

distilled water.

3. FILLING AND DRAINING THE VESSEL

Pipets, burets and flasks have at least one index mark engraved

on their glass bodies which serves to define their reference

volume. Calibration consists of determining the volume of water

required to fill the vessel to the index mark (containment

volume), or the volume of water which can be drained from the

vessel under specified conditions after filling (delivery

volume)

.

The difference between containment volume and delivery volume is

significant. Since these volumes are determined in weighing

experiments, it is essential to avoid splashing droplets of water

on to supposedly dry surfaces and it is equally important to assure that a surface is uniformly wetted when required by the

procedure.

In all cases, it is necessary to fill the reference volume of the

test vessel with water. This involves adjusting the height of

the liquid surface to coincidence with the horizontal plane

through the defining index mark.

This surface, or meniscus, is not flat; it is concave— that is,

its lowest point is in the center of the surface as shown in

figure 3. There are several criteria for deciding when

coincidence is achieved. Inasmuch as differing criteria result

in different surface heights, it is important that the same criteria be employed during use of the vessel as was employed

during calibration. Experience has shown that the following

generally used technique is easy to apply and adequately

- 2 -
reproducible. In this procedure, the lowest point in the

meniscus is brought to the same horizontal level as the

horizontal plane through the engraved index line on the glass

vessel.

In order to observe the lowest point, it is necessary to place a shade of some dark material immediately below the meniscus. This

renders its profile dark and clearly visible against a light

background. A method or device for this purpose is a collarshaped section of thick black rubber tubing, cut open at one side

and of such size as to clasp the tube firmly, as shown in figures

A and 4A. The position of the lowest point of the meniscus with

reference to the graduation line is such that it is in the plane

of the middle of the graduation line. This position of the

meniscus is obtained by making the setting in the center of the

ellipse formed by the graduation line on the front and the back

of the tube, as observed by having the eye slightly below the

plane of the graduation line. The setting, the procedures for

which will be discussed later, is accurate if, as the eye is

raised and the ellipse narrows, the lowest point of the meniscus

remains midway between the front and rear portions of the

graduation line. By this method, it is possible to observe the

approach of the meniscus from either above or below the line to

its proper setting.

The foregoing procedure applies when the index line runs completely around the neck of the vessel. On some vessels, such

as measuring flasks, figure 1, some of the lines go only one-half

way aroiind the neck. Under these conditions the operator has

only one-half of an ellipse to assist him in defining the

horizontal plane through the index line. Experience has shown

that, although the 360° index line is most convenient for the

operator, there is insignificant difference between the

achievable reproducibility from this complete index, and one which extends only 180° around the neck.

On some graduated neck vessels the lines are very short indeed,

extending less than one-fourth the way around the neck. Under

these circumstances, there is no reference line behind the

meniscus to help the operator in estimating the vertical position

of the horizontal index plane. When faced with this problem, it

is necessary for the operator to place his eye in his

best estimate of the horizontal index plane while observing the

meniscus. With experience, an operator should be able to judge

the position of this plane to within one or two centimeters. The

operator's eye will be (perhaps) twenty-five centimeters in front

of the short index line while the center of the meniscus will be

only one centimeter behind this line (for a two centimeter neck

on the vessel) . The geometry of this situation dictates that the

vertical position error of the meniscus will be only one twenty-

- 3 -
fifth of the operator's error in estimating the position of the

horizontal index plane. Although an optical system (e.g. a bubble level cathetometer) could reduce this error to

insignificance, there is little point to such a calibration

procedure unless a similar system were employed by the user of

the vessel.

Having filled the reference volume of the test vessel using the

meniscus observation technique procedure described above, the

problem is to determine the volume of water contained, or the

volume which can be drained out under specified conditions. This

volume is calculated from the density of the water from table 2

and its measured mass.

In the case of a flask "to contain," this mass is the difference

between the mass of the empty flask, and its mass after filling as described above. For the flask "to deliver" it is the difference

between the mass of the filled flask and the mass after the

specified drainage period, 30 seconds, has occurred but before

the walls have had a chance to become dry .

It is not necessary to weigh burets and plpets because they are "delivery" instruments. Under these circumstances their delivery

volume is drained into a weighing flask. Weighing this flask,

before and after loading, provides the mass of water delivered by

the buret or pipet.

The detailed procedures in use at NBS for filling and draining

the various test vessels are given in the following paragraphs.

A. BURETS

Clamp the buret vertically on a support stand; also clamp a plain

glass tube, large enough to hold a thermometer, near the buret if

the buret is of such a size that is not large enough to insert a thermometer in the top for observing the temperature of the

water. A typical setup is shown in figure 5. Fill the buret

from the top to the zero mark with distilled water from a reservoir or storage bottle. Drain and record the delivery time.

Delivery time is determined by the unrestricted outflow of the

water from the zero mark to the lowest graduation mark with the

stopcock fully open. Refill the buret to approximately 1 cm

above the zero mark and fill the plain glass tube that holds the

thermometer; record the temperature. Set a meniscus on the zero mark using the buret stopcock to lower the liquid level and touch

the tip with the wetted wall of a beaker to remove any excess

water. A weighing flask which has been lightly stoppered and

weighed empty is placed with the inside of the neck in contact

with the tip of the buret (the flask will be at a slight angle)

.

The stopcock must be fully open until the water is only a few
millimeters above the line being tested and then slowed so as to

make an accurate setting. When the setting has been completed, move the flask horizontally, breaking contact with the buret.

The flask is then stoppered and weighed a second time, after

which the thermometer tube is refilled and the next interval

tested in the same manner as the first one - from the zero mark

to the next interval needed.

B. PIPETS

Fill pipet with distilled water by suction to the index mark and

measure delivery time with the tip in contact with the glass

surface or the internal side of a beaker as shown in figure 6.

Refill by suction slightly above index line. Record the

temperature of the distilled water in the beaker from which the

pipet is filled. Any water on the outside of the tip is removed

with filter paper after the filling is completed. The meniscus

is then slowly lowered to the index using either the stopcock or hose clamp for "fine control." The tip must be in contact with

the wet wall of a beaker while the setting is made on the index

line. Any water remaining on the tip at this time is not

removed. The pipet is held in a vertical position while water is

delivered into a previously weighed weighing flask with the tip

in contact with the inside wall of the neck of the flask as indicated in the figure 6A. Contact is broken immediately after

outflow ceases. The flask is now stoppered and weighed with its

contained load.

