imh
•<r
_^tf
 
r=*i   -i
WASHINGTON, D.C
ARMY MEDICAL LIBRARY
       FOUNDED 1S36
-o
S&;
V 
&m»<i_s:s&t^
4,ff**
DUE TWO WEEKS FROM LAST DATE
} m$
OPO 16—71341-1 
I
\
^ 
COURSE OF CHEMICAL INSTRUCTION
MEDICAL DEPARTMENT
Ei)c gUtftersfta* of tymm$ltomin.
11M MAE» mH>*

   PROFESSOR OF CHEMISTRT.
FOR THE USE OF HIS PUPILS.
REPRINTED, WITH CORRECTIONS AND ADDITIONS.
       PHILADELPHIA:
Clark <J Baser, Printers, No. 33, Carter's Alley.
            1825. 
GO)
 bo
,«,:.■ -<«»,i^. 
^
£*
^ (k^CZ^Zy  JU-ZuZl&Zc *feZZ£x. A ^^/A^^ta,
i- %✓ <^ .
If 
^fc &GL ,-/«..y 4 <*"*"■•*«" "  " -***}



 
&c.  &c.
           INTRODUCTORY LECTURE,

ON THE RISE, PROGRESS, AND PRESENT STATE OF CHEMISTRY,
               AS AN ART, AND AS A SCIENCE.
        LECTURE
ON THE STUDY OF CHEMISTRY.
 ON THE CAUSE OF THE PHENOMENA AND OPERATIONS OF THE
                       PHYSICAL WORLD.
  Reaction between different portions of matter, is conceived to
be the fundamental cause of the phenomena and operations of the
physical world;  for if there were no such reaction, every particle,
or mass, would be as if no other existed.

                          REACTION,*
  Is distinguished as taking place  between masses, between a mass
and particles, and  between particles only.

                  REACTION BETWEEN MASSES,

  Is sublimely exemplified in the  solar system.

         REACTION BETWEEN A MASS, AND PARTICLES,

  Is exemplified by the  reflection, refraction,  or  polarization of
light;  as by the moon, the rainbow, the Iceland spar.

 REACTION BETWEEN PARTICLES, OR CORPUSCULAR REACTION,

  Is exemplified by a fire or the explosion of gunpowder.
  * In Mechanicks, action is said to produce reaction: but in the case of an
innate property, which mutually causes different portions of matter to  be self-
attractive, or repellent, it is impossible to distinguish the agent from the re-
agent. From our first acquaintance with any bodies so situated, they may be said
mutually to react, or to exercise reaction.   Hence I employ this word, to distin-
guish the  action which bodies exert, reciprocally, from any joint action against
other bodies. 
                               4

                NATURAL PHILOSOPHY DEFINED.
  In its most extensive sense, it treats of physical reaction gene-
rally.  In its more limited and usual acceptation, it treats of those
phenomena, or operations of nature, which arise from reaction be-
tween masses, or between a mass and particles.
                     CHEMISTRY DEFINED.
  It treats of the phenomena, and operations of nature, which arise
from reaction between the particles of inorganic matter.
                     PHYSIOLOGY DEFINED.
  Physiology treats of the phenomena and operations, which arise
from  reaction between  the masses, or atoms, of organic, or living
bodies.

  THE REACTION OF  PARTICLES, OR CORPUSCULAR REACTION,
  Is distinguished into repulsive reaction, or repulsion, and attrac
tive reaction, or attraction.
                     OF ATTRACTION.
  Attraction is distinguished, as it takes place between particles, of
the same kind, or, homogeneous; and as it exists between particles
of a different kind,  or, heterogeneous.
  The attraction which takes place between  homogeneous parti-
cles, is designated as attraction, of aggregation, of cohesion, or as ho-
mogeneous affinity.   The attraction which arises between hetero-
geneous  particles,  is  called  chemical affinity,  or heterogeneous
affinity.

ON ATTRACTION OF AGGREGATION, OR COHESION: ALSO  CALLED
                   HOMOGENEOUS  AFFINITY.
  It is the force which mechanical division subdues.*  Overcoming
it, does not alter the chemical  nature of a substance.  It is the
cause of crystallization.
                      CRYSTALLIZATION,
  Is that process of nature, by which bodies, passing from the fluid
to the solid state, assume regular forms called crystals. All matter
is presumed to be capable of assuming crystalline forms.

                          CRYSTALS,
  Are found in nature and are produced  artificially.

               EXAMPLES  OF NATIVE CRYSTALS.
  The precious stones are splendid productions of this kind.  Cal-
careous spar,  common  salt,  gypsum,  are native  products, often
crystalline in form.

ON  THE VARIOUS MEANS  OF CAUSING ARTIFICIAL  CRYSTALL1
                           ZATIOX.
  Fusion followed by congelation.—Instances: Sulphur, bismuth^
antimony, zinc. 
5
  Solution followed by evaporation in open vessels.—Exempli-
fied by salts, acids, alkalies, sugar.
  Solution with heat, followed by refrigeration.
  Most of the substances which yield crystals  by the process last
mentioned, yield them likewise in this way.
  Solution followed by vaporization at the boiling heat.
  Crystals may be thus obtained from many salts; but are always
minute—as in the case of basket salt.
  Solution followed  by saturation.—Instances: Pearl ash satu-
rated by carbonic acid or chlorine.
  Sublimation.—This comprises the idea of vaporization and con-
densation.   Instances: Corrosive sublimate, calomel, iodine, ar-
senic.
  Solution  followed by precipitation.—Arbor  Dianae,  arbor
Saturni.
          SUBJECT OF CRYSTALLIZATION CONTINUED.
  Other things being equal, crystals  are larger in  proportion as
their growth is slower.   They prefer to shoot from extraneous
bodies, as the sides of the receptacle, or from strings, or sticks, to
forming themselves in an isolated manner.  Agitation hastens their
production,  but confuses them.  The crystalline texture  of some
of the trap  rocks, is attributed to slow cooling.   The same matter
fused, and allowed less time to cool, forms a  glass.
                     CRYSTALLINE SPECIMENS.
   A wooden  arch,  about fifteen  inches high, and a foot
wide, encrusted with  fine blue crystals  of the  sulphate of
copper.
   Crystals of corrosive sublimate, and of calomel.
   Crystals  of sulphur,  arsenic,  bismuth, antimony,  and va-
rious other specimens.
                EXPERIMENTAL ILLUSTRATION
   Of the consequences of excluding the air from a saturated solu-
tion of sulphate of soda, while boiling.
       RATIONALE OF THE PROCESS OF CRYSTALLIZATION.
     OF THE OBSERVATIONS OF ROME  DE L'lSLE, OF GHAN, OF
                     BERGMAN, OF HAUY.
                OF HAUY's CRYSTALLOGRAPHY.
OF THE ATTRACTION, WHICH OPERATES  BETWEEN HETEROGE-
  .\EOUS PARTICLES; CALLED AFFINITY, OR HETEROGENEOUS AF-
  FINITY.
  This  attraction is never subdued  mechanically, unless  when
neWly balanced by repulsion; as in the case of compounds, which 
6
may be  exploded by percussion, or elastic fluids condensed  into,
or'combined with, liquids.
  To sever  elements, united  by chemical  affinity, the finest edge
which human art can produce, were utterly incompetent.

     Instances:—
  Whiting consists of lime and carbonic acid;  Plaster of Paris, of
sulphuric  acid and  lime; Vermilion, of  sulphur  and mercury.
These substances may be reduced into  powders perfectly impal-
pable.   Yet  the  minutest particle of either  contains the same in-
gredients as  the mass, and in the same proportion.

DIFFERENT CASES OF AFFINITY, ACCORDINGLY AS MORE OR FEWER
                 PARTICLES ARE CONCERNED.
                   1st case—Simple Combination.
  A and B, two heterogeneous substances, united in the compound
AB.
     Instances:—
Copper  and zinc       form Brass.
Lead and  tin           „   Pewter.
Oil and  alkali           ,,   Soap.
Acids and alkalies      „   Salts.
~,,  .     ,^i         ( Chlorides, as  for instance calomel or
Chlorine and metals    „  <         '     •     ul-  „.
                       "  I        corrosive sublimate.
Sulphur and metals     „   Sulphurets.

                       2d Case of Affinitt.
   Called simple  elective attraction, or affinity.
   A and B, two  heterogeneous particles,  being united in compound
AB,—C,  another particle, being blended  with them  in solution,
unites with one of them, as A, to the exclusion of B.
   In this  case, C is said to decompose AB, and to have a  greater
affinity  for A than B.

     Instances of simple elective affinity:—
          C of Silver      decomposed by Mercury.
   Nitrate < of Mercury         „        Copper.
          (of Copper           „        Iron.
   Muriate of Lime             „        Sulphuric Acid.
   o 1 u *.  Cof Alumine ?              „ ,  .
   Sulphate  £ of Magnesia $     »        Potash-

                       3d Case of Affinity.
   Called double elective attraction, er complex affinity.
   The  compound formed by the particles A and B, being blended
 in solution with the compound formed by  C and D,—A combines
 with D, and B with C. 

o^-^sZLj
 


CC^~
£ /z<-^/£^^Z£*~*  <&<-£- d$^~~^  ^
^ . :'   .   , . .         ...    >.   v* ~
 
7
   Instance of double elective affinity:—
            A       B              AD
         Sulphate of Zinc }       C Sulphate of Lead
         being mixed with V gives <     and
         Acetate of Lead,)       (Acetate of  Zinc.
            CD              C        B

         VARIOUS OTHER EXPERIMENTAL ILLUSTRATIONS.

                     4th Case of Affinity.
  A, B, and C, being in union, on adding D, it combines with B,
which it would not do were not C present.
  Instance:—Ammoniacal nitrate of copper, or silver, added to a
solution of white arsenic in water.  The arsenious  solution will
not, per se, decompose the nitrates.

                     5th Case of Affinity.
  A and B, being in union, C, added in excess, combines with both
A and B.
  Instance:—Ammonia added  to solutions of  copper, or silver,
gold, &c.

  ON COHESION AS AN OPPONENT OF CHEMICAL COMBINATION.
   EFFECTS OF MECHANICAL DIVISION EXPERIMENTALLY ILLUSTRATED.
   Action  of  an acid upon  a  lump of metal, compared with
the action of the same acid  upon an  equal weight of  the
same metal in filings.
       INFLUENCE OF SOLUTION EXPERIMENTALLY ILLUSTRATED.
   Tartaric acid, and a carbonate, although pulverized, and
 intimately intermingled, are observed not  to react until
 moistened, when a lively effervescence ensues.

  EXCEPTION TO THE LAW, THAT CHEMICAL ACTION REQUIRES FLUIDITY—
                  EXPERIMENTALLY ILLUSTRATED.
    Quicklime and muriate  of ammonia, being powdered and
 mixed, the pungent fumes of ammonia are perceived.

                    ON TABLES OF AFFINITY.
   Any substance being placed at the head of a column, other sub-
 stances are placed under it, in  the order of their attraction for it. 
$
                         AN EXAMPLE.
                      SULPHURIC ACID.
                         Barytes,
                         Strontites,
                         Potash,
                         Soda,
                         Lime,
                         Magnesia,
                         Ammonia.

                 ON DEFINITE PROPORTIONS.
  The proportions have been long known to be invariable, in which
substances must be mixed, in order to saturate each other; or  to
produce a compound,  in which the peculiar characters, or affinities
of the ingredients, are extinguished.
  When substances combine in other proportions, than those of sa-
turation, their ratio is no less definite, and constant.
  There is not, in any case, except the peculiar one of solution, an
indefinite gradation in the proportions in which bodies combine.
There are rarely more than four gradations.
  The number, representing the least proportion, in which a  sub-
stance is known to combine, will almost always divide the numbers
representing the greater proportions, without a fraction.
  Let A, B, and C, be certain substances, and let X, Y, and Z, be
other substances, severally having an affinity for either A, or B,  or
C.  Let each of the  former,  and each of the latter, be combined
in the  least possible proportion.   Consequently, the least combin-
ing proportion of each substance, will be found three times.  It
will appear that the proportions of A, B,  and  C, found by com-
bining them with X, will  be  in  the same ratios to each other,  as
the proportions found by combining them  with Y, or Z; and  reci-
procally, that  the proportions of X, Y, and Z, will have the same
ratios, whether ascertained by their combination with A, B, or C.*
This uniformity of the ratios existing, between the least combining
proportions of substances, will be found to prevail, if, instead of six
substances, the comparison be made with any larger  number.
   Chemical  equivalents  are numbers, representing  the least
combining proportions of the substances to which they belong.
They are usually assumed so, as  either to make the equivalent of
oxygen, or that of hydrogen, unity.

              TABLES OF CHEMICAL EQUIVALENTS,
   Are very useful; for as the equivalent number  of any compound,
is to any weight of the compound, so is the equivalent of either of
  * That is, as A, in AX, is to B, in BX, or to C, in CX—so is A, in AY, to B, in
BY, or to C, in CY:—and so is A, in AZ, to B, in BZ, or to C, in CZ.—Again, as
X, in AX, is to Y, in AY, or to Z, in AZ—so is X, in BX, to Y, in BY, or to Z, in
BZ:—and so is X, in CX, to Y, in CY, or to Z, in CZ. 
 
*>
> 
9
its ingredients, to the quantity of such ingredient in the said weight
of its compound.
  And as the equivalent of any compound, is to that of any sub-
stance, capable of decomposing it;  so  is the weight of the com-
pound, to be decomposed, to the weight of the substance, just
adequate to effect the decomposition.

            WOLLASTON'S SCALE OF EQUIVALENTS.
  By this, the computations requisite in using the equivalents, are
performed by a slide.
  The equivalents may be expressed in any  numbers having the
same ratios to each other as the least combining proportions of the
substances which they represent. The slide enables us to adopt such
other numbers as may be convenient. Equal distances on the slide,
give the same ratios in different numbers. If,  by moving the slide,
we vary one  equivalent, to 100 for instance, the other equivalents
vary proportionably.
                      THEORY OF ATOMS.
  The ratio of the equivalent numbers, is supposed to be depend-
ent on, and identical with, that of the integral atoms of the  sub-
stances to which they appertain.
   It is probable, that there are elementary atoms, indivisible either
by mechanical, or chemical means.  Mechanical division is limited
by the imperfection  of edges, or surfaces.—Were atoms chemi-
cally divisible, ad infinitum, any  one substance, however small in
quantity, would be equally diffusible throughout  any other, how-
ever great.   The fact is otherwise: whence,  elementary atoms are
inferred to be chemically indivisible.

                      BINARY COMPOUNDS.
   A compound, in which the ingredients are both reduced to the
smallest  possible  proportions, is considered as having as many
atoms of  the  one  as of the  other; and each  integral atom of the
compound, as consisting of an atom of each ingredient. Such com-
binations are called binary, because they contain but two atoms.

                     TERNARY COMPOUNDS.
   When the quantity of either ingredient is the double of its least
proportion, it is supposed that the number of its atoms is doubled;
and the other ingredient being in its least proportion,  it is inferred
that there are two atoms of the former to one of the latter; hence
it has been called a ternary compound.

                   QUATERNARY COMPOUNDS,
   Are those, in which  the proportion  of one of the ingredients is
tripled, so tha,t it is supposed to contain four atoms. 
10
               ON CALORIFIC REPULSION.

'A PRIORI PROOFS, THAT THERE  MUST  BE A MATTER, IN WHICH
         REPULSION EXISTS AS AN INHERENT PROPERTY.
   The existence of repulsion and  attraction  between the particles
of matter, is as evident as that they exist.  Opposite qualities, cannot
belong to the same particles.  There must be particles, in which
repulsion is inherent, as well as others  in which attraction  is in-
herent.

EXPERIMENTAL  PROOFS, OF THE EXISTENCE OF A  MATERIAL
              CAUSE, OF CALORIFIC REPULSION.
   If ice at 32° be mixed with water at 170°,—the mixture, when
the ice is melted, will be at  32°.  But if water at 32°, be mixed
with water at 170°,—the mixture will be at a mean heat.  Water
exposed to a fire, does not grow hotter  after it  boils, but steams
more or less, according to the activity of the fire.  The steam ap*
pears to carry off the  principle  which the  fire communicates.
Steam, only heated  to  the  boiling point,  or 212°, will raise the
temperature of nearly ten times its weight  of water, 100 degrees.
                           INFERENCE.
  The heat, which would raise ten parts of water to 100 degrees,
if it were concentrated into one  of those parts, would probably
raise it to 1000 degrees nearly, which is  about equal  to a red  heat.
It follows, therefore, that as much heat  is absorbed in  producing
steam, as would  make the water, of which it consists, red hot, if
prevented from assuming the aeriform state.
  These facts, and deductions, induce  chemists  generally to be-
lieve, that the cause of calorific repulsion is material—that it con-
sists of a fluid, of which the particles are  self-repellent, while they
attract  other  matter—that by the union of this  fluid with other
matter, it imparts a repulsive property which counteracts cohesion,
so as to  cause, successively, expansion, fluidity, and the aeriform
state.
                   OF  THE TERM CALORIC.
   Propriety of using a new word (caloric) to designate the
material cause  of calorific repulsion, illustrated by a fulmi-
nating  powder, which, though cold, contains more  of the
material cause  of heat, than red-hot  sand.

          ORDER PURSUED IN TREATING OF CALORIC.
Of its effects.  On the  modification of the effects of Caloric by
  atmospheric pressure.  Means of producing  heat, or render-
  ing Caloric sensible.   On the communication of heat.  Slow
  communication:  Quick communication.   Means of  pro-
  ducing, cold,  or rendering Caloric  latent.   On the  various
  states, wherein Caloric exists in nature. 
— » > . v
)-)*■■ 



^  &?
jfe
 
11
  EXPANSION, THE MOST OBVIOUS, AND UNIVERSAL EFFECT OF
                          CALORIC.
Qn the expansion of Solids.   On the expansion of Liquids.
  On the expansion of Elastic Fluids.  On the opponent agency
  of Atmospheric Pressure.
                    EXPANSION OF SOLIDS.
  A ring and plug, which, when cold, fit each other, cease to do so
when either is heated: and a tire, when red-hot, is made to embrace
a wheel, otherwise too large for it.

   A pyrometer shown, in which expansion is multiplied by
levers.
  Metals are the  most expansible  solids, but some are more ex-
pansible than others.

SUPPOSED  EXCEPTION TO  THE LAW,  THAT SOLIDS EXPAND BY
  HEAT, IN THE  CASE  OF CLA\ ,  WHICH  CONTRACTS IN  THE
  FIRE.
   The clay loses bulk, by losing water.  Granular aggregates  sink
before fusion.  Each grain  may expand, while the mass contracts.
The size of  the masses after fusion, probably would be found  in
proportion to their*temperature.
                   WEDGWOOD'S PYROMETER.
   The  contraction,  induced in cylinders of clay,.in proportion as
 they have  been heated, measured by a scale, supposed to indicate
 the heat to which they have been exposed.

    Wedgwood's pyrometer exhibited.
 FXPANSlON OF FLUIDS, WHICH ARE ALMOST INCOMPRESSIBLE OR
             NON-ELASTIC,  AS WATER, OIL, ALCOHOL.
    For  the sake of brevity,  these will be called liquids.
            LIQUIDS MORE  EXPANSIBLE THAN SOLIDS.
    Expansion of liquids, sh.own by matrasses with long nar-
 row necks, filled to the origin of their necks with fluids dif-
 ferently coloured.
                      ON  THERMOMETERS.
 OX THE ORIGINAL INSTRUMENTS OF SaNCTORIO AM) VAN HELMONT, AND THE CAUSE
                       OF THEIR IMPERFECTION.
 O-V MERCURIAL AND  spirit ThermometeRs^and THE METHOD OF FILLING AND GRA-
                          DUATING T]|p6M.
    The distance between the freezing arid, the boiling points of water,
 is divided by Celsius into 100°,  by.-Re*umur  into 80°, and by
 Fahrenheit into 180°.  Hence, jt  is evident, that the degrees of
 their  thermometers, are, to «acfe other, as those numbers—or as
  10, 8, 18, or 5, 4,  9.  The method of Celsius is the best—that of
  Fahrenheit the worst. 
12
            BELT-REGISTERING THERMOMETERS.  PALM 9LASS.
                   DIFFERENTIAL THERMOMETERS.
  EXCEPTION TO THE LAW, THAT LIQUIDS EXPAND BY HEAT.
  Between  freezing and 40° (F.)  water contracts.  Ice is one-
ninth more  bulky than the water forming it.   But for  these pro-
perties, lakes and  rivers might freeze  to a depth destructive of
aquatic animals, and so as not to thaw in summer.
               EXPANSION OF ELASTIC FLUIDS.
  The bulk of aeriform fluids is regulated by pressure  as well as
heat.
                DEFINITION OF ELASTICITY.
  It is the power of resuming shape, position, or bulk, on the cessa-
tion of constraint. The degree of it is not dependent on the force, but
on the perfection, of recoil. A watch spring, is not less elastic than
a coach spring.  Atmospheric air, and all other aeriform fluids, are
perfectly elastic.  Elasticity is erroneously spoken of as a varying
property in air.
MODIFICATION  OF THE  EFFECTS  OF  CALORIC  BY
              ATMOSPHERIC  PRESSURE.
  DIGRESSION TO DEMONSTRATE THE NATURE 'AND EXTENT OF
                  ATMOSPHERIC PRESSURE.
         EXPERIMENTAL PROOF THAT AIR HAS WEIGHT.
   The air being allowed to enter an exhausted globe, while
accurately poised  upon a  scale  beam, causes it to prepon-
derate strikingly.
   For, the pressure of any fluid upon any area, assumed with-
in it, the pressure  of a column, of any other fluid having said
area for its base, may  be substituted, without destroying the
equilibrium, provided it be as much higher, as lighter\ as much
lower, as heavier:  or in other words, the weights of the  respec-
tive fluids, must be as their gravities, inversely.
   Four glass jars, severally four  inches in diameter, and
thirty inches  in height; in each a stratum of mercury about
two inches deep:—also a  tube, one  and a half inches in dia-
meter,  exceeding jar,  in height, one foot, and open at both
ends—lower orifice under the mercury.
   Water being poured into the jars until  nearly full—for
every  foot which it rises  in  them,  mercury elevated, in
tubes,  nearly an   inch.   Mercury indicates, by its height,
pressure of water.
   The  columns  of mercury are obviously substituted for 
13
columns of water; which would have occupied  tubes, had
there been no interposition.
   Water being  gradually introduced; when mercury sinks
to a level with mercury, water  attains the level of water.
   Into one of the tubes, containing columns of mercury, as
above  described, ether is introduced—into another, alcohol
—and into the third, a  solution of copper; until mercury,
within them, is level with mercury without.   Cupreous so-
lution  lower than surrounding water—alcohol higher—ether
still more exceeds water in  height.
                          INFERENCE.
   Pursuant to  the preceding  experiments, the pressure  of  one
fluid may be  substituted for that of another; it being,  however,
necessary, that the heights  of the respective  fluids, be inversely as
their gravities.  It follows, therefore, that if, in  lieu of water, the
mercury were pressed  by air, without  the tube, unbalanced by air
within, a column would be elevated proportionable to height  and
weight of the  air.
                INFERENCE VERIFIED, EXPERIMENTALLY
   Tube, closed  at  one  end, is  filled  with mercury, and in-
verted—its lower orifice immersed in an adequate quantity
of the  metal.
   Column, 30 inches in height  nearly, remains in the tube,
supported  by pressure of surrounding air, and an index  of
its weight.
                          INFERENCE.
   Base of mercurial  column,  thus  supported, being  equal to a
square  inch in  area,  would weigh  fifteen pounds.  Atmospheric
pressure on every square inch in the earth's superficies, equally
great, or equivalent to that of a mercurial stratum of the depth of
thirty inches nearly.
ANOTHER DEMONSTRATION BY MEANS OF A TALL  JAR, TULL OF WATER, AND A TUBE
                  SHAPED LIKE A SHEPHEUd's CROOK.
                   OF THE WATER PUMP.
  The  admission of the  atmosphere is necessary  to  the  suction
of the water from a receiver; air may  be  removed  from close ves-
sels by the same process.   Water rises  by pressure of  the  at-
mosphere.  Air presses out by its own elasticity.
                 EXPERIMENTAL ILLUSTRATIONS.
   Mechanism  and action of the suction pump rendered evi-
dent by means of a model, with a  glass chamber.   Differ- 
li
ence between pumping an  elastic fluid, and a liquid, illus-
trated by an appropriate contrivance.
   ACTION OF THE AIR PUMP SHOWN, BY MEAN'S OF GLASS CHAMBERS.

           OF THE ELASTIC REACTION OF THE AIR.
Air is dependent on its own weight for its density, and enlarges
  its bulk in proportion as the sjiace allotted to it is enlarged.
                EXPERIMENTAL ILLUSTRATIONS.
  Gum elastic bag closed,  after being partly distended and
placed in a receiver, from which the air is withdrawn,  by
the air pump—also a vessel nearly full  of water inverted,
its orifice being under water in a jar.
    EXPERIMENTAL PROOFS, OF THE WEIGHT OF THE ATMOSPHERE,
  Glasses  for showing unresisted atmospheric pressure  on
the hand;  on a bladder; on Otho Guericke's brass hemis-
pheres.
Proof that the pressure arising from elasticity within, is equal
                  to the pressure without.
   Square bottle broken under receiver, by exhaustion of air
from within, or from without.
   The height of the column  of mercury which balances the
atmosphere, shown  by exhaustion.  Result compared with
the Torricellian experiment.
rSEJUL CHEMICAL IMPLEMENT FORMED BY MEANS OF A GVM-ELASTIC BAG AND A TUBE
                        WITH A UULB.
                  PROCESS OF RESPIRATION.
  The elevation of the sternum, rarefies the air in the cavity of the
 thorax.  The atmospheric  pressure,  not being balanced, the  air
 rushes through the trachea  into the lungs,  dilating all  its cells.
 The depression of the sternum and diminution of the cavity, causes
 the air which had  thus  entered, or an equivalent portion, to flow
 out.
                  EXPERIMENTAL ILLUSTRATION.
   From the open neck of a tall bell-glass, or receiver, a
 bladder is so suspended  as to descend into it  rather more
 than one-third of its height.  The atmosphere has access
 to the cavity of the bladder, but not to  the space between
 it and the internal  surface of the receiver.   Hence when 
*,* u
/ 


r
r 
15
this vessel is  subjected  to  an alternate movement  up and
down, in water, the air alternately enters, and escapes from
the  bladder,  as  it  passes  into and out  of  the lungs  in
breathing.

                         RATIONALE.
  Were not the bladder inflated, so as  to compensate the enlarge-
ment of the space in which it is suspended, the air in that space
would be in a state of rarefaction,  inconsistent with an adequate
resistance to the atmospheric pressure,  acting against  the internal
surface of the bladder.
ADDITIONAL PROOF, THAT THE HEIGHTS OF FLUIDS ARE INVERSELY AS THEIR GRAVITIES,
             BX MEANS OF AX HYDROMETER CONTRIVED BY ME.
           ON  THE ALTITUDE OF THE ATMOSPHERE.
  Supposing the atmosphere as dense  above, as  below, its height
would be  to that of the column of mercury which balances it, as
the weight of air to the weight of mercury, inversely. Hence the
height of mercurial column, (or 30 inches) multiplied by 11152
(=334560 inches, or 278S0 feet) is the height  which the atmos-
phere would have, if uniformly as dense as  at the earth's surface.
Density of the atmosphere being caused by  its own weight, it has
been demonstrated, geometrically, that, the  heights being in arith-
metical progression, densities will be in geometrical progression.
  Thus, the density being, by  observation,
at 3	mi	es \		at 18 mi		es	it	will be tt1-	
6		„ it will be -]			21	»		»	i 12lf
9		»• » ~g			24	„		ii	1
12		» » 16"			27	>,		»	i
15		» » 3 2			30	ii		ii	Tors
or rarer than		in the most perfect	ai	•tificial	vacuum.				
           ON THK MEASUREMENT OF HEIGHTS BY THE BAROMETER.        .  •

EXPERIMENTAL PROOF THAT ELASTIC FLUIDS  ARE EXPANDED,
   EITHER BY REMOVAL OF PRESSURE, OR INCREASE OF HEAT.

   A fluid excluded from a bulb, by a portion of air, either
by heat,  or  by exhaustion  of the surrounding air.

DEMONSTRATION, THAT ATMOSPHERIC  PRESSURE OPPOSES, ANI>
   LIMITS, CHEMICAL ACTION, WHERE ELASTIC  ELUIDS ARE TO
   BE GENERATED OR EVOLVED.

