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aside for this investigation, which was afterwards conducted in
the laboratory.

Of the Results of Fractional Condensation, — Such of the sam-
ples above mentioned as promised to yield the different constit-
uents of the naphtha in the largest proportion were subjected
to repeated series of fractionings by my process of " Fractional
Condensation." " As full details of this process have already
been given in the memoir referred to, it will be needless to re-
peat them here. It will suflBce to say that the fractioning in
this case was conducted in all respects as there described, and
continued until the whole of the naphtha taken, boiling between
80° and 170"^, had accumulated at the four points already indi-
cated, viz: at 80°, 110°, 140°, and 170° ; or so nearly the whole
that the intermediate quantities had become too small to admit
of being further operated upon. Having, therefore, so thor-
oughly exhausted the intermediate fractions, I can have no hesi-
tation in asserting that no other body than those alluded to was
E resent in the naphtha, — at least, in appreciable quantity,—
ence, that the parabenzole of Church was probably only a mix-
ture of benzole and toluole. I may here remark that each of
the sample-gallons employed, when subjected to my process of
fractioning, was found to contain, in variable proportion, all of
the constituents of the naphtha.

Of some of the Properties of the Bodies obtained by Fractioning, —
1. Benzole.— Specific gravity, 0-8957 at 0°, and 0-882 at 15°-5."

" Memoirs of the American Academy, 1864, and last volume of thia Joarnal.

" It would appear that the specific graTities of liquids are usually determined
at the temperature of the air. The result of this is that the determiuatioos made
by different observers are not comparable with one another. That these specific
grayities are not uniformly taken at 0" C— the temperature which, on account of

Am. Jour. Sol— Second Skribs, Tol. XL, No. 118.— July, ISW.
13



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98 Ct M. Warren on the Volatile Hydrocarbons.

Determination of Boiling-point. — This experimcTit was con*
ducted in a tubulated retort, operating on 150-200 c. c. of the
benzole, containing some pieces of sodium. The benzole em-
ployed had previously been repeatedly boiled with sodinm, until
the latter ceased to have any action. The thermometer bulb
extended into the liquid" nearly to the bottom of the retort
A second thermometer was attached, by means of flexible bands,
to the side of the one in the retort; the bulb being placed, dur-
ing ebullition^ at a point midway between the center of the cork
(—5°) and the upper end of the mercurial column, vi2: at 85°.
A paper screen^ closely fitting the thermometer spindle, was pla-
ced across at the top of the cork. With the retort neck slightly
indined upwardj and cooled to prevent the escape of vapor,
ebullition was continued for a considerable time, until the mer-
cury in the thermometer ceased to rise. The lamp being removed
for the moraentj the neck of the retort was then turned down-
ward, and quickly inserted in a Liebig*s condenser. On replac-
ing the lamp, distillation commenced almost immediately at 79^.

Observations. —

Tempeniture. Tlmej Tamper, by ■id« tbermom.

o b. in.

79-0 at 2.40. . ^,v^*^

79-2 " 2.46{,^ "^'^^^^^ 22^

79-4 •* 8.00{ tZ ., 24'.

79-5 •* 8.12 i^ .. 26^

79-6 " 8.82( '■^ „ 26^

79-6 " 8.60^ ^^ 26^.

greater convenience, etc., li geueraHy acknotrl^ed to be preferable— is pfobablj
due to the fact that the more common spedfio grayity bottle is not anitea to thU
purpoee. Indeed, with a Tolatile body toat bottle cannot serve for
an accurate determination at any temperature. A reform in this re-
gard being highly desirable, I itrould call attention to a specific gravitr
bottle which I obtained a fSsw yean ago ftom Fastrd, in Paris, whicti
it admirably adapted for taking specific gravities, even of volatile
liaoids, at a loir temperature. The accompanying figure represents
this bottle one-half its natuhil size. Who Was the author of this
particular form I am not informed, although it may have been
already noticed in some publication. A botUe analogous to this is
figured by Schiel (** Einleitung in das Studium der oi^ganischen
C^mie," page 76) ; out his bottle has an oval bottom, which mskes
it less convenient The particular advsntafe of this bottle orer the
more common one, which advantage Scbiel omits to notice, consists
in this : that the space or chamber above the line on the capillary
neck is large enough to allow for the expansion of the liquid conse-
quent upon tlie elevation of temperature from 0^ to that of the sur-
rounding air ; and that the ground stopper fits so closely that no
perceptible lots from evaporation can take place during the time
occupied by an experiment.

In order to furnish determmations of the specific grravitles of the
bodies to be treated of in these researches, which shall be comparable with correa-
ponding determinations by other observers, I shall generally record one or mom
spedal determinations made for this purpose.