C. FLASKS (TO CONTAIN)

After cleaning and drying, weigh the empty flask including the

stopper. Place an appropriate sized funnel in the flask to

discharge the water below the stopper. Fill from beaker or supply line to a point slightly below the graduation line,

maneuvering the funnel so as to wet the entire neck below the

stopper. Let stand for about two minutes to allow the walls to

drain. Place the flask under the buret and complete filling and

setting the meniscus and place stopper in neck to lessen

evaporation and weigh. A pipet or dropper with a finely drawn

tip may be used instead of the buret. Determine the temperature

by placing a thermometer in the filling beaker or in one which

has been filled from the supply line. The temperature may be

taken after final weighing by placing a thermometer directly in

the flask, provided the flask is of sufficient size to

accommodate it.

D. FLASKS (TO DELIVER)

Flasks calibrated to deliver are not dried prior to the test.

Fill slightly below the index line and empty in 30 seconds by

gradually inclining the flask so as to avoid splashing of the

- 5 -
walls as much as possible. When the main drainage stream has

ceased, the flask will be nearly vertical. Hold in this position

another 30 seconds and touch off the drop of water adhering to

the top of the flask. Place a stopper, or cap, on the flask to

reduce evaporation and weigh immediately. Take water temperature

and fill the flask, and make the meniscus setting on the index

line. Place a cap, or stopper, on the filled flask and weigh.

4. WEIGHING PROCEDURE AND CALCULATIONS

Most laboratories employ single-pan direct-reading balances for

their weighing work. Although the manufacturers' instructions

for usje differ in minor detail from brand-to-brand, the major

operating features are essentially the same. Most instruments

are equipped with a screen upon which an imiage is projected of a small reticle attached to the beam. Under ordinary

circumstances, a slight "zero" adjustment is made to the screen reading with the balance pan empty. When the pan is loaded by

the unknown object, the operator manipulates dials which

mechanically add or remove built-in weights from the internal

balance structure. On some balances, the screen readings will be

"off-scale," either high or low, depending upon whether the

operator should increase or decrease the dial-operated load.

When the screen is "on-scale" the balance is ready to read. Some

balances have colored lights to indicate whether an increase or decrease of built-in load is called for. The more sensitive

direct-reading balances are constrained from swinging freely

until the proper dial-operated load is in place. This condition

is called "partial arrestment." On the other hand, the

relatively insensitive top-loading balances (used when the

physical size of the weighing flask is large) are never arrested

except when the balance is being moved.

When the manual adjustment of the dial-operated load is complete,

the numerical balance indication should be observed in accordance

with the manufacturer's instructions. The coarse decades are usually observed on the weight manipulation dials, and the last

two (or three) decades are projected on the screen. There are

two such indications , l£ referring to the empty vessel, and I,,

the loaded vessel. The indication referring to the water Is

obtained by subtraction:

I =1-1^ w L E ,

.

,

If l£ and 1^ are observed under the same conditions the zero adjustment, called for in the operating instructions, may be

eliminated

.

These numerical indications are normally not the mass of the

unknown. They are a measure on an arbitrary scale called

- 6 -
Apparent Mass (see appendix) of the load of built-in weights

which exert the same force on the balance as the xjnknown load

under the ambient conditions existing at the instant of the

weighing. We can write an equation indicating the equality of

the forces exerted on the balance by the water and the built-in

weights associated with I^. After eliminating "g" from both

sides, we have

1 - —

' B

(1)

where and pg are the mass and density of the built-in weights,

M^, the mass of water, and the air density at the instant of

measurement. If we rearrange terms and divide both sides by the

density of water, we obtain an expression for the sought after

volume of water, V.

V = Pw - Pa

1-^ (2)

Although the volume, V, in equation (2) is the volume of water in

the weighing flask at the instant of the weighing, it is also the

calibrated volume of the vessel under test at temperature, T. To

obtain this volume at 20 °C (the usual reference temperature) re- quires multiplication by the thermal expansion factor, K, which

involves the test temperature, T, and the temperature coefficient

of cubical expansion, a, of the material from which the vessel is

made, thus,

K = 1 - a(T-20)

and

20 Pw - ^

1-^

Pb

(3)

As explained in the appendix, the mass of the balance weights,

Mg, which exert the same force as the water is given by the

product of the balance indication for the water, I^, and the

apparent mass conversion factor, Q, where

w L E

PbP20 - -QQ^^Pb

and

20 Pw - Pa

1 - Pa(4)

Equation (4) shows the numerical value of the calibration, V^q,

to be the product of five easily evaluated terms.

- 7 -
TERM 1 is the difference obtained by subtracting the

balance indication in grains associated with the

empty weighing flask from that associated with the

loaded flask.

TERN 2

Q

is the apparent mass conversion factor. An acceptable value may be found in table 3 based upon the

density of the balance weights, pg, and the apparent

mass scale to which they are adjusted, D2o. Both Pg

and D^Q may be obtained from the manufacturer of the

balance if the information is not on the name plate.

This value need be calculated only once for each

balance.

There are two density terms which

of air density, p^, water densit

density of the balance weights, Pg.

be adequately estimated by table 1.

is obtained from table 2. The

balance weights, pg, is obtained f maker. His quoted value will be

20°C. Inasmuch as the test tempera

near 20° and the coefficient of e the quoted value is adequate for th

require knowledge

y, p^^, and the

Air density may

Water density

density of the rom the balance

the density at

ture, T, will be

xpansion is small

is work.

TERM 5 H

The thermal expansion factor is obtainable from

table 4 based upon water temperature, T„, assumed

equal to test temperature, T, and the coefficient of

expansion of the vessel, ex.

A sample calculation based on typical data is shown on the flow

diagram, figure 7.

Examination of these numerical values shows that the value of

V20' equation 4, is primarily dependent upon the term showing the

two balance indications, ~ ^E * other four terms, all near unity, are corrections to the balance term for the various

factors mentioned above. For calibration work which is satisfied

by an uncertainty of a percent or so, these four terms may be

ignored.

Use of this complete format is a tedious task which requires the

use of four tables and the performance of a five-multiplier

product. This is because the format is designed to accommodate a very wide range of input data. However, this format offers a number of advantages:
a. It satisfies the requirements for the calibration

of fused silica vessels of enormous thermal

stability as well as plastic vessels of extreme

thermal sensitivity.

b. It accepts data from the rather old direct-reading

balances which were equipped with brass weights as well as the modern instriments with steel weights.

c. It is adaptable to balances having built-in weights

adjusted to the old apparent mass vs 8.3909 scale

and the new apparent mass vs 8.0 scale.

