Oscar Oldberg.

Inorganic general, medical and pharmaceutical chemistry, theoretical and practical; a text-book and laboratory manual, containing theoretical, descriptive, and technological chemistry; online

. (page 15 of 49)
Online LibraryOscar OldbergInorganic general, medical and pharmaceutical chemistry, theoretical and practical; a text-book and laboratory manual, containing theoretical, descriptive, and technological chemistry; → online text (page 15 of 49)
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platform with raised edges is useful. A plentiful and convenient
supply of water with taps or faucets wherever required is very
important here.



FURNITURE AND APPARATUS. l8l

The waste-pipes from steam kettles, stills, etc., are to be con-
nected with an ample outlet.

BALANCES, ETC.

340. A special room or place for the balances is necessary in
all large laboratories. In a pharmacy where the laboratory con-
sists of a work-room adjoining the officine, all weighing and meas-
uring may conveniently be done with the same instruments that
are used for other work. In large manufacturing laboratories the
materials required by the laborants are supplied from a general
store-room upon special orders, and the analytical work is done
in another room specially equipped for that purpose.

A well-furnished pharmaceutical establishment, even if very
little manufacturing is done in it, should have several balances.
Balances are now made in the United States which are in no wise
surpassed by any foreign made instruments of the same kind.

The most suitable balances for a well ordered pharmaceutical
establishment are:

1. An analytical balance upon which quantities ranging from
I milligram to 50 grams may be weighed. When not loaded this
balance should be sensitive enough to respond to i milligram by
a 2 millimeters' deviation of the point of the needle from the
center of the dial ; when this balance is loaded to the extent of 50
grams the needle point should deviate 2 millimeters from the
center of the dial on the impulse of 5 milligrams.

2. The ordinary prescription balance should be used to carry
loads of from 5 milligrams to 5 grams. The sensitiveness of this
balance should be such that when the pans are not loaded the
needle should deviate 2 millimeters from the center of the dial
under the impulse of 5 milligrams ; when the pans are loaded with
50 Gm each the point of the needle should deviate 2 mm from the
center on the impulse of 20 milligrams.

3. The gram balance should be designed for loads of from i
to 250 Gm. Its sensitiveness should be such that when the pans
are not loaded the impulse of 20 milligrams placed on one pan
should be sufficient to cause the needle to deviate 2 millimeters
from the center of the dial ; and when the pans each carry a load
of 250 Gm, the addition of 50 milligrams to the load on one pan



l82 FURNITURE AND APPARATUS.

should cause the needle to deviate the same distance from the
center.

4. The kilogram balance should be constructed to carry loads
of from 5 to 2000 Gm, and its sensitiveness should be such that
the needle point deviates from the center by 2 millimeters on
the impulse of 50 milligrams when the pans are not loaded and on
the impulse of 200 milligrams when they are loaded with 2000
Gm each.

One or two larger balances may also be necessary.

A Mohr-Westphal balance is of great value.

All balances should be placed on solid tables where they will
be safe against jarring and injury, and must be kept well pro-
tected against dust. They should be kept scrupulously clean and
dry, and no chemicals should be permitted to come in contact with
them. They should above all be protected against corrosive sub-
stances. When not in actual use they must be at perfect rest,
with the knife-edges relieved from friction.

The weights should also be kept clean and accurate.

341. Graduated glass measures, commonly called "graduates,"
are necessary in every pharmaceutical establishment. They
should be graduated in accordance with but one system; those
graduated according to the old system of fluid measure on one
side and in cubic-centimeters on the other side,, should never be
used for any purpose because such double graduation leads to
frequent errors.

The metric system having now been adopted in every pharma-
copoeia, the world over, pharmacists should do all in their power
to shorten the time required to complete the change from the
old to the new, not only because resistance to the inevitable is
useless but because they will certainly find the new system far
more convenient.

Graduated cylinders, flasks, pipettes, burettes, an accurate
pycnometer, and a set of reliable hydrometers are required for the
analytical work inseparable from the work of producing and dis-
pensing chemical preparations. (See Chapter XV.)

HEATING APPARATUS.

342. Much can be done with the stoves, furnaces and burners
constructed for use with gas as the fuel. Illustrated descriptive



FURNITURE AND APPARATUS.



catalogues of such heating apparatus are freely furnished by deal-
ers and manufacturers so that any one may learn more from
them than can be presented in any text-book. Among the most
efficient gas burners are the "Fletcher low temperature burner,"





Fig. 115. Graduated glass measure.