   Water would boil  at a lower temperature than 212° (F.), if the
atmospheric  pressure were lessened; for when  it has  ceased to
boil in the open air,  it will begin to boil again under a receiver
exhausted by the air pump; and for every 530 feet of elevation, the
boiling point is lowered one degree of Fahrenheit's thermometer. 
16
   Ebullition by cold, and by exhaustion, shown.
PROOF THAT SOME LIQUIDS WOULD ALWAYS BE AERIFORM, WERE
       IT NOT FOR THE PRESSURE OF THE ATMOSPHERE.
   A  flask,  filled  with mercury,  excepting a  small space
occupied  by  ether,  being inverted in a jar  of mercury,
under a receiver:  on exhausting  the air,  the ether  as-
sumes the gaseous form, and excludes the mercury:  on  re-
admitting the air, the ether returns to its previous state, and
the mercury re-occupies the vessel.
AS THE ROILING POINT OF LIQUIDS. IS LOWERED  BY A DIMINU-
  TION OF  PRESSURE,  SO IS IT RAISED IF THE PRESSURE BE IN-
  CREASED.
   Small strong  glass flask, with narrow neck  and smooth
orifice.   Small quantity of ether on  the  bottom heated  till
it boils: the orifice being closed by the finger, the ebullition
is stopped: on the removal of the finger, it recommences
with increased violence.
   Very strong and close iron boiler containing water, with
mercury at the bottom, a tube in the axis, and a thermome-
ter on  one side.   Fire being  applied, the mercury rises
in the tube, from the increasing pressure of the steam, and
in the thermometer, proportionably, from a corresponding
elevation of the temperature.
 WHY A JET OF HIGH STEAM DOES NOT SCALD, AT A DISTANCE
             AS GREAT AS MIGHT BE EXPECTED.
  An admixture of air with aqueous particles, produces cold, as
may be perceived when the wetted finger is held up to the wind.
The quantity of such particles in high steam, is greater in propor-
tion to the quantity of caloric,  than in  low  steam; yet they are
projected into the air, with greater violence, and of course  are
mingled with it  more rapidly.

                    O? CONDENSATION.
          ._     CONDENSER EXHIBITED AND EXPLAINED.
     PHENOMENA OF CONDENSATION, ILLUSTRATED EXPERIMENTALLY.
  The bulk of air lessens as the pressure which it sustains aug-
ments; and the resistance arising from its elasticity, when con-
fined, increases as the  quantity  is enlarged, or the confining
space diminished.
  Inflated bag, reduced  in  size, by exposure  to  air con-
densed within a receiver. 
 
					• v —
	..••■. ■	»»'*			, ^v<.
	<r:*.-. £.	/T	/ * / .	~."	
	y	t			
£-<-*v	•^ ^				
 
                            17

   Inverted flask similarly exposed, its orifice under water.
As condensation proceeds liquid  rises into flask—when it
occupies  half the cavity, a column of mercury, exposed to
same pressure,  reaches same height, as  that of mercurial
column in the barometer.
   Mercury being poured into a cylindrical jar,  having no
other aperture than the bore of a  glass tube descending to
its  bottom, nearly; when  the jar  becomes half  full of the
metal, a column of it will be supported, at the same height,
as in the previous experiment.

ON  THE INFLUENCE  OF PRESSURE ON THE ESCAPE OF GASEOUS
              SUBSTANCES  FROM COMBINATION.
  Sulphuric acid, in its action, on carbonates, and carbonic  acid
gas, in its union with water, are influenced by atmospheric  pres-
sure.
  Carbonates and wood have been fused under great pressure  with-
out decomposition, and  to this the production  of bituminous coal,
and some kinds of calcareous spar, has  been  ascribed by philoso-
phers, who derive the existing structure, of  the globe, from the
action of fire.
                 EXPERIMENTAL ILLUSTRATION.
   Effervescence of an acid with a carbonate, is lessened by
the condenser,  and increased by the air pump.

ON THE CHEMICAL AND MECHANICAL EFFECTS OF THE ATMOS-
                           PHERE.
   Experimental proof, that the atmosphere, by its affinities,
promotes evaporation while it retards it, by its weight.

   Water frozen by boiling ether—also, by its evaporation.

THE MOST VOLATILE SUBSTANCES IN THE AIR, NOT ALWAYS THOSE WHOSE
                     BOILING POINT IS LOW.
     Instances:—
    Oil of turpentine, camphor, petroleum, or naphtha.
                   ON THE STEAM  ENGINE.
    Principle of Savary's, illustrated by a matrass with a long
 neck.
         Newcomen's   1
         Watt's         > Engine.
         High pressure )
   geological speculations on the possible  consequences of extraordinary
                    HEAT APPLIED TO OUR GLOBE.
                              c 
as
            COLD CONSEQUENT TO RAREFACTION.
  Condensation in the receiver, on exhausting it, shown by
means of the air pump. Also, by a small receiver with a gum
elastic bottle,  and a thermometer.   Cold produced  by the
palm glass.
               EXPANSION OF ELASTIC FLUIDS.
  This is sufficiently intelligible from the experiments and obser-
vations already  made.  Their volume appears to be  inversely as
the pressure to which they are subjected, and directly as the heat.

   SPECIFIC HEAT, AND THE CAPACITIES OF SUBSTANCES FOR
                           HEAT.
  The effects of equal weights of different substances, equally cool,
(added successively to equal quantities of hot water, at the same
degree of heat,) in lowering the temperature, will be found very
different.  Thus the effect of a given weight of water being 1000,
the effect of a like  weight of glass will be  137; of copper 114; of
tin 60; and of lead 42; and if equal bulks be tried, the effect of
copper, 1027, glass, 448, lead, 487, tin, 444.  If equal weights of
water and mercury at different temperatures be  mixed, the  effect
on  the water  will be no greater, than if instead of the mercury,
1.28 of its weight of water had been added; and it takes twice as
much mercury by measure, as of water heated to the same point,
to have the same influence.
      APPARATUS  TO ILLUSTRATE CAPACITIES  FOR HEAT.
  The specific heat of bodies is, of course, always as  their capaci-
ties for heat, or the comparative quantities of caloric  which they
contain when exposed to the same temperature externally.

         ON THE COMMUNICATION OF  HEAT.
          ON SLOW COMMUNICATION—ON RADIATION.
                  ON SLOW COMMUNICATION.
            CONDUCTING PROCESS.  CIRCULATION.
     ILLUSTRATION OF THE CONDUCTING PROCESS IN  SOLIDS.
  Hold one end of a brass pin in the fingers, the other in a candle
flame.

           ON  INEQUALITY OF CONDUCTING POWER.
   Effect of a pin compared with  that of a splinter of wood,
or  a glass  filament of the same size,  by cementing them se-
verally, at one end, to a stick of sealing wax, and heating
them at their other ends.

  The fracture  of  glass  and porcelain, exposed  to fire, is the con-
sequence of an  inferior conducting power; as the heat is not dis- 
 
 
19
 tributed with quickness enough to prevent inequality of expan-
 sion.  Hence glass is less  liable to  crack by heat, in proportion
 as it is thinner.
   It may be divided by a heated iron ring; or by a string steeped
 in oil of turpentine and inflamed; or by the heat generated by fric-
 tion.
            METALS BY FAR THE BEST CONDUCTORS.
   Silver and copper are among the best conducting metals.   Lead
 and platina among the worst.
      CALORIC PROBABLT EXISTS IN METALS, AS AN ESSENTIAL CONSTITUENT.
          ON THE PROCESS BX WHICH IT MAY BE CONDUCTED BX THEM.
           ON THE CONDUCTING PROCESS, IN LIQUIDS.
 PROOF THAT LIQUIDS ARE ALMOST DEVOID OF THE POWER TO C0NDu6t
                            HEAT.
   Through a cork in the pipe of a glass funnel, nearly fill-
 ed with water, pass the  stem of  an air thermometer, (bulb
 uppermost) till within about a fourth of an inch of the sur-
 face of the water.   Over the water pour ether, and inflame
 it.  The  thermometer will not be affected by the heat  of
 the flame, though sensible to  a slight touch from the finger,
 even while under the water.
   PROOF THAT HEAT MAY,  IN SOME DEGREE, BE CONDUCTED BY
                          LIQUIDS.
         REFERENCE TO MURRAY'S EXPERIMENT WITH A VESSEL OP ICE.
     PROCESS  OF  COMMUNICATING HEAT  BY CIRCULATION.
   A tall cylindrical jar of glass, with a stratum of water co-
 loured  red, in the upper part, colourless solution, in the
 middle,  and a cupreous solution, below. Heat, being applied
 to the red stratum, does aot cause its descent, but the  stra-
 tum rendered blue, by the copper ascends, as  soon as an
 accession  of temperature is  acquired from a heated ring,
 which  is made  to  encircle the jar, in the vicinity of that
 stratum.  The particles coloured  blue, do not  rise among
 those coloured red, because these  were previously heated.
   Water in glass vessel, with pieces of amber.   Lamp ap-
 plied.    Circulation shown by the amber.
      QUICK COMMUNICATION OF CALORIC, OR RADIATION.
   The heat from a fire, received in opposition to the draught, as in
roasting  and toasting, is the effect of radiant caloric.  A kettle
placed over a fire, receives  heat  both by radiation, and the  con-
ducting process.  Caloric proceeds in. rays, or  radii,  from every 
20
body warmer than the surrounding medium,  and towards every
one which is colder.   Radiant heat is reflected by bright metallic
surfaces, agreeably to the same laws as light, and may be collected
in a  focus, in a like manner.
   The rays which come to a concave mirror, parallel to each other,
proceed to its  focus.   Those emitted by a body in the focus, after
meeting the mirror, proceed from it parallel toe#ch other, and may
be made to fall on another concave mirror, and concentrate them-
selves in its focus.

                       ILLUSTRATIONS.
   Model  for illustrating the operation of mirrors in  collect-
ing and transmitting radiant caloric.
   Matrass with  boiling water in one focus, affects a differ-
ential  thermometer  in the other.   Phosphorus ignited  at
twenty, and  even at sixty feet, by an incandescent  cannon
ball.

               RADIATION OF COLD, SO CALLED.

   Snow-ball placed  near, mirror, produces cold  enough  in
the focus to be detected.

                RATIONALE OF THE RADIATION OF COLD.

ON THE DIFFERENCE OF POWER, IN DIFFERENT SUBSTANCES, TO
                 RADIATE, OR REFLECT HEAT.

       BEST CONDUCTORS, WORST RADIATORS--AND VICE VERSA.

   Cubical canister,  having one side  coated with charcoal,
another with writing paper, a  third with a pane of glass, the
fourth uncovered: Effect of the charcoal on a thermometer
in focus of mirror,  as 100, of the paper as 98, of the glass
as 90, while the effect of the  metal only as 12.

  Thus, metals which  conduct best, radiate worst; and charcoal,
which is one of the worst conductors, is the best radiator.

 HATICJ\AXE OF THE DIFFERENCE OF CONDUCTING POWER, AND RADIATING POWER, I\
                 METALS, CHARCOAL, GLASS, POTTEHT.
              WORST  RADIATORS, BEST REFLECTORS.
  The  same constitution which  prevents radiation, causes reflec-
tion.  When brass andirons are exposed from morning till  night to
a fire, so near as that the hand,  placed on them, is scorched into-
lerably in a few seconds, they do not grow hot.
  To preserve heat,   in air, or to refrigerate, in water, vessels
should  be made of bright metal.  Fire-places should be constructed
of a  form  and materials to favour radiation: flues, of materials to
favour  the conducting  process. 
21
MEANS OF PRODUCING HEAT, OR RENDERING CALORIC SENSIBLE.
   Solar beams.   Lenses, mirrors.  Burning of the Roman
ships by Archimedes.   Button's experiments.

                       ELECTRICITY.
   Lightning.   Electric spark.

                      ELECTROPHORUS.
   Ignition by it exhibited.

                        GALVANISM.
   Galvanic  substitute for the electrophorus and deflagrator
exhibited.

                  COLLISION,  OR ATTRITION.

   Flint  and steel.  Rotatory match box.   Steel  mill for
light.   Bfcces of quartz rubbed.  Metals heat in drilling or
turning.

                        PERCUSSION.
   A rod of iron  rapidly hammered, ignites a  sulphur match; and
phosphorus,  more  easily.   Coin grows hot when struck by the
coining press; but, if repeatedly struck, and  cooled at  each suc-
ceeding stroke, it is less heated  each time.

                         FRICTION.
   Savages  ignite  wood by rubbing sticks  together.   Carriage
wheels, by rapid motion, take fire.

   Glass heated by friction, so as to separate into two parts,
on immersing in water.

                       CONDENSATION.
   Condenser for igniting spunk or tinder.

                       COMBINATION.
   Boiling heat produced, by mixing sulphuric acid  with
water.
   Combustion of platina with tin foil.

                         SOLUTION.
  Solution produces either heat  or cold, according to the nature of
the substance  dissolved, and solvent employed. Nitric acid grows
warm, in acting on  silver, or copper;  and still more so on tin.
  Water becomes cold, in dissolving nitre.
  Sulphuric acid  becomes boiling hot. and freezing  cold, by suc-
cessive additions of snow. 
22
   CHEMICAL COMBINATION, ATTENDED BY DECOMPOSITION.
  Oil of turpentine ignited by nitric, and sulphuric acids.
  Also by sulphuric acid, and chlorate of potash.
  Alcohol inflamed by same means.
  Tin foil ignited by nitrate of copper.

  MECHANICAL ACTION, INDUCING CHEMICAL DECOMPOSITION.
  A fulminating powder exploded by percussion.

    METHODS OF SUPPORTING HEAT, FOR THE PURPOSES OF
                       CHEMISTRY.
PRINCIPLE  OF  AIR FURNACES—OF ARGAND's LAMP—AND OF THE FORGE
                           FIRE.
  Portable  furnaces.
  Cupelling furnace.
  Small  furnace with a drawer.                 +r
  Lamp without flame.

                        BLOWPIPE.
  Mouth blowpipe—method of using it—great utility.
  Enameller's lamp.
  Alcohol blowpipe.

                   COMPOUND BLOWPIPE.
  Fusion and combustion  of iron, steel, platina, copper, &c.
 ON THE  MEANS OF PRODUCING COLD, OR RENDERING CALORIC
                         LATENT.
ON THE STATES IN WHICH CALORIC EXISTS IN NATURE.
ESSAY ON  THE QUESTION WHETHER CALORIFIC REPULSION CAN
                    BE DUE TO MOTION.
 IMPORTANCE OF THE SUBJECT OF HEAT, OR CALORIC, TO THE
                      PHYSIOLOGIST.
  There is  neither any body, nor any process, chemical or vital,
in which its secret or obvious agency is not to be perceived or de-
tected.
  In no characteristics are chemical processes so analogous to those
of life, as in their inseparable  association with caloric, as a cause,
or consequence.
  Seeds and eggs, lie dormant till warmed.
  CONCLUDING OBSERVATIONS, ON THE SUBJECT OF CALORIFIC
                        REPULSION. 
4y  ii £k<UcL. j {fiJ^C ^w ~%LdL^ /y






















  /JL tfu^. &&l<C  O^eL wa£-*, 6U*~ UuZt&L x^r

















U*-d-  Ucfy A*~.l AclcL,   fix  xlhrliLC uMucu^ 
 
23
       ON LIGHT, OR THE MEDIUM  OF SIGHT.
  It must, necessarily, belong to Chemistry, to treat of light, su
far as it  is productive of heat, deoxydizement, or other chemical
effects, and so far as it is evolved by chemical processes.
                      NATURE OF  LIGHT.
  According to Newton, and a majority of modern philosophers,
it is a subtile fluid, which  is either  radiated,  or reflected, from
every visible  point in the universe, in  consequence of its elasticity,
or the self-repellent power of its particles.
                     VELOCITY OF LIGHT.
  It comes from  the sun, about ninety millions of miles, in eight
minutes, or nearly at the  rate of two  hundred thousand miles in a
second.
             INCONCEIVABLE MINUTENESS OF LIGHT.
  The loss of weight in  combustion,  which can be ascribed to the
escape of light, is inappreciable;  yet enough  is emitted  by  the
flame of a candle, or lamp, to be perceived by many hundred mil-
lions of eyes.  A  sphere of  rays  is emitted from every  visible
point in  the universe, in radius equal  to the distance, at which that
point is to be seen.

                    REFRACTION OF LIGHT.
  When a ray of light passes obliquely, from a rarer into a denser
medium, it is bent towards the perpendicular direction.  When
the course of the  oblique ray is from  the denser medium, into one
which is rarer, it is bent from the perpendicular direction.  The
degree of the refraction, varies with the nature of the media causing
it.  It is greater in glass than in water—and in the diamond, greater
than in  either water or glass.
  The rays of light, besides being  thus refracted, sustain another
change, called dispersion.   Some of  them being more, and some
less refrangible than others, they are separated, and appear to be
of various colours, as seen in the rainbow, or in the spectrum, ar-
tificially produced by a triangular  prism  of glass.  The order of
the colours,  is red, orange,  yellow, green, blue, indigo, and violet
—beginning  with  the least refrangible rays, and ending with those
which are most refrangible.  The greatest heating power is found
towards  the  red  end of  the  spectrum—the highest illuminating
power, about the  middle, among the yellow and green rays—and
the greatest deoxydizing power, among the violet rays.   It is  also
ascertained, that beyond the red rays, there are invisible heat-pro-
ducing rays—and  beyond the violet, invisible rays, endowed with
a deoxydizing power.  It has been a question, whether  the heat-
ing and  deoxydizing power,  might  not  exist  in rays,  severally
destined for  these purposes, and distinct  from  those which enable
us to see. 
24
         POLAIUZATION OF LIGHT—BT HEFHACTIOS—11Y INFLECTION.

                  ON THE SOURCES OF LIGHT.
             The Sun.  Combustion.  Electricity  Galvanism.
Decomposition, without heat—as in  light wood.  Life—as
                 by the fire fly, or glow worm.
                  ON THE EFFECTS OF LIGHT.
  In the old bleaching process, by means of the solar rays, light is
probably efficient,  by promoting  the transfer of oxygen, from
water to the  colouring matter, which it destroys.  Certain vege-
table leaves, if exposed to the sun  in water, have been found to
yield oxygen gas.  Some metallic salts especially, and nitrate of
silver, are blackened  by  a  like  exposure,  owing,  as is alleged, to
deoxydizement.   A mixture  of  hydrogen  gas  and  chlorine  gas,
will, in  the dark, remain  for a long time, without combining;  but,
in the direct rays of the sun, will explode.

                 ON  SPECIFIC  GRAVITY.
  A clear conception of it  is necessary, to a comprehension of the
language of the most useful sciences and arts.  It  may be defined,
the ratio of the weight of a body,  to its bulk.

    ON  THE MEANS OF ASCERTAINING SPECIFIC GRAVITIES.
  All processes for this purpose, are  reducible to two—ascertaining
the  weight of known bulk, or the bulk of  known  weight.   When
masses are reduced to  the same bulk, it is only necessary to weigh
them.   When they are reduced to the same weight,  it  is only
necessary to  measure  them.  If water were among a number of
substances reduced to the same bulk, and weighed, and its weight
assumed as a unit, the numbers found would be the same as those
now in use to express  specific gravities.  The gravity of water has
been assumed as the  standard weight, because  this fluid may al-
most always be had, sufficiently pure; and the weight of bodies is
easily compared with the weight of an equal bulk of it.
  In order to obtain the  specific gravity of a body, therefore, we
have only to divide its weight,  by  the weight of a quantity of
water equal to it in bulk.
  The weight of a quantity of water, equal to the body  in bulk,
is equal  to the resistance  which the body encounters in sinking in
water.   Hence, if we can ascertain, in weight,  what  is necessary
to overcome the  resistance which a body encounters in sinking in
water, and  divide by  this weight, thus  ascertained, the weight of
the  body, we shall have its specific gravity.
  In the case of a body which will sink of itself, the resistance to
its sinking, is what it  loses of its weight, when  weighed in water.
  In the case of a body which will not sink of itself, the resistance 
• 
 
<!5
to its sinking,  is its weight added to the weight which must be
used to make it sink.

PRACTICAL  MEANS OF  ASCERTAINING THE RESISTANCE TO A
           BODY'S SINKING IN WATER, EXHIBITED.

  Scale beam.
  Nicholson's hydrometer.
  Steelyards  by Lukens and Coates.
  Sliding rod apparatus contrived by me.

          TO ASCERTAIN THE GRAVITY OF A LIQUID.
  Weigh a glass globe, of known weight, first in pure water,  and
then in the liquid.   As the loss in the first instance, to the loss in
the  last, so is  1000, to  the gravity sought.  If the  ball  loses in
water 1000 grs. the answer  for any other fluid is the number of
grains which it loses in that fluid.
  Or, in a vessel which  will hold  1000 grs. of water, at 60° (F.)
weigh as much  of any other fluid as will  fill it.  The weight in
grs. is the gravity sought.  In like manner may be found the gra-
vity of substances, which are grawular, or pulverulent.

ON  HYDROMETERS, FOR  ALCOHOL, AND FOR ACID, SALINE, AND
    OTHER SOLUTIONS.  ALSO, FOR VEGETABLE INFUSIONS.
  In these a constant weight is used, (to a certain extent,) and the
differences of gravity are estimated, by the quantum of  the stem
immersed.  In  those instruments of this construction, where seve-
ral weights are employed, the effect is the same, as if the stem of
the  instrument  were lengthened as many times, as  the number of
the  weights attached to it.

                   EXPERIMENTAL ILLUSTRATIONS.

  Hydrometers  and Saccharometers exhibited in operation;
also my  hydrostatic  hydrometer as recently  improved.

ON THE NECESSITY OF A STANDARD TEMPERATURE  FOR HYDRO-
                 METRICAL OBSERVATIONS.
D 
OF PNEUMATIC  CHEMISTRY.
  It appears from the phenomena of calorific repulsion, that solid
ponderable matter, by combining with caloric, first expands, next
melts, and finally passes into that elastic state of fluidity, in  which
the repulsive power so far predominates  over the attractive, that
the particles recede from each other as far as external pressure will
permit.   When a substance is naturally aeriform, it is called a gas:
when it retains the  form  of air only in obedience to extraordinary
heat, or in  consequence of a removal of pressure, it is called a va-
pour.
  The chemistry of gaseous substances, has been called Pneumatic
Chemistry.
           OF THE  ORIGIN OF PNEUMATIC CHEMISTRY.
  All gases were considered as common air, variously modified by
impurities,  until Dr.  Black's  discovery  of carbonic acid gas.
Priestley, incited by this to obtain air from other bodies, discovered
oxygen gas, nitrogen gas, nitrous air, or nitric oxide, and various
other aeriform substances.  Cavendish, about the same time, dis-
tinguished  hydrogen gas as a peculiar kind of air.
ON THE MODE OF COLLECTING,  AND PRESERVING GASES IN THE
              PNEUMATO-CHEMICAL APPARATUS.
PNEUMATIC CISTERN CONTAINING WATER  EXPLAINED;  ALSO  A
          PNEUMATIC CISTERN CONTAINING MERCURY.
  Vessels are filled with water, or mercury,  in a pneumatic cistern,
and inverted as in the Torricellian experiment; then  placed  on a
shelf, or part of the cistern, purposely kept, just below the surface
of the water or mercury.   Any gas emitted  under the mouth of a
vessel, so  filled, and situated, rises and displaces the contained  fluid.
                         OXYGEN GAS.
  In the gaseous state, oxygen forms one-fifth of the  atmosphere;
and it pervades the creation, as a constituent of water,  in the ratio
of eight parts in nine.  It is a principal, and universal constituent
of animal  and vegetable matter.  Its combinations with metals, and
various other combustibles, are of the highest importance in the
arts.  It was called oxygen, under the erroneous  impression of its
being  the sole acidifying  principle, from the Greek «|t/«, acid—
ytvof*.*!, to generate.

           ON THE MEANS OF PROCURING OXYGEN GAS.
  It is yielded either by  manganese, red lead, or nitre, when ex- 
 
 
21
posed to a bright  red heat in an  iron  bottle.  There are various
other means of obtaining oxygen  gas.  It is generally supposed,
that in order to obtain it, in a high degree of  purity, chlorate of
potash  must be employed; but I have found the first portions of the
gas,  from nitre, quite  pure: and  Dr. Thomson alleges, that this
salt,  by exposure to a carefully regulated heat, parts with one pro-
portion of unadulterated oxygen.

                 PROPERTIES OF OXYGEN GAS.
  It is insipid, inodorous, and per se incondensable, colourless, and
transparent.  It is but slightly absorbed by water; does not differ
from common air  in appearance,  but is somewhat heavier, and it
supports life and combustion, more  actively.  Under a bell glass
filled with  oxygen gas, an animal  lives, and a candle burns, thrice
as long as when similarly situated, with the same quantity of com-
mon air.
  Oxygen  gas is supposed to consist of oxygen,  a simple  or ele-
mentary substance, rendered aeriform by caloric.
  It has been  mentioned, (page 8) that chemical equivalents are
usually assumed, so as either to make the representative of oxygen,
or that of  hydrogen, unity.  The least combining proportions of
these substances, as ascertained by the decomposition of water, being
as one, to eight, if the  equivalent nf hydrogen be unity,  that of
oxygen will be eight; but if the equivalent of oxygen be unity, hy-
drogen will be represented by a decimal fraction  of .125.   As the
numbers, now almost universally  employed, are founded upon the
equivalent of  oxygen, as unity, I shall adopt this, as the standard
in stating equivalents.
         PROPERTIES OF OXYGEN GA.9, ILLUSTRATED BY EXPERIMENTS.
   Combustion of iron  wire,  charcoal, sulphur, and  phos-
phorus, exhibited in large glass vessels of appropriate con-
struction.   Homberg's pyrophortis,  being  poured  into it,
flashes like gunpowder.   Flame  of caoutchouc,  and other
smoky flames,  are rendered  bright  by surrounding them
with this  gas.   An intense heat is produced in a lamp flame,
urged by a jet of oxygen gas.
                       OF CHLORINE GAS.
   As  a gas, this substance  exists only by artificial means; but as
forming three-fifths of marine salt, it constitutes nearly one-fiftieth
of the matter  in the ocean; and is widely disseminated throughout
the  land, as well as the sea.   It is also an ingredient in some of
the  most active agents, used  in  chemistry, or medicine.   It was
discovered by Scheele,  and called by him dephlogisticated marine
acid—afterwards oxymuriatic acid, by Lavoisier,  and  chemists ge-
nerally, who adopted  his nomenclature.  Its present name was
given  by Sir  H. Davy, from  r>*-;^, green—because  its colour >*
greenish. 
28
               MEANS OF OBTAINING CHLORINE.
  It is obtained by heating manganese,  or red lead, and muriatic
acid, in a glass or a leaden vessel:—or eight parts by weight of
common  salt,  three parts of manganese, four parts  of sulphuric
acid, and four parts of water.

                PROPERTIES OF CHLORINE GAS.
  When pure and dry, it is a permanent gas, of a greenish yellow
colour.  When moist, it  condenses  at  40 degrees of Fahrenheit.
Its  weight  to common air, is as two  and a half to  one,  nearly.
Even when existing in the air, in very  small proportion, it is in-
tolerable to the organs  of respiration, and to respire it alone, would
quickly produce the most fatal consequences.
  That species of chemical action,  which is attended by the phe-
nomena of combustion, is supported by this gas with great energy.
It has a  curious property, first  noticed by me,  I believe, of ex-
citing the sensation of warmth—though a thermometer, immersed
in it, does not indicate that its temperature is greater than  that of
the adjoining medium.  Probably it acts on the  matter insensibly
perspired.  Chlorine is absorbed by  water, and in the solution acts
powerfully on  metals.   It appears to be the only solvent of gold.
Chlorine and silver, exercise a more   energetic affinity for  each
other, than for any other substances.  Hence, they are reciprocally,
the best tests.   The compounds of chlorine with  mercury, so useful
in medicine, will be treated of, when on the subject of that metal.
When the  aqueous  solution of chlorine, is exposed  to the  solar
rays, it forms muriatic acid, with the hydrogen of the  water, while
the oxygen escapes.  It bleaches,  by liberating the oxygen of
water, and  thus enabling it to act on the colouring matter.
  Chlorine gas was considered as a compound  of muriatic acid and
oxygen,  and called  oxymuriatic  acid, till within  about  fifteen
years.  It is now, generally deemed  an  elementary substance, ren-
dered gaseous by caloric.   Oxygen  being one, the chemical equi-
valent, or atomic weight, of chlorine is 4.5.
   EXPERIMENTAL ILLUSTRATIONS OJF THE PROPERTIES OF  CHLORINE.
   Combustion exhibited, of  metals  in leaf, and in powder
—of mercury in vapour—of phosphorus,  by an appropriate
contrivance.   Water tinctured  by litmus, rendered  colour-
less, by merely falling through this  gas.   To two large ves-
sels of clear water, soluble compounds  of chlorine and sil-
ver are severally added—no change ensues,  till the contents
of both vessels are mingled in the third vessel, when a white
cloud appears.
                         OF IODINE.
  This substance, which has only been  detected  in  certain  plants,
nr their ashes, derives importance from  its  analogy with chlorine 
29
and oxygen, especially the former.  It was named Iodine,  from
ftihf, violet coloured.