There are few, if any, calibration laboratories which work on such a wide variety of vessels with so many types of instruments.

The data reduction may be grossly simplified to one table and the

performance of one multiplication by restricting its applicability to the work most frequently performed.

For example, the vast majority of vessels which are submitted to

NBS for calibration are made of borosllicate glass so we may

eliminate ct as a variable and assign to it a constant value of

0.000 OlO/^C so that K becomes a single-valued function of

temperature,

K = 1 - 0.000 010 (T-20).

Additionally, all balances in the glassware calibration

laboratory have built-in weights whose densities at 20 are very nearly 7.78 g/cm^, so we may eliminate as a variable,

assigning to it the constant value

pg «= 7.78 g/cm^.

The built-in weights of these balances have all been adjusted to

apparent mass vs 8.3909, so that we may eliminate Q as a variable, assigning to it a constant value of

Q = 1.000 Oil 2.

Without significant error we may assign values for the density of

air and of water of

0.464554B - A0(.00252T - 0.020582)

^A " 1000(T + 273.16)

where B = barometric pressure in millimeters of mercury and

the value of relative humidity is assumed to

be 40%. [1]*

* Numbers in brackets refer to similarly numbered references at

the end of this paper.

- 9 -
w

(T - 3.9863)^ T + 288.9A14

508929.2 T + 68.129631,. 999973)

which is the Tllton-Taylor formula [2] expressed in g/cm^.

The four correction terms given in equation 4 are now reduced to

experimental constants or quantities which may be expressed in

terms of measured barometric pressure, B, and/or measured

temperature, T. If Z is the product of these four terms

1.000 Oil 2 w

- P 1 - 1 - 0.000 010(T-20)

The right member of equation 5 may be put into the form of a numerical table entered with measured values of temperature and

pressure from which a value of Z may be selected, then

V =

^2 0

The table of values of Z must necessarily span the temperature

range found in the calibration laboratory. Table 5 is an abbreviated form of the table used in MBS glassware calibration. For

the restricted conditions mentioned above (i.e. borosilicate

glass vessels calibrated by balances with weights of 7.78 g/cm^

density adjusted to apparent mass vs. 8.3909) table 5 and equation 6 may be used with no loss of accuracy.

5. THE USE OF EQUAL-ARM BALANCES

Laboratories which employ equal-arm balances in the calibration

of glassware may find adequate procedures in NBS Circular 602

"Testing of Glass Volumetric Apparatus" by J.C. Hughes.*

* This publication is out-of-print but is available for loan at

most Government Depository Libraries throughout the country.
Appendix 1. Apparent Mass

Apparent mass scales (there are two in current use) are attempts

to simplify the calibration and use of weights. They are discussed in detail by Pontius [3]. Their background is of no interest here but the concept should be understood because the

built-in weights of direct-reading balances are adjusted to

nominal values of apparent mass. If water volumes are to be

calculated from knowledge of density and the results of weighing

tests, the weighing results must be in mass, not apparent mass.

The observed numerical indication, I, obtained from a measurement

on a direct-reading balance is the apparent mass of the effective

dial-operated load pertaining to that measurement. The effective

load is the sum of the active built-in weights plus a small

additional amount observed on the screen. It is necessary to

convert observed values of I from units of apparent mass into

units of mass. This conversion follows directly from the

definition of apparent mass.

DEFINITION : When, under specified ambient conditions,

an unknown object exerts the same force on a balance as mass, M, of a specified hypothetical reference material,

the object is said to have an apparent mass versus the

reference material equal to M*, where M* is numerically

equal to M. The specified ambient conditions are (1)

temperature = 20°C, (2) air density = 0.0 0 1 2 g/cm^. The

hypothetical reference material is completely specified

by its density at 20°C. For the older apparent mass

scale, this specified density at 20°C, D^q, is 8.3909

g/cm^, and for the more recent scale, 8.0.

By convention M* is used when the apparent mass scale is referred

to density 8.3909 material, and M** when referred to 8.0 density

material.

In the conversion procedure, the "unknown object" referred to in

the definition is the effective dial-operated load whose mass, M,

is to be calculated. The defining equality between the forces

exerted by the effective dial-operated load and by the mass, I,

of the hypothetical reference material is

where pg is the density of the built-in weights. The 0.0012 is

the specified air density which must exist during the defining

equality. The mass of the effective dial-operated load is then

- 11 -
r

M = I PgD.O - .0012p^

P3D20 - .OOI2D20

Values of Pg and D20* shovm in the balance Instruction

book, are available from the manufacturer.

If Q

- P^D^ - -00120^0

then M = IQ

Values of Q for various values of p and T>2q are given in table 3.

- 12 -
Appendix 2

The nominal values of the reference volumes of vessels are etched

on the glass walls, and may be in units of milliliters or cubic

centimeters. While, strictly speaking, milliliters are no longer

an acceptable unit, for the purposes of this report, they will be

considered as identical to cubic centimeters. The basic SI unit

of volume is the cubic meter, M"'. Due to its large size, it is

rarely employed in glassware calibration work.

Experience has shown that a competent operator should repeat

volumetric calibrations within the limits indicated below.

VESSEL NOMINAL SIZE REPRODUCIBILITY*

1

3 cm 0. 002 3 cm

2 .002

5 .002

10 .003

15 .005

25 < .005

50 .007

100 .010

Flasks 10 3 cm^ 0.005 cm^

25 .005

50 .007

100 .011

200 .014

250 .017

500 .021

1000 .042

Burets 10 cm^ 0.003 3 cm-^ 25 .005

50 .007

100 .012

* The term "reproducibility" means the maximum deviation expected

between two independent determinations of the volume. To

determine the reproducibility of one's process one should

recalibrate one of his own vessels periodically (e.g. once a month) to obtain a sequence of values V,, Vj, V3,.....Vj^. From

these values one can compute an average V and a standard

deviation s.d. = V2(V-V) ^/ (n-1) and use the quantity 3(/2)(s.d.)

as the reproducibility of his process. It is essential that the

recalibration be done far enough apart in time to be truly

independent and representative of the process and the random

errors which affect it.

- 13 -
The volumetric error associated with a faulty meniscus

observation is a function of the magnitude of the observation

error and the cross section area of the vessel's neck.

Some typical values are given below.

