Mrs. (Jane Haldimand) Marcet.

Conversations on chemistry .. online

. (page 42 of 43)
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weather. Whenever a fluid substance is converted into vapor, it
absorbs a quantity of caloric. }n the present case, the eiher takes
from the bulb of the thermometer, the caloric necessary to give it
tbe elastic form. Therefore, every new application of the ether
<?arries off successive portions of heat, and the mercury continues
to sink, until the bulb oecomesso cold, as to absorb caloric from the
surrounding air, faster than it is carried off by the evaporation. This
is the reason why the mercury cannot be depressed below a certain
point by evaporation. The ether, although it assumes the elastic
form, does not receive the caloric necessary for this purpose from
the thermometer, but from the surrounding air. See p. 73.

7. To demonstrate that fluids boil at comparatively small degrees
of heat, when the pressure of the atmosphere is taken off, about half
fdl with water a small retort, or Florence flask (common oil flask,)
and let it boil over a lamp. When the upper part is filled with steara
lake it from the lamp, and instantly cork it air tight. If now it is
put into cold water, it begins to boil violently. If taken out of the
water, it stops boiling, and this may be done many times. This
curious method of making water boil by the application of cold, is
easily accounted for. When the flask is put into cold water^ the steam
with which it was filled, is condensed and returns a^ain io water.
This leaves a vacuumy in which water is converted mto steam, or
boils, at a much lower temperature than in the open air. See p» 58.

8. If the above experiment is made by means of a small retort, a
very curious circumstance may be observed: When the water is
cold, and consequently nearly a perfect vacuum is formed« if the re-
tort is shaken, there is produced a sharp rattling noise, as thongh it
contained shot, instead of wa.ter* so that one would suppose by the
noise that the r§tprt would be broken into a thousand parts at ev-
ery jp(tf)tion. This is owing to the weight with which the water falls
upon the glass, when there is no air to impede its motion. See p. 64.

9. Into^a^thin glass vessel poiir an ounce or two of water, and
tb^ pour in <wo drams of sulphuric acid; the glass will instantly
become too ho4 to b^hejd in the band. ThJ9 experiment elficidat^s
the doctrine of late'pt beat* Qn mixing these two fluids, a chemic-
al combination takes place between their particles, in consequence
Qf which palpric is e^itracted at the oaine time their bulk is dimin-
ished. T^s ^Iso illustrates Pr« Black's laur^ that when substances
p^ss from a rar/sr to a denser state, caloric is g[i?en out. If one
measure of sulphuric acid, and one of water, be mixed togetber, the
mixtnre will not again $11 ib^ measure twice* See p. 77.

|0. To procure nilrogm^ take a bell elass or larger tumbler. an4
invert jt over a jsbort tapcr^ set in ;i sbaQow dish ofwater. The ta-
per burns until it absorbs iXX the oxygen contained ii the air under
the bell glass. What remains is nitrog^en* If now, a lighted taper
be put under Ibe beU g;la98, it will be instantly extiaguisbed, show-
M)g tbe absolute neCfsssity of oxygen for the support of combustion^
See p. 100.

u. XbefbrmatJQpofiraterbjrtbe bumiogef hydrogen, maj W

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EXPERIHEI^S.

shown thus : Take a Florence flask and ponr into it half a pint of
water, then put io about an ounce of gfranulated zinc, or the same
quantity of iron filings, and then pour in half an ounce by measure
pf sulphunc acid. Have ready a cork, pierced with a burning iron,
and the stem of a tobacco pipe passed through the aperture. After
putting in the acid, put the cork in its place, and fix the flaisk up-
right by setting it in a bowl, surrounded by a cloth to make it stand
up and prevent its breaking. As the hydrogen is formed, it issues
through the stem of the tobacco pipe, at the end of which jt is to be
fixed. If now a glass tube two or three feet long, and an inch or
two wide be passed on to the stem so as ib include the flame within
its bore, the tube, in a few moments will be covered on the inside,
with moisture. See p. 109.