             OF THE MEANS OF OBTAINING IODINE.
  It is obtained from the mother waters, of carbonate of soda ma-
nufactured from kelp.   After all  the  soda, in  a lixivium  of  kelp,
has been  crystallized, the residuum  is concentrated,  and distilled
with sulphuric acid, in a  retort:  the  iodine passes  over, and con-
denses in  shining crystals of an intense purple, or black colour.
                OF THE PROPERTIES OF IODINE.
  When solid  it is  of a  bluish black colour—friable—acrid—and
almost insoluble.  It transiently  stains the  skin yellow.   It fuses
at 225° (F.)—volatilizes at 350° in a most beautiful violet vapour.
It is considered as an element.
  Iodine  is incombustible either in  oxygen,  or atmospheric air;
but  forms acids severally with oxygen, hydrogen, and  chlorine,
called  oxiodic, or iodic—chloriodic—hydriodic acids.   In its habi-
tudes with the Voltaic pile, it is more electro-negative, than any
other  matter, excepting oxygen, chlorine, and probably fluorine.
With starch or fecula, iodine produces an intense  blue colour;  so
that these substances  are reciprocally tests for each other.   The
equivalent (or atomic  weight) of iodine, is 15.5.
                  EXPERIMENTAL ILLUSTRATIONS.
   A glass sphere, containing iodine, on  being warmed, ap-
pears filled with a violet coloured vapour.
   To a large glass vessel, containing some boiled starch dif-
fused in water, a small quantity of iodine being added, the
fluid  becomes intensely blue.
   OF  THE NOMENCLATURE OF THE  COMPOUNDS OF  CHLORINE,
                      OXYGEN, AND  IODINE.
   Agreeably to the nomenclature proposed by the celebrated La-
voisier,  and his coadjutor*, and generally adopted  by  chemists;
when  oxygen, in combining, does'not acidify, the resulting combi-
nations are called oxides.  Hence, by analogy, the compounds <<f
chlorine with other  substances, when not acidified  by it, are called
chlorides; those of iodine, iodides.
                  OF  NITROGEN  GAS, OR AZOTE.
   Nitrogen  gas  forms nearly four-fifths of  the atmosphere.  Its
 ponderable base is a principal element, in  animal  substances.  In
 vegetables, it is only occasionally found.  It was called azote, from
 the Greek £«»», life, and  », privative of;  but as other gases were
 found no less worthy  of  this distinction, the  name of nitrogen was
 o-iven to  it, because it produces nitric acid.
              MEANS  OF  OBTAINING  NITROGEN GAS.
   It may be procured by any substance which will, in a close ves- 
30
sel, abstract oxygen from  the  included portion of the atmosphere;
—as,  for instance,—by the combustion of phosphorus;—by iron
filings and sulphur moistened:—by nitrous gas.

 OF THE PROPERTIES OR  CHARACTERISTICS OF NITROGEN GAS.
  As  a gas, it  is distinguished by a comparative want of proper-
ties.  It  is lighter than oxygen gas, or atmospheric air.   It does
not support life or combustion, but is, obviously, a harmless ingre-
dient  in the air.   It is incondensable, per se, and seems,  in many
instances, to carry its caloric into combination, being a constituent
of a majority of the  most explosive compounds.
  Nitrogen has  been  suspected,  by some chemists,  of  being a
compound substance, but is  generally considered as an  element.
Its compounds with oxygen, hydrogen, chlorine, carbon,  &c, will
be treated of hereafter.   The  equivalent, or atomic  weight, of ni-
trogen, is 1.75.

   EXPERIMENTAL ILLUSTRATIONS OF THE PROPERTIES OF NITROGEN.
  After phosphorus is burnt out in a close vessel, the resi-
dual  air  is transferred to  a convenient  bottle.   A candle
flame introduced into the bottle, is extinguished.
                     ATMOSPHERIC  AIR,
  Is a mixture (not a chemical compound) of oxygen gas, and ni-
trogen gas, with some moisture, and carbonic acid.
  The properties of this compound gas, are such as  might be  anti-
cipated from those of its constituents.  Its active qualities are those
of oxygen, but enfeebled by dilution with the  other inert ingre-
dients.

                      EUDIOMETRY.

               DIFFERENT EUDIOMETERS EXHIBITED.
   Simple graduated  tube.  Hope's Eudiometer.   Henry's?
modification  of Hope's Eudiometer.   Volta's Eudiometer.
Various eudiometrical instruments contrived by me.

                     OF HYDROGEN  GAS.
  In  its gaseous state, it is the principal constituent  of all  ordinary
flame.  Its ponderable base, combined or associated with oxygen,
or carbon, or both, is found in water, and  all  vegetable and animal
substances.  It derives its name from vhg, water,  and yeivo^xi, to
produce.

            MEANS OF PROCURING HYDROGEN GAS.
  It may be obtained by the reaction of  diluted sulphuric, or mu-
riatic acid, with zinc, or iron; or  of steam with  iron  turnings,
made red hot in a gun barrel:—also, by means  of  potassium.  It
may be evolved from water by galvanic agency, and is then purest. 
J7L"*r'-     t%y%fa~..  .  ,{■■;-.,..„ /h>U*>< ^-^/f.
 
 
SI
           ON THE PROPERTIES OF HYDROGEN GAS.
  It is the lightest of all known substances.  A cubic inch weighs
only about a fiftieth of a grain.  It is about  200,000 times lighter
than mercury, and 300,000 times lighter than platina.   In its or-
dinary state, it smells unpleasantly.   When pure, it is alleged to
be without odour.  It is perfectly  incondensable per se.  Its capa-
city for heat is very high.  It does not support life, but is not very
injurious to  it.  In consequence of its levity, it escapes rapidly
from an open vessel,  unless inverted.  It is  the most inflammable
of all  substances, yet extinguishes a taper when immersed in it.
A jet of it ignited, appears like a candle flame, feebly luminous:
and if surrounded by a glass tube, produces a remarkable sound.
Subjected to  the  electric spark, when mixed with oxygen, or at-
mospheric air, it  explodes.  The  oxygen may be esteemed equal
to one-third  of the deficit caused by  the explosion:  hence, by this
process, air may be analysed.  The ponderable base of hydrogen
gas forms water, with oxygen; muriatic acid, with chlorine; hy-
driodic acid,  with iodine; ammonia, with  nitrogen;  and prussic
acid, with cyanogen.  It combines also with carbon—with sulphur
—and with phosphorus.  When pure, its flame is but feebly lumi-
nous.
   Hydrogen gas  is considered as an elementary substance, so at-
tractive of caloric as that, per se, it cannot be  separated from it.
The equivalent, or atomic weight, of hydrogen is .125.

  EXPERIMENTAL ILLUSTRATIONS OF THE PROPERTIES OF HYDROGEN GAS.

   Its evolution  from  a phial, (with  a capillary tube well fit-
ted to the neck) exhibited; and the jet ignited.   A glass re-
tort, with diluted acid and  zinc, employed, to  show the ex-
trication of this gas,  and mode of catching  it in bell glasses
over  the  cistern.   Self-regulating   reservoir  of hydrogen
gas, in glass, exhibited,—likewise a self-regulating reservoir,
in lead.   A candle flame extinguished, and  rekindled, by-
means of a phial,  filled with hydrogen.   Hydrogen ignited
by an  electrophorus—by galvanic ignition—and  by platina
sponge:—also exploded with atmospheric  air, or with oxy-
gen  gas, by  a  taper,—a  calorimotor,—by  electricity.  A
glass  balloon being balanced on  a scale beam, hydrogen is
made to displace  the  air.   The  balloon  rises, becaus^the
hydrogen is  lighter  than  air.  Change  produced in   the
weight of a globe,  by exhausting it  and filling it with hydro-
gen.
 EXPERIMENTS WITH THE COMPOUND BLOWPIPE—PYROTECHNY BY
                     MEANS OF HYDROGEN. 
33
                         WATER

  Is produced by the combustion of hydrogen gas, with  oxygen
gas.   It may be decomposed by passing it in steam, over  iron ig-
nited, in a gun barrel:  by the aid of acids: by electricity:  by gal-
ranism: by the alkaline  metals: by sulphurets, phosphurets, and
vegetable leaves.  Water is vaporizable by heat, and evaporable
by means of its attraction to the air.  A certain proportion of mois-
ture, in  the air, is necessary to health and comfort.
        The equivalent  of oxygen being     1.
        And that of hydrogen              0.125

        Water is represented  by             1.125

ON  SOME  PECULIAR AND IMPORTANT  AGENCIES,  OR  CHARAC-
                   TERISTICS, OF  WATER.
  Water is necessary to some crystals.—It  appears necessary to
acidity—to alkalinity—and to  galvanic processes.   The powers of
water, as a solvent, are peculiarly extensive, and  are increased  by
heat and pressure. It seems to be a substance, sui generis, isolated
from oxides, acids, and alkalies. It unites with, and becomes solid
in, the earths  and alkalies: and produces heat during combination
with them. The compounds resulting, are called hydrates.
      EXPERIMENTAL ILLUSTRATIONS OF THE AGENCY OF WATER.
  Tartaric acid and  bicarbonated  alkali, pulverised, and
mixed.   The addition  of  water produces  effervescence.
Nitrate of copper rolled  up in tinfoil has  no action till mois-
tened—ignition then ensues.  Sulphuric  acid added to zinc
in powder:  the addition of  water produces a violent action.
Heat produced by  caustic earths, or alkalies  with water.
   EXPERIMENTAL DEMONSTRATION, OF THE COMPOSITION OF WATER.
  Water, recomposed  by combustion of hydrogen, emitted
in a jet within a large  glass vessel.    Also, by successive ex-
plosions by means of galvanic ignition.   Decomposed by a
galvanic  apparatus,  and its gaseous elements evolved:—
these are exploded by  the spark, and reduced  again  to the
aqueous form.—Decomposed by sulphuret, and phosphuret
of^ime, and  potassium.

MEANS  OF  DETECTING, OR MEASURING  HUMIDITY
                       IN THE AIR.
                     OF HYGROMETERS.
On HYGROMETERS BT EVAPORATION. On THE HYGROMETER BY MEANS OF AN ORGANIC
  SENSIBILITY TO MOISTURE, IN THE BEARD OF A WILD  OAT.  Of DANIEL'S HYGRO-
  METER. Hygrometers contrived by me. 
 
 
33
          ON THE THEORIES OF COMBUSTION.
   Stahl  supposed the existence, in all combustibles, of a common
 principle of inflammability; which he called phlogiston, fromphlo-
 gizo, to burn.   He inferred that all substances, in burning, give
 out phlogiston.   The  fallacy of this hypothesis is evident, since
 metals  become  heavier during combustion, obviously in conse-
 quence of the absorption of oxygen from the  atmosphere.  Ac-
 cording  to  the advocates of the phlogistic theory, nitrogen was
 confounded with  carbonic acid, and carbon  with hydrogen, because
 both carbon and  hydrogen, were supposed to consist of phlogiston,
 nearly pure; and oxygen, in combining with them, was supposed
 to become phlogisticated air; the name then given  to nitrogen gas.
 It is  now well known, that  with  carbon,  oxygen forms carbonic
 acid,—with hydrogen, water; and that nitrogen gas, contains nei-
 ther carbon, nor  hydrogen.
   Sulphuric, and phosphoric acids, and metallic oxides, were seve-
 rally supposed  to be ingredients, in the sulphur, the  phosphorus,
 or the metals, producing them : thus the compounds were assumed
 to be lighter, and to be contained  by one of their constituents!
 Lavoisier's theory was correct, in suggesting, that in all ordinary
 cases of combustion, oxygen is absorbed.   It was erroneous, in not
 providing for exceptions, as, when  metals  enter into  combustion,
 with sulphur, or  with chlorine.
   Combustion, according to common sense, is an intense state  of
 corpuscular  reaction, accompanied  by an  evolution of heat and
 light.
   It is the general law of nature, that the capacities for caloric,  of
 compounds, are sometimes greater,  sometimes less, than that  of
 their  constituents.   Hence  chemical combination, is sometimes
 productive of heat, sometimes  of cold.
   There is a mysterious and reciprocal dependency, between che-
 mical reaction, galvanism, electricity, and magnetism,  which must
 be explained, before  the phenomena of combustion  can be well un-
 derstood.
   The heat  of combustion appears to be principally due to the ga-
 seous agent; the light, to what is called the  combustible.          s'
   The idea of a class of supporters of combustion, and  of combust
 tibles,  has no other foundation, than that  certain substances are
 more  frequently  agents in  it,  and therefore called supporters.
 Thus, hydrogen will only produce fire, with oxygen and chlorine;
 sulphur, with metals;—and carbon, with oxygen ; but as oxygen
 or chlorine,  will  burn with a great variety of substances, they are
 called supporters  of  combustion, and the substances  with  which
 they combine, during combustion, are called combustibles.  Iodine
is classed among the supporters also, because it  combines with al-
most all the  substances with which they unite, and forms analogous
compounds.   Iodine is not gaseous,  however, and, upon the whole. 
3-1.
is as analogous to sulphur as to chlorine.—The propriety is ques-
tionable, of taking  it into  the class of supporters, and excluding
sulphur.
  Sulphur  is intermediate,  in  its habitudes, between phosphorus
and iodine.  The habitudes of  selenium, a newly discovered sub-
stance, seem to lie between the metals and sulphur.  Hydrogen,
phosphorus, carbon, boron,  and silicon, deserve as well to be called
combustibles, as oxygen, chlorine, and iodine, to be called support-
ers:  but these  appellations are evidently commutable, according
to circumstances; since a jet of oxygen, fired  in hydrogen, is pro-
ductive of a flame similar to the inflamed jet of hydrogen, in oxy-
gen.  If we breathed in an  atmosphere of hydrogen gas, oxygen
gas would be considered as  inflammable, andy  of course, as a com-
bustible.
                   THEORY OF VOLUMES.

    It has been advanced by Gay Lussac, that substances, when aeri-
  form, unite in volumes which are equal; or that the larger volume,
  is double, triple, or quadruple, of the other.  This doctrine is well
  supported by facts.
    It has  been extended, by inference,  to  all bodies,  under  the
  idea, that all are susceptible of the aeriform state.   A volume, is
  said to be the equivalent of another volume, when capable of forming
  with it a definite compound, or when just adequate to displace it
  from combination.  This theory is not inconsistent with the atomic
  theory, if the number of atoms in any one equivalent volume, be
  to those in any other, so, that the lesser, may divide the larger,
  without a fraction.

    Instances, supporting the doctrine of volumes:—

  Water consists  of  1  volume of Oxygen and 2 Hydrogen °-as.
  Ammonia
  Carbonic acid

  Sulphuric acid

v Muriatic acid
  Muriate of
    ammonia
  Sub-carbonate ~)
    of ammonia 5
  Bicarbonate
    of ammonia
  Nitrous gas
Nitrogen
Oxygen

Oxygen

Chlorine
Ammonia
        »

Ammonia

Ammonia
Nitrogen
3 Hydrogen
2 Carbonous
    oxide.
2 Sulphurous >
    acid.    ^
1 Hydrogen.
1 Muriatic acid.

1 Carbonic acid.

2 Carbonic acid.
Oxygen.
  It is in truth well ascertained, that equal volumes,  or multiples
of them, are naturally equivalents of the substances of which they
are  constituted.   Thus supposing a volume of oxygen gas to weigh 
 
 
35
f000 grains, and that a like volume of every other aeriform matter
were weighed, it would appear that numbers expressing the weights
of the volumes in grains, would either be the same, as those which
represent their atoms, or chemical equivalents; or might be ren-
dered the same, by multiplying them, by two, or by four.
  It must be evident that numbers which represent the weights of
like volumes are in the same ratio to each other as those which are
employed to represent their specific gravities, and would in fact be
the very same numbers, were oxygen gas assumed as the standard,
instead  of atmospheric air.
                  ON  THE  ALKALIES.

  Alkali is a word supposed to be derived from the Arabic.   Until
of late, only three alkalies were known—potash, soda, and ammo-
nia.   The two former being difficult to vaporise, have been called
fixed alkalies: the latter, being naturally aeriform, has been called
the volatile alkali.  A new mineral fixed alkali has been discover-
ed lately, and named Lithia.  It is procured  from a stone called
Petalite.  Hence, its name  from the  Greek, Aida«,  a stone.  Alka-
lies have also been recently detected  among vegetable principles;
of which I shall treat in my lectures,  on vegetable chemistry.

                      OF POTASH—SODA.
                MEANS OF OBTAINING POTASH—SODA.
  Potash is obtained by the lixiviation  of the  ashes  of inland
plants, especially wood.   The  ley, thus procured, boiled  down,
forms potashes  of commerce.  Potashes, ignited, lixiviated, and
evaporated to dryness, form pearlash.  Pearlash, dissolved, boiled
with quick-lime, filtered, and boiled down to the consistency of
moist sugar, redissolved  in alcohol, and boiled down gradually;
and lastly, fused at a red heat in a silver vessel, yields the potash
of chemists.  Evaporation being stopped, as soon as the alcohol
has escaped, crystals are obtained.   After fusion at a red heat, it
contains about 20 parts  of water, of which it  cannot be deprived,
per se, by heat.   It is therefore called a hydrate.
  Soda is obtained from  the ashes of certain plants which grow on
the sea shore, as potash  is, by the incineration of those which grow
inland:—also from muriate of soda, and from sulphate of potash.
  Soda is purified, and procured  in the state  of  hydrate,  or  in
crystals, by the  process,  above described, for its kindred alkali.
                 PROPERTIES OF POTASH AND SODA.
  Potash and soda, in common with other alkalies, have a peculiar
alkaline taste: they render tincture of turmeric, brown; syrup of
violets, green;  and alkanet, blue.  Colours, changed by acids, are
restored by them.  They are the opposites of, and  antidotes  to 
36
acids, forming with  them compounds, neither acid  nor alkaline.
They are  incorrectly said to  render vegetable  blues green, as if
this were  universally true.  Alkanet is made blue by them, while
neither litmus, nor indigo, are made green.
  Potash  is much more deliquescent than soda; though its salts
are less soluble.   Both cauterize the flesh.  Potash is most active.
Lapis infernalis,  or common caustic, is  an impure hydrate ot this
alkali.
  Potash is distinguished from soda, by forming a less soluble sail
with tartaric acid, and giving  a precipitate with muriate of platina.
Subjected  to  galvanic  action,  both alkalies are decomposed into
oxygen gas, and  metallic bases, called potassium and sodium.

                 COMPOSITION OF POTASH—SODA.
  Potash and soda are respectively oxides of potassium and sodiumj
metals, which derive their names from  these alkalies.
EXPERIMENTAL ILLUSTRATIONS OF THE PROPERTIES OF POTASH AND SODA.
   Infusions  of  alkanet, of turmeric, of red cabbage, and of
litmus, (reddened by an acid,) are poured into large glasses:
a drop of potash being added to each, the alkanet  becomes
blue, the turmeric  brown, the red cabbage green, while the
litmus regains  its  colour.   To  strong solutions of  potash
and  soda, or their  carbonates, a strong solution of tartaric
acid  being added in  excess, the potash only yields crystals.
Into different salts of the two  alkalies in  solution, muriate
of platina is poured:  a light  yellowish precipitate, distin-
guishes the potash.
                          OF SOAP.
of soft soap, or soap of POTASH, AND HAni) SOAP, OR soap of soda, rationale of
                 the detersive properties of soap.
     OF LITHIA,  THE NEWLY  DISCOVERED MINERAL  ALKALI.
  Pure lithia is less soluble than soda or potash, in water or alco-
hol.   Its carbonate is less soluble in water.  Its muriate  is soluble
in alcohol, and its phosphate insoluble in water.

                        OF POTASSIUM.
              MEANS OF OBTAINING POTASSIUM.
  It was  discovered by Sir  H. Davy, by means of the Voltaic
pile, and  of course  may be thus procured; but the following me-
thod, contrived by Gay Lussac, enables the chemist to obtain it in
larger quantities.  A luted gun-barrel  is  filled with  iron wire, or
turnings, and ignited in a blast furnace,  as highly as possible. Hy-
drate of potash is passed in at one end, so as to fuse  and run over
the iron,  which  arrests  its oxygen.   The potassium meanwhile
volatilizes, and condenses at the other  end of  the barrel, just  be- 
37
yond where it is red hot.  There is great uncertainty in this pro-
cess, from the difficulty of getting the luting to stand the requisite
heat, without which, the gun-barrel soon  burns.  I have substi-
tuted for the luting, a  very thick cylinder of iron, which renders
the process certain.

                  PROPERTIES OF POTASSIUM.
   It appears, and cuts  like lead, only softer; yet it is  so light as
to swim in water.   It fuses at 150°  (F.).  It decomposes water, re-
generating potash, and evolving inflamed potassuretted hydrogen,
upon the water, and even upon ice.   Its avidity for oxygen is pre-
eminently great.  When heated in oxygen gas, in excess, an  oxide
is formed, containing double the quantity of oxygen found in pot-
ash.  If hydrate of potash be applied to a thick plate of iron, in a
state of combustion, the  rosy flame of  potassuretted hydrogen de-
monstrates,  that a decomposition ensues.  The same result obtain-
ed by pouring the fused  hydrate upon iron card teeth, heated to
combustion  in a crucible.
        EQUIVALENTS OF POTASSIUM, POTASH, AND ITS HYDRATE.
     The atom  of potassium, equivalent              5.
       with 1 atom oxygen, equivalent              1.

       forms 1 atom potash, equivalent              6.
       and  with 1 atom water, equivalent         r-  1.125
constitutes 1 atom hydrate, equivalent         7.12:
                          OF SODIUM.
         MEANS OF OBTAINING, AND PROPERTIES OF, SODIUM.
  The analogy between this metal and potassium, is quite as great,
as between potash and soda.
  Sodium is obtained by the same process as potassium.  It is less
energetic, than potassium, in its action.  It does not fuse so easily,
as it requires 200° (F.).  It decomposes water, evolving hydrogen,
but without inflammation.
          EQUIVALENTS OF SODIUM, SODA, AND ITS HYDRATE.
    The atom of soda, equivalent                    3.
       with 1 atom of oxygen, equivalent            1.

       forms 1 atom of potash, equivalent            4.
       which with 1 atom of water, equivalent        1.125

       constitutes 1 atom hydrate, equivalent         5.125
                  EXPERIMENTAL ILLUSTRATIONS.
  The inflammation of potassium upon water, and ice, ex-
hibited,—and regeneration of the  alkali, in  the water em- 
38
ployed, demonstrated by the usual tests:  also, the decompo-
sition of potash, by iron or card teeth,  heated intensely.

           OF AMMONIA, OR THE VOLATILE ALKALI.
  It is named from sal ammoniac, the salt which yields it.

               MEANS OF OBTAINING AMMONIA.
  Sal ammoniac,  in powder, being mixed  with  powdered  quick-
lime, or caustic fixed alkali, ammonia is evolved in the state of a
gas, which may be collected over mercury.  Heat is requisite to
complete the process.
                  PROPERTIES OF AMMONIA.
  Ammonia acts like an alkali, upon the organs of taste, upon  ve-
getable colours, and in neutralizing acidity.   To the smell it is
agreeably stimulating, when very much diluted with the air.  In
any considerable proportion, it is intolerable to the eyes, and organs
of respiration.   It enlarges, and then extinguishes, a candle flame;
yet explodes with oxygen or chlorine.  Its  weight,  to common
air, is as 3 to 5—100 cubic inches weigh 18  grs.  Water absorbs
it with surprising velocity; and will hold from 450, to 670 times
its bulk.   Ice melts in ammonia, quicker than in fire.   Heat either
decomposes, or volatilizes, all ammoniacal compounds; and  either
of the fixed alkalies, or of the three more  powerful alkaline earths,
disengage it from any of the acids.
           COMPOSITION AND ATOMIC WEIGHT  OF AMMONIA.
  Ammonia consists of one atom  or one volume of nitrogen 1.75
  And three atoms or three volumes of hydrogen    .  .  .   .375

           Its atomic weight is therefore                  2.125

  The four volumes, of  which  it consists,  are  condensed into
two.
                 EXPERIMENTAL  ILLUSTRATIONS.
  In  a cavity,  made in a  bit of muriate of  ammonia, a
moistened globule of mercury is supported, in communica-
tion with one of the poles of a Yoltaic  pile.   The mercury
is made to communicate with  the other  pole.   The  metal
swells rapidly,  and assumes  all  the  characteristics  of  an
amalgam.
                         INFERENCE.
  It would be anomalous for an amalgam, to arise from a union of
mercury with any substance not metallic.   It  may therefore  be  in-
ferred, that ammonia is a gaseous alloy of hydrogen and nitrogen—
that these, if obtained in the. solid state, would be metalloidal in
their characteristics. 
 
r*Z I r's £-/ -fa  &  ~7~7s a 9 7s t Jt*- 
39
                     ILLUSTRATIONS RESUMED.
     Sal ammoniac, and quick-lime, being powdered and mixed
  in small glasses, pungent fumes are emitted.  The  same
  mixture contained in Florence flasks, being  exposed to a
  chafing dish of  coals, the ammonia is extricated, and col-
  lected in bell glasses, over mercury.  The introduction of
  a few drops of water, causes the gas to disappear.   Ice, in
  the same way introduced, is  liquefied, and causes a like re-
  sult.   Water, tinctured by turmeric, alkanet,  &c,  changed
  as by other alkalies.
     Evolution of gas shown, by means of  potash and an am-
•  moniacal salt introduced into a glass vessel over mercury.
     A  mixture of ammonia, with  oxygen  gas,  exploded in a
  hydro-oxygen eudiometer.
     Other illustrations are deferred, until muriatic and carbonic acids
  are treated of.
                        OF  EARTHS.

     The substances classed  under this head,  are the principal ingre-
   dients in  the  congeries,  called earth,  in  common  language; and  •
   which, until lately, was considered one of the four  only elements
   of the creation.  The earth of flints, or of sand, is one of these
   substances, and the most abundant.  It is  exhibited, in purity, in
   rock crystal, and is called silex, or silica.
     The earth,  to which clay owes its  plastic property, is  named
   alumine, by chemists;  because it is obtained in purity from alum.
   Next to silex, it abounds  most in  the globe.
     With respect to abundancy, lime has the next grade to alumine;
/  and magnesia ranks next to lime; though  it  may be questionable,
   whether the quantity of this earth, in the  structure of our planet,  .
   exceed that of iron, or carbon.
     The remainder of the substances recognised,  under the  generic
   appellation of  earths, are  unknown to  the mass of mankind, and
   independently of chemical research,  had escaped human observa-
   tion.   These are thebarytes, strontites, glucine, zircon, yttria, and
   thorina, of chemists.
     The earths are divided  into earths proper,  and alkaline earths.

                OF  THE  ALKALINE EARTHS.

     The alkaline earths are, barytes, strontites, lime,  and magnesia.
             OF THE PROPERTIES OF THE ALKALINE EARTHS.
     They are thus designated, because they  are alkaline in taste and 
40
    in their effects on vegetable colours; and because, like the alkalies,
    they lose their  causticity, by a union with carbonic acid.  All are
    more or less soluble; but magnesia the least so; barytes and stron-
    tites, form glass with silex; and with water hydrates, indecomposa-
    ble by heat.  The order in  which they are alkaline, beginning
    with that which is most so, is as follows:  barytes, strontites, lime,
    and magnesia.
                      COMPOSITION OF THE EARTHS.
      The alkaline earths  hold a middle place between the old metal-
    lic oxides, and those of potassium and sodium. The earths, proper,
    are generally inferred  to be metallic  oxides.  To  me, it seems
    more likely, that they form a class of bodies intermediate, between
    carbon,  boron,  and  the metalloids;  or passing  from one,  into
    the other.  This  view of the  analogy between  carbon, and the
    bases of alumine, and silex, is very much strengthened by the dis-
    covery,  in these,  of  a  property,  heretofore supposed peculiar to
    carbon, of forming steel by combining with  iron.
                            OF BARYTES.
      This earth  was named from the Greek, B«f*>s,  (heavy,) because
    the minerals  containing it  are peculiarly heavy, when compared
    with other earthy substances.
                  OF THE MEANS OF OBTAINING BARYTES.
      Carbonate of barytes, or  the sulphuret,  (obtained by igniting
 /  sulphate of barytes intensely with charcoal) is to be exposed to the
    action of nitric  acid,  in a quantity sufficient  to saturate it.  The
    solution  must be  filtered,  and  evaporated, and  then deprived of
    water by an intense heat, in a platina, or porcelain crucible.
      Like the  carbonates of potash and  soda,  those  of barytes  and
    strontites, cannot be decomposed, per se, by heat.  The addition of
    carbonaceous matter, enables us to  decompose them, as it changes
    the carbonic acid to gaseous oxide of carbon, which has no  affinity
    for the earths, and therefore escapes.
                     OF THE PROPERTIES OF BARYTES.
<£,    It is acrid—slakes like lime, and is more caustic and more solu-
    ble in water.  It is gray at first,  but absorbs water and becomes
    white.   Its aqueous solution  is rendered milky by carbonic acid,
    and by combining with the same principle, becomes covered with
    a pellicle of carbonate,  when  exposed to the atmosphere.  From
    its solution in boiling water, barytes crystallizes,  on cooling.   Ig-
    nited intensely,  and exposed  to a current of oxygen gas, it absorbs
    the oxygen, and passes  to the state of deutoxide.  Its solutions are
    the best  tests for sulphuric acid, and reciprocally,  sulphuric acid is
    the best  test for barytes.  This earth is poisonous.
                       COMPOSITION OF BARYTES.
      A paste made of carbonate of barytes, is placed upon a  platina
    tray,  communicating with the  positive pole of a Voltaic  series. 
/'-■'''
/ /VZt  <Zy£ <s£ S <H S**: jS  Z£yz~*Z£*  ^-7rz7A ~A£/  sy^e,


// 777<L  t/Z^C <Z<C A  77- 7~cf<<  ^ <? 7^





  ^v^TZ>/->"  A ^^ Z <2-<:jZ7  //^ 77~^£^A,/Zs<:Ss7^r*'i77V_*7'





   At* <?,JZ   <7lsZ- T-ZtF*/  /**Z-£r7'/ ^  7lS7?Z ST? S/ZiAS^Z&TZ^sZ'


    /77-&^Z-liZ^Z^v^t-  fa/  ^-^.^'/i^^ <&.£-*..&£.  --  77Z <-<^


   ./z- Z  <?A * 7£-<a£-  A  A-7-jcA  T^tiJiC&T-t^yt  TTzTc-S Zt ^f----

  y       '        £       .