Fig. 116. Fletcher burner
("low temperature burner").



which affords a wide range of temperatures from gentle heat up
to red heat ; it is so constructed that it can be attached to a pipe
from a bellows when a very high heat is to be produced, and it




Fig. 117. Fletcher radical burner.



is so effective that the designation "low temperature burner" is
an unfortunate one since it emphasizes one of its merits that the
heat can be thoroughly controlled and kept very lew if desired



1 84



FURNITURE AND APPARATUS.



at the expense of the equally valuable feature which enables the
operator to apply an exceptionally high heat.




Fig. 118. The Jewel gas heater.




Fig. 119. Foot blower.



Fig. 120. Iron retort for the production gases in
"the dry way" and for other processes re-
quiring very high heat.





Fig. 121. Triple Bunsen burner. Fig. 122. Bunsen burner with cone.

The Fletcher "radial burner" (made by Buffalo Dental Mfg.
Co.) and the "Jewel" gas stove (made by Geo. M. Clark & Co.,
of Chicago) are particularly serviceable for heating large vessels.



FURNITURE AND APPARATUS.



A foot-blower or bellows is frequently useful.

Bunsen burners are made in great variety, and two or more




Fig. 123. Seven-tubed Bunsen burner.



Fig. 124. Erlenmeyer's burner.



well-made ones are necessary in any pharmaceutical laboratory,
however small.

Bunsen burners are so constructed that a mixture of gas and
air in proper proportions is first
produced and more complete and
rapid combustion and a maximum
temperature are secured by burning
that mixture.

The supply of gas admitted
through the tube of the Bunsen
burner can be regulated by the gas
stopcock, and the supply of air by
means of the movable collar which
is provided with two opposite cir-
cular openings acting as a valve
which may be partially or entirely
closed by turning the collar so as
to place it in the required position
opposite the openings in the lower
outer tube of the burner, immedi-
ately below the top of the gas tip
which it surrounds, as seen in
the cut.

343. When sufficient air is supplied in




125. Shows the construction of
the Bunsen burner.



proportion to the gas,



l86 FURNITURE AND APPARATUS.

the flame is non-luminous or bluish, because the combustion is
then complete ; but when the supply of air is shut off the flame is
luminous, yellow and smoky. When the current of gas is too
low in proportion to the air admitted it frequently happens that
the gas ignites back, the flame receding down into the tube to the
pin hole orifice of the gas tip. The whole tube then at once be-
comes very hot so that .the rubber tube attached to the burner
may melt, the escaping gas then becoming ignited and a destruc-
tive fire may result. It is, therefore, dangerous to leave a Bun-
sen burner in operation with the gas turned low. Whenever it is
found that the flame of the Bunsen burner has receded to the





Fig. 126. Bunsen burner flames; the cuts contrast a proper flame
with that resulting when the gas is "lighted back" into the
tube.

base or "lighted back" the gas should be immediately shut off,
and the burner allowed to cool off completely before it is again
re-lighted; it may be cooled off quickly by letting cold water
flow upon it.

344. In cases where it is necessary to allow a Bunsen burner
to remain lighted a long time without constant attention, it should
be placed on a fire-proof table and the gas should be supplied
to it not by means of rubber tubing but through a piece of gas-
pipe directly attached to the burner.

345. The introduction of a diaphragm of fine wire netting in
the tube, just below the top, prevents the flame from "striking
back," but it also reduces the intensity of the heat of the flame.



FURNITURE AND APPARATUS.



i8 7



The mixture of gas and air passing through the wire netting is
ignited above it. Gas burners constructed on this principle can
be easily obtained.

Special burners are made for use with acetylene as the fuel,
and acetylene burners produce a much higher temperature than
gas burners.

346. The Roessler gas furnace is a very efficient apparatus
for small crucible operations where extremely high temperatures
are necessary. It can be used with either gas or acetylene.

Its construction is shown in the accompanying cut. It will




Fig. 127. Roessler furnace.

heat a crucible about twelve centimeters high having a diameter
of seven centimeters at the top. The length of the chimney may
be extended to about two meters and to insure a strong draft
through it a second burner is used at its foot.

347. When gas is not available gasoline burners may be ad-
vantageously used, and in many cases a good coal stove or a
charcoal furnace may be found useful.

Spirit lamps are extremely valuable for small and brief opera-



1 88



FURNITURE AND APPARATUS.



tions where a perfectly smokeless flame and high heat are de-
sired.

348. In the use of Bunsen burners spirit lamps and other burn-
ers which afford one solid vertical
flame, the most intense heat is just
below the middle of the flame.