If the orifice of the tube is quite small at the end where tlie gas is
fired, the above experiment serves to produce the musical tones. —
See p. 118.

12. An exhibition of ^as light my be made as follows : 'Into the
bowl of a common tabacco pipe put a piece ofmineral^ or what is
called sea-coal, and cover the coal closely with clay. When the
clay is dry, place the bowl in the fire and heat it slowly. In a few
•minutes the gas, called carburrcltcd hydrogen will issue from the
end of the pipe stem ; set fire to it with a candle, and it wilt bum
with a beautiful bright flame. This is the gas with which the streets,
factories, kc, are lighted io many of theEuropean cities.

In the absence of mineral coal, a walnut, small piece of pine
knot,.or butternut meat, &;c. may take the place of coal. See p. 120.

13. The following gives an example of the manner in which sul-
phuric acid is formed.

Mix with a small quantity of the flowers of sulphur, about one
fifth part of finely pulverized nitre. Make a stand by hollowing
with a hammer a large button, and attaching wire to the eye, for
feet, so that the button will be two inches high ; or, by any other
means, place the sulphur and nitre about this height in a shallow
dish, containing an mch or two of water. Set fire to the mixture
with a hot iron, and immediately invert over it a bell glass, or large
tumbler. The sulphur as it burns, absorbs oxygen from the air
contained under the bell glass, in a proportion which would const!*
tute sulphurous acid. At the same time, the heat which this pro-
cess occasions, compels the nitre to give out another proportion
of oxygen, which is absorbed by the sulphurous acid, and this addi-
tional quantity of oxygen, constitutes sulphuric acid. See p. 130.

14. Take three parts of nitre, two of potash, aodoneofsnlpbnr,
and mix them intimately, by rubbing in a mortar. This compound
is cdled/t(/mtna/t9ig potcder. On placing a little of it en a shorel
orer a hot fire, it explodes with great violence, and with a pecnlinrij
stunning report.

The comnustion of phosphuretted hjfdrogen in oxygen gas, nf-
fords one of the most striking and beautiful among chemical exper*
iments. It is done as follows ; Take some phosphuret of lime, wrap
it in a paper and push it under a ressel, as a wide mouthed ml, fiUad
with water, and mrerted on the shelf of the water bath. As soon at
the water penetrates through the paper so as to wet the pbosphni^t of
lime, bubbles of phosphuretted hydrogen, begin to rise up throa^ '
the water. While this is going on, ml a strong glass Tcssel^ a« a
tumbler, or a piece of thick glais tube stopped at onftend, with os -

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387

f«ii ns. lorert tbis also on the shelf of the water bath. When
the pbospburetted hydrogen is coHected, take the ressel containing
. it in one hand, and that containiDg the ozjgen in the other ; bring
the month of the former, by sinking it deeper in the water, under
the edge of the latter yessel, then by carenilly depressing the bot-
tom of the yessel containing the pbospburetted hydrogen, let up «
bubble at a time into the oxygen gas. If this experiment is madt
in a darkened room, the flashes of light appear astonishingly riwid
and beautiful. See p. 136.

16. Take six or eight grains of oxy^muriate ofpoiathf put it into
a mortar and drop in with it about a grain of solid phosphorus, cut
into two or three parts ; then rub them together with the pestle.—-
Very yiolent detonations are produced by these small quantitiet.
It is best, therefore, not to use more than is here mentioned at a
time. The hand, holding the pestle, ought always to be protected
with a glove or handkerchief.