Error in

Meniscus Position

Typical Neck

0.5 cm 1 cm Diameters

2 cm 3 cm

0.005 cm 0.001 cm^ .004 cm^ .016 cm^ .035 cm^

0.01 " . .002 " .008 " .031 " .071 "

• 0.05 " .010 " .039 " .157 " .353 "

0.10 " .020 " .078 " .314 " .707 "

0.20 " .039 " .157 " .628 " 1.414 "

REFERENCES

[1] Bowman, H.A. and Schoonover, R.M., Procedure for High

Precision Density Determinations by Hydrostatic

Weighing, J. Res. Nat. Bur. Stand. (U.S.), 71C (Eng.

and Instr.), No. 3, pp. 179-198, (July-Aug. 1967).

[2] Tilton, L.W. and Taylor, J.K., Accurate Representation

of the Refractivity and Density of Distilled Water as a Function of Temperature, J. Res. Nat. Bur. Stand.

(U.S.), 18, RP971, pp. 205-213 (Feb. 1937).

[3] Pontius, P.E., Mass and Mass Values, Nat. Bur. Stand.

(U.S.) Monogr. 133, 33 pages (1974).

- 14 -
TABLE 1

Air Density

TABLE lA.

Listed below in table lA are the approximate average Winter

(January) and Summer (June- July) air densities for a group

of selected cities throughout the continental United States.

These densities are for an assumed temperature of 23°C and

are based on information about the barometric pressure and

relative humidity supplied by the Weather Bureau.

It should be remembered that these are average air densities

and that the actual air density at a given time and place

may differ from that given by as much as 3 percent in either

direction, which may result in errors in Vjq of 0.05%.

This data may be used as a guide in estimating values of

required for the calculation of V^q , equation 4.

NOTE CAREFULLY

in equation 4 must be expressed in g/cm^ and the values

tabulated below are in mg/cm^. Therefore, tabulated values

must be multiplied by 0.001 (1.18 mg/cm^ becomes 0.00118

g/cm^).

This table is taken from Appendix 1 in NBS Monograph 133,

Mass and Mass Values, by Paul E. Pontius.

TABLE IB.

This table provides values of air density calculated from

temperature, barometric pressure and assumed relative humidity of A0%. Errors in Vjq which result from use of this

table are insignificant.

- 15 -
TABLE lA

PUic

City

Birmin^sm..

Montgomery.

FUgslaff.. Pho«nu...

Tucion... Yumi

Liiile Rock

.

Lot Angeles...- Oakland

S«n Difgo Ssn Friincisco.

Denvrr Grand Junoiion. Pueblo

Hartford

Washington.

Jacksonville.. Key West.... Miami Tampa

Atlanta Augusta

(Aiken. S C.i Savannah

Boise

Cairo Chicago

Motine

Springfield.

Fort Wayne..

Indianapolia..

Burlington... Oes Moines.. Dubuque

Siou< City...

Concordia... Dodge Cily

.

Topeks

Wichita

Louisville.

New Orleans. Shreveport

Easlport.

Boston...

Alpena

Detroit Grand Rapids Marquette

Sault Ste. Marie

Dululh Minneapolis

Si. Paul (Airport)..

Vicksburg

Kansas City.

St. Louis

Springfield...

Havre

Helena...

Kalispell..

Air density PUce

Winter

(mj/irm')

1 16

1.18

092

1.15 1.08

1 19

1.18

1.17 1.19

1.13

1 18

0. 98

1. UO

I 00

1 18

1.19

1 19

1.19

1 19

1 19

1.15

1 18

1 19

1.07

1.18

I 16

1 17

1.16

1.15 1.15

1.16

1 15

I 16

1 IS

1.13

1.08

1 IS l.U

1.17

1 19

1.18

1.18

1 18

1.16

1.16 lis MS

I 16

1.14

1 15

I. IS

i.ia

1.15

1 17

I U

1.08

1.02

1.03

Summer

[mulcm')

1.16

1 18

09J

l.U

1.08

1 18

1.18

1.16 1.16

1.18

1 18

0.98

1 00

1 00

1.18

1 IS

1.18

1 18

1 18

1.18

I 14

I 18

1 18 1.07

1.17 1.16

J.17

1.16

1.15

1 IS

1 IS lis

1.15 1.13

1.12

i 08 LIS

1.13

1.17

LIB

LIS

1.18

1.18

1.16 LIS

LIS

LIS

1.16

I 14 LIS

LIS

1.18

I IS

1.16

1 13

i.oe

1.02

1.03

Stale

Nebraska.

Nevada.

New Hampshire . New Jersey New Mexico

.New York

North Carolina....

North Dakota

Ohio

Oklaimma

Oregon

Pennsylvania. .. Rhode Island. . South Carolina

.

City

South Dakota .

Tenn

Tesas..

Utah

Vermont..

Virginia...

Waahinglon

.

West Virfinia..

Wyoming..

Lincoln North Platte..

Ely Las Vegaa..

Concurd Newark

Albuquerque.. Albany

Buffalo

Hatteras..

Raleich...

Bismarck

Devils Lake. Fargo

WiUiston

Cincinnati

.

Dayton

Cleveland..

Oklahoma City

.

Baker Medford .. Portland... Roacburg.

Philadelphia.. Providence...

Charleston.... Columbia Hunin

Rapid City. ..

Knuiville (Oak

Ridge). Memphis

Nashville

Abilene

Amarillo

Austin

Brownsville .. Fort Worth...

El Puo

Houston San Antooio..

Salt Lake City Burlington

.Norfolk Richmond

Seattle... Spokane

Walla Walla.

Elkins Parkersburg..

Green Bay.. .Madison Milwaukee..

Casper

Cheyenne..

Sheridan...