349. When a vertical flame is
used it is often necessary to dis-
tribute and moderate the heat by
interposing zvire-gause or asbestos-
cloth between the flame and the ves-
sel heated. The gauze or cloth may
sometimes incidentally serve as a
support for flasks, beakers and
other vessels to which the heat is
I!;;, applied. But wire gauze is soon
''burnt out." Asbestos cloth is

Fig. 128. Earthed spirit .amps. much tQ be preferred .

350. Sand-baths are frequently useful for supporting flasks,
retorts and dishes which are to be strongly heated, serving to







Fig. 129. Showing the effect of the interposition of wire cloth;
the gas may be lighted either above or below the wire cloth.

distribute the heat. Shallow sand-bath dishes are used for the
support of beakers and evaporating dishes and also flasks ; deeper
sand-bath dishes are necessary for heating retorts which must



FURNITURE AND APPARATUS.



I8 9



sometimes be completely covered with the sand. Two forms of
sand-bath dishes, made of the best "Russia iron" are shown in
the cuts. A still deeper sand-bath is occasionally required.
Iron pots are used for large sand-baths.

The sand used for the sand-bath should be clean, hard flint
sand, not too fine but free from gravel.

The interposition of the sand-bath between the flame and the





Fig. 130. Tripod with rings.
For use with burners.



Fig. 131. Support for use
with a Bunsen burner.



vessel distributes the heat very effectively ; but it also causes con-
siderable loss of heat and lowers its intensity.

351. Water-baths are round vessels of copper, or of heavy
tinned iron, with either spherical or flat bottoms. Copper vessels
are by far the best because, if made of moderately heavy sheet





Fig. 132. Shallow sand-bath dish of
Russia iron.



Fig. 133. Deeper sand-bath dish of
Russia iron.



copper and given reasonable care, they last for many years of con-
stant use and because copper is an excellent conductor of heat.

Water-baths are indispensable in pharmaceutical laboratories.
One or two sizes are required, if not more. For general use in
comparatively small operations the best water-baths are those
provided with sets of concentric rings to fit different sizes of
dishes or flasks.

Water-baths without rings are used for special purposes.

Water-baths with constant level are very convenient, for the



190 FURNITURE AND APPARATUS.

ordinary water-bath requires watching and frequent replenishing
with water to prevent their running dry or too low, which usually
results in damage. The constant level water-bath is so con-
structed that the water vapor does not escape, but is condensed
and runs back into the body of the vessel. The bath shown in Fig.





Fig. 134. Small round-bottomed copper Fig. 135. Small flat-bottomed water-
water-bath, bath.




Fig. 136. Water-bath with attachment to maintain a constant
level of the water.

137 is, as seen, differently constructed. Various kinds may be
found described in the catalogues of dealers in chemical ap-
paratus.

The water-bath when in use should be kept from one-half to
three-fourths rilled with water, and the vessel placed upon it
should not fit so tightly that there is no escape for the steam,
for the pressure may then become so great as to throw the vessel



FURNITURE AND APPARATUS. 19!

off the bath or to cause a sudden outburst of steam which might
do injury.

The temperature afforded by the water-bath when well man-
aged may be made to range all the way from the ordinary
room temperature up to about 95 C.

352. Salt solutions (for from 100 to 160), glycerin (up
to 165), and paraffin (up to 250) are frequently employed in
baths instead of water for the purpose of imparting heat. The
temperatures afforded vary according to the boiling points.
When temperatures below the respective boiling points of these
several liquids are required it is necessary to use thermometers in
order to be able to guard against a higher heat than that desired.
Thermometers are especially necessary in water-baths when the
temperature must not be permitted to exceed a given degree. At
the same time the water-bath may then be placed a greater or
less distance above the flame, and the flame or fire may be regu-
lated as circumstances require.

353. Hot water coils may be advantageously used to heat
sand or water in large sand-
baths or water-baths em-
ployed in the practice labora-
tories of technical schools for

the use of the classes. Such
sand-baths and water-baths
may be made to afford a
reasonably uniform tempera-
ture anywhere between 30
and 70.

354. Hot air chambers,
heated with steam or hot wa-
ter, and tightly closed, may
be employed for maintaining
nearly uniform temperatures
for various laboratory pur-

rpi n i Fig. 137. Instantaneous water heater.

poses. They are usually made

of plate glass in frames of wood, and the temperature of the air

in them is observed by means of thermometers.

Hot air ovens and hot water ovens of copper are used for drying
small quantities of various substances.