" For critical remarks on the question of propriety of placing the the r mome t er
bulb in the liquid, etc. ; and for further detliils of the method of taking boiling-
points, especially at low temperatures, see a following memoir, " On thelnfluenoa
of C^Hs on the boiling-points in Homologous Series of Hydrocarbons," etc



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C M. Warren on the Volatile Hydrocarbons. * M

Distillation therefore oocupied one honr and ten minutea, daring
which time the thermometer rose only 0^*6, being fiily minutes
in rising 0**'2 from 79°-4 to 79*^*6, at which temperature it had
distilled nearly to dryness. Height of the barometer during the
experiment reduced to 0^ =761-«»™. Taking 79''-4, this being
the average of the last five observations, and applying the cor-
rections for the upper column of mercury, and for atmospheric
pressure, according to the directions given by Kopp," we find
the corrected boiling point of benzole to be 80^*1.

Analysis. — 0-2839 gram of benzole gave, by my process" of
combustion in a stream of oxygen gas, 0'790S of carbo^nic acid,
and 01683 of water,

CatootaU^. FoiMia.



Carbon, C., ?^
Hydrogen, H^ 6


92-31


921«


7-69


7-99


78


10000


10014


Determination of Vapor Density. —






Temperature of balance,




16*


Temperature of oil bath,




171^


Height of barometer,


764-1


»"» at 9*


Increment of balloon.




0-2447


Capacitjr of balloon.
Density of vapor found.




265 ce.




2*6€8


Theory, C^2Hg=4 volume*.




2'69«



2. ToLUOLE.— Speeific gravity, 0-8824 at 0^, and 0:872 at 15^
Determination of Boiling-point. — The preparation employed for
this determination had also been repeatedly boiled with sodium
until the latter ceased to have any action upon it. X)perating im
this case also upon a pretty large quantity, the distillation occu*
pied about an hour. The experiment was conducted as detailed
under the head of benzole. Distillation commenced at IXO^'jS;
two minutes later, the temperature had fallen to 110°*4, at which
point it remained absolutely constant during the lapse of forty-
eight minutes. Five minutes later the temperature had risen
again to 110°-6; and five jninutes later to 110®-8, at which
point, having distilled nearly to dryness, the operation was sus-
pended. The corrections for pressure (— 0°16) and for the upper
column of mercury — which, with the thermometer used in this
experiment, was only 7° in length, — gives 110***8 as the corrected
boiling-point of toluole. Church** remarks that toluole, when
distilled in the ordinary manner, is liable to become oxydized,
and its boiling-point thereby raised, in conseauence of the upper
part of the retort becoming heated above tne boiling-|)oint of
toluole. He found that toluole which, by .ordinary distillation,

^* Poggendorff's Aonaleo, 1847, Izzii, SS.

" Pro^edings of ihe American Academy, 18K4, y.^!, and tbii Jour., xxxir, SSft.

'* PbUosophKal Magazine, 1866, [4], is, 266. '



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100 ' CM. Warren on the Volatik Hydrocarbons.

had come over between 108° and 109°, would distil eigbt-tentbs
between 103° and 104°, after repeated purification with sodium.
I would therefore state that my preparation of toluole was never
subjected to a temperature above its boiling-point ; and that I
have never uoticea any reduction of the boiling-point of this
body by purification with sodium.

Analysis. — 0*1628 gram of toluole gave, by combustion in a
stream of oxygen gas, 0*5447 of carbonic acid, and 0'1815 of water.

Calculated. Found.

Carbon, C,^ 84 91-3 91-20

Hydrogen, Hg 8 8-7 8-97

92 lOO-O 100-17

Determination of Vapor Density. —

Temperature of balance, 17**

Temperature of oil bath, 209®

Height of barometer, 760-1"*" at 16*
Increment of balloon, 0-287

Capacity of balloon, 249'6 c. c.

Density of vapor found, 8-2196

Theory, Ci4H8 = 4 volumes, 3-1822

3. Xylole {Cumole of Mansfield and Bitthausen), — Specific
gravity, 0-878 at 0°, and 0*866 at 15°;5.

Determination of Boiling-point. — This determination was made
in all respects like that of benzole, the xylole employed having
been also subjected to the same treatment The quantity ope-
rated upon was, however, smaller, and the experiment conducted
more rapidly. Distillation began at 138°'6, and terminated at
139°, having distilled almost to dryness. The time occupied
was seventeen minutes. Taking the average of these observa*
tions, viz: 138°*4, and applying the customary corrections, we
find 139^*8 to be the corrected boiling-point of xylole.