- 16

Air density

Winter Summer

{mflcm') l.U

1.07

0. 95

1. U

1.17

1.19 1.00

1.18

1.16

LIS

LIB

I. II 1.12 LIS

1.11

1.16 LIS LIS

1.14

I 04

1.13 1.18

1.17

1.18 1.18

1.19

1.18

1 U

LOS

I 16

LIB

1.17

1.12

1.04

1.17 1.19 1.16

1.04 LIS

1.17

1.02

1.17

1. 19

1.18

1.18 L19 LIS

1.11 1.16

1.16 LIS

1.16

0.97 094

103

1. 17

t.IS L13

I.ll 1.16

L16

LIS LIS

0.97

0.96

1.04
BAROMETRIC

PRESSURE

(MM OF HG)

TABLE IB

I6°C 18°C 20 °C 22 °C 24 °C 26 °C 28 °C

600 0.00096 0.00095 0,00095

605 0.00097 0.00096 0.00095

610 0.00098 0,00097 0.00096

615 0.00098 0.00098 0.00097

620 0.00099 0.00099 0.00098

625 0.00100 0.00099 0,00099

630 0.00101 0.00100 0.00099

635 0.00102 0.00101 0.00100

640 0.00102 0.00102 0.00101

645 0.00103 0.00103 0.00102

650 0.00104 0.00103 0.00103

655 0,00105 0.00104 0.00103

660 0.00106 0.00105 0.00104

665 0.00106 0.00106 0.00105

670 0.00107 0.00107 0.00106

675 0.00108 0.00107 0.00107

680 0.00109 0.00108 0.00107

685 0,00110 0.00109 0.00108

690 0.00110 0.00110 0.00109

695 0.00111 0.00110 0.00110

700 0.00112 0.00111 0.00110

705 0.00113 0.00112 0.00111

710 0.001 14 0.001 13 0.001 12

715 0.00115 0.00114 0.00113

720 0.00115 0,00114 0.00114

725 0.00116 0.00115 0.00114

730 0.00117 0.00116 0,00115

735 0.00118 0.00117 0.00116

740 0.00119 0.00118 0.00117

745 0.00119 0.00118 0.00118

750 0.00120 0.00119 0.00118

755 0.00121 0,00120 0.00119

760 0.00122 0.00121 0,00120

765 0.00123 0,00122 0.00121

770 0.00123 0,00122 0,00122

775 0.00124 0.00123 0.00122

780 0.00125 0.00124 0.00123

785 0.00126 0.00125 0.00124

790 0.00127 0.00126 0.00125

795 0.00127 0.00126 0.00126

0,00094 0.00093 0.00093 0,00092

0.00095 O0OOO94 0.00093 0,00093

0,00096 0.00095 0.00094 0»00093

0,00096 0,00096 0.00093 0,00094

0.00097 0.00096 0.00096 0.00095

0.00098 0,00097 0.00096 0,00096

0,00099 0.00098 0,00097 0,00097

0,00099 0,00099 0,00098 0.00097

0,00100 0,00100 0,00099 0.00098

0,00101 0,00100 0,00100 0,00099

0.00102 OeOOlOi 0,00100 0,00100

0,00103 0,00102 0,00101 0,00100

0,00103 0,00103 0,00102 0.00101

0,00104 0.00103 0.00103 0.00102

0.00105 0,00104 0.00103 0.00103

0.00106 0.00105 0.00S04 0.00103

0,00107 0,00106 0,00105 0.00104

0,00107 0.00107 0.00106 0,00105

0.00108 0,00107 0.00107 0.00106

0.00109 0.00108 0,00107 0,00107

0.00110 0.00109 0,00108 0,00107

0.00110 0.00110 0,00109 0,00108

0.00111 0.00110 O.OOUO 0.00109

0.00112 0.00111 0,00110 0,00110

0,00113 0.00112 0.00111 0,00110

0.00114 0.00113 0.00112 0,00111

0.00114 0.00114 0.00113 0,00112

0.00115 0.00114 0,00114 0.00H3

0,00116 0.00115 0.00114 0.00113

0,00117 0.00116 0,00115 0,00114

0.001 18 0.00117 0.00U6 0,00115

0.00118 0,00118 0,00117 0^00116

0.00119 0.00118 0,00117 0,00117

0,00120 0,00119 0,00118 0,00117

0,00121 0.00120 0.00119 0.00118

0.00122 0.00121 0.00120 0.00119

0,00122 0,00121 0,00121 0,00120

0.00123 0,00122 0.00121 0,00120

0,00124 0,00123 0,00122 0.00121

0,00125 0,00124 0,00123 0.00122

- 17 -
T 0.0°C 0. l°C 0.2 °C 0.3*0 0.4°C 0.5°C 0.6°C 0. 7°C 0.8°C 0.9°C

.0 .999840 .999846 . 9998 5 3 .999859 . 999865 . 999871 .999877 . 999883 .999888 .999893

1.0 .999899 . 9S9903 .999 ',08 .9 9S'-n3 .999917 .999925 .999929 .999933 . 999937

2-0 . 9999^^0 .99994 3 , 999946 .999949 . 999952 .999954 .999956 .999959 ,999961 .999963

3.0 .999964 .999966 .999967 .999968 .999969 .999970 .999971 . 999971 .999972 . 999972

4.0 .999972 .999972 . 999972 r. 999971 .99997 I .999970 .999969 .999968 .999967 .999965

5.0 .999964 ,999962 .990O0O .999953 . 9999 56 , 999954 .99995 I , 99991^9 . 99994^ , 999943

6.0 . 99994 0 .999937 . 999933 .999930 . 999926 .999922 .999916 •999914 .999910 .999906

7.0 .99990 1 ,9'.9696 . 999892 •999567 . 999d8l . 999876 .999871 .999865 .999660 ,999854

8.0 .999848 ,999842 , 999(335 •999829 •999822 .999816 .999 809 .999802 .999795 , 999787

9.0 .999780 ,999773 .999765 .999757 • 999749 .999741 .999733 .999725 .999716 ,999707

10.0 . 99969 9 •999690 , 99<) tig 1 .99 9672 • 99966 2 . 999653 .999643 . 999634 .999624 . 9996 14

1 1.0 ,999604 .999594 ,999583 ,99''573 .999562 •999552 .999541 .999530 .999519 . 999507

12.0 .999496 . 999-^85 ,999473 ,999461 .999449 .999437 .999425 .999413 .999401 . 999383

13.0 ,999376 .999363 ,999350 ,999337 .999324 . 999311 .999297 .999284 .999270 .999256

14.0 .999243 . 999229 ,999215 .999200 .999186 .999172 .999157 . 999142 .999128 .999113

15 .0 .999098 .999083 . 999067 .999052 , 999036 . 999021 .999005 .998989 .998973 . 998957

16.0 .99894

1

,998925 ,998908 .998892 .996875 .993858 .993841 ,998824 .998807 .998790

17-0 .998773 ,998 75 5 . 998738 .998720 .998"'02 ,998684 .998666 " ,99 864 8 .993630 . 998612

18.0 .99659 3 .998575 .998 556 .99(j537 . 998519 , 998500 .993480 .998461 .998442 .998422