                  /■/
                         7
     7 7>& zTZA tx-  7 7'Z^ / 7^-? ✓v ^  T^z^ 77  sZ ^ <^**L .
      Z   _.         6         c

      C '£? sTst^-t/ Z^l <i   7/-- <? Z< ~r~  Z^c  77 *//- 7 7 t/A/S z  J/^ Z
                /                                                /

     /7Zz-<£cJ/<:  7Z-7 c cZ 
cUc<~&  Zct-cz Atcsn; —
/  J<7/^^£7  jZ?azc^*~)  ty AL^Z//€czZtn~^



 7/tZ /cc<^l- /£ct-Z* a.-Z*^.












7Zt^&6JAz^~~ 
41
A hollow being  formed in the paste,  a  globule of mercury is
introduced  into it,  and  made to communicate  by a wire with the
other voltaic  pole.  The mercury is  converted into an  amalgam,
which by distillation in a glass  tube,  yields a metallic substance of
a dark gray colour, with a lustre inferior to that of cast iron, which
fuses below a red  heat, and is susceptible of volatilization, and of
acting upon the glass recipient, if sufficiently heated.
  To this metal, or metalloid, the name of barium has been given.
  The equivalent  of barium is.....8,75
  Hence, as barytes is a protoxide of barium, and consists of
      an atom of the metal, with one atom of oxygen, equi-
      valent to       .......1 go
  The equivalent of barytes is.....9.75

                   EXPERIMENTAL ILLUSTRATIONS.
  Barytes, free  from  water,  exhibited:  also  in crystals.
Barytic water rendered  milky by the carbonic acid of the
breath, blown into it  by means of a  tube.   Solutions of
barytes, or of sulphuric  acid,  introduced  into distinct ves-
sels of pure water, have  no effect; but portions mingled, in
the same vessel,  produce a cloud.  Water,  coloured  by
alkanet, turmeric, &c.  changed by  barytes, as  in the case
of the alkalies.
                      / STRONTITES.
  It is as analogous to barytes, as  potash to soda, in its properties
and composition.  It is distinguished from barytes, by the red colour
which its solutions communicate to flame—by its crystallization—
by, its being more soluble in boiling water, and less so in cold.  ^^-
  V v   *■ * >  -V-        fc
                         COMPOSITION.
  Strontites is a protoxide of strontium, a metalloid obtained  by
Sir H. Davy, by the process already described, in the case of  ba-
rium, excepting that the native carbonate of strontites,  was substi-
tuted  for the carbonate of barytes.

  The equivalent of strontium is       -                     5.5
  Hence,  as it forms strontites, with one atom of oxygen,
       equivalent to.......1.0
*
The equivalent of this earth must be                      6.5
EXPERIMENTAL ILLUSTRATIONS.
   Turmeric—alkanet—and red cabbage, changed by stron-
titic water, as by alkalies.
   Red colour of  inflamed alcohol,  containing  strontites,
shown.
                              F 
42
                                        /
                               ON LIME.

                   ON THE MEANS OF OBTAINING LIME.
       This earth may be procured from oyster shells, or white marble,
     by calcination.

                      ON THE PROPERTIES OF LIME.
       Lime is less alkaline, than the preceding earths.  Its carbonate
     does not retain its water and acid, when heated intensely.
       Quicklime is pure lime, or limestone deprived of its water and
     acid.  When moistened it grows very hot and falls into powder,
     which is called slaking.  The earth absorbs, and causes the con-
     solidation  of,  the moisture, which  is consequently abandoned  by. ,.
     the caloric, to which water is indebted for its fluidity.*
       Water takes up about y^ of its weight, of -this- earth, forming
     lime water.  On this, a pellicle arises, as in* the case of- banytgs,
     soon after exposure to the  air,  by the union of the lime with the
'"   carbonic acid,  which always exists in  the  atmosphere.  Though
     lime is  precipitated by carbonic acid,  in the state of  carbonate,
     water, impregnated with this acid, dissolves the carbonate—hence
     limestone water.   Oxalic acid is the best test for lime.   This earth
     was first fused by me.

                              COMPOSITION.
       By a process analogous to that employed in the case of barytes,
     and strontites, a paste  made of pure linje, or its sulphate,  yields
     with mercury  an  amalgam.  From  this, in  one instance only, Sir
     H. Davy succeeded in  obtaining calcium  by volatilizing the mer-
     cury from it,  in a glass tube:  but even, on that occasion, the tube
    J&s destroyed so  as to prevent a satisfactory examination.  The
     colour of calcium appeared to be silver white.
       Lime  is inferred to consist of one atom of calcium, equi-
           valent to.......2.5
       And one atom of oxygen     -    -    -     -    -    1.0

   *  Hence the equivalent of the earth is     -     -    -    3.5

                       EXPERIMENTAL ILLUSTRATIONS.
       A glass of  lime water, is  not  irrade«turbi*d, by air from  a
     bellows, but becomes  so  on propelling the breath through it.
     Carbonic acid in bells, and bottles:—absorption of it, shown.^
     Lime precipitated from solutions, of its muriate, or nitrate,^
     by sulphuric,  or oxalic acids.

                             OF MORTAR.
* See page 10. 
z^^AT?*^ j/^  - a^** <c~r z/Uz%f /Ae^zcUL





A^cc^c  &_ zZz^c^t. zz*^**, z**AmZ a.  ZS&& zf7*^-



                             Ay   &c<^zZ? zZz*^.
zZiz^^.^
~ fr^A£~Z , AjA ^<-^l-^r^r Ay  <&z*^zA


*- ^ZZl^A7.  zZ^r^^z^yc^^^c^^ z^tZz^co*. &






/ <c<*<^ A2z<^^


CA&^. A&z*.^  sZ4tz£c~<  TZt^yzzlL^z^, <r> ^  z^Ahrw



                         z>Z^w<7 t~~ Zz^j^AA*/, t7*/A-



                                 <?* sZt^C^ArZ*'* Z&&-
                        A
Alz~a~~ Z&%£?*z*~/ ,  zfZ {fzZ^zzz*-^ <  zfA^Z^Zz*.
■Z*-Z*/ /£***—  Kc- sA*-
/^£-  X/£cAyZz£^<-*.  ^0^, ^ AAA?** A^i^
<s/  6,  /~C*^-c-^C^: £f 0ZZ^Z,£^^. 
£z*                           ,? ~


—AZ:a/A&'%*£- *^<*


    z?     '7      -         &3
   //t4,74st. ''AUAydCtS/O'


   (Ac^c.  'CA-***-*-'        .A\t -..■■T /'->=~
                    £fa^_MAJ---


  JZ^MZU, 77Z7H r **JZ£, ^ #*&^


 €rZ^i *At> „•*£*-*,  y~ ^^


~*j!u /U~Z*y /Z~Z- jZ^Jcy^ -5*^
 ii a* 7? Z Zcc+~*~ J6-^'ZZZp7<*/i*e-

 ■fa/n™™.!, 7Z~*<z^t<z*'<'A"',c$~'f


     -/%A^^T^ J£^^~ z~Z*~ aZt**3*

  (V^-t^^ .^«=^^ ^^^~^Z7 
                             43

                        OF MAGNESIA.
                 MEANS OF OBTAINING MAGNESIA.
  This earth may be precipitated by potash, or soda, from a solu-
tion of Epsom salts.

               OF THE PROPERTIES OF MAGNESIA.
  Magnesia is  nearly insoluble in pure water, but dissolves to a
considerable extent in water, containing  carbonic acid, forming a
bicarbonate, or soluble  magnesia.  The affusion of concentrated
sulphuric acid, on calcined magnesia, produces great heat, and even
ignition.
  Magnesia is  distinguished from the other alkaline earths, not
only by being less energetic, in its affinities and alkaline proper-
ties, but by the solubility of its sulphate.
  Lime and magnesia are among the most fixed, and  refractory
substances  in nature: and were deemed infusible, until I operated
upon them, with the compound blowpipe.

                         COMPOSITION.
  The analysis of magnesia, rests on the same basis as that of lime;
an amalgam having been  obtained from  it, in the same way; but
not the metal from the amalgam, to  a satisfactory extent.
  Magnesia is a protoxide  of magnesium, the  metalloid, which
amalgamates with  the mercury in the process just alluded to.
  The "atom of magnesium,  is inferred  to have for its equi-
       valent    ........1.5
  And as it constitutes magnesia, with one  atom of oxygen  1.

  The equivalent of this earth must be                   2.5

                  EXPERIMENTAL ILLUSTRATIONS.
  Its  precipitation  from a solution of Epsom salts, exhibit-
ed.   Also, discolouration of alkanet, and  of turmeric.

                   OF  EARTHS  PROPER.

                     OF  SILEX,  OR SILICA.
                 MEANS OF OBTAINING SILEX.
 ♦ Quartz  being powdered,  and fused  with double the weight  of
pearlash, and  lixiviated;  a  liquor  silicum results:  from which,
when poured into an acid, the earth separates.  Thus obtained, it
is slightly contaminated by  potash.   Fluoric acid, by its action on  ^—
glass, or flints, takes up silex, or its base, and, according to Brande,
deposites it in a state of sub-fluate, on meeting  with water.

                *N THE PROPERTIES OF SILEX.
  Pure silex  is white—tasteless—inodorous—and  insoluble.   It
was deemed infusible, until  fused by me in 1802.  Itdoe^noteo- 
                              44

here when wetted.  In pwvder, it is acted on by alkaline solutions.
Glass consists of silex, united  with about one half its weight of
fixed alkali.   The proportions are those, of the liquor silicum in-
verted, in which the quantity of alkali is double that of the earth.

                         COMPOSITION.
  Silex, or silica, is a compound of oxygen, with a peculiar sub- \
stance, which by many chemists is classed among the metals, and
called silicium.  By others,  it is  classed, more reasonably as  I
think, with carbon, and boron;  and is called  silicon.   Silex is re-
markable  for having the attributes of an acid, so far  as respects the
highly characteristic property of combining energetically with al-
kalies, whilst for acids it has scarcely any affinity.   It is, however,
far more deficient of solubility, in water, than any other acid.
  Agreeably to the arduous investigations of Dr. Thomson, the ato-
mic weight, or equivalent, of silex,  is 2.

           OF  GLASS.   OF THE ANNEALING PROCESS.

                  EXPERIMENTAL ILLUSTRATIONS.
   Silicate of potash—a soluble glass—exhibited:—also the
solution of it, called liquor silicum, which is made to preci-
pitate its silex, by means  of an acid.
   Prince Rupert's* drops  exploded, by a slight fracture—
a  glass  tube  breaks in  pieces,  in  consequence  of being
scratched with a file.

          OF ALUMINE, OR THE PURE EARTH OF ALUM.

             OF THE MEANS OF OBTAINING ALUMINE.
  It is found pure in  the gems called by jewellers oriental, and
classed by Brogniart under  the head of Corindon  Telesie.  The
ruby, sapphire, amethyst, and topaz, of the most  beautiful kinds,
are thus designated.   They have  the  highest  specific  gravity of
stony minerals, and are only inferior to the diamond in hardness.
Differing  from each other,  only in colour, they yield by analysis
little else than pure alumine.  There are other jewels of the same
name and colour, which ought not to be confounded with  those
here alluded to.
   Alumine is obtained  sufficiently pure, by potash,  from a solution
of alum.

               OF  THE PROPERTIES OF ALUMINE.
   It is inodorous, insipid, and infusible in the furnace.  It is plastic
when moistened—soluble in alkalies and acids—and combines with
colouri-ng matters, forming  the precipitates called lakes.  It  is the
only earth which  was fused, before the compound blowpipe was 
45
    invented.   Its property of contracting and hardening by heat, was
    noticed, when on the subject of Wedgwood's pyrometer.*
      In consequence of experiments, analogous to those mentioned in
    the case of magnesia and lime, it has been inferred that alumine is
    a protoxide, consisting of one atom  of a  metalloid, called alumi-
    num, and one atom of oxygen.
      As 1.25 has been deduced  as the equivalent of aluminum, to
    this adding the equivalent, of one atom of oxygen, we have 2.25
    for the equivalent of the earth.
                        EXPERIMENTAL ILLUSTRATION.
       A solution of alum precipitated by  an alkali.
                OF ZIRCON, GLUCINE, YTTRIA, TII0RINA.
      As they are objects merely of^scientific curiosity, attention to
    their details would  be injudicious, until other knowledge be ac-
    quired.


                           OF ACIDITY.
 *    Acidity As originally  synonymous with" sourness—but all the
    substances now called acids, are not  sour.   They generally make
0  vegetable blues red; yet sulphurous acid whites litmus, and indigo
    is not reddened  by any  acid.  ^\.cids  always  neutralize alkalies,
  ^rand restore colours destroyed by them.   Acids do  not combine
    with acids—nor  alkalies with  alkalies,—but acids and alkalies unite
    energetically  with  each  other.   Acids are generally  soluble in
    water.   Silex furnishes an exception.   The idea of a universal acid
    principle, commenced with Paracelsus,—was supported by Beecher
    and Stahl, and afterwards by Lavoisier;—but it was questioned by
    Berthollet.
       The existence of a common cause, not only of acidity, but of al-
    kalinity, still, to me, appears  probable.
       It will be shown hereafter, that if any light bodies,  be electri-
    fied, either by glass or resin,  they will separate:  but that if one,
    be electrified  by glass, and the other by resin, they will attract
    each other.
       The cause of galvanic  phenomena has  been supposed by  many
    great philosophers, to be the same as that of electricity produced
    by glass, or resin;  but modified by some  unknown  cause, so as to
     act between atoms, instead of masses.
       The pole,  or  end  of a  galvanic  or voltaic series, terminating
     with the most oxidable metal, has been found to show a very fee-
     ble electrical  excitement,  of  the  same kind as that produced by
     glass;—while the other termination of the galvanic series,  displays
     the opposite excitement,  of resin.
       Agreeably  to  a  very extensive  experience, it would seem, that
     of any two substances in nature, simultaneously exposed to wires.
* See page 11. 
46
severally proceeding from the different poles of a galvanic series,
—one will  go to  the  positive, the other to the  negative  pole.
Atoms  are  inferred to be in electrical  states,  diflerent  from the
poles to which they are severally attracted: and are said to be
electro-negative, when attracted by the positive pole—and electro-
positive, when attracted  by  the negative pole.   Oxygen  is con-
ceived to be more  invariably attracted by the positive  pole, than
any other substance.   Next  to  oxygen, chlorine is  most electro-
negative:—and iodine next to chlorine.   Other substances, as for
instance, metalloids, and  metals,—also hydrogen, carbon, sulphur,
and phosphorus, are  comparatively electro-positive.  Substances,
of the two opposite classes, in combining with each  other, consti-
tute particles, which are either electro-positive, or electro-negative,
accordingly as the different energies of their ingredients preponde-
rate.  Thus, in alkalies, consisting  of oxygen united with metal-
loids, the electro-nogoiirc character of the  metalloids  predomi-
nates ; but the reverse is true, of acids consisting of the same elec-
tro-negative principle, oxygen, in combination either with sulphur,
nitrogen,  phosphorus, carbon, boron, or other substances, of an
electro-positive character.                           ^
  At a  mean  point, between the extremes, at whichWxygen and
the alkaline metalfcuds are placed, there  are substances^ whose re-
lation to the  pile^bequivocal, or*wavering; and it  should be un-
derstood,  that this relation  is  always comparative.- Chlorine  is
electro-positive  with  oxygen,  and  electro-negative with evel^r
other body.   Iodine  is electro-positive, either  with  chlorine, or
oxygen, and,  with other substances, electro-negative.
  I avail myself of the language, which has arisen from the hypo-
thesis by which these polarities  are  ascribed to electricity,  though
I do not think their existence thus  adequately accounted  for.
  I suspect, that alkalinity, and acidity, and  these  galvanic  pola-
rities, have  a common  cause, perhaps in some appropriate  combi-
nations of the imponderable,  but material, causes of heat,  light, and
electricity.   To other combinations of these imponderable princi-
ples, the sweetness of sugar, the pungency of mustard, or of pep-
per,  and the activity of certain vegetable poisons,  may be due.   It
is known that in morphia, and  strychnia, and in certain  vegetable
acids, the acid, and alkaline properties, are adventitious, being at-
tached to elements, which exist in  other compounds, without in-
ducing  acidity, or alkalinity.
     ON THE NOMENCLATURE OF ACIDS, AND THEIR SALTS.
  Where substances form by a union with oxygen,  two oxides, or
two  acids—one containing a larger—the other a lesser proportion;
—the acid,  or oxide, having  the lesser proportion, is distinguished
by the  name of the  substance  oxygenated,  and a termination in
ous:—that containing the larger  proportion of oxygen is desig-
nated in the same  way, substituting ic for ous—as sulphurous acid,
and  sulphuric acid—nitrous  and nitric oxide, or acid—carbonic 
 <£-  zz^AZZZy z^r~z*^Zy^  yfk^^ — A^r
/tz^yt^ z^A^^  AAL z^^c^^ ^ z*z^Az^A£Az





 A^eszZ^Ar /&zzAAZZAz*A^/ J^^z^i^^rz/'


 ZL^jt^ /£^£^ zk.*^^ 
 
47
 acid, carbonous oxide.*  Acids, of which the names terminate in
 ous, have their salts distinguished by a termination in ite.  Acids,
 of which the names end  in ic, have  their salts distinguished by a
 termination  in ate.  Thus, we  have nitrites, and nitrates—sul-
 phites, and sulphates.  If there  be a third acid,  having still more
 oxygen, the letters oxy are prefixed.  If the alkali be in excess,
 the  word sub is prefixed; as sub-sulphate. If the acid be in excess,
 super is prefixed, as super-sulphate.   The letters bi are placed  be-
 fore the name of salts having a double proportion : hence carbonate,
 and bi-carbonate.

       OF CERTAIN ELEMENTARY SUBSTANCES,

  CALLED ACID1FIABLE, AND THEIR ACID AND OTHER COMBINA-
                             TIONS.

                    ON CARBON,  OR CHARCOAL.
   Nature presents us with the most beautiful, and  purest specimens
 of this substance.  The diamond is pure  carbon. When equal
 weights of charcoal and diamond are  severally exposed to the rays
 of a powerful lens,  in oxygen gas, included in different bell glasses,
 they are both converted into carbonic acid.  In like manner, when
 diamond  powder is heated with nitre, or iron, the effects are analo-
 gous to those which would arise from charcoal.
   Carbon is very abundant in nature, in the various kinds of fossil
 coal; from anthracite, in which it is nearly pure and unallied with
 bitumen,  to the highly bituminous variety called  candle, or cannel
 coal.  In bituminous coal, there is much  hydrogen.  Carbon per-
 vades vegetable, and animal matter, as an essential element.   It is,
 especially, a constituent of the fibres of wood.
             OF THE METHODS OF OBTAINING CHARCOAL.
   In the laboratory, charcoal is obtained,  sufficiently pure,  by in-
 tensely heating wood in close vessels: in the large way, by igniting
 large quantities of wood, so covered  with earth, that the access of
 air may at first be controlled, and afterwards prevented.
                  OF THE PROPERTIES  OF CARBON.
   It is usually black, inodorous,  and  insipid.   Charcoal of wood is
 one of the best radiators, and worst  conductors, of heat.  There
 is reason for believing this peculiarity to result from its excessive
 porosity;  as in the form of anthracite, carbon  conducts heat better,
 and  probably radiates  it worse.t  Charcoal  is highly susceptible
 of galvanic ignition.
   With abundance of oxygen, carbon produces  carbonic acid—
 with an inadequate supply, carbonous oxide.  Carbon combines

  • This practice, as  respects oxides, has only extended to the instances here
given. Carbon yields only one oxide and one acid, hence there is no carbonic
oxide, nor carbonous acid.
  t Lehigh coal is the species called, by mineralogists, anthracite. 
48
also with hydrogen, sulphur, and  nitrogen; and, as lately ascer-
tained, with chlorine; with which, however, it cannot be made to
enter into combustion, even bj' the intense ignition of  the voltaic
pile.
  The atomic weight, or equivalent of carbon, is .75.
05 THE HIGHLY INGENIOUS EXPERIMENTS, AND OBSERYATIONS ON THE VOLATILIZATION
   01 CAHHON, BETWEEN THE POLES OF THE GALVANIC DEFLAGRATOR, BY PROFESSOR
   SILLIMAN.
                      OF CARBONIC ACID GAS.
     This gas constitutes about a hundredth part of the atmosphere,
   so that lime-water cannot be exposed to it, without becoming cover-
   ed with a pellicle of carbonate of lime.   Carbonic acid is an inces-
   sant product of combustion, and of the  respiration of animals.  It
   is a principal ingredient in marble and limestone.
   UN THE PRODUCTION OF CARBONIC ACID, BT COMBUSTION:--«T  CALCINING CARBO-
            NATES :--BT ACIDS :--BX FERMENTATION : — BX RESPIRATION.
                 ON THE PROPERTIES OF CARBONIC ACID.
A   It causes precipitates in lime, barytic and strontitic waters, or in
   a solution of acetate  of lead.   It  destroys  life, and extinguishes
   flame.  It is salubrious to breathe, when diluted with atmospheric
   air; and  however  it  may be concentrated in water, is innocent in
   the stomach.  Potassium  burns in it.  It may be  absorbed by
"f- water,  but is evolved from it  unchanged,  either  by rarefaction,
   ebullition, or frost.  It reddens litmus.  It combines with earths
   and alkalies,  forming carbonates.   It is  very antiseptic.  Plants
   probably absorb it, retain its carbon, and give out its oxygen.  The
   respiration of animals, tends to compensate  this change, by carbo-
   nizing the oxygen of the air.   Under  very great pressure it be-
   comes a liquid.
                            COMPOSITION.
     Carbonic acid consists of one volume, or one  atom of car-
          bon, equivalent to   .....-    0.75
     And two atoms, or one volume of oxygen, equivalent to   2.00

     Hence the equivalent of the acid  is  -     -     -    -    2.75
                   EXPERIMENTAL ILLUSTRATIONS.
   Evolution of the  gas shown—also, its  property of extin-
guishing a candle.—Its difference  from  nitrogen, rendered
evident by means of lime-water.  Litmus, reddened by car-
bonated water—colour restored by boiling.
   Analysis of mixtures, containing the gas, by means of the
sliding rod eudiometer, with lime-water. 
 TtnZ*  *j£ rfr 01m*. 4rzr£u**^A~ -  UuvtU,  *-> j"*yL.



  & ^.  ---


  Al*  &u.  Ac*^cu~  c*  jUdLcJCc A.   &c<~. (L&c2>,a^




 /*L.  At^.o^ZA<x~<*c~ A&i4t*A2' —
~z?      •              /
 &6U. Tie* V c*  &>t<.sc^A4**£.  4UZ2T z&so*.-  Zwirf* (<A^

 6C  lAAc*  a~  ^LaZe^ZzTZz< r* S-  0r*zi<?2Z&p c/z^Ar'Aac-cuL-




  Jtc&i^  *A a. <u*t  Jua^t &Ue#v<*zAtzcs4 feu- az<z>. -

   &&*^- Zic*2 , JW2 Ztu+sUtu****,   Ctc*Z£z<it£zuz£cl* 
  ZWecx.  ~rfcE~ ZcA*c+z4 /UcAtrazA *y£sZ&Zx- yy




YkA fayte«~  fUi~  7^L  dCuA&u^<^ ac<.7>, %ZA&«x 
49
   Being generated in a vessel having apertures at different
 heights, it escapes through the lowest of them, which may
 be open; or when all of them are shut, overflows the brim
 like a liquid.
   These characteristics made evident, by means of an ap-
 propriate apparatus, and of the yellow fume which accom-
 panies the gas, when extricated from carbonate  of ammo-
 nia, by deep orange coloured nitric acid.

                OF IMPREGNATING APPARATUS.
                   EXPERIMENTAL ILLUSTRATIONS.
   Woulfe's  and Pepy's  apparatus^ shown: also,  my substi-
 tutes for Woulfe's, and my apparatus  for regulating the sup-
 ply by absorption.
    ON THE MEANS EMPLOYED IN MANUFACTURE OF ARTIFICIAL MINERAL WATERS.
                                                        >
                    OF CARBONOUS OXIDE.
•          MEANS OF OBTAINING CARBONOUS OXIDE.
   It may  be obtained by calcining whiting with iron filings, in a
 gun-barrel, at a white heat.

                PROPERTIES OF CARBONOUS OXIDE.
   It is a gas highly deleterious to life, and incapable of supporting
 combustion.   Even when diluted with air, it is pernicious, as it is
 to this we must ascribe the noxious influence of burning charcoal.
                         COMPOSITION.
   Carbonous  oxide is supposed to contain one atom, or a half a vo-
 lume of oxygen less than carbonic  acid;  of course its equivalent
 must be 1.75.
                   EXPERIMENTAL ILLUSTRATIONS.
   Carbonous oxide gas  evolved by process abovementioned,
 and collected in bell glasses over  water—Combustion, and
 detonation of  it shown, and its consequent absorption by
 lime-water.

 OF THE GASEOUS COMBINATIONS OF CARBON WITH HYDROGEN.
   It is these varieties of inflammable  gas, that constitute the in-.
 flammable matter of our culinary fires, and of the flames of candles,
 lamps, and gas-lights.
   Carbon and h)'drogen  are  in the opposite extremes, as respects
 their susceptibility of the aeriform state.   Carbon is probably, per
 se, more difficult of volatilization by heat,  than any other substance
in  nature.  Hydrogen, on the other hand, as far as our experience
goes, is not susceptible of condensation, even into the non-elastic
state of fluidity.  There is, however,  a powerful affinity between
these substances; and hence,  when a compound, which contains
                             G          _-  -    .. 
50
 them, is subjected to heat,  they are made to combine in various
 proportions, according to the intensity of the ignition, and the in-
 fluence  exercised by  the nitrogen, or oxygen,  which may have
 been  associated with them in the compound, from which  they are
 evolved.
   Until of late, only two  varieties  of carburetted hydrogen were
 recognised: carburetted, and bi-carburetted,  or  super-carburetted,
 hydrogen—also called olefiant gas, from  its forming an etherial oil
 when mixed with chlorine gas.
   Dr. Thomson, in  his late work upon the principles of chemistry,
 alleges the existence of the following compounds of hydrogen and
 carbon.
   The first consists  of—one volume of carbon vapour, and one vo-
 lume  of hydrogen  condensed  into one  volume specific gravity
 .4861, atmospheric air being 1.  One volume of this  gas requires,
 for its combustion, 1| volumes oxygen.
   The second, is the gas usually called olefiant—which consists of
 two volumes of carbon vapour, and two of hydrogen gas condensed
 into one  volume.  Its  specific gravity is 0.9722.  It  requires,  for
 its combustion,  three volumes  of  oxygen  gas, with which it pijfe
 duces two volumes of carbonic acid.                          ^^
  The third consists of three volumes carbon vapour,  and  three of
 hydrogen gas condensed into one volume.   Its  specific gravity is
 1.4583.   It requires 4± volumes of oxygen for its complete com-
 bustion, and the residual gas is three volumes of carbonic acid gas.
 Pursuant to the observations of Mr. Dalton, the  oil gas employed
 in gas-lighting,  is principally of this kind.
  The fourth compound consists of four volumes of carbon vapour,
 and four volumes of hydrogen  condensed into  one  volume.   Its
 specific gravity  is 1.9444.   It requires six times its weight of oxy-
 gen for its complete combustion; and a volume,  thus  burnt, leaves
 four volumes  of carbonic acid as a residue.  Combined with  one
 volume of aqueous vapour,  this  gaseous  substance constitutes the
 vapour of sulphuric ether; which consists of one volume of quadro-
 carburetted hydrogen = specific gravky                 1.9444
 and one volume of the vapour of water, of specific gravity of .6250

And hence the specific gravity of the etherial vapour is    2.5694

  A fifth species, of carburetted hydrogen, is alleged  to consist of
 six volumes of carbon  vapour, and six volumes hydrogen  eas con-
 densed into one volume:  its specific gravity being 2.9166.^ It re-
 quires nine times its volume of oxygen gas to  consume it thorough-
ly, and leaves, as a residue,  six volumes of carbonic acid gas.   Of
 this kind, the vapour of naphtha from coal is alleged to be.
  Another crystalline compound, of carbon and hydrogen, has been
noticed, called naphthaline;  composed of one a.nd a half atoms car-
bon, and  one atom hydrogen. 
 
       f^A d*ll> ;/&*<£  Ah /n5£A<- t&* jAzio
 fr  iztA" mA~0cu<i7£-- fa fee**. t«#>+4 / 9*- Azt^ca^y
 77tA &a<sd zt-u^6u**~
  lAu  Yfu <****_ fi£ &*A ^ a rc%*«*^>jA? Ay
 L*4 ( W// £  &y & Apu*cA 1Z f fz<u.£A&s if
3 £<32£z£iZzrf Ate £*%^  -  tfiy /fyru**'- ^A
3<£. -Zlu^t^z? c&^eZ&j 3a0.  Zza^e eeu.S>ZL* Af* 
' *>    »  ♦              51
     M>EANS OF OBTAINING THE GASEOUS COMPOUNDS OF CARBON AND
     /                       HYDROGEN.
       By the destructive distillation of bituminous coal, wood, oil, tar,
     and other inflammable substances, the various forms of carburet-
     ted hydrogen are obtained.
       Olefiant g^is obtained, purest, by passing alcohol through an
     ignited porcelain tube: or, by distilling one part alcohol, with four
     parts of sulphuric acid?  The first  kind  is alleged to be  evolved,
     purest, from  the  mud of stagnant waters in summer.   The fire
,- v damps*, so destructive to^ miners,  is a species of carburetted hy-
 •\£tin«gen.   <"•
       The illuminating power of these various forms of gas, seems to
     be, in proportion to the  quantity of carbon condensed into  a vo-
     lume; provided there be  oxygen enough to consume it: but, other-
     wise,  the excess  of carbon, renders the flame smoky.  Hence the
     greater brilliancy of small flames, or those excited by a current of
     air; as in the Argand lamp.
       The same  flame which  in common air is unpleasantly fuligi-
     nous,  transferred to oxygen gas, displays an  uncontaminated bril-
     liancy.
                      EXPERIMENTAL ILLUSTRATIONS.
        Corks, cotton seed,  caoutchouc, nuts, introduced in small
     quantities into  a gun-barrel,  of which  the but  has  been
     heated to a bright red  heat.  Brilliant jet of flame proceeds
     from  the touch-hole.   Inflammation of gas  extricated by
     distillation from bituminous coal, or oil.  Also of olefiant
     gas.  Carburetted  hydrogen gas, mixed with  oxygen gas,
     and exploded in a sliding rod eudiometer.  Residue renders
     lime-water milky.
                  PHOFESSOIl OLMSTEAD's METHOD BT COTTON SEED.
     WHY MOISTURE CAUSES  SOME MINERAL COALS TO  BURN  BETTER.
                      ON morey's WATER-BURNER.