Analysis. — 01333 gram of xylole gave, by combustion in a
stream of oxygen gas, 0*4413 of carbonic acid, and 01186 of water.



Calculafed.


Foond.


Carbon, C^g 96
Hydrogen, H,<j 10


90-67
9-43


90-29
9-87


106


100-00


100-16


Determination of Vapor Density. —

Temperature of balance,
Temperature of oil bath.
Height of barometer,
Increment of balloon,
^Uapacity of balloon.
Density of vapor found.
Theory, €,eH,^,


16^-6

207^-6

760°»» at 14*

0-3628

228 c. c.

8-7^17

8-6666



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C M. Warren on the VokUik Hydrocarbons. lOl

These results show clearly that this body has the formula
C, eH, ,, and that it is doubtless the third member of the ben-
zole series." Although xylole, first discovered by Cahours in
the oil separated from wood-spirit, has had a much lower boil-
ing-point assigned to it, I have retained that name for this bodv,
since the results which I have obtained in the study of the light
oil from wood-tar indicate that when the corresponding b^y
from this source is in a state of equal purity, its boiling-point
will agree with the above determination. I may here mention
that in my researches on the light oil from wood-tar I have ob-
tained a body at about 140^, but nothing between that and 110^
(these temperatures are not corrected), although special pains
were taken to work up the intermediate fractions. So that I am
in a position to justify the assertion that no other body was
present in appreciable quantity between the temperatures men-
tioned.

That this body from coal-tar naphtha, boiling at 140^, is not
identical with cumole from cuminic acid, will be made apparent
on comparison of the results above stated, with those which will
be given when treating of cumole.

4. IsocuMOLE {Cymole of Mansfield). — Specific gravity, 0*8643
at 0°, and 0-863 at 15^.

Determination of Boiling-point — This was conducted with the
usual precautions, and under conditions similar to those detailed
above. The distillation, as in the foregoing determinations, was
continued nearly to dryness, and occupied twenty-five mintftes.
Before distillation was commenced, the temperature of the boil-
ing liquid was found to be 166^-5, and at the close of distilla-
tion 167^. Applying the customary corrections to the average
of these observations, viz: 166°*75, we obtain for the corrected
boiling-point 169o-8.

Analysis. — 01944 gram of the substance gave, by combustion
in a stream of oxygen, 0.6366 of carbonic acid, and 0*1896 of
water.

Caleolated. FouDd. *

Carbon, C^g 108 90-00 89-31

Hydrogen, H,2 12 1000 10-84

120 100-00 100-15

" As thif memoir is passing throoffh the press, the receipt of my jomnals for
September calls attentioD to Ute pablicatioDS of Hugo MiiUer, B^amp, and
Naqoet concerning this hydrocarbon. MiUler concludes that it is xylols, a result
which agrees wi£ my own. (Annalen der Chemie uiid Pharmaoie, 1864, czxxi,
821.) &champ, on the contrary, erroneously regards it as being a new hydrocar-
bon, not belonffing to the benzole series. (Bulletin de la Soci6t6 Chimique, Paris,
1864, 204.) Naquet also calls it a new hydrocarbon, and giyes it the formula
Ci,H„. (IWd., p. 206.)



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lOS C Jf. Warren xm the VotatUe Hydrocarbons.

Dderminatwn of Vapor Density. —

Temperature of balance, 13®'5

Temperature of oil bath, 241**-0
Height ef barometer, 7«9-6""» at 9**

Incperoent of balioou, 0*4206

'Capacity of balloon, 230 c c.

Density of vapor found, 4301 9

Theory, C^eH^,, 4161

Hence it appears that the calculated density oa the formula
C, jH. J, is O'lSl less than that found by experiment The cal-
culated density on the formula C,oHi«j which has previously
been assigned to this body, — ^althougk, as above stated, without
an analysis or determination of vapor density, — is 4-645 ; which
is 0*802 greater than that found by experiment. It will be ob-
fierved that the difference between the density found and that
calculated on the formula C, ^H, ^ is not only more than twice
as large as the corresponding difference calculated on the for-
mula C, ,H,„ but that the error is reversed; being with C, ,H, ^
a defidehcy^ while with C^gH,, it is an excess. This circum-
stance has to my mind a good deal of significance, as it goes
strongly to show that the lower formula is the true one. For
of the many vapor densities of hydrocarbons which I have de-
termined, I have but rarely met with an instance in which the
density found was not greater than the theoretical density. And
Z ha^re usually observed that the excess of the experimental over
the theoretical density is larger in proportion as the boiling-
poiht of the body is higher, a fact which needs explanation.
Wurtz" observed a similar difference between the determined
and calculated vapor densities of bodies of the formulae CnHa
andCnHn+a, which he accounted for on the ground that his
preparations contained an admixture of bodies less volatile, the
vapors of which would remain in the balloon, and increase the
density. But I cannot accept this explanation for the substances
here Jtreated of, since they invariably distil without residue with-
in a range of one degree of temperature. I would rather rely
xi^xk the supposition tha^i the high temperature employed causes

I)artial decomposition of the substance, which would be the more
iable to occur the higher the boiling-point of the bpdy. I do
not^ however, offer this as an explanation, but merely make the
suggestion.