19.0 . 998403 ,996383 . 998364 . 998344 .998324 .998304 .993284 .993263 .996243 , 998222

20.0 .99820 2 .998181 . 998 160 .996139 . 396118 . 998097 .998076 .998055 .998033 .998012

21.0 ,997990 ,997968 .997947 ,997925 .997903 ,997881 .997858 .997836 .997814 . 997791

22.0 .997768 ,997746 . 997723 ,997700 . 997677 , 997654 .997630 .997607 .997584 .997560

23.0 .997536 .9975 13 .997489 .997465 .997441 , 997417 .997392 . 997366 .997344 . 997319

24.0 .997294 ,997270 .997245 .997220 ,997195 ,997170 .997145 .997119 .997094 ,997068

2 5.0 . 9 9704 3 . 9970 17 , 99 6991 .996966 , 996940 .9969 1

3

.996687 . 99686

1

.996835 . 996608

26 .0 ,996782 .996755 .996728 .996702 . 996675 . 996648 .996621 .996593 .996566 .996539

27.0 .99651

1

. 996484 , 99o456 .996428 .99 640

1

.996373 .996345 .996316 .996268 . 996260

28.0 .996232 .99o2 03 . 996175 .996140 .996117 , 996008 .996060 .996031 .996001 .995972

29,0 .995943 .995914 .995884 .995855 .995825 , 995795 .995765 .995736 .995706 . 9956 76 30.0 .995645 .995615 . 995585 .995554 . 995524 .995493 .995463 .995432 .995401 . 995370

31.0 .995339 .995308 .995277 .995246 .995214 . 995183 .995151 .995120 .995088 .99 5056

32.0 .99502'.- . 994992 . 994960 . 594928 •994896 .994804 .99483

1

.994799 .994766 . 994734

33.0 .994701 .994668 . 9946 35 •994602 .994569 .9945 36 .994503 •994470 .994436 .994403

34.0 .994369 .994336 . 994302 ,994266 .994234 . 994201 .994 16 7 . 994132 .994098 . 994064

35.0 .994030 . 993995 . 9939ol .993926 . 993891 .993857 ,993322 •993787 .993752 .993717

36.0 ,993682 .993647 ,99 361 I .993576 .993541 . 993505 ,993469 . 993434 .993398 ,993362

37.0 .993326 .993290 ,993254 .993218 .993182 .993146 .993109 .993073 .993036 .993000

38.0 ,992963 .992926 .992889 .992652 .992815 .992778 .992741 .992704 .992667 . 992629

39.0 .992592 .992554 .992517 .992479 . 992442 . 992404 .992366 .992328 .992290 .992252

TABLE 2: Density of Air Free Water In g/cm ^ as a Function of the Celsius

Temperature Scale, Based on the Work by H. Wagenbreth and W.

Blanke, PTB-Mlttellungen 6-71.

- 18 -
0 Q when Q when

D^Q = 8.0000 g/cm^ = 8.3909 g/cm

7,70 1 .0000058 1,0000128

7,72 1 .0000054 1,0000124

7,74 1.0000050 1.0000120

7.76 1 .0000046 1.00001 16

7.78 1 .0000042 1.00001 12

7.80 1 .0000038 1 .0000108

7.82 1 .0000035 1.0000104

7.84 1 .0000031.0000101

7.86 1 ,0000027 1 .000009 7

7.88 1 . 0000023 1 ,000009^3

7,90 1 .0000019 1.0000089

7 .92 1 . 000001

5

1 . 0000085

7,94 1 . 00000 1

1.000008

7 ,96 1 . 0000008 1 . 0000077

7,98 1 . 0000004 1 • 0000074

8.00 1 .0000000 1.0000070

8 •02 0,9999996 1 . 0000066

8.04 0.9999993 1 .0000062

8.06 0.9999989 1,0000059

8.08 0.9999985 1,0000055

8.10 0,9999981 1,0000051

8.12 0,9999978 1 ,0000048

8.14 0.9999974 1 ,0000044

8.16 0.9999971 1,0000040

8.18 0.9999967 1,000003 7

8.20 0.9999963 1,0000033

8.22 0,9999960 1.0000030

8.24 0.9999956 1,0000026

8.26 0.9999953 1« 0000023

8.28 0.9999949 1,0000019

8.30 0,9999946 1,0000016

8.32 0,9999942 1.0000012

8.34 0,9999939 1,0000009

8.36 0.9999935 1,0000005

8.38 0,9999932 1,0000002

8.40 0,9999929 0,9999998

TABLE 3: Values of the apparent mass conversion factor,

Q, defined In the appendix as PgCD^o - .0012) ^ " DjJPg - .0012)

when Pp Is the density of the balance weights

in g/cm^, and Djq is the apparent mass scale

to which the weights are adjusted.

- 19 -
Fused Boro- roly— PolyWater Silica Silicate Sort Propylene Carbonate

Temp (Quartz) Glass Glass Plastic Plastic

( C) a—1 . o a=»10 a=25

18*0 1 ,000003 1 .000020 1 .000050 1 ,000480 1 ,000900

18.5 1.00€002 1 ,000015 1 .000038 1 ,000360 1 .000675

19.0 1 .000002 1 ,000010 1 .000025 1 .000240 1 •000450

19.5 1 .000001 1 ,000005 1 ,000013 1 .000120 1 •000225

20.0 1 .000000 1 .000000 1 ,000000 1 .000000 1 .000000

20.5 0.999999 0.999995 0,999988 0.999880 0 .999775

21.0 0.999998 0,999990 0,999975 0.999760 0 .999550

21.5 0.999998 0,999985 0,999963 0.999640 0 ,999325

22.0 0.999997 0,999980 0,999950 0.999520 0 .999100

22.5 0.999996 0.999975 0.999938 0.999400 0 •998875

23.0 0.999995 0,999970 0.999925 0.999280 0 •998650

23.5 0.999994 0,999965 0,999913 0.999160 0 »998425

24.0 0.999994 0,999960 0,999900 0.999040 0 .998200

24.5 0.999993 0,999955 0,999888 0.998920 0 ,997975

25.0 0,999992 0,999950 0,999875 0.998800 0..997750

25.5 0,999991 0,999945 0,999863 0.998680 0..997525

26.0 0,999990 0,999940 0,999850 0.993560 0,.997300

26,5 0,999990 0,999935 0.999838 0.998440 0,,997075

27.0 0,999989 0,999930 0.999825 0.998320 0..996850

27.5 0,999988 0.999925 0.999813 0.998200 0..996625

28.0 . 0,999987 0,999920 0.999800 0.998080 0.996 400

28.5 0,999986 0.999915 0.999788 0.997960 0<.996175

29,0 0,999986 0.999910 0.999775 0.997840 0,,995950

29,5 0,999985 0,999905 0.999763 0.997720 0.995725

30.0 0,999984 0.999900 0.999750 0.997600 0.995500

TABLE 4: Values of the expansion factor K as a function of test

temperature for various materials from which laboratory ware

is made. The numerical values of a, the volumetric

coefficient of therroal expansion, given in the column

headings are parts per million per degree centigrade. In

, plastics, columns A and 5, this coefficient may vary from

batch-to-batch, and the values stated are typical, mid-range

values. In the text K is defined as

K » 1 - a(T-20)