17. To make liquid phosphorus, take an ounce vial and half fill it
with olive oil, put into the oil a piece of phosphorus of the size of a
pea ; gradually heat the bottom of the vial, until the phosphorus it
melted, taking care to keep the thumb on the mouth ; then cork it
air tight. If this vial is first shaken, and then the cork be taken
out, it becomes luminous, first near the mouth, and gradually down
to the oil, at the bottom. The light which a bottle prepared in this
way gives, particularly if warmed, by holding it in the hand, is suffi-
cient to tell the hour of night by a watch. This luminous appear-
ance, when the cork is removed, is owing to the union of the oxy-
gen of the atmosphere with the phosphorus. It is slow combustioB,
attended with light, and most probaoly with some heat.

18. If drawings be made on silk with a solution of nitrate of sil-
rer, and the silk first moistened, is exposed to a stream of hydrogen
1^, or in any other way exposed to the action of this gas, the metal
18 instantly revived, and the silk is covered with figures of silver. —
See p. 155.

19. If a few drops of a solution of nitrate of silver in water, be
placed on a bright surface of copper, the silver is revived, and inves
the copper a brilliant white coat of that metal. This is explained
on the principle of affinity. The copper has a strone^er attraction
for the acid which composes a part of the nitrate of silver, than the
silver itself has. Therefore it attracts the acid from the silver, in
consequence of which this is received, and at the same time preci-
pitated on the copper. See p. 155.

80. Take a little of the white arsenic of the shops, and mix it with
some finely ground charcoal ; put the mixture into a small glass
tube closed at one end, and expose the part where the mixture is to
a moderate degree of heat gradually raised ; the arsenic will be re-
ceived, and will attach itself to the upper part of the tube, giving it
a brilliant metallic coat like quick silver. The arsenic may be
preserved in this state by stopping up the tube. See p. 155.

21. Dissolve a tea-spoonful of sugar of lead in a quart of rain
water. Put this into a decanter, or white glass bottle, and suspend
in it by means of a string a piece of zinc. The zinc decomposes
the acetate of lead by depriving it of its oxyjg^en ; the consequence
is, that the lead is precipitated in the metalhc state, on and around
the zinc, and forms a brilliant tree of metal.

22. Pour a solution of nitrate of silver into a glaii yetieli and im'

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936 . lacfWmUxttTs-

merse a few slips of copper in it. In a ^tt time, a portion of cap*
per will be dissolved, and all the sityer precipitated in a metallic
rorpi. If the solutioa whibh now contains copper be decanted into
another glass, aod pieces of iron added to it, tbis metal will then ba
dissolved, and the copper precipitated, yielding a striking instance
of peculiar affinities. See p^ 176.

23. Ivory may be coated with silver by the following process :
Make a strong solution of nitrate of silver io pure water ; into this,
immerse a piece of ivory until it turns yellow ; then take it out aifid
immediately plnnge it into a vessel of distilled water exposed to the
direct rays of the sun until it turns black. On rubbing it gently 4t
will appear covered with a brilliant coat of silver, resembling a bar
of that metal. This curious effect is owing to the solar light wMoh
decomposes the nitrate of silver, by taking the oxygen from it,
which flies off in the form of oxygen gas.

24. Through a vessel of lime water, recently made, pass bubbUn
of carbonic acid gas by means of a bladder and tube, the lime water
instantly becomes white and turbid, and finally deposits a qoamtity
of carbonate of lime in the form of powdered chalk. If now the wat«r
be evaporated, a white powder remains which effervesces witii
acids. If this powder is put into a retort, and sulphuric acid diluted
with water, is poured upon it, the beak of the retort being under &
vessel filled with water, the carbonic acid is again obtained, and the
salt remaining in the retort will be sulphate of lime or gypsum.

25. Mix one part of nitric acid with 6 or 6 parts of water in a vial ;
into this put some copper filings, and in a few moments pour off the
liquid ; it will be colourless. If now there b^ added some liquid
ammonia, another colourless fluid, the mixture becomes of an in-
tense and beautiful bltie. Hence ammonia is a most delicate test
for the presence of copper, with which it strikes a deep blue co-
lour. See p. 187.