PduiT XL — Hydrocarbons from Oil of Cumin and Cuminie Acid.

The oil of cumin employed in this research was furnished by
Messrs. Reed & Cutler, wholesale importers of drugs, etc., of
Boston. The package bore the label of Eduard Biittner, manu-

** Balletin de la Sod^t^ Chimique de Paris, 1868, 809.



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C. M. Warren on the Vokztile Hydrocarbons. 108

factnrer, of Leipzig, and purported to be a genuine preparation^
answering in all of its obvious pbysical properties — odor, color,
etc. — the description given of this oil by Gerhardt and Cahours*'
in their original memoir on this substance, who, it appears, also
employed a commercial preparation. Its behavior in distilla-
tion left no doubt of its being a genuine article ; and this was
afterwards confirmed by treatment of the cuminole with fused
potash, for the production of cuminic acid, its comportment with
this reagent being in all respects identical with that described
by Gerhardt and Cahours. Subjected to repeated series of frao-
tionings by my process of fractional condensation already re-
ferred to, it gave, in addition to cymole and the residue of cu-
minole, a body boiling at about 155^, which so closely resembles
oil of turpentine in odor, etc., as to be hardly distinguishable
from the latter substance. The presence of this body may ac-
count for the very low boiling-point which Gerhardt and Ca-
hours assigned to cymole, viz: 165^. The boiling-point of
cymole was subsequently found by Gerhardt" to be 175^, but
my own determination places it still lower by about 6^. It is
evident, therefore, from a comparison of their own determina-
tions, that the oil of cumin which they originally operated upon
contained an oil boiling below cymole ; and hence the finaing
of such an oil in that which I employed need not raise a doubt
as to its being genuine. This lighter body is present in so small
a quantity as hardly to admit of its being detected, or at least
identified, by the old process of fractiouing; and its detection
and isolation by the new process is but another illustration of
the superior excellence of this method.

1. Of the Body RESEMBLma Oil op Turpentine.— Spe-
cific gravity, 0*8772 at 0^, and 8657 at 15°.

Determination of Boiling-point. — The quantity of material at
command was too small to admit of attaining so high a degree
of purity for this body as was desirable. The product obtained,
however, distilled almost to dryness between 153°'4 and 155° 5.
Taking the average of these observations, and applying the
usual corrections, we obtain 155°-8 for the boiling-point of this
body.

Analysis, — 0*2575 gram of the substance gave, by combustion
with oxyd of copper, 0-8288 of carbonic acid, and 0-2766 of water.

Calculated. Pound.

Carbon, C^^ 120 8824

Hydrogen, H,^ 16 11-76

186 10000 99-67

" AimaleB de dnmie et d« Thjnqne, 1841, [8], i, 60.
* IMd., 1846, [8], iv, 111.



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16^




211*


768**


•4»» at 14°




0*49d(^




221 cc




4-7281


«,


4-7028



104 CM. Warren on the Volatile Hydrocarbont^

Determination of Vapor Density. —

Temperature of balance.
Temperature of oil bath,
Height of barometer,
iDcrement of balloon,
Capacity of balloon,

Density of vapor found,

Theory, C2<,Hjg=4 volumes,

Excess found, '0253

The calculated density on the formula C, ,H , ^ is 4*686 ; which,
compared with the density found, would increase the excess to
093. Although the determination agrees more nearly, indeed
almost exactly, with the calculated density on the formula C, ^
H,„ the calculation on the formula CjoH,^ does not show a
greater variation from the density found, than we have observed
to be quite frequent with hydrocarbons of so high boiling-point;
80 that it may be questionable which of these formulae is the true
one. I cannot regard the determination of a vapor density as
reliable for fixing the formula nearer than to within two equiva-
lents of hydrogen. In the absence of opposing evidence, it will
be wiser, however, to take the formula which agrees best with
the results of experiment; at least until it shall be shown that
the discrepancy between the calculated and observed vapor
densities of bodies of high boiling-point, which appears to be so
frecjuent, is nearly constant, or variable by some fixed law by
which the amount of the error, in any given case, may be pretty
nearly estimated. I shall therefore regard this body as having
the formula C,oHt8» which is also better supported by the re-
sults of analysis. On account of its source, and close resemblance
to oil of turpentine, I think of no better appellation for this body
than cumo-oil of turpentine ; thus adding another to the long list
of isomers of the lormer substance, the chemical relations of
which stand in so much need of being further studied.

