The Seattle post-intelligencer. [volume] (Seattle, Wash. Terr. [Wash.]) 1888-1914, 1900-12-30

grape and cane sugar and has prepared
many new varieties; and II appears hhSey
that the terpehes, a class Of bodies alileu
to turpentine, and comprising most OF the
substances TO which the odor OF flowers Is
due, may thereby find their explanation
II may be mentioned in passing that Pas,
teur. having found that ordinary mold
destroyed one variety of tartaric acld
rather than the other in mixture OF the
two, and made use of this observation IN
order TO prepare the unattached variety
in state of purity. was led 70 STUDY the
action OF organisms more or less resem-
bling mold: and that this has led TO the
iology, which has had an enormous innu-
ence on our views regarding fermentation
IN general, and guides the work OF our
physicians our surgeons witness Listers
antiseptic treatmenD, our sanitary engi-
neers in their estimate of the purify OF
drinking water and OF the uisposai OF
spirits, of wine growers, and more re-
Gently of farmers. All these processes
depend upon the action of organisms IN
producing chemical changes, whether IN
the tissues of the body, causing or curing
disease, or in the production OF naNored
alcohol from sugar. or in the manufacture
of butter and cheese. or in preparing the
land for the reception of crops. We also
owe to the genius of Van L Hon the most
important advance of recent times in the
region of physical chemistry. 1t had been
observed by Rnoult. professor at
Grenoble, that the freezing point of sol
vent as a general rule is lowered to the
same extent If there be dissolved IN IL
quantities of substances, proportional TO
their molecular weights. Thus suppos-
ing 1.S0 grams of grape sugar be dis
solved in 100 grams of water and the So
luton cooled below degree with constant
stirring, ice separates suddenly in thin
spicules, and the temperature to-OlsS de
gree. If 3.42 grams of cane sugar be
similarly dissolved in 100 grams of water.
the freezing point of the solution is again
-0.1S5 degree. Now $50 and 3.i2 are re-
spectively the hundredths part OF the
weights Of grape sugar csHH oJ
and cane sugar, CiaHgo.i. Similarly:
Raoult found that quantities proportional
to molecular weights dissolved In solvent
depress the vapor pressure OF that solvent
thing, raise its boiling point by an equal
number of degrees. But ordinary salts,
such as sodium chloride, potassium
nitrate, etc. dissolved in water. give too
and too high a boiling point. Next, It
had been observed by botanists, Devrles.
Pfeffer and others, who had examined
the ascent OF sap in plants, that II yes
sci of unglazed porcelain, so treated as
TO cause a film of cupric ferrocyanide "a
shiny red compound) TO deposr in the
pores of its walls, be filled with weak
(about l per cent? solution Of sugar or
similar substance, and plunged In "A yes
sci of pure water, water entered through
the pores. BY attaching a monometer to
the porous vessel the pressure exerted by
the entering water could be measured.
Such pressure was termed "osmotic
passage through the walls of the vessel.
Such prepared walls are permeable freely
to water. but not to sugar or similar
bodies. Van t Hoff pointed out that the
total pressure registered is proportional
to the amount Of substance in solution,
and that 10 is proportional to the absolute
temperature, and he showed, besides,
that the pressure exerted by the sugar
molecules is the same as that which
would be exerted at the same temperature
were an equal number of molecules OF
hydrogen to occupy the same volume as
the sugar solution This may be expressed
by stating that when in dilute solution
sugar molecules behave as II they were
present in the gaseous state. Here again.
however, IL was noticed that salts tended
10 give higher pressure IT was difficult
to construct a semi-permeable diaphragm,
however, which would resist the passage
of salt molecules while allowing
those of water to pass freely. Lastly, Ar
rhenius of Stockholm had shown that the
conductivity of salt solutions for electric
that when a salt, such as X NOa, is dis
solved In water, II associates into por-
lions similar in number and kind to those
1t would yield IL electrolyzed land II no
secondary reactions were to take place..
Such portions OK and NOs for example)
had been named 4ons by Faraday. The
conductivity OF such solutions becomes
greater per unit of dissolved salt, the
weaker the solution, until finally a limit
is reached. after which further dilution
no longer Increases conductivity. Now,
Van { HoH united all these Isolated OBJ
servations and showed their bearing on
each other. Stated shortly, the hypothe-
sis is as follows: When a substance is
dissolved in large quantity Of a solvent
its molecules are Separted from each
other to distance comparable with that
which obtains in gases. They are, there
fore, capable of Independent action;. and
when placed in a vessel the walls of
which are permeabIe to the solvent. but
not to the dissolved substance ("semi-
permeable membraneD, the imprisoned
molecules OF the latter exert pressure on
the interior surface OF these walls as IL
they were gaseous. Van { Hon showed
the intimate connection between this phe-
nomenon and the depression of freezing
point and the use of vapor pressure al
ready alluded 10. He pointed out further
that the exceptions to this behavior, no.
ticed in the ease OF dissolved salts, Is due
TO their electric association or "ioniaa-
ton" as Il Is now termed: and that in a
sufficiently dilute solution of potassium
nitgate for example, the osmotic pressure
and the correlated depression OF freezing
point and rise Of boiling point are prac-
Ideally equal to what would be produced
were the salt 10 be split into its ions, X
and Mo- These views were vigorously
advocated by OSWALD professor at Leip-
rie) in his "Zeitschrif fur Physikalische
Cheme," and he and his pupils have done
much 70 gather together facts in confir-
nation OF this theory, and in extending
its scope.
II must be understood that the ions X
and Mo- are not, strictly speaking, atoms.
they are charged atoms; thu X retains
r. and the NO a - charge. on miners
ing into the solution the poles Of bat
terry, one charged r and the other ~,
the + X atoms are attracted to the
pole. and arc there discharged; as soon
rs they lose their charge. they are free
TO act on the water. when they nbeTate
their equivalent OF hydrogen. Similarly,
the - No groups are discharged at the r
pole. and abstract hydrogen from the wa
ter. li1erating an equivalent quantity OF
oxygen. Thus the phenomenon of elec-
tr0lysis, so long mysterious process,
finds a simple explanation. The course
Of ordinary chemical reactions Is also
readily realized when viewed ia the light
Of this theory, Take. for example, the
ordinary equation.
AgNOs. AqtNacl. As=AgCi+NaNo, Az.
l. e.. solutions OF silver nitrate and sodium
chloride give a precipitate % silver chlu-
ride. leaving sodium nitrate ia solution
by the new views, such an equation must
be written.
y
Ak. AqtNo, Aq+Na,. Aa+ Aq=AgCl+-
Ma, Aq = NO. Aq.
The compound silver chloride. being in
soluble In water. Is formed by the union
81 the IONS AZ and CT. and their cobse-