                        ON  THE SAFETY LAMP.
                      EXPERIMENTAL ILLUSTRATIONS.
        The efficacy of the safety lamp, in preventing explosions,
     experimentally shown, by enveloping it, while burning, in
     hydrogen gas.  The flame seems to go  out, but on the re-
     admission of the air, is seen to resuscitate.

                   OF  CHLORINE WITH OLEFIANT GAS.
        OF CHLORINE WITH OLEFIANT GAS—ALSO WITH CARBON.
       Olefiant gas received its name, from its condensing with chlorine
     gas, into a liquid of an  oleaginous consistency.   On exposure to 
52
*   •
chlorine gas and the solar rays, this liquid yields a perchloride tff
carbon; which  by passing over quartz, in an ignited  glass tube,
yields  a  protochloride.   A  sub-chloride of carbon has also been"
accidentally produced.

          OF CARBURET OF NITROGEN, OR CYANOGEN.
            ON  THE MEANS OF OBTAINING CYANOGEN.
  Distil prussiate of mercury, in  a coated *glass tube,  at a heat as
nearly approaching to redness, as the  glass will  bear.  The tube
must have a smaller one adapted to it, to convey the gas under the
bells, in the mercurial pneumatic cistern.                     •• •

         PROPERTIES AND COMPOSITION OF CYANOGEN.
  It is a true gas.   It is characterized by burning with a beautiful
violet flame.  It is nearly twice as heavy as common air.   Water
absorbs four and  a half volumes—pure alcohol, twenty-three vo-
lumes.  One hundred parts of it,  detonated with oxygen,  produce
200 parts of carbonic acid, and 100'parts of nitrogen.   It is ab-
sorbed by alkalies, and alkaline earths.  With hydrogen,  it forms
prussic, or  hydrocyanic acid.  In relation  to the galvanic  poles, it
is electro-negative.  An instance is  thus afforded of the adventi-
tious character  of this species of polarity—since carbon and nitro-
gen, the elements of cyanogen, are both  electro-positive.
  Cyanogen consists of two volumes of carbon vapour, and one of
nitrogen, condensed  into one volume.   Hence  as the volumes, of
these gases, are equivalent  exactly to their  atomic weights,  the
composition of cyanogen must be two atoms carbon, equiva-
    lent to 75x2=.   .......1.50
And one atom of nitrogen, equivalent to  -                  1.75

Hence the equivalent of cyanogen is    -    -     -  .   -   3.2,

                 EXPERIMENTAL ILLUSTRATIONS.
   The gas evolved agreeably to the process abovemention-
ed, and  its flame exhibited.  Also  mixed with oxygen gas
and exploded.
                        ON SULPHUR.
  It is a well  known  mineral production, sold in the shops,  in
rolls, under the name of brimstone—also  in flowers.   It is found
pure in the vicinity of volcanoes,  of which it  is a product.  In
combination with metals, it is widely disseminated.  From some of
these, called pyrites, it is sublimed,  in flowers, by heat.

                   PROPERTIES OF SULPHUR.
  It is insipid,  and inodorous, unless when  burning—electric by
friction—cracks from the warmth of the hand.   At 180° (F.) it eva-
porates slowly, yielding an  inflammable solution  in air—melts at
225°—thickens between 350° and 400°—sublimes at 600° in flow- 
ers, which appear  crystalline when viewed  by the microscope.
Its purity may be proved by its total evaporation from platina leaf.
It is soluble in boiling oil of turpentine.  It combines with metals,
earths, and alkalies, forming sulphurets.   An acid precipitates it
from solutions of alkaline,  or earthy sulphurets.   It forms  with
oxygen,  the sulphurous and  the sulphuric  acids.  Other combina-
tions are alleged to  exist.  The weights of oxygen, and sulphur,
in sulphurous acid, are equal.  In sulphuric acid, there is one half
more oxygen.   Sulphur combines with hydrogen gas, in  two pro-
portions, forming sulphuretted,  and super, or bi-sulphuretted hy-
drogen.

  The atomic equivalent of sulphur is   .     .         .2.
  With one atom of oxygen  it  forms hyposulphurous acid,
     equivalent    ........   3.
  With two atoms of oxygen it forms sulphurous acid,
     equivalent........4.
  With  three atoms of oxygen  it forms  sulphuric acid,
     equivalent........5.
  With  one atom of hydrogen it  forms sulphuretted hy-
     drogen, equivalent      ......   2.125
  Two atoms  sulphur, with one hydrogen, forms  bi-sul-
     phurettcd hydrogen, equivalent     ....   4.125

                 EXPERIMENTAL ILLUSTRATIONS.
   The combustion of sulphur with common air and oxygen
gas, exhibited by means of appropriate apparatus.
   The  combustion of Dutch gold  leaf  by sulphur—also,
combustion of an  iron bar,  and iron wire, shown.

                     OF SULPHURIC ACID.
            MEANS OF OBTAINING SULPHURIC ACID.
  T|tas acid is obtained, by  burning  sulphur and  nitre, in leaden
chambers, or by the old process of distilling copperas, or green vi-
triol; whence the almost obsolete name, oil of vitriol.  It is best
purified by distillation.

               PROPERTIES OF SULPHURIC ACID.
  It is a gas, when uncombined with water; but this absorbs so
much of it, as to double its specific gravity nearly.  Its aqueous
solution  is oleaginous  in its consistency—caustic, when concen-
trated—intensely acid, when dilute.—It heats greatly, when mixed
with water, especially when to 73 parts of acid, 27 parts of water
are added.  Hot water explodes  with it as with a melted metal.
Its strength is reduced  by the absorption  of  moisture, when ex-
posed to  the air. 
EXPERIMENTAL ILLUSTRATIONS, OF THE PROPERTIES, AND THE MEANS OF
                  PRODUCING, SULPHURIC ACID.
   The production of sulphuric acid, shown in a large glass
globe.  Its effects, upon  litmus—barytes—metals—and or-
ganic products, displayed: also,  in heating water.
   Water frozen,  when placed over a broad vessel  contain-
ing this acid, under an exhausted receiver.
   Poured upon snow, it is at first  heated almost boiling
hot;  but  if more snow be added, becomes freezing cold.

                   OF SULPHUROUS ACID.
           MEANS  OF OBTAINING SULPHUROUS ACID.

  It is formed, when  sulphur is burned under ordinary circum-
stances: or,  by boiling sulphuric acid  on sulphur, mercury,  and
other substances, by which it may be partially deoxidized.

              PROPERTIES  OF SULPHUROUS ACID.
  It is a gas, intolerable to the organs of respiration, deleterious to
life, and incapable of supporting combustion.  Water takes up 33
times its bulk.  Unlike  other acids, it  whitens  litmus—bleaches
silk and wool.   It is decomposed by substances, which attract oxy-
gen more  powerfully than sulphur.  When, on the other hand,
oxygen  is  presented to it freely;—by absorbing this principle, it
passes into the state of sulphuric acid.
                EXPERIMENTAL ILLUSTRATIONS.
   Fumes of burning sulphur, drawn through water.   Ef-
fect of  the water, thus impregnated  with sulphurous acid,
upon litmus.
OF SULPHATES, OR SALTS, FORMED BY SULPHURIC  ACID WITH
         THE EARTHS, ALKALIES, AND OTHER OXIDES.
  Their solutions, all yield  precipitates with solutions of barytes.
Heated with charcoal,  they  are converted into sulphurets, which,
if moistened, smell  like rotten  eggs.
                       OF SULPHITES.
  Sulphites are rarely met with.  They are known by having the
smell  (especially when heated) of sulphurous acid gas.   They pass,
when  in solution, or moistened, to the state of sulphates.

                      OF SULPHURETS.
              MEANS OF OBTAINING SULPHURETS.
  Sulphurets of the earths, or fixed alkalies, are obtained by fusing,
or boiling  them with sulphur.   When  formed in the  moist way,
they are contaminated  by sulphuretted  hydrogen, which (water
being present) is always evolved  by  them.—Sulphuret of ammonia 
^tu#Lc~- afi. fta. /
J.ffA 
 
55
 is obtained by distilling at a gentle heat, one  part of quick-lime
 one part of muriate of ammonia, and half a part of sulphur.

              OF THE PROPERTIES OF SULPHURETS.
   When moistened, they smell like rotten  eggs,  or the washings
 o  a gun  barrel.—They change vegetable  colours like alkalies-
 blacken the skin—and are decomposed by  acids, yielding sulphur
 in a white precipitate.   They absorb oxygen, and are, therefore,
 used in eudiometry.  They are erroneously said, to effervesce vio-
 lently  with acids.

                   EXPERIMENTAL ILLUSTRATIONS.
   Sulphurets  exhibited,  and their solutions, from  which,
 by the addition of an  acid, sulphur  precipitates in a white
 powder.
   Air, confined over a solution of sulphuret  of lime, parts
 with its oxygen to the sulphur, generating a pellicle of sul-
 phate  of lime.

              OF SULPHURETTED  HYDROGEN GAS.
        MEANS OF OBTAINING SULPHURETTED HYDROGEN.
   This is most easily obtained  from sulphuret of iron, by diluted
 sulphuric acid.

        OF THE PROPERTIES OF SULPHURETTED HYDROGEN.
   It is  a permanent gas, with the odour, as already described, of
 rotten  eggs, absorbable by water,  inflammable,  and explosive,
 forming, by combustion, with air or oxygen  gas, water, and a mix-
 ture of sulphurous and sulphuric acids.  It tarnishes metals;  espe-
 cially preparations of lead, of which it is a test, and by which it
 may be detected.   It is evolved from privies—blackening the ce-
 ruse, or carbonate of lead  in paint.   Its aqueous solution  reddens
 litmus:  combines with earths and alkalies,  forming hydrosulphu-
 rets, and has, therefore, some attributes of acidity.  It is found in
 native mineral waters.   It  is decomposed  by various substances,
 having  affinity for one or both of its constituents—as, for instance,
 by chlorine—potassium—sodium—sulphurous acid—ignited carbon
 —and  by successive electric explosions.   Sulphuretted hydrogen
 decomposes all metallic solutions, unless those of iron, nickel, co-
 balt, manganese,  titanium, and  molybdena,  in consequence of the
 attraction between hydrogen and oxygen, or chlorine; and between
 sulphur and the metals.   Atmospheric air, is said to be rendered
 deleterious to life, by the addition of ^ of this gas.

                  EXPERIMENTAL ILLUSTRATIONS.
   Method of extricating sulphuretted hydrogen gas exhibit-
ed—also, the impregnation of water with it.   Effects of its
aqueous solution on litmus—and  on  various metallic solu- 
mo-
 tions.   Characters written,  with  dissolved acetate of  lead,
 are blackened by exposure to the gas,  or its aqueous  solu-
 tion.
                    ON HYDRO-SULPHURETS.
           MEANS OF OBTAINING HYDRO-SULPHURETS.
   They  are obtained by saturating with the gas, as it is generated,
 alkalies,  and earths, dissolved, or suspended in water.   The  appa-
 ratus, for impregnating carbonates, may be used for this purpose.

                         PROPERTIES.
   Hydro-sulphurets  all form colourless solutions  in water, are
 changed  to a greenish hue by time, and blacken the bottle, by de-
 oxydizing the lead, in the glass.  An acid discharges the sulphu-
 retted hydrogen, by combining with the base.   The hydro-sulphu-
 rets precipitate  all metallic solutions; the solvent being attracted
 by the base,  and the metal and oxygen by the sulphur and hydro-
 gen.  In analyses for metallic poisons, the hydro-sulphurets are of
 course useful.
                  EXPERIMENTAL ILLUSTRATIONS.
   Production of hydro-sulphurets, shown—also, their effects
 on metallic  solutions.
            OF SULPHURETTED HYDRO SULPHURETS.
   They are said to exist  always in  solutions of sulphurets; and
 differ from simple hydro-sulphurets, only, in containing a  double
 proportion of sulphur.
                   METALLIC  SULPHURETS.
   They are treated of, under the head of their metals.
                   SULPHURET OF CARBON.
   It is obtained, by  passing sulphur, in vapour, over pieces  of
 charcoal, intensely ignited, in a porcelain tube.

            PROPERTIES OF SULPHURET OF CARBON.
   It is colourless and transparent—acrid—pungent to the taste—
caustic—somewhat aromatic—smells nauseously, and is very in-
flammable, volatile, and difficult to freeze.
COMBINATIONS OF NITROGEN WITH OXYGEN.
                       OF NITRIC ACID.
  It has already been mentioned, that with about a hundredth part
of carbonic acid, and  some aqueous vapour, nitrogen and oxygen,
in a state of mixture, (not of combination,) constitute the atmos-
phere.   Nevertheless, when in due proportion, subjected to a suc-
cession of electric sparks, they combine, and form  nitric acid, one
of the most active  and important agents of chemistry.   There is 
 
 
57
some other unknown mode, in which a chemical union is  induced
between these atmospheric ingredients,  whence the great quantity
of nitrate of potash, found in nature.

              MEANS OF OBTAINING NITRIC ACID.
   The production of nitric acid, by  electricity, is too laborious to
be resorted to, for the purpose of the chemist.  Possibly lightning
might be made to produce it.   The  mode, usually employed, is to
pulverise and distil nitre with one-half its weight of the strongest
sulphuric acid, in glass, porcelain, or iron vessels.

         PROPERTIES AND COMPOSITION OF NITRIC ACID.
   It is nearly one-half heavier than water—usually, orange-colour-
ed—when pure, colourless.  It cannot be obtained free from water.
It acts powerfully on almost all the  metals,—also on organic sub-
stances, causing them to be oxydized.   It stains and destroys the
skin.  It may be considered as the  matter of atmospheric air, in
the  liquid  form; but with twelve  times as much of  the  active
principle, oxygen.  It is  the most energetic principle in gunpow-
der.  It ignites  oil of turpentine, charcoal, and phosphorus.
   Nitric acid consists of one volume,  or one atom, of
       nitrogen, =-      ..__--    1.75
     with 2| volumes, or five atoms, of oxygen =      -    5.

     Hence the equivalent of the acid is     -              6.75

   The strongest acid which Dr. Thomson was  enabled to procure,
had the specific gravity of 1.534.  He  infers, that if the acid con-
tained,  for every atom, only one atom of water, its gravity would
be 1.55.  I quote from this celebrated author the following table,
showing the specific gravity of aqueous solutions, of this acid, for
every definite compound between the strongest acid, and that which
contains 15 atoms of water, for  one  of acid.
Atoms of	Atoms of	Acid in	Specific
Acid.	Water.	100.	Gravity.
	1	85-714	1-55
	2	75-000	1-4855
	3	66-668	1-4546
	4	60-000	1-4237
	5	54-545	1-3928
1	6	50-000	1-3692
	7	46-260	1-3456
	8	42-857	1-3220
	9	40-000	1-3032
	10	37-500	12844
	11	35-294	1.2656
	12	32-574	1-2495
	13	31-579	1-2334
	14	30-000	1-2173
1	15	28-571	1-2012
H 
58
                 EXPERIMENTAL ILLUSTRATIONS.
  The extrication and distillation of nitric acid, shown, by
means of a glass retort and receiver, heated by a lamp—a
chafing dish—or small sand-bath.  Its  action on various
substances exemplified.

            OF NITROUS AIR, OR NITRIC OXIDE GAS.
            MEANS OF OBTAINING NITRIC OXIDE.
  It is evolved during the reaction between nitric acid, and cop-
per, silver, and other metals.

     PROPERTIES AND COMPOSITION OF NITRIC OXIDE GAS.
  It is permanent over water, by which it is slightly absorbed:—
is rather heavier than common air.  It is not acid.   It extinguishes
a candle  flame, but ignites Homberg's pyrophorus, and supports
the combustion of phosphorus, if inflamed before  immersion in it.
It is fatal to animals—renders the flame of hydrogen green by mix-
ture—does not explode with it, but  does explode with ammonia.
It unites rapidly with the oxygen of the air, or of oxygen gas, or
any gaseous mixture containing it, producing remarkable red acid
fumes, which redden litmus paper, if pasted inside of the glass in
which the mixture is made.  It is absorbed by the sulphate or mu-
riate of the black oxide of iron.  The solution absorbs oxygen, and
is, therefore, used in eudiometry.  It is decomposed by moistened
iron filings:  by ignited charcoal, arsenic, zinc, or  potassium.
  One volume, or one atom, of nitrogen, equivalent    -     1.75
  And one volume, or two atoms, of oxygen, equivalent      2.

  Constitute three volumes, or one atom, of nitric oxide, >    „ --
       equivalent    -    -    -    -    -     -    -3
  The volumes, of oxygen, and nitrogen, exist, in this gas, without
condensation.

  EXPERIMENTAL ILLUSTRATIONS OF THE PROPERTIES OF NITRIC OXIDE.
   Copper or silver  subjected to nitric  acid, which  ought
not to be very weak.  The nitric oxide gas, is  extricated,
and collected in bell glasses, either  over water, or mercury.
   Absorption of nitric oxide gas, by green muriate, or green
sulphate of iron, shown:  Also, the  method  of ascertaining
its purity, by the sliding rod eudiometer—and, its  applica-
 tion  to eudiometry, in various ways, by means of that, and
other eudiometrical instruments.
    Self-regulating reservoir of nitrous gas, for eudiometrical
experiments.   Absorption  of  oxygen gas, by nitric oxide,
and the consequent  acidity, made evident by the effect on
litmus. 
 

7iAA Zt'/*+;**■ **t4*4.
         fat*****-'****
0*-	
0%	-------- - • %
Ot-	"\ J± /
%'it	1 /
Uy
By
nih
1
■J/Attr 
59
      OF GASEOUS OXIDE OF NITROGEN, OR NITROUS OXIDE.
              MEANS OF OBTAINING NITROUS OXIDE.

   It may be obtained by the action of dilute nitric acid upon zinc ■
 by exposing nitric oxide gas to iron filings, sulphites, or other subl
 stances, attractive  of oxygen.   It is procured  best from nitrate of
 ammonia, by distillation.  The strongest acid may be saturated by
 the carbonate of ammonia of the shops, in  the retort to be used for
 the distillation,  and the distillation proceed forthwith.  Nitrous
 oxide may be advantageously received  and kept for use in leather
 bags, the junctures riveted, filled by an  appropriate apparatus.   As
 it is absorbed  by water, it  cannot be kept over this fluid, without
 loss.

 HATIONAIB OF THE FORMATION OF NITIlOt79 OXIDE, BY  THE DI9TIL1ATION OF NITRATE
                           OF AMMONIA.
        PROPERTIES AND COMPOSITION  OF  NITROUS OXIDE.
   It is a permanent gas.  Its weight to  common air, is as 16 to 10.
 It supports the combustion of a candle-flame vividly; though nitric
 oxide gas, containing twice as  much oxygen, does not.  Phospho-
 rus  is difficult to inflame in it,  but burns, with rapidity, when once
 on fire.  The habitudes of sulphur are, in  this respect, analogous
 to  those of phosphorus. An  iron wire burns in it, as in oxygen
 gas.  Nitrous oxide may be  exploded with hydrogen,  forming
 water,  and sometimes nitric acid.  It combines with alkalies, only
 when nascent, which nevertheless remain alkaline.   It has no at-
 tribute of acidity.   It stimulates, and then destroys, life.  Its ef-
 fects on the human system are analogous to a transient, peculiar,
 various, and generally very vivacious inebriety.  It  is much more
 rapidly and extensively soluble in water,  than oxygen, and does
 not produce red fumes, or undergo condensation by admixture with
 nitric oxide.   It  is supposed to contain twice as much nitrogen, or
 half as  much oxygen, in volume, as nitric oxide does.

  Haifa volume of oxygen  gas, or one atom,  equivalent   1.
  With one volume, or one atom of nitrogen, condensed
     into one volume, equivalent   -                       1.75

  Constitute one  atom of nitrous oxide,  equivalent  -    -   2.75

                  EXPERIMENTAL ILLUSTRATIONS.
   The process  and apparatus for producing, catching, and
breathing, the nitrous oxide gas, exhibited.  The effect on
a lighted candle,  and on  an iron wire, shown:—also, the
effects  of breathing the gas,  on the human system.
                      OF THE NITRATES.
  They  are characterized by  deflagrating with charcoal, and  de-
composition,  per se, by heat,  leaving  a residuum of their base- 
60
 Chlorates also deflagrate with charcoal,  but are rarely met with—
 and leave a chloride,  after exposure to a red heat.   Nitrate of
 potash, or nitre, is one of the most important productions of nature,
 forming five-sevenths of the ingredients  in gunpowder.   It is ob-
 tained by lixiviation, from the soils of certain territories  in India
 and Spain, and other countries; also from the earths of cellars, and
 large caves.
                       OF NITROUS ACID.
   This is a compound of one atom  of nitrogen, with four atoms of
 oxygen.  It  is formed by mixing, in an exhausted  receiver, one
 volume of oxygen gas, with two volumes of nitric oxide.   As ni-
 tric oxide contains a volume of each gas, the acid formed  must com-
 prise two volumes oxygen, equivalent to four  atoms, and  one vo-
 lume of nitrogen, equivalent to one atom.
   This acid is formed when nitrates are moderately heated, in which
 case, they lose  a half volume of the oxygen, of their nitric acid, or
just so much, as is requisite to convert the one acid, into the other.
   From the  nitrite of lead  thus prepared,  the acid  may  be  libe-
 rated, by sulphuric acid, and may be condensed  in water,  or in a
 receiver, surrounded by snow and salt.
   Nitrous acid  is interesting,  rather as an object of scientific curi-
 osity, and from its relation to nitric acid, than  from any inherent
 usefulness.
OF THE COMPOUNDS OF CHLORINE.
            OF MURIATIC, OR HYDROCHLORIC ACID.
  Chlorine and hydrogen gases,  when mixed, in  equal  volumes.
slowly combine, and form muriatic  acid.  If exposed  to light, or
the electric spark, a detonation ensues.  The direct rays of the sun
are not necessary,  according to  Silliman's experiments.  When
dry, muriatic acid is produced in the form of a gas;  but is  absorb-
ed, if a small proportion of water be present, and forms liquid mu-
riatic acid.

          MEANS OF OBTAINING MURIATIC ACID GAS.
  Distil two parts of common salt, with one part of sulphuric acid.
in a glass, porcelain, or iron retort.

    PROPERTIES AND COMPOSITION OF MURIATIC ACID GAS.

  It has all the attributes of a gas—It is colourless—and although
 ess active than chlorine gas,  is, to the organs of respiration, into-
lerably irritating—and, if not very dilute, deleterious to life.  On
escaping into the air,  it produces white  fumes, from  its meeting 
61
with aqueous vapour.  Its affinity for water, is so great, that this
liquid will take  up 420 times its bulk—and ice melts  in it,  as if
surrounded  by fire.  The  alkaline metalloids  decompose  it, by
combining with  its chlorine, while  its hydrogen separates  in the
gaseous state.  It is susceptible both of decomposition,  and recom-
position, by electricity.   Equal weights of potassium separate the
same  weights, or volumes  of hydrogen, from  muriatic acid, and
from water; a result coincident with the atomic theory.__Muriatic
acid gas is resolved, when electrified with oxygen, into water and
chlorine.  It combines with pure barytes and strontites, producing
a chloride, and water.   On being mixed with ammoniacal gas, very
dense fujnes are produced of muriate of ammonia.   The fumes
arising thus  from the mixture of ammonia with muriatic acid gas,
renders either susceptible of detection, by means of the other.
  One volume, or one atom, of chlorine, equivalent    -     4.5
  With one volume, or one atom, of hydrogen, equivalent    .125

  Constitute two volumes,  or one atom, of muriatic acid
       gas, equivalent......4.625
                   OF LIQUID MURIATIC ACID.

         MEANS OF OBTAINING LIQUID MURIATIC ACID.
  It is obtained, by saturating water with the gas, in  a Woulfe's
apparatus,—or in mine.  The solution is nearly pure, in all the re-
ceptacles, excepting the first.  The liquid acid is also procured, by
distilling a solution of common salt with sulphuric acid, and con-
densing the product in a receiver.

            PROPERTIES OF LIQUID MURIATIC ACID.
  When concentrated, it produces suffocating fumes, from an es-
cape of gas.  When pure, it is colourless—though usually straw-
coloured, from  a minute adulteration by iron.   Muriatic acid can
be said to combine with those alkalies, earths, and oxides only,
which form, with it, soluble salts.   Its combinations  are, for the
most part,  by heat, and desiccation,  convertible  into chlorides;—
muriate of magnesia, and muriate of alumine, are exceptions—also
muriate of ammonia, of which there can be no chloride, since chlo-
rine decomposes it, by its affinity for hydrogen.
  Dr. Thomson informs us that the strongest acid, which he could
obtain, consisted of one atom of acid, equivalent  4625,  united with
six  atoms of water, which being 1125, each  makes the aggregate
weight of the water 6750.  Of course the  proportion of the one to
the other was as those numbers or nearly, as 100 to 40.  I subjoin
a table, from this author, showing the number of atoms  of  acid,
and water, in solutions of different gravities. 
62
TABLE EXHIBITING THJE SPECIFIC GRAVITY OF MURIATIC
         ACID OF DETERMINATE STRENGTHS.
Atomi of	Atoms of	Acid in	Specific
Acid.	Water.	100.	Grarity.
	6	40659	1-203
	7	37-000	1179
	8	33-945	1162
	9	31-346	1149
	10	29134	1-139
	11	27-206	11285
	12	25-517	1.1197
	13	24-026	11127
	14	22-700	1-1060
	15	21-512	1-1008
1	16	20-442	1-0960
	17	19-474	1-0902
	18	18-590	1-0860
	19	17-790	1-0820
	20	17-051	1-0780
EXPERIMENTAL  ILLUSTRATIONS.
  Equal volumes of hydrogen and  chlorine, being  mixed
and'subjected to the solar rays, or galvanic ignition, ex-
plode, and form muriatic acid gas.
  Evolution of muriatic acid gas from  a  retort, containing
common salt and sulphuric acid, aided  by heat.
  Gas collected over mercury in tall jars.   Water, coloured
by litmus, being introduced, rapidly changes to a red co-
lour, and causes the disappearance of the gas.   Ice intro-
duced, melts quickly into water, which absorbs the  gas.
Ammonia  being mixed with it in  due  proportion,  dense
fumes of sal ammoniac  ensue.
  The gas being passed through water in an impregnating
apparatus,  the aqueous  solution  is obtained.

ON THE DIFFERENCE BETWEEN A CHLORIDE, IN SOLUTION, AND
                       A MURIATE.
  A chloride, when dissolved in water, contains the same elements
as a muriate, but in a different order—as may be seen, by writing
them down as follows :
    Hydrogen, chlorine.                   Oxygen, metal.
Muriatic acid
---v---
 Oxide.
Muriate. 
 
 
                         63

Hydrogen, oxygen.                    Chlorine, metal.

      Water.                             Chloride.
   V-------------------------------_-------------------v---------------------------------------------------->
                  Dissolved Chloride.
  It is probable that the order last mentioned, prevails in the com
pounds found by muriatic acid, with barytes, strontites, lime, pot-
ash, and soda;  because,  by ignition, they are  deprived of their
oxygen and hydrogen, in the form of water; leaving their chlo-
rine and metal  united.   But the other arrangement exists, proba-
bly, with respect to the muriates of magnesia, and alumine; since,
on exposure to ignition,  hydrogen and chlorine escape from them,
as muriatic acid, leaving the oxygen in union with the metal.  Be-
sides these  equivocal compounds, there are substances,  formerly
called muriates, now decidedly considered as chlorides.  As, for
instance, calomel, luna cornea,  plumbum corneum,  butter of anti-
mony, or of bismuth, fuming liquor of Libavius, and other metal-
lic combinations, either insoluble in water, or incapable of mixing
with it, without some striking change.