26. Put into a vial of pure water a f6w drops of the tincture of nttt
galls, made by steeping the galls in water ; into another vial of purtt
water put a grain or two of the sulphate of iron. If these colour-
less fluids are mixed, they instantly become black. Tincture of ^bBs
is a most delicate test for the presence of iron, with which it strikes
a black. These two substances form the basis of ink. See p. 187.

27. Take two small glass jars, or tumblers, and fill one with tar-
bonic acid gas ^ and the other with oxygen gas. Have thein cet up-
right with a cover on each. If a lighted taper be plunged into the
vessel containing the carbonic acid, it is extinguished instantly; hat
if it is immediately plunged into the other jar containing the oxy-
gen, it is as instantly lighted with a sort of explosion. See p. 5B86.

28. Put eight or ten grains of oxy-muriate of potash into a tea-cup,
and then pour in two or three drachms of alcohol. — If now about two
drachms of sulphuric acid is added, the mixture begins to dart foi^
little balls of blue fire, and in a minute or two, the whole barstt
into flame. The alcohol is inflamed' by the chlorine which is^tet
f)ree from the salt, in consequence of the combination which takes
place between the potash and the sulphuric acid. See p. 236.

29. into a glass tube half an inch or an inch wide, two or three
inches long, with a bulb at the end, put a grain or two of iodine.
Warm the tube, (but not at that part where the iodine is,) and^ioi-
mediately cork it tight ; the tube remains colourless, there bein^

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BXFEBUIEITTS.

only a few little specks here and there. If at any time the tube be
warmed at that part where the iodine is^ it is instantly filled with a
gas of a most beautiful violet colour. If care is taken to keep the
tube well closed, so that the iodine does not escape, when it takes
the form of gas, this effect will always be produced whenever the
tube is warmed. A tube with two bulbs, like what is called iipulu
glatSf containing the iodine hermetically sealed, would be better. —
Such a little apparatus would be quite a curiosity to those who
know nothing of the nature of iodine. See p. 238.

30. Write on paper with a solution of the nilrat of silver, taking
care not to have it so strong as to destroy the paper. So long as it
is kept in the dark, or if the paper be closely folded, the writing re-
mains invisible ; but on exposure to the rays of the sun the charac-
ters turn yellow, and finally black, so that they are perfectly legible.

Mr. Accum says, that tnis change of color is owing to the par-
tial reduction of the oxide of silver, from the light expelling a por-
tion of its oxygen ; the oxide therefore approaches to the metallic
state ; for when the blackness is examined with a deep, or powerful
magnifier, the particles of metal may be distinctly seen.

31. Write on paper with a dilute- solution of common sugar of
lead ; the writing will remain invisible. But on moistening the lines
with a pencil, or feather dipped in water impregnated with sulphu-
retted hi^drogen, the metal is revived, and the letters appear in me-
tallic brilliancy.

The author above cited, says, that in this instance, the hydrogen
of the sulphuretted hydrogen gas, abstracts the oxygen from the ox-
. ide of lead, and causes it to re-approach to the metallic state ; at the
same time, the sulpbui: of the sulphuretted hydrogen gas combines
with the metal thus regenerated, and converts it into a sulphuret
which exhibits the metallic color.

32. Write on^aper with a solution of the sulphate of copper. If
this is strong, the writing will be of a faint green color ; if weak,
the characters are invisible. On holding the paper over a vessel
containing some liquid of ammonia, or if it be exposed to the action
of this gas in any other way, the writing assumes a beautiful blue
■color. On exposing the paper to the sun, the color disappears, be-
cause the ammonia evaporates.

33. Put a small piece of phosphorus into a crucible, cover it close-
\j with common chalk, so as to fill the crucible. Let another cru-
cible be inverted upon it, and both subjected to the fire. When the
whole has become perfectly red-hot, remove them from the fire, and
when cold, the carbonic acid of the chalk will have been decompos-
ed, and the Black Charcoal, the basis of the acid, may be easily
perceived amongst the materials.