2. CuMOLE. — This body was first obtained by Gerhardt and
Cahours," by the dry distillation of a mixture of six parts of
crystallized cuminic acid, and twenty-four parts of caustic baryta.
Abel" obtained the same result by substituting caustic lime for
the baryta. His product, however, was found to boil 4® above
that of Gerhardt and Cahours. My preparation was also made
by the use of lime. Although the results of my experiments
confirm the conclusions arrived at by Gerhardt and Cahours as
to the composition of this body, yet the numerical results differ
considerablv from theirs. I have also observed some new facts
regarding the formation of this body. They have described the

•■ Annales de Obimie et de Physique, 1845, [8], iv, 87.
** ADoalea der Chemie uod Pharmade, 1847, \xvr, 818.



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C. M, Warren on the Volatile Hydrocarbons. 105

reaction between the baryta and cuminic acid as being much
more simple than mj experiments seem to indicate. On this
point they remark : ** The formation of camene is easily explain-
ed. In enect, the cuminic acid being represented by C^ ^^H, ^O-,
it appears that C^O^, that is to say, 2 equivalents of carbonic
acio, are retained by the baryta, while Cj^H, ^ are set free.""

In another place (p. 88) they remark, that ** by suitably man*
aging the heat, and employing no more than 6 gr. of cuminic
acid at a time, no other products are ever obtained than those
which we mention."" My experiments show that this reaction
is by no means so simple as thus described. The crude product
obtained from the mixtufe of lime and cuminic acid, when sub-
jected to a simqle distillation from a tubulated retort, was found
to distil between 155° and 250°, leaving a residue at the latter
temperature which became semi-fluid on cooling. The distillate
thus obtained gave, by my process of fractional condensation, an
oil boiling at 151°*1, and a residue at 170°. It is not improbable
that the latter may prove to be mostly cymole, C, ,H, ^ ; but the
quantity was too small to admit of pursuing this inquiry with
tne probability of deciding the question. There is evidence,
however, that the product obtained by Gerhardt and Cahours
was not simply pure cumole, as they described it, but a mixture
of dififerent Dodies, which would necessitate a more complicated
reaction than that which they assigned. Gerhardt and Cahours
found the boiling-point of their cumole to be constant at 144°,
Four years later, Gerhardt,'* having occasion to make a very
accurate determination of the boiling-point of this body, in con-
nection with his research to find a Taw governing the boiling-
eoints of the hydrocarbons, found its boiling-point to be 9°
igher, viz. 153°, which is but 2° higher than my own deter-
mination. The disagreement between their determinations, it
being so considerable, may be more reasonably accounted for
on the supposition that they operated, in the first instance, upon
a mixture of different bodies ; and yet I cannot see how they
could have obtained the product boiling below 150°. Additional
evidence on this point will be found in the discrepancy which
appears between their determination of the vapor density, and
that calculated upon theory.

^ ** La formation du cum^ne s'ezplique ais^ment En effet, I'acide cuminique
etant repr^ntS par C40H24O4 on voit que C4O4, c'est-adire 2 equivalents
cTacide carbouique sont retenus f)ar la baryte, tandis que C3QH34 sont d^gag^."
— Annales de Chimie et de Physique, 1841, [8], i, 89.

** '* En dirigeant la cbaleur convenabletnent et en n'employant, pas plus de dsr-
(Tacide cuminique i la fois, on u'obtient jamais d'autres produits que ceux que
Doos Tenons de nommer."

•• Annales de Chimie et de Physique, 1846, [8], xiy, 107.

Am. Jour. 801.— Second Sbribs, Vol. XL, No. 118.— Jult, 1866.
14



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106 Ci M. Warren on the Volatile Hydrocarbons.

The specific gl^vity of ray preparation of cumole was foimd
to be 8792 at 0^ and 0-8675 at 15^.

Determination of Boiling-point. — Thequantity of material being
quite small, this determination was made in a large test tube,
-y^ith the usual precautious. It had not a perfectly constant
boiling-point, the distillation ranging from 148 4 to 151°'6. Ap-
plying tne proper corrections to the mean of these observations,
gives, for tne boiling-point of cumole^ 151°'l, which is doubt-
less a little too high from the impracticabilitv of making a com-
flete separation with the small quantity of material employed,



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