" 20 -
TEMP BAROMETRIC PRESSURE (MM OF HQ)

<°C) 620 640 660 680 700

18.5 1.002390 1.002416 1.002446 1,002473 1,002501

19o0 1 .002480 1 .002508 1.002536 1,002564 K 002592

19.5 1.002573 1.002601 1.002629 1,002657 1.002685

20.0 1.002669 1.002697 1.002725 1,002753 1,002780

20.5 1.002768 1.002795 1 • 002823 1,002851 1,002879

21 .0 1 .002869 1 .002897 1.002924 1.002952 1„ 002980

21 .5 1.002973 1.003000 1.003028 1.003056 1 ,003083

22.0 1.003079 1,003107 1.003134 1,003162 1,003190

22.5 1.003188 1.003216 1.003243 1,003271 1 , 003298

23.0 1 .003299 1.003327 1.003354 1.003382 1,003410

23c5 1.003413 1.003441 1.003468 1.003496 1,003523

24.0 1.003530 1.003557 1,003585 1,003612 1 ,003640

24.5 lo003649 1.003676 1,003704 1.003731 1,003758

25.0 1.003770 1.003797 1,003825 1,003852 U 003880

25.5 1 .003894 1.003921 1.003949 1.003976 1,004003

26.0 1.004020 1.004047 1.004075 1.004102 lo004129

26.5 1 .004149 1.004176 1.004203 1.004231 1 ,004258

27.0 1.004280 1.004307 1.004334 1.004361 1,004389

27.5 1 .0044 13 1.004495 1.004522

1.004549 1.004576 1.004603 1 « uuioou

TEMP BAROMETRIC PRESSURE (MM OF H6)

(°C) 720 740 760 780 800

18.5 1 .002529 1.002557 1.002585 1,002613 1 ,002641

19.0 1 .002620 1.002647 1,002675 1.002703 1,002731

19.5 1 .002713 1.002740 1,002768 1,002796 1,002824

20.0 1 .002808 1.002836 1.002864 1,002892 S ,002919

20.5 1 .002906 1 .002934 1,002962 1,002990 1,003017

21.0 1.003007 1 .003035 1 .003063 1,003091 1,003118

21.5 1.003111 1.003139 1.003166 1,003194 1,003222

22.0 1 .003217 1.003245 1.003272 1,003300 1,003328

22.5 1 .003326 1.003353 1.003381 1,003409 1,003436

23.0 1 .003437 1 .003465 1,003492 1.003520 1,003547

23.5 1 .003551 1.003578 1.003606 1.003633 1,003661

24.0 1 .003667 1.003695 1.003722 1,003 750 1,003777

24.5 1.003786 1 .003813 1.003841 1.003868 1,003896

25.0 1 .003907 1.003934 1.003962 1 .003989 1,004017

25.5 1 .00403

1

1.004058 1.004085 1,004113 1,004140

26.0 1 .004157 1 .004184 1,004211 1,004239 1,004266

26.5 1.004285 1.004312 1.004340 1.004367 1 ,004394

27.0 1 .004416 1.004443 1.004470 1,004498 1,004525

27.5 1.004549 1.004576 1.004603 1.004631 1,004658

28.0 1 .004685 1.004712 1,004739 1,004766 1 ,004793

TABLE 5: Values of Z (equation 6) as Explained In the Text.

- 21 -
INDEX

LINE

TO CONTAIN

NOMINAL

VOLUME

VOLUMETRIC

FLASK

TO

DELIVER

TO

20"C

DELIVERY

TIME

IN

SECONDS-^

54a ho

113 ISEC

PIPET BURET

50

/ \

100 ml to* C

10 SEC

to* c

10 S(C

^J9

MEASURING

FLASK

CYLINDRICAL

GRADUATE

FIGURE 1

SHOWN HERE ARE THE VARIOUS TYPES

OF VOLUMETRIC APPARATUS WHICH

MAY BE CALIBRATED BY -THE TECHNIQUES DESCRIBED IN THIS REPORT.

- 22 -
FIGURE 2

DRY AIR BOTTLES AND DRYING RACK

USED TO DRY VOLUMETRIC GLASSWARE

PRESSURE IS ABOUT 1 LB PER SQ IN.

DRYING USUALLY TAKES LESS THAN 10 MINUTES

- 23 -
MENISCUS SURFACE

FRONT SIDE OF

INDEX LINE

REAR SIDE OF

INDEX LINE

BRIGHTLY ILLUMINATED

SCREEN

EXAGGERATED CURVATURE

MENISCUS SURFACE

CIRCUMFERENTIAL INDEX

LINE ON VESSEL

LINE-OF-SIGHT TO

FRONT SIDE OF INDEX

OBSERVERS EYE

LINE-OF-SIGHT TO

REAR SIDE OF INDEX

LINE-OF-SIGHT TO

MENISCUS

OBSERVER'S VIEW FROM SLIGHTLY

BELOW THE HORIZONTAL LEVEL OF

THE INDEX LINE.

BLACK RUBBER OPAQUE SCREEN

PLACED A FRACTION OF A

MILLIMETER BELOW THE INDEX

LINE. -

SIDE VIEW

FIGURE 3

THESE DIAGRAMS ILLUSTRATE THE PROCEDURE FOR OBSERVING

THE MENISCUS POSITION DESCRIBED IN THE TEXT.