34. Into a large glass jar inverted upon a flat brick tile, and con-
taining near its top a branch of fresh rosemary, or any other such
shrub, moistened with water, introduce a flat, thick piece of heated
iron, on which place some gum benzoin in gross powder. The ben-
zoic acid, in consec^uence of the heat, will be separated, and ascend
in white fumes, which will at length condense, and form a most
»>eautiful appearance upon the leaves of the vegetable. This will
serve as an example of Sublimation.

35* Mix a little acetate of lead with an equal portion of sulphate
of zinc, both in fine powder ; stir them together with a piece of
glass or wood, and no chemical change will be perceptible ; bat if

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340 sxpasnoEim.

thej be rubbed tog'etber in a mortar, tbe two solids will operate on
each other; an intimate union will take place, and a fluid will be
produced. If alum or Glauber salt be used instead of sulphate of
.zinc, theexperiment will be equally successful.

36. If tbe leaves of a plant, fresh gatliered, be placed in the sun,
Tprf pure oxygen ffas may be collected.

37. Put a little fresh calcined magnesia in a tea-cup upon the
hearth, and suddenly pour over it as much concentrated sulphuric
acid as will cover the ma^esia. In an instant sparks will be tnrowD
out, and the mixture will become completely ignited.

28. If a few pounds of a mixture of iron filings and sulphur be
made in paste with water, and buried in the ground for a few hours,
the water will be decomposed with so much rapidity, that combus-
tion and flame will be the consequence.

39. For want of a proper glass vessel, a table spoonfull of ether
may be put into a moistened bladder, and the neck of the bladder
closely tied. If hot water be then poured upon it, the ether will
expand, and the bladder become inflated.

40. Procure a phial with a glass stopper accurately ground: into
it ; introduce a few copper filingfs, then entirely fill it with liquid am-
monia, and stop the phial so as to exclude all atmospheric air. If left
in this state, no solution of the copper will be effected. But if tba
bottle be afterwards left open for some time, and then stopped, the
metal will dissolve, and the solution will be colorless. Let the stop-
per be now taken out, and the fluid will become blue, beginning at
the surface, and spreading gradually through the whole. If this blue
solution has not been too long exposed to tbe air, and fresh copper
filings be put in, again stopping the bottle, the fluid will once more
be deprived of its color, which it will recover only by the re-ad-
mission of air. These effects may thus be repeatedly produced.

41. If a spoonful of good alcohol and a little boracic acid be stir-
red together in a tea-cup, and the^ set on fire, they will produce a
beautS'ul green flame.

42. Alloy a piece of silver with a portion of lead, place the alloy

Xn a piece of charcoal, attach a blow-pipe to a gasometer, charge-
nth oxygen gas, light the charcoal first with a bit of paper, and
keep up the heat by pressing upon the machine. When the metals
get mto complete fusion, the lead will begin to burn, and very soon
will be all dissipated in a white smoke, leaving the silver in a state
of purity. This experiment is designed to show the fiixity of the no*
ble metals.

43. Burn a piece of iron wire in a deflagrating jar of oxyg;en gas^
and suffer it to burn till it goes out of itself. If a lighted wax taper
be now let down into the gas, this will burn in it for some time, and
then become extinguished. If ignited sulphur be now introduced,
this will also burn for a limited time. Lastlj], introduce a morsel of
phosphorus, and combustion will also follow in like manner. These
experiments show the relative combustibility of different substances.

44. Drop a piece of phosphorus, about the size of a pea, into m
tumbler of hot water, and from a bladder, furnished with a stop cock,
force a stream of oxygen gas directly upon it. This will afiord the
most brilliant combustion under water that can be imagined.

45. Take an amalgam of lead and mercury, and another ama^m
of bismuth, let these two solid amalgams be mixed by triture^ anci
they will instantly become fluid.