355. Steam heat is invaluable in large manufacturing labora-




192



FURNITURE AND APPARATUS.



tories. Even small steam boilers of very simple construction
are of great utility in moderately equipped pharmaceutical labora-
tories. Where steam power is used, the steam also furnishes the
heat for pans, stills, etc.




Fig. 138. Small drying oven in use.



The temperature imparted by steam-heating apparatus may be
regulated so that it can be kept within narrow limits at any




Fig. 139. Double-walled copper oven.



Fig. 140. Copper drying oven.



point within the extreme range of from a few degrees above the
ordinary room temperatures up to 100. The steam used may
be under a pressure of from three or four pounds to the square



FURNITURE AND APPARATUS. IQ3

inch up to twenty-five pounds or more. For some special pur-
poses, as in the fractional distillation of hydrocarbons on a
large scale (in the manufacture of gasoline, benzin, lamp oil, etc.)
the steam is conducted by means of iron pipes through a furnace
fire to raise its temperature to a very high degree (even to a
point at which it makes red hot the iron pipe through which it
passes after leaving the furnace) before it is applied. Steam so
treated is called "superheated" or "dry steam."

Steam heat is applied in three different ways: i, by means
of coils ; 2, by means of jackets ; and 3, by conducting it directly
into the liquid to be heated.

A coil of steam pipe placed in the pan, kettle or still is very
effective for heating the contents.

The "steam jacket" consists of an outer shell or second bot-
tom riveted and soldered to the regular bottom of the pan, ket-
tle or still, so as to make a steam-tight compartment between the
two bottoms or shells. This "jacket" usually extends about one-
third of the way up around the vessel, and leaves a space of
about two inches between the shells at the center under it. The
steam enters the jacket on one side near the center of the
bottom through a horizontal pipe provided with a globe steam-
valve. The condensed steam is let out through a vertical steam-
pipe fitted to the outer shell at its lowest point, and this pipe
also has a valve by which it can be opened or closed. The side
pipe is connected by coupling with the regular steam supply pipe
and the outlet pipe at the bottom is coupled to another connected
with the "waste pipe."

A jet of steam issuing from the bottom of a single shell or pan
through a pipe may also be used for heating vessels placed upon
that shell and fitting it rather snugly, as a dish is placed over a
water-bath.

For heating liquids in tanks, barrels, or other deep vessels,
steam may be conducted through a straight pipe to the bottom of
the liquid in which the steam condenses giving up its latent heat
to the contents. This method is, of course, applicable only in
cases where there is no objection to the admixture of the water
from the condensed steam, and is, therefore, employed only for
heating liquids but never for evaporation or distillation.

For all ordinary operations where steam-heat is utilized the

Vol. 1113



!Q4 FURNITURE AND APPARATUS.

steam may be advantageously used under a pressure of four
pounds or even less.

OTHER APPARATUS.

356. Earthenware pots, thoroughly glazed and acid proof, are
indispensable. They can be procured of all sizes from 5 liters to
300 liters, or even larger. They are used for solution, filtration,
precipitation, washing, crystallization, etc.

Wooden vessels (tubs and barrels) may be used for some spe-
cial preparations made on a large scale.

Glass and porcelain precipitation jars and wide-mouthed bot-
tles are employed for smaller operations, and for still smaller
quantities Erlenmayer flasks and beakers.

357. Porcelain casseroles, with handles preferably of wood,
are most serviceable when of about i liter's capacity. Porcelain
or "white ware" pitchers may also be used to a considerable extent
for transferring liquids from one vessel to another, but not so
conveniently as casseroles for hot liquids.

Tinware dippers (well tinned) may be used for many purposes
in the laboratory.

358. Bottles for both solids and liquids, glass-stoppered as well
as others, are required in plenty. Glass-stoppered so-called
"tincture bottles," for acids and other solutions, may be used
as large as of 12 liters capacity with great advantage, if large
quantities of the liquids are employed ; but larger bottles are less
convenient and more liable to breakage.

359. Evaporation dishes have been sufficiently described in
Chapter VII, crystallizers in Chapter IX, and mortars and pestles
in Chapter I.

Funnels for filtrations, for collecting and washing precipitates
and crystals, and for other purposes have been described in the
chapters discussing those operations, and flasks, retorts, beakers,
wash-bottles, and other requisite glassware, including tubing and
fittings, were also mentioned to a sufficient extent in preceding
chapters. Some apparatus will be more specifically described in
Part II as occasion requires.