- 2k -
VARIOUS RUBBER COLLARS USED TO ASSIST

IN THE MENISCUS SETTING DURING THE

CALIBRATION OF BURETS, PIPETS AND FLASKS

- 25 -
FIGURE 4A

A FLASK WITH A COLLAR-SHAPED PIECE OF BLACK

RUBBER TUBING IN PLACE BELOW THE INDEX LINE

WHICH RENDERS THE PROFILE OF THE MENISCUS

CLEARLY VISIBLE AGAINST A LIGHT BACKGROUND

- 26 -
FIGURE 5

APPARATUS USED IN THE CALIBRATION OF A SGML BURET. THE USHAPED TUBE AT THE TOP IS CONNECTED TO A DISTILLED WATER

SUPPLY LINE USED TO FILL THE BURET. THE WEIGHING FLASK

UNDER THE BURET IS IN POSITION, WITH ITS TIP IN CONTACT

WITH THE NECK OF THE FLASK TO RECEIVE THE MEASURED VOLUME.

THE BLACK COLLARS AT THE TOP OF THE BURET ARE AN AID IN

SETTING THE MENISCUS. THE THERMOMETER IS USED TO OBTAIN A

MEASURE OF THE TEMPERATURE OF THE WATER IN THE BURET.

- 27 -
FIGURE 6

TRANSFER PIPET CLAMPED VERTICALLY ON A STAND IN FRONT OF A

FROSTED GLASS LIGHT BOX. THE TIP IS IN CONTACT WITH A PIECE

OF FROSTED GLASS WHILE THE SETTING OF THE MENISCUS IS MADE.

THE HOSE ON THE GLASS TUBE ABOVE THE STOPCOCK IS CONNECTED

TO A TRAP BOTTLE WHICH, IN TURN, IS CONNECTED TO THE VACUUM

LINE. THE HOSE CLAI-IP IS USED TO SLOW THE FLOW WHILE MAKING

THE MENISCUS SETTING. THE STOPWATCH IS FOR TIMING THE

DELIVERY OF THE PIPET. THE TEMPERATURE OF THE DISTILLED

WATER IS TAKEN IN THE BEAKER FROM WHICH THE PIPET IS FILLED.

- 28 -
FIGURE 6

A

THE PIPET IS DELIVERING ITS MEASURED VOLUME INTO

A WEIGHING FLASK, WITH ITS TIP IN CONTACT WITH

THE NECK OF THE FLASK. WHEN THE OUTFLOW HAS

CEASED THE FLASK IS REMOVED, STOPPERED AND WEIGHED.

- 29 -
m

ON

ON

On

ON

MOwH

OHU

:3QowH

CO>H

w > H

l_ o W

1—1

CDCO^ w oH

CJ 52:

H

M

pc3

M

u

H

U

H

t—1 W w Q 0

CJ

r5

Q 00

ON

CM

rHoo

00

<r00

ONON

ON i Bu

00 rH 00

in NO

ON 0

o>

ON ON

ON ON

II IIawH

H

HwH

PiwH3 oc

•H

tn 3KWHHWH

CJ

I—I ow

CJ eu

00

P3 Qw I H H

hJM CO

M

H

H CQ CO

M 0

>^H

w

M (J

H CO

CJ Z < uQ

PQZ 0 (—1

CQ

Q. oooo

II

i4B

CJ00 OnO

C3N n

c»

II o

Csl Q

w

Q

u

WH 0 CO

C/2

CAI CQ CO

CH

<:

H

M Z COH

n£> O

00 ro

<r

in

C3N

C3N

II

m

fHin

00 Sa

inm

ONo

CM

0iWH

CJ CQ u en

CJoo O

M

CO

C/0

W

uM

PiH

QW

CO

PS C/i

pL.

CQQ

M

CQ ^ W CQ M H ^ w cry " H EC w >

PiM< ^ CO W CO S <3
r

FIGURE 8

1200G TOP-LOADING DIRECT READING BALANCE SUITABLE FOR THE RAPID

WEIGHING OF LARGE FLASKS . IT IS SHIELDED BY A CARDBOARD BOX

TO PREVENT AIR CURRENTS FROM AFFECTING THE BALANCE READING.

- 31 -
FIGURE 9

lOOG SINGLE-PAN BALANCE USED TO

WEIGH SMALL TO CONTAIN FLASKS.

- 32 -
NBS-114A (REV. 7-73)

II C r^CDT" r\ C r\kAKA U.5. DtKI . (J r U.UMIV1. BIBLIOGRAPHIC DATA

SHEET

1. IHIMLK A I'lON OK RKPOK I NO. NBSIR 74-461

2. (iov 't Acci-ssion No.3. Recipient's Accession No.

4. TITLI- AND SUHTITI.lCalibration of Small Volumetric Glassware

5. Publication Date December 1974

6. rertorming Organization Code

7. AUTMORfS)

Josephine Lembeck

8. Performing Organ. Report No. NBSIR 74-461

9. PERFORMING ORC.ANl/.A I ION NAMK AND ADDRKSS

NATIONAL BUREAU OF STANDARDS

DEPARTMENT OF COMMERCE

WASHINGTON, D.C. 20234

10. Pro,ect/Task/Work Unit No.

11. (-ontract/Grant No.

12. Sponsoring Orj;aii izat mn Name and ( ompleti- Address (Street. City, State, ZIP)

SAME

13. Type of Report & Period Covered

Final

14. Sponsoring Agency Code

15. suppli:mkntary no i i;s

16. ABSTRAC I' (A 200-word or less factual summary of most stgfiificant information. If document includes a significant

bibliography or literature survey, mention it here.)

This report describes a procedure for testing

small volumetric apparatus. The procedure is

based upon a determination of the volume of

water either contained or delivered by the

vessel. There are techniques described for

cleaning, reading the meniscus, filling,

draining and weighing the contained or delivered volume.

17. KEY WORDS (six to twelve entries, alphabetical order; capitalize only the first letter of the first key word unless a proper name; separated by semicolons

)

Burets; capacity; flasks; meniscus; pipets; volumetric calibration.

18. AVAll.AHU.n Y [Jx linlimiicd

E or Official Distribution. Do Not Release to NTIS

Order I' rom Sup. of Doc, U.S. Government Printing Office WashioKton, D.C. 20402. SD Cat. No. (.H

Order ! rom National Technical Information Service (N TIS) Springfield, Virginia 22151

19. SECURITY CLASS

(THIS REPORT)

UNCL ASSIFIED

21. NO. OF PAGES

34

20. SECURITY CLASS

(THIS PAGE)

UNCLASSIFIED

22. Price

USCOMM-DC 29042-P74