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INDKX. 341

46. Into diitilled water drop ti little spiritoos solution of soap, no
chemical effect will be perceived ; but if some of the same solutipn
be added to hard-water, a milkioess will immediately be produced,
more or less, according to tbe degree of its impurity. This is a good
method of ascertaining the purity of spring water.

47. To silver copper or brass.— Clean the article intended to be
silvered, by means of dilute nitric acid, or by scouring it with a
mixture of common salt and alum. When it is perfectly bright,
moisten a little of the powder, known in commerce by the name of
silvering powder, with water, and rub it for some time on the per-
fectly clean surface of copper^ or brass, which will become covered
with a coat of metallic silver. It may afterwards be polisl^ed with
soft leather.

, The silvering powder is prepared in the following manner : Dis-
solve some silver in nitric acid, and putpiecesof copper into the so-
lution ; this will throw down the silver in a state of metallic powder.
Take fiAeen or twenty grains of this powder, and mix witn-it two
drachms of acidulous tartarite of potash, the same quantity of com-
mon salt, and half a drachm of alum. Another method : Precipi-
tate silver from its solution in nitric acid by cooper, as before ; to
half an Ounce of this silver, add common salt and muriate of ammo-
nia, of each two ounces, and one drachm of corrosive sublimate ;
rub them together, and make them into a paste with water. With
this, copper utensils intended to be silvered, that have been pre-
viously boiled with acidulous tartarite of potash and alum, are to be
rubbed ; after which they are to be made red-hot, and polished.

48. To prove that the air of the atmosphere always contains car-
bonic acid. This may be shewn by simply pouring any quantity of
barytic water, or lime water, repeatedly from one vessel into an-
other. The barytic water when deprived of the contact of air, is
perfectly transparent ; but it instantly becomes milky, and a white
precipitate, which is carbonate of barytes, is deposited, when
brought into contact with it for a few minutes only.

The quantity of carbonic acid contained in the atn^osphere, sel-
dom vaxiM, except in the immediate vicinity of places where respi-
ration and combustion are going on in the large way^ and is about
one hundredth part.



INDEX*

. A Agate, 105

A^cnlture, 274

Absorbent ressels, €98 Air, 95

Absorption of caloric, 40, 45 Albumen, 287

Acetic acid, 252, 253 Alburnum, 283

Acetous fermentationi 267 Alchemists, 15

acid, 253 Alcohol, or spirit of wine, 2M

Acidulous gaseous mineral wa^ Alembic, 127

ter8,226 Alkalies, 181

salts, 254 Alkaline earths, 182^ 194

Adids, 202 Alloys, 162

Aeriform, 31 Alum, or ndphat of alwMM,
Affinity, 23, 174 196, 212 Digitized by GooqIc



342



nCDKX.



Alumine, 196
Alumium, 19
Amalgam, 163
Ambergris, 320
Ametbjst, 197
AmiantbuS) 201



Blood, 303, 305
Biood-vesseh, 309
Boiling water, 67
Bombic acid, 292, 204
Bones, 295
Boractc acid, 204, 226



Ammonia, or volatile alkali, 169, Boracium, 19, 227



181, 188
Ammooiacal gas, 188

how obtained, 191
Analysis, 138

of yegetable8,241
Animals, 288
Animal acids, 292 ,

colors, 294

heat, 311

oil, 292
Animalization, 287, 296
Antidotes, 191
Antimony, 20
Aqua fortis, 216

regia, 160
Arrak, 262
Argand's lamp, 107
Anjenic,20, 163, 165
Arteries, 298
Arterial blood, 3U6, 308
Asphaltum, 270
AssafiBtida, 249
Assimilation, 297
Astringent principle, 253
Atmosphere, 61,^95, 10^
Atmospherical air, 95



Online LibraryMrs. (Jane Haldimand) MarcetConversations on chemistry .. → online text (page 42 of 43)