Sieves, spatulas, scoops, spoons, strainer holders, iron stands,
hammer and anvil, cork borer, files, tongs, knives, shears, and
many other implements and tools are needed in laboratories.



FURNITURE AND APPARATUS. 1Q5

The catalogues of dealers in chemical and pharmaceutical ap-
paratus should be consulted for further information and details.
Such catalogues are abundantly illustrated.

360. In the training laboratories of pharmaceutical and other
technological schools it is customary to have large water-baths
and sand-baths, drying closets, fume chambers, and balance room
for general use by all students, and to issue to each student a set
of apparatus for his individual use, and special: apparatus as re-
quired.

361. An outfit of apparatus sufficient for the production of
experimental quantities of the great majority of the preparations
included in Part II of this volume, but not including preparations
requiring special apparatus, may be as follows :

An iron stand with heavy base and three rings of different sizes
(respectively of 75, 100 and 125 millimeters diameter)
on the rod ("retort stand").

One copper water-bath, 150 millimeters diameter, with three
rings, and with two opposite handles.

One Russia-iron dish, 150 millimeters diameter and 25 milli-
meters deep, for a sand-bath.

A gas burner (or, in its place, a coal oil burner or a spirit
lamp).

One No. 4 or 5 mortar and pestle.

One or two mm porcelain evaporating dishes (Meisen or
Berlin ware).

One or two graduated glass measures, on foot, each of about
200 Cc. capacity (metric glass "graduates").

Two or three thin glass beakers, of about 250 Cc. capacity.

One glass flask with wide neck of medium length and flat bot-
tom, capacity 600 Cc.

One round bottom glass flask, 600 Cc.

One round glass (or porcelain) dish, about 150 millimeters
diameter and 35 to 50 millimeters deep, for use as a
crystallizer.

One 150 mm glass funnel, 60 angle, with long stem having
beveled end.

One 100 mm glass funnel of same kind.

One Elenmeyer flask of 500 Cc. capacity.

One Elenmeyer flask of 300 Cc. capacity.

One Elenmeyer flask of 200 Cc. capacity.



196 FURNITURE AND APPARATUS.

One Elenmeyer flask of 100 Cc. capacity.

One Elenmeyer flask of 50 Cc. capacity.

One wide-mouthed 2-liter bottle.

Two wide-mouthed i -liter bottles.

Two wide-mouthed half-liter bottles.

A dozen 150 mm test-tubes.

One double ended 150 mm horn spatula.

Half a dozen glass stirring rods, assorted sizes, 150 to 300
millimeters.

Two packages of coarse (rapid filtering) filter paper ("S. & S., n
or Swedish, or French) to fit the 150 mm funnel.

One package of the same kind of filter paper to fit the 100
mm funnel.

Corks, tapering, XXX, extra long, assorted sizes.

This outfit will enable the student to make moderate quan-
tities of nearly all the chemicals mentioned in this manual. For
the remaining preparations a few additional pieces of apparatus
are required, such as retorts, wash bottles, glass tubing, rubber
tube connections, thistle tubes, perforated rubber stoppers, etc.



CHAPTER XX.

SOME LABORATORY RULES AND PRECAUTIONS, AND WHAT TO DO
IN CASE OF CERTAIN ACCIDENTS

362. Order, system and cleanliness must prevail to the utmost
possible extent.

But as the materials and products handled are generally such
as would quickly ruin clothing", the laborant should wear "over-
alls," or at least apron and sleeves of rubber cloth.

The laboratory floor, fixtures and furniture must be kept clean
and free from dust.

Whenever any substance is spilled on a table or elsewhere the
accident should receive immediate attention.

Especial care should be exercised in handling acids, alkalies,
bromine, phosphorus, and other corrosive or inflammable sub-
stances.

Operations attended by the evolution of irritating or dangerous
vapors should be performed out of doors, or under the hood or
fume chamber. When such operations are performed outdoors
the operator should place himself in such a position that the
vapors or gases evolved are carried away from him by the air
currents.

Reactions liable to be violent must be carefully performed,
watched and controlled to prevent explosions, fire, breakage,
spattering of corrosive or hot liquids, or the sudden evolution of
large volumes of noxious gases.

Operations involving danger should never be undertaken ex-
cept when necessary.

It must be remembered that powerful oxidizing agents and
reducing agents generally react upon each other with great
velocity frequently attended with explosion, fire, or other dangers.



Online LibraryOscar OldbergInorganic general, medical and pharmaceutical chemistry, theoretical and practical; a text-book and laboratory manual, containing theoretical, descriptive, and technological chemistry; → online text (page 15 of 49)