  GENERIC CHARACTER  OF MURIATES, OR SOLUBLE CHLORIDES.
   They precipitate solutions of silver, lead, or black oxide of mer-
cury.  When concentrated, they give off muriatic acid gas, by the
affusion of sulphuric acid.  They are not generally decomposable by
heat.   Muriate of magnesia  is  the only  important exception.
They do not deflagrate with charcoal—nor do they, like sulphates,
after being heated with  it, on being moistened,  yield the odour of
sulphuretted hydrogen.
            COMPOUNDS OF  CHLORINE WITH OXYGEN.
   Chlorine, passed into alkaline  solutions, decomposes water-
forms muriatic acid with hydrogen—and another acid with oxygen,
called chloric  acid.  The acids thus generated, form,  severally,
 chlorates and muriates.
                      ON THE CHLORATES.
                  03T THE PROCESS FOB OBTAINING THEM.
                PROPERTIES OF THE CHLORATES.
    They deflagrate like the nitrates, but leave a residuum of chlo-
 ride, after the  ignition.   They yield pure oxygen at a temperature
 just below a red heat.  When mixed with combustibles, as sulphur
 or phosphorus, they ignite by triture, or percussion—also,  by the
 affusion of sulphuric acid.  With  the same acid, they inflame alco-
 hol and oil of  turpentine, and phosphorus even  under water. 
64
                 EXPERIMENTAL ILLUSTRATIONS.
  Apparatus for procuring chlorates, exhibited.
  Chlorate of potash, and sulphur, being separately pulve-
rized, and then  mixed, a blow, or friction,  causes the mix-
ture to explode.
  Phosphorus being minced by a knife, and mingled with
chlorate, a portion of the mixture,  rubbed by a pestle, ex-
plodes.
  Another portion, being allowed to sink to the bottom  ot
a glass vessel  containing water, sulphuric  acid is  poured
down by means of a tube, when a brilliant  ignition  ensues.

           OF EUCHLORINE, OR OXIDE OF CHLORINE.
  OF THE MEANS OF OBTAINING EUCHLORINE, OR OXIDE OF CHLORINE.
  It is obtained by heating, gently, a portion of chlorate of potash,
under about twice as much muriatic acid, of moderate strength, as
will cover it.  The retort should only be subjected to the  flame of
a small spirit lamp.  This should be applied immediately under the
acid, so as not to heat the body of the vessel,—otherwise an explo-
sion will probably take place.
 OF THE PROPERTIES OF EUCHLORINE, OR OXIDE OF CHLORINE.
  Euchlorine is gaseous, but absorbable by water, to the extent of
eight or  ten  times its volume.  It is a  binary compound of one
atom of oxygen, and one of chlorine.  The warmth of the hand,
is sufficient to cause it to detonate, and to separate into its gaseous
elements, occupying one-fifth more space.  Antimony, or arsenic,
in powder, or Dutch leaf,  causes it to explode, by an attraction for
the chlorine.
                 EXPERIMENTAL ILLUSTRATIONS.
   Euchlorine,  generated by  the process abovementioned,
and collected over mercury.   A tube, filled with it, is made
to  explode by surrounding it by a red-hot  iron ring.  En-
largement of bulk, after the explosion, shown, and subse-
quent absorption of the chlorine by the mercury.    The re-
sidual gas shown to be oxygen.  Portions of euchlorine ex-
ploded, by Dutch gold, antimony or arsenic.

                 OF PEROXIDE OF CHLORINE.
     ON THE MEANS OF OBTAINING PEROXIDE OF CHLORINE.
   It is obtained by mixing chlorate of potash, with sulphuric acid,
 and distilling with great caution, at a heat below 212°.   The pro-
 cess is too dangerous to be repeated without great caution. 
 
 
                              65

        OF THE PROPERTIES OF PEROXIDE OF CHLORINE.
  They are those of euchlorine, but are more intense.  According
to Brande, it is only a purer euchlorine.
                    EXPERIMENTAL ILLUSTRATION.
  Mixture of chlorate of potash, and sulphuric acid, intro-
duced  into a glass tube  suspended, by a wire,  within  a
strong glass cylinder.   Heat being applied, the peroxide is
evolved, and exploded; while the surrounding cylinder, pro-
tects the operator from injury.

                       OF CHLORIC ACID.
             MEANS  OF OBTAINING CHLORIC ACID.
  It is obtained  by  passing chlorine through water,  containing
exide of silver in suspension.
             OF THE  PROPERTIES OF CHLORIC ACID.
  It is colourless—sour and  astringent.  When warm and concen-
trated, its odour is pungent.   It reddens litmus.   It does not pre-
cipitate solutions of  lead, mercury, or silver.   It is partially de-
composed by distillation.  With muriatic acid, it produces water,
and chlorine.
            OF THE COMPOSITION OF  CHLORIC ACID.
   It is supposed  to consist of one atom of chlorine, and five atoms
of oxygen.
                        OF PER-CHLORIC ACID.

                    OF NITRO-MURIATIC ACID.
   It is a mixture of  nitric, with muriatic acid.
             PROPERTIES OF NITRO-MURIATIC ACID.
   The colour of nitro-muriatic acid is much deeper than that of its
 constituent acids; and its fumes are more pungent, being evidently
 chlorine, the muriatic acid having been dehydrogenated  by the oxy-
 gen of the nitric acid.  The effects of nitro-muriatic acid differ from
 those of a solution of chlorine in water, only in being more  power-
 ful, as there is a greater quantity of chlorine in the same space.
                 ACTION OF CHLORINE  ON  GOLD.
    Some gold leaf  is  placed  in two glasses—nitric acid  is added to
 one glass, and muriatic acid to the other glass:   The gold is not
 acted upon.  The contents of one glass being  added to the other,
 the gold disappears.
 ©N THE  COMPARATIVE ACTION OF SULPHURIC, NITRIC, MURIATIC,
                   AND NITRO-MURIATIC ACIDS.
    Sulphuric acid carbonizes organic products,  by its avidity for the
 elements of water.   In this respect, it has more analogy with caus- 
66
tic alkalies than *ids.   When boiled on metals, they are oxidized
at its expense.  When cold,  and diluted with water, the metals,
on which it acts, are oxidized, at the expense of the water.
  Whether cold, or hot, nitric acid acts both on metals, and upon
organic products, by imparting oxygen.   Hence, when cold, its
action on metals is analogous to sulphuric acid, when boiling.
  The action of muriatic acid on organic products  is very slight:
—upon metals, with heat, it resembles that of nitric acid, and
boiling  sulphuric acid; excepting, that it imparts chlorine, instead
of oxygen.  When it acts on  metals, in the cold, it evolves hydro-
gen; which may come from the decomposition of the acid, though
usually supposed to  arise  from the decomposition of water;  since
dilute sulphuric, and muriatic  acids, may  both be considered as
containing simple radicals, acidified by the joint agency of hydro-
gen, and oxygen.

                ON THE BLEACHING PROCESS.

      ON THE OLD THEORY OF THE NATURE  OF CHLORINE.
  Muriatic  acid was deemed to  be a compound  of oxygen and
some unknown radical—When distilled from  oxide of  lead, or
manganese, it was supposed to combine with a portion of the oxy-
gen of the oxide, forming oxygenated muriatic acid.   The oxygen
was supposed  to be  held by a weak affinity, as in nitric acid.  To
this oxygen, thus contained, its activity, as  a  supporter of combus-
tion, or a solvent of metals, was ascribed.  It has since been proved,
that  when  dry, it does  not oxydize.  Charcoal  is  not acted upon,
when ignited in dry chlorine by  voltaic  electricity :  nor  are me-
tals.   They are converted into substances now called  chlorides.
The chlorides of sulphur and phosphorus, which result from expos-
ing these substances to chlorine, are devoid of acidity, though the ad-
dition of water, converts the one into muriatic and sulphuric acids,
the other into muriatic and phosphoric acids. If chlorine be an oxy-
genated acid,  the discovery of euchlorine,  and chloric  acid, must
establish the following anomaly—that the radical of muriatic acid,
acidified by oxygen, on further additions of the acidifying princi-
ple, loses  its acidity, and  forms two oxides—chlorine and euchlo-
rine; and  yet, by a subsequent addition  of  the same principle, re-
gains the acid  state.
  Thenard has lately oxygenated muriatic acid; or, more properly,
the water in it.  The fluid, thus containing muriatic acid and oxy-
gen in excess, has no resemblance to chlorine.
  The process, by which iodine is obtained from hydriodic  acid,
is analogous to that, by which chlorine  is obtained from muriatic
acid; yet  iodine is sot considered as an oxygenated acid.

                       OF PHOSPHORUS.
              MEANS OF OBTAINING PHOSPHORUS.
   It is obtained from the phosphate of soda in urine, or the phos- 
 
 
67
phate of lime in  bones.  Phosphoric acid is extricated from the
earth of bones, by the stronger affinity of sulphuric acid.*  Phos-
phoric acid is decomposed  by ignition with charcoal  in a retort,
from which it distils in tears, which are melted and strained under
water.   The  phosphate of soda is decomposable by nitrate of lead,
by complex affinity.  The resulting phosphate of lead, is decom-
posable by distillation, at a high heat, with carbon.

              OF  THE PROPERTIES OF PHOSPHORUS.
  It is often  of a light  flesh colour—but when pure is colourless
and  translucent.  It is  rather harder than wax, but  more easily
split by the knife, under which, after some pressure, it yields sud-
denly.  It boils at 550° (F.) and in a retort filled with hydrogen
may be distilled.   By these means, it may be separated from the
phosphuret of carbon, which, more or less, according to Thenard,
always contaminates it.   Hydrogen is evolved by electro-chemical
action; but is  present in the phosphorus, as an impurity, not as a
constituent.  Phosphorus is susceptible' of a  slow,  and of a quick
combustion,  producing  phosphorous arid phosphoric  acids.  The
existence of other compounds of phosphorus and oxygen has been
alleged.   Phosphorus forms a  compound with sulphur, which is
spontaneously inflammable.   The equivalent of phosphorus is 1.5.
                  EXPERIMENTAL ILLUSTRATIONS.
   Phosphorus exhibited, and its combustion in oxygen and
in chlorine.    Phenomena of its reaction with nitric acid:—
also, with chlorates.  A  combination of sulphur, and phos"
phorus, spontaneously inflames.

                     OF PHOSPHORIC ACID.
           MEANS OF OBTAINING PHOSPHORIC ACID.
  It is obtained,  not only,  as abovementioned, by the combustion
of phosphorus, or decomposition of bones,  but  best by adding
phosphorus, gradually, to nitric acid, heated in a retort.

           OF THE PROPERTIES OF PHOSPHORIC ACID.
  Though composed of volatile ingredients, phosphoric acid is one
of the most fixed, and, per se, unalterable acids, by heat.  Evapo-
rated to dryness, and fused, it forms a glass.  It is soluble in water
—is not odorous.  It is supposed to consist of two atoms of oxygen,
with one atom of phosphorus.  Its equivalent is therefore 3.5.

                    OF PHOSPHOROUS ACID.
           MEANS OF OBTAINING  PHOSPHOROUS ACID.
  It is obtained,  by slow combustion; but is then contaminated by
phosphoric acid:  better, by the distillation of phosphorus with cor-

  * The phosphoric acid is said to be in the state of super-phosphate of lime
when thus obtained. 
68
rosive sublimate.  Chloride of phosphorus results, which, when
mixed with water, produces muriatic and phosphorous acids. The
muriatic acid, being most volatile, may be separated by heat.

          OF THE PROPERTIES OF PHOSPHOROUS ACID.

  It is distinguished from phosphoric acid, by its odious smell, and
susceptibility of volatilization.
  It consists of one atom of oxygen and one of phosphorus.  Con-
sequently its equivalent is 2.5.

            OF THE PHOSPHATES, AND PHOSPHITES.
  They have the  same relation to each other, as sulphates and
sulphites—and nitrates  and nitrites.  The earthy and  alkaline
phosphates  are not decomposed by ignition in contact with char-
coal.  The metallic phosphates  yield phosphorus, when so treated.
Hence the necessity of transferring the acid, from soda, to lead, in
one of the processes for obtaining phosphorus.
                 EXPERIMENTAL ILLUSTRATIONS.

   Precipitation of silver, lead,  and lime,  &c  from solution,
by phosphate of soda.

      OF HYPO-PHOSPHOROUS,  OR PER-PHOSPHOROUS  ACID.
  This acid is said to consist of two atoms of phosphorus, and one
atom of oxygen.

               OF PHOSPHORUS AND CHLORINE.
  There are two  chlorides of phosphorus—a chloride and a bi-
chloride.  The latter is solid, and consists of one atom of phospho-
rus, and two atoms of chlorine;—the other of one atom of phos-
phorus and one of chlorine. The bi-chloride produces, with water,
muriatic and phosphoric acids ;—while the  chloride, or proto-
chloride, produces muriatic, and phosphorous  acids,  with water.
The bi-chloride having a double proportion of chlorine,  requires
twice as much hydrogen,  and of course liberates twice as much
oxygen,  from the water,  to act on the same proportion of phos-
phorus.

DF THE  COMBINATIONS OF PHOSPHORUS, WITH  THE ALKALIES,
    AND EARTHS;  CALLED PHOSPHURETS:—ALSO, ON THE ANA-
    LOGY BETWEEN  PHOSPHURETS, AND SULPHURETS,  BOTH AS
    TO THEIR ORIGIN, AND THEIR EFFECTS UPON WATER.

                  EXPERIMENTAL ILLUSTRATIONS.

   Decomposition of water by the  phosphurets of lime, and
potash.   Spontaneous combustion and detonation  of phos-
phuretted hydrogen, in atmospheric air,  and  in  oxygen gas 
69    .
                       OF BORACIC ACID.
  There is a salt called borax, found in Thibet and- China, which
consists of this acid and soda in excess.

          OF THE MEANS OF OBTAINING BORACIC ACID.
  To a saturated solution of borax, add half the weight of the salt,
in sulphuric acid.  The boracic acid crystallizes, by precipitation,
in shining scaly crystals, contaminated by sulphuric acid, till puri-
fied by fusion.  Boracic acid is fusible into a  glass, decomposable
in the.voltaic circuii into oxygen, and an olive-brown matter which
is considered as  the  base  of the acid, and is called boron.   By
means of potassium, which combines with  the oxygen of the acid,
boron may be procured in  greater quantity, in the  form of a dark
olive powder.

                           OF BORON.
   This  substance, as above obtained, takes fire in the  air at 600°
(F.) and burns brilliantly when ignited in oxygen gas.  It is acidi-
fied, when exposed to nitric, or sulphuric acids.
   The equivalent of boron is 1; and as the acid is a ternary com-
pound,  of boron and oxygen, its equivalent is 3.

                          OF BORATES.
   Borax, or  sub-borate of soda, above spoken  of, is the only im-
portant combination under this head.  Fused  into a glass, it is  of
great use  in blow-pipe assays, and in soldering.

                       OF FLUORIC ACID.
          OF THE MEANS OF OBTAINING FLUORIC ACID.
   Fluor spar is  pulverized,  and heated with twice its weight  of
strong sulphuric  acid, in a leaden  retort, adapted to a leaden re-
ceiver, surrounded by snow and  salt.  The acid  condenses in a  li-
quid state in the receiver.

            OF THE PROPERTIES OF FLUORIC ACID.
   It is  so volatile, that it  cannot, in a close apartment, be decant-
ed,  without  subjecting the  operator  to intolerable fumes.  This
operation must be performed where there is a current of air to carry
them off.  It ulcerates the skin wherever it falls.  It corrodes glass
so rapidly as to  leave an  indelible trace  in running over^its sur-
face. It must be  kept in vessels of silver or lead, accurately closed.
It may also be received in water, in which it may more easily  be
condensed and preserved.

                   EXPERIMENTAL ILLUSTRATIONS.
   Powdered fluor heated with  sulphuric acid, in a leaden
retort, adapted  to  a  receiver surrounded by snow and  salt.
 Same  process,  substituting a  receiver with water, by means 
•   70
of Knight's apparatus.   Effects of fluoric acid upon glass,
shown.
              OF THE NATURE OF FLUORIC ACID.
  It is probably composed of hydrogen, and a principle called fluo-
rine, supposed analogous to chlorine and iodine, and which  forms
acids with hydrogen, silicon,  and boron.
PROOFS OF THE EXISTENCE OF FLUORINE, FOUNDED ON VOLTAIC
                          ANALYSIS.

OF FLUORIDE  OF SILICON, OR FLUO-SILICIC  ACID GAS, USUALLY
              CALLED SILICATED FLUORIC ATIID.
  It is obtained by adding, to the materials for producing pure fluo-
ric acid, one half the weight  of the fluor, in powdered glass, in a
glass retort, and distilling.  The product, being gaseous, is received
in bell glasses, over mercury.

  PROPERTIES OF SILICATED  FLUORIC, OR FLUO-SILICIC ACID.
  It is a gas permanent over mercury.   On  mixing with air, it
fumes, in consequence of the moisture; in which respect, as well as
in its odour, and other  obvious  habitudes, it much resembles mu-
riatic acid.  When presented to water,  a white  deposition  takes
place, while the gas appears to be absorbed.  This deposition was
heretofore  considered as pure  silex.   According to  Brande,  the
igas, on  meeting with water, forms two compounds, of fluoric acid
with silex—one insoluble and insipid, the other soluble and acid.

                  EXPERIMENTAL ILLUSTRATIONS.

   Production of the fluo-silicic acid shown.  Its absorption
by  water—precipitation  of silex.
      OF THE FLUATES—OR, MORE PROPERLY, FLUORIDES.
  The fluates are not of much importance in the arts.  The alka-
line fluates are tests for lime.
  The fluates, so called, are properly fluorides; as  are the muriates,
when yielding chlorides (not  oxides) by heat.*

                    FLUORINE WITH BORON.
        FLUO-BORIC ACID GAS, OR FLUORIDE OF BORON.
  It is obtained by distilling fluor spar, in powder, with diy bora-
cic acid, (in proportion of one part of the  acid to  two parts of the
fluor or fluoride of calcium,) in an iron tube at a  strong heat.   Or
the same materials  may be distilled, by means of a glass retort,
with twelve parts of sulphuric acid.
   Fluo-boric acid  gas is  produced,  and may be  collected, in  the
gaseous state, over mercury.
See page 62. 
 
 
71
PROPERTIES  OF FLUORIDE, OF BORON, OR FLUO-BORIC ACID 6AS.
  It is analogous to fluoride of silicon, but more intensely attracts
moisture.   Water  absorbs  700 times its bulk, becoming nearly as
heavy, and coy^ve  of  organic matter, as concentrated sulphuric
acid.   In this^Prfe, it appears to consist of the same elements as
fluoric and  boracic acids;—but, as it does not corrode glass, there
seems  to be  an intimate union of the fluorine with the boron, as
well as with the hydrogen.              *

           EQUIVALENTS OF  FLUORINE AND ITS COMPOUNDS.
  An atom of fluorine is equivalent  to 2.25, and with one atom of
hydrogen,  forms fluoric  acid, equivalent, 2.375.   With one atom
silicon, forms fluo-silicic  acid  gas, equivalent 3.25—also, with two
atoms  of boron, each equivalent 1. forms fluo-boric acid, equivalent
4.25.  Fluor spar consists of one atom calcium, equivalent 2.5,
and one atom fluorine, and  of  course is equivalent to 4.75.
                   OF THE METALS.

   Besides the alkaline metalloids already treated of, there are
twenty-nine metals.  Their names are:  gold, platina, silver, mer-
cury, rhodium,  palladium, iridium, osmium, copper, iron, nickel,
tin,  lead, zinc,  bismuth, antimony,  tellurium,  selenium, arsenic,
cobalt,  manganesium, chrome,  molybdenum, uranium, tungsten,
titanium, columbium, cerium, cadmium.
          GENERIC CHARACTERISTICS OF THE METALS.
   Substances belonging to this class, have a specific  gravity, not
less  than six,  and, when newly cut, a peculiar  lustre.   They arc
the best conductors of heat, and  electricity; the worst radiators,
and  best reflectors, of  heat.   All combine, directly or indirectly,
with oxygen,  chlorine, and sulphur, in one or more proportions—
forming oxides, chlorides, and sulphurets;  and all are susceptible
of solidity and fluidity, and probably of  the aeriform  state.  Mer-
cury and arsenic are easily volatilized: and  gold,  silver, and pla-
tina, though very difficult to  burn or volatilize, are  nevertheless
dissipated and oxidized, by means either of the  compound blow-
pipe, galvanism, or electricity.
 OF  THE PROPERTIES POSSESSED BY SOME METALS, BUT NOT BY
                           OTHERS.
  The properties which come under this head, are: permanency of
lustre in the fire and air—malleability—ductility—elasticity—sen-
sibility to the  magnet—susceptibility of the welding process—and
of acquiring, by a union with  carbon, silicon, or aluminum, the
property of hardening by sudden refrigeration.
  The metals remarkable for permanency of lustre, are—gold, pla- 
72
tina, silver, and palladium.  Those principally remarkable for mal-
leability, are—gold, silver,  platina,  copper,  palladium,  iron, tin,
lead.   Among these, iron and platina only, can be advantageously
hammered at a very high temperattfre.          ^-A
  The metals distinguished  for elasticity, are—4Mb copper, and
silver.  It is a quality which appears dependent onrne approxima-
tion of their particles, and expression of their caloric by the ham-
mer, rollers, or  wire drawing.  Iron, in the state of steel,  when
duly tempered, is pre-eminent for  this property.
  The metals remarkable for ductility, are—gold, iron,  (either as
iron or steel,) silver, copper, platina, tin, and lead.   In large rods
or pipes, lead and tin are the most ductile.
  The magnetic metals are—iron, whether  pure, in the  state of
steel, or in that of protoxide, and nickel.  Those susceptible of the
welding process, are, iron and platina.   Iron only, is  capable of
uniting with carbon, silicon, or aluminum, and hardening,  conse-
quently,  by  quick  refrigeration.   Gold  and platina,  are distin-
guished by their superior gravity, which is between two and a half,
and three times greater, than that of iron, tin, or zinc.   The gra-
vity  of mercury is about one-third, that of lead one-half less than
gold or platina.
  The perfect metals are  those which, like  gold, silver, platina,
and palladium, possess  ductility and malleability, and  which are
not tarnished by exposure to the  air,  or  oxidized by the  highest
heats of the air furnace, or forge.
          OF THE BRITTLE METALS, OR SEMI-METALS.
   The latter appellation was given to those metals, which, like
bismuth, antimony, cobalt, &c. could not, from their brittleness,  be    *•
wrought under the  hammer.   They are now called,  by  some che-
mists, brittle metals.  Zinc, till lately, was placed among the semi-
metals; but, at this time, ought to stand between the two classes,
being laminable by rollers, but not malleable.
                          OF ALLOYS.
   This term is  given  to  the compounds formed by the union of
diferent metals.   There is always  copper in  gold and silver coin;
and  in the metal, employed under those names by the smiths and
jewellers, there are various proportions of the baser metal.  Brass
consists of copper and zinc.   Pewter, of lead and tin; or tin, cop-
per, and antimony.                                                ,
                        OF AMALGAMS.
   These are the compounds of mercury with other metals.
OF THE NOMENCLATURE OF METALLIC OXIDES,  CHLORIDES AND
                          SULPHURLTS.
   Metals are susceptible of different degrees of oxidizement.  To
distinguish  these,  the  terms protoxide, deutoxide,  and tritoxide,
are used, to designate  the  first, second, and third degree.  That
oxide which contains most oxygen, is called the peroxide.  In like 
 
 
73
  manner, chlorine and sulphur  combine  in different proportions.
  Hence we have proto-chloride and proto-sulphuret, deuto-chloride
  and  deuto-sulphuret,  and  per-chloride and per-sulphuret;  also,
  chloride and bi-chloride, sulphuret and bi-sulphuret, or super-sul-
  phuret.                                                  r
                             OF  GOLD.
                    MEANS OF OBTAINING GOLD.
    Gold  is occasionally found in nature,  nearly  pure.  It is not
  liable, like other metals, to be  degraded  by a union with oxygen
  or sulphur.  The precipitate obtained from a solution of gold  coin,
  in nitro-muriatic acid, by green sulphate of iron,  is  pure  gold.
  This metal is also purified by exposure to  heat and  air, or nitric
  acid, by which means baser metals are oxidized, as in the processes
  of cupellation,  and parting.
    From  the sands or ores in which they exist naturally, minute
  portions of gold are collected, by trituration with mercury, in which
  they dissolve.    They are separated  from the mercury, by distilla-
  tion.
               OF dUARTATION AND PARTING--OF CUPF.HATION.

                        PROPERTIES OF GOLD.
    Its colour and lustre are well  known.  Its gravity is 19.3; that
  is, the weights of equal bulks of  gold, and water, are,  to each other,
  as 19.3 to one.   It is the most malleable and ductile metal, and suf-
  fers the  least by exposure to air  and  moisture.  Gold  leaf, which is
  about 1000 times thinner than  printing paper, retains its lustre in
  the air.   Gold leaf transmits  a  greenish  light, but it is questiona-
  ble, if it be truly translucent.  Placed on glass, and  viewed by
  transmitted light, it appears like a retina.   It is erroneously spoken
  of, as a continuous superficies. *
    Gold  fuses at a low white heat, but requires the  temperature pro-
  duced by the compound  blowpipe, or galvanism,  or  the explosive
  power of electricity,  to volatilize or oxidize it.   Its  not being lia-
  ble to injury from exposure, is due to its weak affinity  for oxygen
  or sulphur.  There are two oxides of gold, a protoxide, and a per-
^ oxide—It is uncertain whether the latter contain  2, or  3 atoms, of
  oxygen.
    Neither sulphuric, nor nitric acid,  has any action on gold.  With
  the oxides, they combine, but the compounds, thus formed, are not
  crystallizable.
    It has been already stated, that chlorine exercises  a  very ener-
  getic affinity  with gold.  A combination between them  ensues,
  whether the metal be heated in  the gas, or presented to it in the
  aqueous  solution, or in nitro-muriatic acid.*  The dissolved chlo-
  ride,  or muriate  of gold, yields triple salts with the alkalies.   The

                           * See  page 65,
                                 K 
74
compound formed with ammonia, fulminates by percussion, or at a
heat of about 400° (F.).
  Sulphuretted hydrogen precipitates gold in the state of a sulphu-
ret, which may be dissolved by liquid alkaline sulphurets.
  When a solution of muriate of gold is mixed with sulphuric
ether, the ether  takes the  metal  from the acid,  and dissolves  it.
If iron or steel be moistened with this ethereal solution, it is pro-
ductive of a slight gilding.
  Phosphorus, carbon, and  the baser metals, also hydrogen gas and
its compounds, by attraction for  oxygen, precipitate gold in the
metallic form.  Muriate of tin, or tinfoil, furnishes a purple preci-
pitate.  Hence tin, especially in the state of muriate of the protox-
ide, or dissolved proto-chloride, is the best test for gold.
  Gold combines  with almost all the metals, and amalgamates
eagerly with mercury.
  The equivalent for gold is 25.
                  EXPERIMENTAL ILLUSTRATIONS.
   Gold dissolved by  nitro-muriatic acid, and precipitated
by sulphate of iron, or  by muriate of tin.   A cylinder  of
phosphorus, immersed in a solution of the metal, acquires the
appearance of a cylinder of gold.    Separation of gold, from
its solution, by ether.   Effects of  the ethereal  solution ex*
bibited.  Action of mercury on gold leaf.

                  OF PLATINA, OR PLATINUM.
                MEANS OF OBTAINING PLATINA.
  This  metal,  in the crude state of its native grains, as it comes
from South  America,  may be dissolved in nitro-muriatic acid.   A
solution of sal ammoniac being attyed,  an orange coloured precipi-
tate results, of ammoniacal muriate of platinum.  Ignition develops
the metal from  this precipitate,  but in a divided state.  By intense
pressure, the minute particles, thus procured, are  made to cohere,
so far, as to sustain the welding process.  By this they are made to
coalesce, into a perfectly solid and coherent mass.

                  PROPERTIES OF PLATINUM.                  \
  The colour of this  metal is intermediate between that of silver,
and steel.  Its specific gravity is 21.5.   It is the  heaviest body in
nature, being about twice as heavy as lead, and nearly three times
as heavy as iron.  A cubic inch weighs nearly a pound.  It is less
ductile  and malleable than gold,  but harder and more tenacious—
though, in these respects, inferior to iron.  Like iron, it is suscepti-
ble of being hammered and welded at a white heat.  It can neither
be oxidized nor melted, by the highest temperatures of the air furnace,
or forge.  It was first fused in a focus of the solar rays—afterwards
by means of a stream of oxygen gas on ignited  charcoal—but much
more easily by my compound blowpipe, under which, it was first 
 
 
75
 oxidized  and dissipated by heat.   It fuses and  burns easily in the
 voltaic circuit,  and is dispersed and oxidized by mechanical  elec*
 tricity.   It is one of the worst conductors of heat among metals.
   In its habitudes with oxygen, chlorine, or the acids, it is very
 analogous to gold, being, like that  metal, detected by muriate, or
 proto-chloride of tin, which produces a claret colour with platina.
 It unites  so energetically with tin, at a red heat, as to occasion the
 phenomena of combustion.  With mercury  it amalgamates by tri-
 turation,  when  in a divided state, as obtained by igniting the am*
 moniacal  muriate.
   The equivalent  of platinum is  12.  It forms two oxides, one
 containing an atom, the other three atoms, of oxygen.—The latter,
 only, has been isolated.

                   EXPERIMENTAL ILLUSTRATIONS.
   Platina  exhibited, in  the state of native grains,  and  in
 that of  larger masses.   Precipitated  from its solution, by
 muriate  of  ammonia, and muriate of  tin.   A precipitate
 produced in salts of potash,  by muriate of platina, distin-
 guishes  them  from  salts of soda.   Combustion of  platina
 with tinfoil.
                           OF SILVER.
              MEANS OF RENDERING SILVER PURE.
   A solution of silver coin, in nitric acid, may be precipitated by*
 mercury, and the precipitate ignited  to drive off the mercury,
 which adheres to the precipitate.  The first  portions of the preci-
 pitate,  obtained  by means  of copper,  are sufficiently pure.   The
 chloride obtained from the  same solution, by common salt, ignited
 with pearlash, gives pure silver, and it may also be produced, by
 simply igniting  the white  crystals, which result, on evaporating
 the solution, or  which spontaneously form in it, when sufficiently
 concentrated.
                    PROPERTIES OF SILVER.
  In malleability, silver is inferior to gold only.  It is  also very
 ductile, and tenacious.   Its specific gravity is 10.5.   It is the best
 conductor of caloric.   It fuses at a low  white heat:  It is as difficult
 to oxidize in the fire, as gold, but is more liable to tarnish, when
 indiscriminately exposed in the atmosphere,  from its susceptibility
 to the action of sulphur, and chlorine.   Hence  it is blackened by
 eggs, and salt water.
  By the compound blowpipe,  by electricity, or by galvanism,
silver is fused, oxidized, and dissipated, as  gold is  by the  same
means.  Exposed to nitric acid, it is oxidized by one portion, and
dissolved  by the other.  In fact, this  acid  is its proper solvent.
Sulphuric acid has no reaction with silver when cold.  At a boil-
ing heat, the metal is oxidized at the expense of one portion of the 
76
acid; and the oxide, thus formed, is dissolved by another portion,
as in the case of nitric acid.
   Silver unites with chlorine, when heated in it.   The chloride of
silver, is one of the most insoluble combinations.   Hence silver is
not  soluble in nitro-muriatic acid; and hence, soluble  chlorides
yield a precipitate when solutions of this metal are added to them:
for,  in any  mixture,  those  substances  will usually unite,  which
when united, are  most insoluble.  Gravity, unbalanced by  attrac-
tion  for the solvent, aids in separating them from substances which
are so attracted.*
   Nitrate of silver, fused, forms lunar caustic; the fused chloride
forms horn silver, or luna cornea.
   Silver combines with iodine, and sulphur.  It forms several ful-
minating compounds.
   The equivalent of silver is 13.75. It forms a protoxide and pro-
tochloride, of which the equivalents are of course 14.75 and  18.25.
A suboxide of silver is alleged to exist.
                  EXPERIMENTAL ILLUSTRATIONS.
   Oxidizement and  solution of silver in nitric acid.  Its
precipitation by muriates, phosphates, chromates, arsenites,
and  arseniates,  exhibited: also, by copper  and mercury.
Detonation of fulminating silver.

                OF MERCURY, OR QUICKSILVER.
               MEANS OF PROCURING  MERCURY.
   This metal may be found in nature, nearly pure, but much more
abundantly in the state of sulphuret, from which it is obtained in
purity, by distillation with substances calculated to detain the sul-
phur.
               OF THE PROPERTIES OF MERCURY.
   It is the only metal, which is  fluid at the ordinary temperatures
of the atmosphere. In colour  and  brilliancy it resembles, and
rivals, silver.  Its specific gravity is 13.6.  At — 39° (F.) it freezes
into  a malleable solid, and boils  at about 660° of the same  scale.
It forms two oxides, two chlorides, and two sulphurets. The prot-
oxide, or  oxide, containing  one proportion of oxygen, is black—
the deutoxide, containing two proportions, red.  The black oxide
may be made by mechanical agitation without heat—the red, by
long exposure to heat; the air  having free access in both  cases.
The  red oxide, is usually obtained by expelling the acid  from the
nitrate by heat;  when thus produced, it retains some nitrogen.  It
is decomposed at the temperature, at which mercury boils.

  * Chloride of silver is, however, very soluble in ammonia, and the solution some-
times yields a fulminating compound.  It is said to be decomposable by a  current
of hydrogen, in the light, but not in the dark; also, by fusion with zinc, or tin:—
with zinc, the reaction is violent, so as to cause the fusion of the silver, 
77
  When nitric acid, whether cold  or hot, is  poured on mercury,
one portion of the  acid is decomposed, imparting oxygen to the
metal.  The oxide, thus  formed,  is  dissolved by the remaining
portion of the acid.  When the metal is  in  excess, the protoxide
is principally  formed.  When the  acid is in excess, the deutoxide
predominates.  Usually, more or less of  each oxide is  formed.
The crystals of the nitrate of the black oxide, are white;  those of
the nitrate of the red oxide, yellowish.
  No reaction arises from adding cold sulphuric acid to mercury;
but, when it is boiled on  mercury, the phenomena are similar to
those which ensue in the case of nitric acid.   One  portion of the
acid, yields oxygen to the metal, the  other, combines with the
oxide thus created.  Each oxide of mercury, forms three salts with
nitric acid, a  sub, a super, and neutral nitrate.  The neutral ni-
trates of mercury,  subjected to water, yield insoluble sub-nitrates,
and soluble super-nitrates.   The same is true of the sulphate of the
deutoxide, which yields  turpeth mineral,  or  the insoluble sub-sul-
phate, and the soluble super-sulphate, by the affusion of hot water.
The nitrate of the protoxide, gives  cajomel, or proto-chloride of
mercury, when presented to muriate of soda.   The nitrate of the
deutoxide yields, under like circumstances, deutochloride of mer-
cury, or corrosive sublimate.   Thus a single proportion of oxygen
in the  oxide, disengages  a single proportion of chlorine; and in
like manner, a double proportion  of oxygen  disengages a double
quantity  of chlorine.  The  complex affinity which  causes these
changes, operates either  in the wet, or dry way;  that is, whether
the  substances are  mixed in solution, or sublimed together.   The
sulphate of the deutoxide of mercury produces these results, when
sublimed with certain  compounds of chlorine, as common salt for
instance.   Corrosive sublimate is  thus  procured,  and, by tritura-
tion with mercury, a second  sublimation, and washing  in water
acidulated with  muriatic acid, may be converted into calomel, or
proto-chloride.  Or the deuto-sulphate of mercury being converted
into proto-sulphate, by trituration with a further portion  of the
metal, sublimation  with common salt, yields calomel directly.
   Chlorine does not combine with mercury in  the indirect mode,
abovementioned, only.   A jet of  chlorine burns spontaneously in
mercurial vapour, forming either,  or both of the  chlorides.   The
processes for manufacturing these  important compounds of mercu-
ry, are very numerous.  They have, however, but one  object-
that of presenting chlorine and mercury to each other in due quan-
tities, and in  a  divided  form.  In proportion as the chlorine pre-
dominates, corrosive sublimate is formed; and, reversing the pro-
portions,  calomel.
   Corrosive sublimate, is white,  more  or  less  crystalline, and
transparent,—soluble in about twenty parts of cold water, but more
so in hot  water—whence crystals are obtained by cooling.   It dis-
solves in two parts of alcohol, and in  three parts of ether, by
weight.   It is not soluble either in sulphuric, or nitric acid.  With 
78
the muriates of ammonia, potash, soda, barytes, and magnesia, it
forms  very soluble compounds.  These solutions, and  those  by
ether and  alcohol, undergo no  change from light.—The caustic
earths, and alkalies, disengage an orange precipitate, which deepens
by keeping.  Corrosive sublimate has  a most  nauseous metallic
taste, and is a virulent poison.
   Calomel is also white and crystalline,  but usually much more
compact.   It is tasteless and insoluble—is blackened by alkalies,
and presents a yellowish stroke, when scratched.
   Pure ammonia occasions a white precipitate from the solution of
the deuto-chloride, called  in the pharmacopoeias, hydrargyrum,
precipitatum album.
   According to an analysis of Fourcroy, founded on the idea of
chlorine being oxygenated muriatic acid, this precipitate contains
81 parts of oxide of mercury,  16  parts of  muriatic acid, and 3
parts of ammonia.  Agreeably to the view now taken, it is there-
fore probable, that the ammonia takes chlorine from the  mercury,
and hydrogen  from the water, to form  with  them muriate of am-
monia, which remains in solution; while the  oxygen and  mercury,
liberated, precipitate as oxide, together with a portion  of proto-
chloride of mercury and ammonia.   The same precipitate is  ob-
tained, because the same precursory circumstances arise, on adding
a fixed alkali to the  solution of muriate of ammonia, and deuto-
chloride of mercury.  The  alkali liberates from the muriate, am-
monia, which then acts as if added  to a simple solution of deuto-
chloride.
   Heated together, mercury and iodine combine, forming either
protiodide, or periodide, or both. Iodides are also produced from
the nitrates, in  the wet way, by the addition of the alkaline iodides,
as chlorides are by addition of alkaline chlorides.  The protiodide
precipitates—the deutiodide, or periodide does not.  Mercury com-
bines with cyanogen.   The compound is called cyanide, prussiate,
or cyanuret of  mercury.  It is singular  that the compound formed
by mercury with this factitious principle, should be analogous to
those, formed with chlorine and iodine.
  Mercury with  sulphur forms two  compounds, which are  black
or red, according to the proportions,  and the process.
  The black compound has been called Ethiops mineral, the red,
cinnabar.
  Ethiops  mineral is made by heating and triturating one part of
mercury with three of sulphur;  cinnabar, by the fusion and subli-
mation of five  parts of mercury, with one of sulphur.   Cinnabar
has also been formed by triturating the black sulphuret, with a so-
lution of the caustic potash. Sulphuretted hydrogen deoxidizes the
mercury, in mercurial salts, and  precipitates  it as a sulphuret.   It
is precipitated from its solution, in nitric acid, by borates, arsenites,
arseniates,  chromates, and phosphates.
   All metals combine with mercury, directly or  indirectly.   The 
^.XJAz&z,    a%. y,^
c&^t<~
 £L h _^ ASA
>[^aI&' /\zT
&*\ '
i   •  r   / / *------\ *
\  As«A       \
j5Zru-t£.
\ 
can- 
79
compounds have the generic name  of amalgam.   In the case of
gold, silver, zinc, lead, tin, and bismuth, the amalgamation  is ra-
pidly effected.  It is less easily produced with copper, unless when
this metal separates mercury from the acids.   It is difficult to unite
mercury with platina, and still more so with iron; owing, proba-
bly, to the great difference in fusibility.
  Mercurial  compounds  are all volatilizable by heat, and mercu-
rial salts, when moistened and rubbed on copper, cover it with a
film  of mercury.
  The equivalents of mercury, and  its compounds, with oxygen,
chlorine, and sulphur, are as follows:                         ■
Mercury,......equivalent to 25.
Protoxide, 1  atom mercury with 1 atom oxygen   -    -     26.
Peroxide,  1         „      „  2 atoms  „      -    -     27.
Protochloride, 1     „      „  1 atom chlorine   -    -     29.5
Perchloride,  1       „      „  2 atoms   „      -         34.
Proto-sulphuret I    „      „  1 atom sulphur   -    -     27.
Persulphuret 1       „      „  2 atoms   „      -    -     29.

                     OT FULMINATING ME1XCUHY.
                 EXPERIMENTAL ILLUSTRATIONS.
  Ebullition and  distillation of mercury.   Its  compounds
with oxygen and sulphur exhibited.   Action  of nitric acid,
and of sulphuric acid, on the  metal.   Resulting salts sub-
jected to hot water.   Black oxide, and  red oxide, severally
dissolved in nitric acid.  Muriatic acid  precipitates calomel
from the one,  but occasions no precipitate in  the other.  Al-
kalies produce a black precipitate in the nitrate of the black
oxide, or protoxide;  an orange  precipitate in the nitrate of
the  red oxide or  deutoxide.   Similar  results obtained, by
adding them  to calomel  and corrosive sublimate; the first
giving the black, the last the red oxide.   Inflammation of
chlorine with  mercurial vapour.   Explosion  of fulminating
mercury.

                         OF COPPER.
  Copper is found nearly pure in nature.  The copper of commerce
contains, according to Berzelius, about one-half of a grain of sul-
phur and carbon, in one hundred grains.

              MEANS OF OBTAINING PURE COPPER
  Copper may be purified by solution in  concentrated boiling mu-
riatic acid, and subsequent precipitation by a  bright plate of iron.
  The colours,  and lustre of this metal, are well known.  Its spe-
cific  gravity is  nearly 9.  It is very malleable, very ductile,  and
tonacious.  It fuses at a bright white heat.  By exposure to air,  it 
80
 sustains a slight oxidizement, which is not accelerated nor increased
 by moisture.   At a red  heat it  oxidizes  rapidly,  being convert-
 ed into red oxide, which scales off, if it be afterwards hammered.
 By further calcination, it is reduced to the state of black oxide.
 The precipitate from nitrate of copper, by potash, being exposed
 to a red heat, forms the oxide.
   Copper,  in thin leaves, takes  fire in chlorine, and forms two
 chlorides—a  fixed proto-chloride, and a  volatile per-chloride.   The
 per-chloride, when dry, is of a faint yellow colour, but if moistened
 becomes  green—hence it acts as a sympathetic ink, rendered visi-
 ble by the breath.
   Hydriodic acid precipitates copper from  its solutions, in the state
 of an insoluble iodide.
   Nitric acid, diluted  with three  parts  water, peroxidizes and dis-
 solves copper.  The solution is of a bright blue.   It forms elegant
 blue deliquescent crystals, which moistened and rolled up in tinfoil,
 ignite it.   Heated, they pass to the state of sub-nitrate, of the deut-
 oxide.  Sulphuric acid, boiled on copper, per-oxidizes and dis-
 solves it, as nitric  acid does without heat.  The sulphate resulting,
 forms beautiful blue crystals,  called}n commerce blue vitriol.  This
 salt is obtained also by the torrefaction of the sulphuret of copper,
 and subsequent exposure to moisture and air.
  Carbonate  of copper is produced, when copper  is precipitated
 from its  solutions by alkaline carbonates.   It forms on copper,
 when  exposed  to  most air.   It is found native,  in  various forms,
 remarkable for beauty.
  Alkalies  combine with the per-oxide of copper, and  with the
 salts of this metal.  Ammonia especially dissolves its oxides; and
 when  they are united to acids, produces  triple  salts by its union
 with the compounds.   Cuprum ammoniatum is made, by triturat-
 ing sulphate of copper, with  sub-carbonate of arnpionia.
  Alloyed with a small quantity  of tin, copper forms  bronze—
 with a larger  quantity, bell metal.  Fuzed  with zinc, or subjected
 to the  vapour of an ore of this metal, it  is converted into brass.
  The equivalent for copper is usually  assumed  as  4, but may be
 8.—The equivalents of its compounds may be found, by adding the
 equivalents of oxygen,  sulphur, or chlorine, to one  of these num-
 bers.*

  *  Whether the equivalent of copper be 4, or 8, in the red oxide, the oxygen is,
 to the copper, as 1 to 8, and the black oxide, as 1 to 4. The equivalent of this
 oxide must be 10, in one case—in the other, 5.  The same observation applies to
 the chlorides, adding 4.5 for chlorine, to 8 for the first chloride—and adding
 4.5 to 4, or 9 to 8, for the second chloride.  If the number  for  copper be 8, the
 red oxide is a protoxide, and the black oxide, a deutoxide, or peroxide; the first
 chloride is a proto-chloride, the second a deuto-chloride, or  per-chloride.  If the
number for the metal be assumed as 4, which seems to be preferred, the red oxide
is a suboxide, the black oxide a protoxide; and  the chlorides are a sub-chloride,
and a proto-chloride.  The  case of tfie sulphurets, will be analogous, excepting
that, as there are three sulphurets, one will be a bi-sulphurct, in case copper is 4;
and a tri-sulphuret, in case it is 8. 
 
f ."l
i*Z 
81
  OF TEI1DICBI8, 08 SUBACETATE OF COFFER.--OF CRYSTALS OF TINPS, SIITIIXSS
                   VERDIGRIS, OR ACETATE OF COPPER.

                  EXPERIMENTAL ILLUSTRATIONS.

  Solution of copper, and its precipitation by iron.   Effect
of ammonia:  also of ferro-prussiate of potash.

                            OF IRON.
  The mechanical qualities of this metal, are too well known to
need description.   It is one of the most generally distributed prin-
ciples in the creation, and probably the most universal colouring
matter.  It combines greedily with oxygen, forming a black oxide,
and  a red oxide, and probably others which are of minor impor-
tance.   Ores of iron are principally of the  black, or the red oxide.
The black oxide is magnetic; the other maybe rendered magnetic,
by exposure on charcoal to the blowpipe.  The rust of iron is red
oxide, combined with more or less carbonic acid.  The finery cin-
der, which flies off from incandescent iron in forging, is the black
oxide.   This oxide is formed rapidly, when iron wire is ignited in
oxygen gas; also, when steam is passed over the metal while white
hot.  The  quantity of  oxygen in red oxide,  to  the  quantity in
black, is as three to two.   Water combines chemically with these
oxides, forming hydrates.  Ochre is a hydrate, mixed  with earthy
matter.
   Iron is oxidized and dissolved, when subjected either to diluted
muriatic, or sulphuric acid.  The metal is at first in  the state of
black oxide, but passes  to  that of red oxide, by absorbing the oxy-
gen of the air.  The green muriate, evaporated to dryness, forms
a proto-chloride.   The  per-chloride is formed  by the combustion
of iron in chlorine gas.
   Nitric acid  oxidizes iron, and dissolves  the oxide, as in the case
of other metals.
   Acetic acid causes iron to absorb  oxygen slowly, and  dissolves
the oxide as produced.
   The red oxide of iron combines with carbonic acid, and is solu-
 ble in water impregnated  with this gas.^
   There are two native sulphurets of iron, a proto-sulphuret and a
 deuto-sulphuret:  the former only is magnetic, but the latter may
 be rendered magnetic by roasting, or exposure before the blowpipe,
 by which it loses one proportion of sulphur, and passes to the state

   *  The black oxide, in its nascent state, seems to  me to be soluble in water: for
 when copper, or silver, disks, are alternated with this metal, in pure water, a
 chalybeate taste  is acquired; and a precipitate, of red oxide, soon appears.   The
 solution of the black oxide and precipitation of the red  oxide, may be observed
 also at the Yellow Springs, and other chalybeate waters where iron is in solution
 without any adequate assistance from carbonic acid.
L 
82
 of proto-sulphuret.  It is the proto-sulphuret which is formed by
 the combustion of iron with sulphur.   Iron filings and flowers  of
 sulphur, moistened with water, after some time take fire: heated,
 they incorporate, with the appearance of combustion.
   Iron at a welding  heat,  if touched  with a roll of brimstone,
 falls instantly in drops of melted  proto-sulphuret:  and  an  iron
 wire  burns brilliantly, when exposed to  a jet of Sulphur in va-
 pour,  as it issues from the touch-hole of a red-hot gun-barrel, as I
 have recently ascertained.
   Iron combines with phosphorus.  The presence of this substance
 in a small proportion, renders it brittle, while red-hot.
   With carbon,  iron combines in various proportions,  forming
 steel,  cast iron,  and  plumbago.  PJumbago  consists  of carbon,
 combined with about six per cent,  of iron.   It is  very difficult of
 fusion and combustion.  It was first fused by me  in  1802.   The
 finest kind is seen in the  best  English pencils.  Plumbago of an
 inferior kind, is used as a material for crucibles and small  furnaces.
   Cast iron contains not  only carbon, but silicon, sulphur, and
 phosphorus, and probably sometimes calcium.  It is purified by
 lon^ continued fusion, frequent stirring, and subsequent  hammer-
 in0".
   Pure malleable iron, thus obtained,  is converted into steel, by •
 being  heated in contact with charcoal in ovens  without access  of
 air.   The process is called cementation.  The bars are blistered by
 the operation, as they are  seen in commerce.   Broken  up and
 welded again, they form shear steel.  Fused, they  form  cast steel.
 It has lately been advanced, that silicon is a more necessary ingre-
 dient in steel, than carbon—and that wootz, or Indian steel, owes
 its excellence to aluminum as well as silicon.
   The hardening and tempering of steel and cast iron,  seems to
 depend on crystallization.   The specific gravity is lessened by the
 hardening.
   Iron is equivalent to 3.5, and its protoxide, consequently,  is
 equal  to 4.5.  The oxygen in the peroxide is the same as if two
 atoms of iron = 7 were united with three atoms of oxygen:  of
' course its number would be ten, but it is usually represented as
 consisting of one atom of  iron, and \\ atoms of  oxygen,  or 3.5 +
 1.5=5.  Either  will answer for practical  purposes, but the latter
 is inconsistent with  the atomic theory, agreeably to which  there
 can be no half atoms.
 on Perkins's process for decarbonizing steel,  and recar-
                 bonizing the iron obtained.

     on hardening and annealing malleable metals in
                           GENERAL.

    ALLOYS OF STEEL WITH RHODIUM, PLATINUM, AND SILVER.
ON TINNING, AND TIN PLATE. 
Zt^Zzzz: ^Z£_  *  /5*f ^_^_^
~£*.
A'rt^c £*A?fc&£*tA^ z^Lc  &A
y^C **£r yZZ^r-* *^?ztt- 22feAlf. 
V
N
,•»'*■*■
v
-   A1*-'
ZZf
/,.
A A, A.
***■
At «*  <(V"3^>- 
83
                   OF THE TESTS FOR IRON.
  Iron, in the state of red oxide, is precipitated blue by ferro-prus-
siate of potash—purple or ink-coloured,  by infusion of galls  or
other astringent vegetables—and brown, by  succinates, or  salts
formed by the acid of amber.
  There are four principal classes of ferruginous minerals:—mag-
netic black oxides,  and red oxides not magnetic:*—magnetic  pro-
to-sulphurets, and deuto-sulphurets not magnetic.—Hence the ores
of iron, if not obedient to the magnet, generally become so,  after
exposure on carbon to the blowpipe, by which the excess of  oxy-
gen, or sulphur, which destroys the magnetic power, is expelled.
                  EXPERIMENTAL ILLUSTRATIONS.
   Iron dissolved by muriatic and sulphuric acids.   Red and
black  oxides of iron, and  their solutions, exhibited:  preci-
pitated by galls, and by ferro-prussiate  of potash.  Effects
of  muriate of tin on the  colour of the precipitates.    Iron
burned  in oxygen gas—also,  by sulphur,  and by galvanism.
Ores rendered magnetic by the blowpipe.
       #                  OF NICKEL.
  The colour of nickel is white.   It is magnetic—difficult of fusion
—malleable—and  not  easily oxidized  by the air.   If it could be
procured in sufficient quantities, it would be very valuable in the
arts.  It combines with oxygen, chlorine, iodine, sulphur, and me-
tals.  Its oxides are soluble in the acids.   Its habitudes with them,
are much like those of copper.  The solubility of  its protoxide in
caustic ammonia, is an important mean of separating it from  its
alloys.
                            OF TIN.
   It is sold in  commerce under the name of block tin, to distin-
guish it  from tinned iron  plates.  In utensils newly made of these,
its colour and lustre are seen.   It tarnishes slightly by exposure.
It is very malleable and  ductile.  Its specific gravity is 7.9.  Ex-
cepting  bismuth,  selenium,  and mercury,  it is the  most fusible
metal.   It melts at 442° (F.)  Tinfoil is ^^ of an inch thick.
   Tin  is distinguished by producing a  peculiar  crackling noise,
when its ingots are bended^ to and fro..  It  fprms  two oxides, and
two chlorides.  The- deutO-chloride..is a very singular fuming li-
quid.   A small quantity of water congeals it;  but a larger,  restores
its fluidity.  This chloride has long been known by the name of the
fuming liquor  of Libavius.—The protoxide of tin is soluble  in di-
luted nitric acid.   In  strong acid, it  becomes peroxidized, and, in
that state,  is not soluble.  Boiling sulphuric  acid, whether strong
or weak, converts it into a protoxide,  and dissolves it.  Solutions

  * Considering the number of the oxides of iron doubtful, I designate them by
their colour. 
84
of the nitrate, or sulphate, absorb oxygen,  and deposite the perox-
ide, in a state of sub-sulphate, or sub-nitrate.   Muriatic acid is its
proper solvent;  and the compound produced, is usually considered
as the muriate of the protoxide.  This solution absorbs oxygen,
and deoxidizes oxides, in other solutions.  Hence  it precipitates
gold,  and platina, and hence it destroys the colour of ink, and Prus-
sian blue.  It is always acid.*
   Nitro-muriatic acid dissolves tin with violence, producing much
heat,  and forming a per-chloride  in  solution.   Tartaric acid dis-
solves tin. Either brass or copper are tinned slightly when boiled
with powdered, or leaf tin, and cream of tartar. When cleaned and
immersed in  melted tin, with addition of  oil  WLcosin, to prevent
oxidizement, they become covered with a coat of the fused metal.
   Tin forms  two sulphurets.   The per-sulphuret is of a golden co-
lour, and was known formerly as aurum musivum.

   The equivalent for tin is         -    -     -     -     -  7.25
   That of its protoxide   -------  8.25
       of its peroxide   -------   9.25
       of its proto-chloride......11.75
   The perchloride is probably      -----   16.25
   Although the fuming  liquor of Libavius appears to contain  an
excess of chlorine.

                  EXPERIMENTAL ILLUSTRATIONS.

   Tin exhibited, in the state of  ingots,  and  of tinfoil:  its
deuto-chloride, or the fuming liquor  of Libavius, shown.
Reaction of nitric acid, or nitrate of copper, with tin pow-
der.   Solution of  tin, by muriatic  acid—and effect  of the
muriate, thus  obtained, on  other metallic solutions.   Dis-
colouration  of ink, and of Prussian  blue.

OF BRONZE—OF BELL-METAL—OF  SPECULUM-METAL—OF .PEW-
                             TER.

                           OF LEAD.
  The colour, lustre, and  malleability of this metal, are well known.
It fuses at about 600°  (F.).  Its specific gravity is  11.352.  It is
the most ductile metal in large masses, as it may be  drawn into
pipes  of four  inches bore—but it is too deficient in  tenacity, to  be
drawn into fine wire.  It is very useful to chemists, being employ-
ed in the  manufacture of sulphuric acid and chlorine.   Leaden tubes
and vessels are not easily injured by moisture, or acid fumes.
  Two oxides of lead are usually  met with in commerce.  One

  * This does not arise from an excess of acid, as there is none in it which is not
essential to the  compound.  Hydrogen, oxygen, and chlorine, are present—and
though tin be combined with them, it does not totally destroy those attributes
of acidity, which they otherwise display when united. 
85
called massicot,  or when vitrified, litharge; the other minium,
or red lead.
  A peroxide of lead, of a puce colour, is obtained by exposing red
lead, suspended  in water, in an impregnating apparatus, to chlo-
rine gas.
  Lead is  oxidized  and  dissolved, when subjected to nitric acid.
Neither sulphuric, nor muriatic acid, has any action on it, when
cold.   Sulphuric acid, when boiling and concentrated, oxidizes,
and combines with it, forming an insoluble sulphate.
   Lead is also oxidized and dissolved by acetic  acid, and forms a
soluble acetate, and sub-acetate.   The acetate is called in commerce,
Sugar of Lead.
   When exposed to  the fumes of vinegar, which consist of acetic
acid, and carbonic acid gas, lead  is oxidized by the acetic acid, and
combines with the carbonic acid, forming ceruse, or the white lead
of commerce.                         4
   Chlorine  combines with  lead, but the resulting chloride being
fixed and insoluble, protects the metal from further erosion.  Hence
the utility of leaden  vessels, in manufacturing chlorine in the large
way.
   The most prolific ore of  this metal, is the sulphuret, called ga-
lena.   Exposed  to the  blowpipe, the sulphur of galena is driven
off, and the metal  appears in a globule.
   Lead is precipitated from its solutions by sulphates,  chromates,
phosphates, and  muriates; and its presence in very small quantity,
is shown by sulphuretted hydrogen.

   Lead is equivalent to-    -    -     -    -    -    -13
   Its protoxide  to    --------   14
   And its peroxide to     -    -    -     -    -    -    -15
   An oxide, which Dr. Thomson calls the deutoxide, is alleged by
him to consist of 2 atoms of metal, united with three atoms of oxy-
gen ;  and of which the equivalent is 29: or, considering it as a
compound of 13 lead, and 1| atoms of oxygen, its equivalent  is
14.5.
                  EXPERIMENTAL ILLUSTRATIONS.
   Solution of lead in nitric acid.   Its solutions precipitated
by sulphates, muriates, phosphates, and chromates.  Also
by sulphuretted  hydrogen.   Precipitation  of carbonate of
lead, from  the  sub-acetate,  by  the  carbonic  acid of  the
breath.   Galena decomposed by the blowpipe flame.
                           OF  ZINC.
   This metal is  best known in commerce, under  the name of Spei-
tre, or Spelter.  It is usually adulterated by lead  and sulphur;  and
sometimes by a  metal lately discovered, called Cadmium.   It may
be obtained;^] re, by allowing  diluted sulphuric acid to act on-an
excess of the metal, when the zinc will be taken up in preference. 
86
The oxide is to be precipitated from this solution by pearlash, and
the metal revived by ignition with charcoal.

                     PROPERTIES OF ZINC
  Its colour is brilliant white, slightly tinctured with a leaden hue.
Its  specific  gravity about  6.86, being, excepting the metalloids,
among the lightest of the metals.  Under ordinary circumstances,
it is not malleable, but  may  be laminated by rollers, at a heat
somewhat above boiling  water.  It melts at about 6S0° (F.).   Its
structure is strikingly crystalline.  It is slightly oxidized by expo-
sure to the atmosphere; but at a white heat, burns rapidly, giving
off  fumes of oxide.   This is  the only  known oxide of zinc,  and
consists of about 80 parts metal, and 20  oxygen.
  Water is rapidly decomposed, when passed in the state of steam
over ignited zinc, or when presented to  it together with a due pro-
portion of sulphuric, or muriatic acid.
  Zinc is soluble in nitric and muriatic acids, being  oxidized  by
the water in the one case—in the other, at  the expense of a portion
of the nitric acid.  It forms a chloride, when subjected in a divided
state to chlorine gas.   This chloride has been called, from  its con-
sistency, butter of zinc.
  Acetic acid may be combined with zinc, by mixing its sulphate,
with acetate of lead.
   Brass is an alloy of zinc with copper.
   The equivalent  for zinc  is 4.25.  It forms but one oxide, whose
equivalent is 5.25; as it  contains only one  atom of oxygen.
                  EXPERIMENTAL ILLUSTRATIONS.
    Zinc subjected to diluted sulphuric, and diluted muriatic
 acids, severally.   Arbor Saturni, produced by it, in  a  solu-
 tion of acetate of lead.   Combustion of the metal in an in-
 candescent crucible.   Its habitudes with the blowpipe.

                          OF BISMUTH.
    This  metal  is found in commerce in a state of sufficient purity.
 Its fracture is crystalline,  like that of zinc  and antimony; but a pe-
 culiar blush distinguishes it.   Its specific gravity is 9.822.   It is
 not malleable.  Excepting selenium, mercury, tin, and the metal-
 loids, it is the most fusible metal.  Its fusing point is 476° (F.).
 It is oxidized, when kept in fusion in the  air.
    Subjected to sulphuric acid,  bismuth is  partly dissolved,  and
 partly converted  into an insoluble oxide.
    Nitric acid dissolves bismuth, and  forms a compound, which,
 when added to water, yields  an insoluble hydrated oxide, called
 magistery of bismuth, or pearl white.
  iJBismuth, when subjected,  in a divided state, to chlorine  gas,
 takes fire, and forms a chloride.                  0
    Most of the metals may be alloyed with bismuth.   Eight parts 
^A- £y    A e   i
&L-
(A,
c /,
/::.&
t-r.-^-e i*.
Z?C d   ,
ti^j  ^   y z c
             /
j-f-i*  'Z~~   tteeet^  c*  /Pt^t.<-cA.   —    '/  ZA <  /«■   a  t.-1>.
■  ~Cu...... Kjl-
.'. ■ -U-c<.
6  Z^-t
U*~ .  /   ,-,.,    I    7<U.C/>  AA.^h   Aci
{.■ [ t J C <~L*L t
A-
f-/    .//•■' ' *''**■ *'    £*-■  CrA*hi t*^. •   #„.
X>"3
^«y  Sct-K,^ ,   u- P  A*-*. A*  c^Z
            zZ               -^     /
/A    S  v    /
h.
jf? **--( * A'i  Z «t-%-~l*- ■'    n,  J  ;•;.-<«..

   (AAOf 7U**+,-''t7  Sc±* Zy   At. i<_ , ,  Ac c-/  .  iu', C  Zc*t i..

 ■*■  ! << i t est  £t*    V*- "??;..., /tow ,  Vt/   Ju/~ /c  /%'.-.<  '■ 
 
87
 of this metal, with five of lead, and three of tin, form a compound,
 fusible in boiling water.
   Bismuth is used in solder, to render it more fusible.

                  EXPERIMENTAL  ILLUSTRATIONS.
   Bismuth, and its oxide, exhibited.  Its hue, and habitudes
 with the blowpipe, compared  with those of zinc, antimony
 and arsenic.

                         ON ANTIMONY.
   This metal, in the state of regulus, has become an object of com-
 merce, on account of its utility as an ingredient in type-metal, and
 in pewter.

                   PROPERTIES OF ANTIMONY.
   It is crystalline in its fracture, and of a very fine silver white.
 It does not tarnish much in  the  air.   It is neither malleable,  nor
 ductile.   Before the blowpipe, it fuses at a low red heat, and  oxi-
 dizes rapidly, and if thrown upon a board, while melted, is  dis-
 persed in  red-hot globules, whose temperature appears to be  sus-
 tained by their combustion.
   The information given by different chemists,  on the subject of
 antimony, is very discordant.  According to Berzelius, there are
 four  oxides.  According to Proust,  and Brande, there are only
 two.   Henry considers the argentine flowers,  which  volatilize
 during combustion, as the  peroxide, while Brande alleges  that
 they are the  protoxide.  Dr. Ure informs us, that antimony forms
 four oxides,  probably—certainly three;  and that the deutoxide of
 Berzelius, is the efficient oxide, which enters into the most  useful
 preparations.
   There seems a coincidence between these chemists, so far as this,
 that the medicinally efficacious antimonial oxide, is that which may
 be precipitated from a  solution of antimony in muriatic acid, by
 an alkali, or which is  obtained by boiling* sulphuric acid on  the
 metal to dryness.   The oxide thus obtained, by sulphuric or  mu-
 riatic a/;id, appears to be the same as that which exists in tartrate
 of potash and antimony, (tartar emetic,) however this  triple com-
 pound may be made.
   Hence the protoxide of Brande, or deutoxide of Ure,  the oxidum
 antimonii of  the pharmacopoeias,  may be obtained by adding to  a
 solution of tartrate of potash and antimony, sub-carbonate of ammo-
 nia, and boiling the mixture till the oxide precipitates.
   The peroxide of antimony, is formed by igniting powdered anti-
mony, with six times its weight of nitre.   The compound is attrac-
tive of alkalies rather than of acids; and therefore maybe consider-
ed as belonging to the latter class.  It is alleged to be inert, medi-
cinally.
   There is an oxide of antimony produced, by dissolving the metal
in nitric acid, evaporating to dryness, and  igniting  the residuum. 
88
This, by Berzelius, Ure, Henry,  and others, is considered  as  aq
intermediate oxide, between that obtained by muriatic or sulphuric
acid, or from emetic tartar, and the peroxide (or acid) procured  by
the action of nitre.   It is alleged to have acid properties, and to be
the same compound, as the precipitate produced in a nitro-muriatic
solution of antimony, by the addition of water.   This precipitate
has been called powder of Algaroth.   It is obtained, when chloride
of antimony is thrown into water.  The formation of this chloride
was  shown, in order to  illustrate the properties of chlorine  as  an
agent in  combustion.   Pulverized  antimony  was spontaneously
ignited, in falling through the gas, and chlorides, or butter of anti-
mony, formed.   The same compound results from  the distillation
of corrosive sublimate, with antimony in powder.
  Sulphur and antimony exercise a powerful affinity for each other.
This metal exists most abundantly in nature, in  the state of sulphu-
ret.  It is thus found in commerce, under the name of crude anti-
mony; while the metal,  as used by type-founders is called regulus of
antimony.   To obtain antimony from  its sulphuret, we are directed
to ignite two parts of it, with one of iron  filings, and half a part of
nitre.  The sulphur having a greater affinity for iron, leaves the
antimony for this metal, and the nitre probably  oxidizes any excess
of the sulphur.   In order to complete the purification, the  impure
antimony, thus  obtained, must be dissolved in  nitro-muriatic acid,
and the compound produced subjected to water: the  oxide result-
ing,  is then revived by ignition with crude super-tartrate of potash.
  When the sulphuret of antimony is roasted, under such circum-
stances, as to expel a portion of the sulphur, and  partially to oxi-
dize  the metal; the residuum may be  fused into a glass, containing,
according to Henry,  " eight parts of oxide and one of sulphuret,
with ten per cent, of silex."  If the quantity of sulphuret  be dou-
bled, a  compound, called  crocus metallorum,  is  obtained.   The
metal, in these compounds, is  not  peroxidized, and is probably in
the same efficient state as in tartar emetic.  When the sulphuret of
antimony is boiled with potash, sulphurette&hydrogen is produced,
by the decomposition of  the  solvent. Thti^ombines with the
oxide, and forms a hydro-sulphuret of antimony, which«precipi-
tates.  This hydro-sulphuret has long been known under^thc name
of kermes mineral.   After a solution, from which kermes'has been
precipitated, is cooled,  an acid causes a  further  precipitation  of
oxide of antimony, combined with bi-sulphuretted hydrogen.   The
compound  thus procured, may be deemed a sulphuretted hydro-
sulphuret, and has been known under the name  of golden  sulphur
of antimony.
  Sulphuret of antimony, and boiled hartshorn shavings,  roasted
first, and afterwards  ignited in a covered  crucible to  prevent the
too great oxidizement of  the metal, constitute the  materials of
James's powders, or the oxide of antimony with phosphate of lime,
or pulvis antimonialis of the pharmacopoeias.
  According to Brande, the preparations sold under this name, 
 
 
89
vary, both with respect to the  proportion of the ingredients, and
the degree of oxidizement of the metal.   According to Philips,
they are often inert from containing peroxide only."  A solution
of known quantities of phosphate of lime (or bone-earth) and of an-
timony, in muriatic acid, and  precipitation  by ammonia, has been
proposed as a process, for making a  preparation, of a more  certain
efficacy.   It is however suggested, both by Brande and by Philips,
that the tartrate of potash and antimony may be advantageously
substituted for every other antimonial medicine.
   Dr. Thomson, in his late work upon  the principles of chemis-
try, alleges that there are three oxides of antimony : a protoxide,
which consists  of  one atom of metal with  one atom of oxygen;
a deutoxide, consisting of two atoms of metal, with three of oxygen;
and a peroxide, consisting of two atoms of oxygen, with  one of
metal.
   According to the same author, the equivalent of antimony is  5.5
   Of its protoxide   --------   6.5
   Of its peroxide   --------   7.5
   Whilst  the equivalent  of  its deutoxide may be assumed as equal
to 7, or  to  14,  accordingly as  it is estimated  to consist  of two
atoms of metal, with three of oxygen, or one atom of metal, with
one and a half atoms of oxygen.
   According to the same author, there are two chlorides of anti-
mony :
   A subchloride, consisting of 2 atoms metal    -     -     11.
                           of 1  „   chlorine -     -      4.5
                                                     15.5

Also, a protochloride, consisting of 1 atom metal   -      5.5
                              of 1  „   chlorine       4.5
10.
  Kermes mineral, agreeably to the same authority, contains of
antimony, sulphur, oxygen, and hydrogen, each one atom: that is,
of
                                          Antimony     5.5
                                          Sulphur        2.
                                          Oxygen        1.
                                          Hydrogen      .125
                                                        8.625
  It may be considered a compound of one atom of sulphuret of
antimony, and one atom of water; and may be viewed either as a
hydrated sulphuret, or hydro-sulphuretted oxide.   In the golden
sulphur of antimony, there is probably one atom of sulphur  more
than in the kermes.
             * See Annals of Philosophy, for October, 1822.
                              M 
00
                  EXPERIMENTAL ILLUSTRATIONS.
  Antimony and its sulphuret exhibited and exposed to the
blowpipe; also the  crystals and solution  of tartar emetic.
Kermes mineral, and golden sulphur of antimony, exhibited.
Antimony subjected to acids.
                         OF ARSENIC.
  This metal is sold in commerce under the name of cobalt, and
is vulgarly known as fly-stone.  In this state,  as it  is very full of
crevices, and exceedingly attractive of oxygen, it is difficult, even
by a fresh fracture, to see  the  true colour  or lustre of the  metal.
  In order to obtain this object in perfection,  the cobalt, (as it is
absurdly named,) should be pulverized  coarsely, and as much in-
troduced into a glass tube, sealed at one end, as may not more than
half fill it.  The tube should be introduced  into a cylinder of iron
closed below.  The but of a gun-barrel will  answer.  The space
between  the iron and the glass should be filled  with sand, and ano-
ther gun-barrel applied above, so as to catch the fumes, and con-
duct them into a chimney.  That portion of the glass tube, which
contains the arsenic, should be kept red-hot for about half an hour.
After the apparatus is quite cool, the metal  will be found in crys-
tals of great splendour,  occupying that  portion of the glass tube,
which was just beyond the red heat.
  Arsenic is distinguished from other metals, by its yielding white
fumes, which have the odour of garlic, when exposed to the blow-
pipe, or placed on a hot iron.   These fumes,  however,  might be
confounded with those of antimony, by a person deficient of expe-
rience, were it not that the latter fuses, before it fumes, and, thrown
upon a board, after fusion, spreads itself abroad, in red-hot balls.
  According to  the. opinion of Berzelius, which is adopted byThe-
nard, the black  matter  into which arsenic  is  converted, by expo-
sure to the air, is a protoxide, and the fumes  yielded by the com-
bustion of the metal are the deutoxide.  These fumes, condensed
as they are evolved, on a large scale, during some metallurgic ope-
rations, constitute  the white arsenic of the shops.  By Henry, and
many other chemists, white arsenic is considered as the  protoxide
—and they deem the black matter, into which  arsenic is converted
by  the action of  the air, as a mixture of white arsenic with metallic
arsenic.  This conclusion  appears irreconcileable with the fact as-
certained by Berzelius, that the exposure  of arsenic to air, never
causes an absorption of more than eight per cent, of oxygen, while
the white oxide  contains thirty-two per cent.  It seems very im-
probable, that, under the  same circumstances, one portion of the
metal should absorb thirty-two per cent, of  oxygen, while,  by ano-
ther portion, none is absorbed.
  There is also  another combination of arsenic with oxygen, ob-
tained by deflagrating the metal with nitre,  or  by digesting it with
nitric acid.   In  this the oxidizement is admitted to be at a maxi-
mum.   The white oxide of arsenic, and the peroxide, are also call-
ed  arsenious and arsenic acids, as they combine with alkalies, and
do  not combine  with acids. 
 '■;<  Z^<u^* tA^AsZ/z^^  Ay  ZzZsc^c+Z/7^ ^A^z^z'cC
7L-A~  ZZZ^  ,~<z*^a <*Z, &^<2 ^j^^-  7^7 &AZZZ^ZZ
 -  a ZLrZiA^z:^^ ^_ /U^y fZZZZZz7 zt^~^AL


 A   7A~ ~z£AL a, z*^z£zz& -  z%£/L^. 7tc<AzZ7r
 d  &-  A ZiZA ZtyfZ^ Az> ^f <AA- y^^A ^.
 ^ ^^1^, , 72^2 ~~7%A«« „ jA^*^,  Z^x^Ce  {Zc^se^gL
AZA
/
  Ac*-* ** <■ 7  ^V oAA x^a^sZy  a**-, zf^zt^Ay^
yy^          '              Z   . Z
Z/<Lt^  tZt^c-sZ*^^ n ■ ~A^ ZZoC*- z£AA^ZZ^_
                         7%ZAc~<r*~-,  ^a^ZUs^,
<2.yi*-^£— Z*-z^  ^.  z^Acft^^- ZA *^A/ zt^-Z^ 7%A^r
A^
a
z^*c
  sA JA<*><^*£  *£- ~Z%Z  Az* &A PzL^^  z^Aa^z^
//,z^~*A-- *Zy tUc^A. A^- AZAc^, A- —  tACz
Szi~%zfe  A^ic^f  AJA-   d^c</ £<^<l-*t.
a*-£~z>
/*■ /t~*~
Ol^u^-Zi
<r^
7
2 z^ ZrzrzAAZizly ZZZex. 
d, -	« -:A# /JL*' <£>* < ■-* */*-*• <*/ ^AZt. <<^t
AA ,,- .-■«	<• ' -.le-C-V , -AAA <£■••■ /**-«,- *V.-.-- «?
4c*~C*	V^/,- *-.\, /^ • .& *-/<?*
W Atr	<,♦ £*- f' w<-
/'
/
^^f.  ^  yZr-e.c£A>, <kLt-  Tt-rys Z^-
zs
~7
z>Z%Z.
u
fu~*~<~.. &A
^1^_
A?
.r*s
2 *   z,^
  ZyA /%ZZ sZi^yAzZ^!^-




   sAr-tsc-c-*, /^A^m^AL.  a. ^zAA*A y* z£**~—-^



 '^€^-^^2^t: —  ^Z£—   4L   A&^^'Z *Z K6.zXc.a-



y&£Az^f  iA  /&7~z**~-z^b s A «-*'  £*?-*«- y zi  ^*<A
/z
-■&.
y^A /*-*<—  &***








Zc^t^.yy? ju—y  Ste**^TD 4L' ~Z&=d
Y'
*^ i^Z2>
t^  aZa*^
>y&^^.&>y£:<-. 
91
  Fowler's solution, is madeT5y boiling pearlash on the white ox-
ide.   It is an arsenite of potash.  An arseniate is obtained, by de-
flagrating white oxide with nitre, agreeably to one of the processes
of the Pharmacopoeias.
  Arsenic is found, in nature, in combination with  sulphur, in dif-
ferent proportions.  The compound containing the least sulphur,
is of a fine red colour,  and is called realgar—the other sulphuret is
yellow, and is called orpiment.
   The arsenites, or arseniates,  yield precipitates with solutions of
copper or silver, and destroy the blue colour of the ioduret of starch.
In the instances of copper and silver, arsenites or arseniates of those
metals are formed.  The arsenite of copper is  of an apple green,
called Scheele's green.—The arsenite of silver is yellow—the arse-
niate, brick red.
   The equivalent of arsenic is.....4.75
   Of arsenious acid, which contains two atoms oxygen, the
     equivalent is--------  6.75
   Of arsenic acid, which contains three atoms of oxygen   -  7.75
   Besides these  there is the black oxide, or protoxide,  probably
consisting of one atom  metal, and one atom of oxygen.
                     OF ARSKNURETTED HYDROGEN.
OF THE MEANS OF DETECTING  ARSENIC IN FOOD OR DRINK, OR IN
   THE CONTENTS OF A STOMACH, IN CASES WHERE POISONING IS
   SUSPECTED.
                   EXPERIMENTAL  ILLUSTRATIONS.
   Habitudes of arsenic,  as obtained by sublimation,  in its
metallic crystalline form, contrasted with those of zinc,  an-
timony, and bismuth.  White oxide, and its solutions,  exhi-
bited:  also,  Fowler's solution,  or  arsenite  of potash.   To
large vessels of clear water, measured quantities of arsenic
are added,  and detected  by various  tests.  Combustion of
arsenuretted hydrogen displayed.

           OF VARIOUS METALS OF MINOR IMPORTANCE.
OF RHODIUM, IRIDIUM, OSMIUM, COBALT, MANGANESE,  CHROME,
   MOLYBDENUM,  URANIUM, TUNGSTEN,  TELLURIUM, SELENIUM,
   TITANIUM, COLUMBIUM, OR  TANTALUM, CERIUM.
                    END OF THE MINUTES.

  For the rest of the course, see " Supplement to the Minutes," containing lectures on
vegetable and animal chemistry.
  I shall conclude this volume -with a quotation, from some tables, recently published by
Dr. Thomson, in his Principles of Chemistry.   In placing them before the medical
student, I am actuated by the desire of facilitating, 7-athjr than enforcing, attention to
the curious and useful knowledge -which they contain. 
                92



           TABLE  I.
SPECIFIC GRAVITY OF THE GASES.
Air       ...
Hydrogen  .
Carbon vapour
Carburetted hydrogen
Ammonia
Steam
Phosphorus vapour
Phosphuretted hydrogen   .
Hydrocyanic acid vapour   .
Bihydroguret of phosphorus
Carbonic oxide
Azotic gas  .
Olefiant gas
Deutoxide of azote
Oxygen
Sulphur vapour
Sulphuretted hydrogen
Muriatic acid
Oil gas
Carbonic acid
Protoxide of azote .
Cyanogen  .
Protoxide of chlorine
Chlorine
Naphtha vapour
Nitric acid  vapour
Oil of turpentine vapour


                           TABLE II.

SPECIFIC  GRAVITY  AND  ATOMIC WEIGHTS  OF  THE
      GASES REFERRED TO  OXYGEN GAS AS UNITY.

     I. GASES WHOSE ATOMIC WEIGHT = SPECIFIC GRAVITY.
ATOMIC WEIGHT.	SPECIFIC GRAVITY.
	
SP. GRAVITY
  AT 60°.
1
0-0694
0-4166
05555
0-59027
0625
0-8333
09027
0-9375
09722
0-9722
0-9722
0-9722
104166
Mill
11111
1-1805
1-28472
1-4583
1-5277
1-5277
1-8055
2-4444
2-5
2-9166
375
5-0130
ElGHTOtflUW
UBICINCHES
IX GRAINS.
 30-5
  21180
 12-6083
 16 9444
 18-0035
 19-0620
 25-4166
 27-5376
 28-5720
 29-6527
 29.6527
 29-6527
 29-6527
 31-7708
 33-8888
 33-8888
 36-0069
 39-1839
 44-47917
 465972
 46-5972
 55-0694
 74-5555
 76 25
 88-9583
114-375
152-8960
Oxygen gas      ......     1       1
Fluosilicic acid    ......     3-25     3-25 
93
II. GASES WHOSE ATOMIC WEIGHT IS DOUBLE THE SPECIFIC
                           GRAVITY.
a. Simple Bodies.
Hydrogen gas
Carbon vapour
Phosphorus vapour
Azotic gas
Sulphur vapour
Tellurium vapour
Chlorine gas
Arsenic vapour
Selenium vapour
Iodine vapour
ATOMIC	SPECIFIC
WEIGHT.	GRAVITY.
0-125	0-0625
0-75	0-375
1-5	0-75
175	0-875
2	1
4	2
4-5	2-25
4-75	2-375
5	2-5
15-5	7-75
b.  Compounds of Simple Combustibles and Hydrogen.
Carburetted hydrogen
Phosphuretted hydrogen
Subphosphuretted hydrogen
Bihydroguret of phosphorus
Olefiant gas
Oil gas
Sulphuretted hydrogen
Telluretted hydrogen
Oil of turpentine  .
Arsenietted hydrogen
Selenietted hydrogen
ATOMIC	SPECIFIC
WEIGHT.	GRAVITY.
1	0-5
1-625	0-8125
1-25	0-625
175	0-875
1-75	0-875
2-625?	1-3175?
2-125	10625
4-125	2-0625
9-125 ?	4-5625?
4-875	2-4375
5125	2-5625
c.  Compounds of Simple Combustibles and Oxygen.
Steam
Carbonic oxide gas
Carbonic acid
Protoxide of azote
Nitric acid vapour
Sulphurous acid
Sulphuric acid vapour
ATOMIC	SPECIFIC
WEIGHT.	GRAVITY.
1-125	0-5625
1-75	0-875
2-75	1-375
2-75	1-375
6-75	3-375
4	2
5	2-5
d. Miscellaneous Compounds.
Cyanogen  .
Fluoboric acid
Bisulphuret of carbon
Chlorocarbonic acid
ATOMIC WEIGHT.	SPECIFIC GRAVITY.
3-25 4-25 4-75 6-25	1-625 2-125 2-375 3125
 
91
in.
GASES WHOSE ATOMIC WEIGHT IS QUADRUPLE THE SPECIFIC
                      GRAVITY.
^Vmmoniacal gas
Hydrocyanic acid vapour
Deutoxide of azote
Muriatic acid
Hydriodic acid
ATOMIC	SPECIFIC
WEIGHT.	GRAVITV.
2-125	0-53125
3-375	084375
3-75	0-9375
4-625	1-15625
15-625	3-90625
                   TABLE III.

ATOMIC WEIGHTS, OR CHEMICAL EQUIVALENTS,
         ALPHABETICALLY ARRANGED.
      03* See Thomson's Principles of Chemistry, vol. 1, p. 94.
	ATOMIC		ATOMIC
	WEIGHTS.	Chloride of potassium	WEIGHTS.
	Oxy. = 1		Oxy. = 1
Acetic acid	6-25		9-5
Ditto, in crystals	7-375	silver . .	18-25
Alcohol ....	2-875	sodium	7-5
Alum ....	60-875	strontium	10
Alumina ....	2-25	sulphur .	6-5
Aluminum	1-25	tin .	11-75
Ammonia ....	2-125	Chloride of zinc	8-75
Antimony ....	55	Chlorine ....	4'5
Arsenic ....	4-75	Chromate of lead	20-5
Arsenic acid	7-75	Chromic acid	6-5
Arsenious acid .	675	Citric acid ....	7-25
Azote ....	1-75	Ditto, in crystals	9-5
		Copper ....	4
Barium ....	8-75	Cyanogen ....	3-25
Barytes ....	9-75		
Bitartrate of potash	20-125	Ether, sulphuric	4-625
Boracic acid	3		
Boron f . . .	1	Fuming sulphuric acid	11-125
Brucia ....	51-5		
		Gallic acid	7-75 ?
Calcium ....	2-5	Gold.....	25
Carbon ....	0-75	Gum.....	11-25
Carbonate of ammonia	3-875		
barytes .	12-5	Hydrogen ....	0-125
iron	7-25	Hyposulphurous acid	3
lead	1675		
lime	6-25	Iodine ....	15-5
magnesia	8-625	Iron.....	3-5
potash .	11		
soda	18	Kermes mineral	8-625
Carbonic acid .	2-75		
oxide . . .	1-75	Lead ....	13
Carburetted hydrogen	1	Lime ....	3-5
Chloride of antimony	10	Lithia ....	2-25
copper	8-5	Lithium ....	1-25
mercury .	29-5		
platinum .	16-5	Magnesia ....	2-5
 
zZA^r z*.JzA ^AZ^z
^ zizzi>,   z^<~2  7t£- z~* s^^zz -sz:<z2  A
^<u c~A^?<ugzs>  z~~ ^—  .:4z$z^y AAztA- /£a*- <z_
 &AI   slt^AzZL-tAL  ^AT5  ^*^L^TD—pC

  7zLA~  AZz^ci^^z^^ Zt-<^A^> J^ 
 
95
	ATOMIC				ATOMIC
	WEIGHTS.	Protoxide of iron			WEIGHTS.
	Oxy. = 1				Oxy. = 1
Mercury ....	25				4-5
Morphia ....	40-25	lead			14
Muriate of barytes	15-5	platinum			13
copper	11-875	potassium			6
iron	12-5	sodium			4
lime	14-875	tin			8-25
Muriatic acid	4-625				
	»	Red oxide of lead			14-5
Nickel ....	3-25				
Nitrate of ammonia .	10	Silica ....			2
barytes	16-5	Silicon			
iron .	19125	Silver			13-75
lead .	20-75	Soda			4
lime .	17	Sodium			3
mercury	35	Starch			17-75
potash	12-75	Strontian			6-5
silver	21-5	Strontium			5-5
soda	10-75	Strychnia			475 ?
Nitrous acid	5-75	Suboxide of copper .			9
Nitric acid	6-75	Succinate of ammonia			10-625
		Succinic acid			6-25
Oil gas ....	2-625	Sugar ....			10-125
Olefiant gas	1-75	Sulphate of alumina .			15125
Oxalate of ammonia .	8-875	ammonia .			8-25
potash	11-625	barytes			14-75
lime	10.25	copper			15-625
Oxalic acid	4-5	iron			17-375
Oxide of bismuth	10	lead			19
copper	5	lime			10-75
silver .	14-75	magnesia			15-375
zinc	5-25	mercury .			33-25
Oxygen ....	1	potash			11
		silver			19-75
Palladium ....	7	soda			20-25
Perchloric acid .	11-5	strontian .			11-5
Peroxide of antimony	7-5	zinc			18-125
gold	28	Sulphur ....			2
iron	5	Sulphuret of antimony			7-5
lead	15	arsenic			6-75
mercury	27	calcium			4-5
platinum	14	copper			6
potassium	8	iron			5-5
tin .	9-25	lead			15
Phosphate of ammonia	7-875	mercury			27
iron	11-375	potassium			7
lead	17-5	silver .			15-75
potash .	10-625	sodium			5
silver .	18-25	zinc			6-25
soda	21	Sulphuretted hydrogen			2-125
Phosphoric acid	3-5	Sulphuric acid .			5
Phosphorous acid	2-5	ether			4-625
Phosphorus	1-5	Sulphurous acid			4
Phosphuretted hydrogen .	1-625				
Picrotoxia	45	Tannin ....			8-75 ?
Platinum ....	12	Tartar emetic .			4425
Potash ....	6	Tartaric acid			8-25
Potassium ....	5	crystals			9-375
Protoxide of antimony	6-5	Tartrate of iron			15
gold .	26	lead		■	22-25
 
96
Tartrate of lime
          potash
Tin   .

Urate of soda
Uric acid
ATOMIC WEIGHTS.	Uric acid crystals Water .... Zinc.....	ATOMIC WEIGHTS.
Oxy. = 1		Oxy. = 1
16-25 16-5 7-25 14-125 9		11-25 1-125 4-25
 
V
<*  . 
:  1
^fc—/t^«-
Or"  £c~,irx^,e^y   &->-  A&~- Z&^**

        zy' ,Zc^-^ c -^  **-r *^- -TZzxZ-




<zzAtz  ZwzA€~*~y£ z^&-<4i7sc*A-




                         <*- s&«... +A




                          Jc~-*aZ&ZZ- .

^
/ 
 

y
\ 
*:*•
      •*•• •"






: v.■•** *;.

";>>;■.
.*. •, * <
  A »
,4
*♦*
,r.

*'»
'.'.i 4
\
...&&.
'$**.;
*w