John Almon.

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F^iedel and Crafts on the Ethers of Silkic Acid. IM

In seeking for the caiues of these fiicts, I have found much
that is interesting) and somewhat that I believe to have been
hitherto unpresented.

The immense proportion of living births to the pregnancies
in the foreign as compared with the native and protestant pop-
ulation of Massachusetts, already referred to, is to be explained
by the watchful protection exercised by the Oatholic church
over foetal life. However we may regard the dogma on which
this rests, the sanctity of infiEtnt baptism, there can be no ques-
tion that it has saved to the world millions of human lives.* But
of the various corroborative testimony to which I have alluded,
and of other matters pertaining to this subject I shall elsewhere
speak.*

Were mankind, in following the advice that has been quoted
from past and present authorities in political economy, content
merely to practice greater abstinence and greater prudence in
sexual matters, less blame could justly be laid. But when we find
infanticide and criminal abortion thus justified, rendered com-
mon and almost legitimated, we may well oppose to the doctrine
of these cruel teachers the words of the indeed admirable Perci-
val, '^ To extinguish the first spark of life is a crime of the
same nature, both against our Maker and society, as to destroy
an infitnt, a child, or a man."t



Art. XVU^—Sesearch on the Ethers of Silicic Add; by C. Prik-
DEL and J. M. Crafts.

The determination of the atomic weight of silicium has given
rise to more discussion than that of any other element ; nor does
this astonish us, when we consider the number and complicated
nature of the compounds^of silicium and the peculiar properties
which separate it from &11 the other elements.

Even at the present day chemists and mineralogists are not
agreed whether to write silica SiO, or SiO„ and recently
&heerer(: has published a paper, in which he brings up the old
arguments in favor of the latter formula, and adds to them some
new ones, based on the study of the action of silicic acid on
carbonate of soda at a red heat, as well as on Wdhler's research
on leuoon.§ We will not discuss these arguments, as we think
that a sufficient reply to them will be found in the facts brought
to light by this research. !^cts which are impossible to reconcile
with the opinion of Prof. Scheerer.

* North American Medico-Chirurg. Review ; Philadelphia, Jan. 1869, et leq.

k Med Ethics, p. 79.

X Joun. lor pnJctische Cbemie, zd, 416.

I Ann. d«r Ohem. n. Fharm., czzrii, 267.



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156 Ffiedel and Crafts on the Ethers of SUicic Acid.

It is not our intention to enter into the history of the discos-
sion of the true atomic weight of silicium ; but it will perhaps
be useful to recall some of its principal phases. In the memo«
table series of investigations by which Berzelius, without fol-
lowing any fixed rule, but with an accuracy of perception all
the more remarkable, established the greater part of the atomic
weights, he assigned to silicic acid the formula* SiO, (Si=21|
0=8). He deduced this result from the analyses of various sili'
cates,^ particularly of orthoclase, relying upon an analogy which
he supposed to exist between silicic ana sulphuric acids.

Dumas, when he called the attention of cnemists in his claasi*
cal memoirf to the importance of the determination of the den-
sity of vapors and its valu^ in establishing chemical formula,
gave, among other examples, that of the chlorid of silicium.
According to him this body ought to have the formula SiCl,,
and consequently silicic acid SiO (Si=7, 0=8, 01=17-75). The
chlorids of tin and titanium follow the same law.

Some years later 6audin,:|: among other remarkable deduc-
tions from the law of Ampere, obtained the formulas SiOl^ and
SiO, for the chlorid of silicium and for silicic acid. At the
same time he noticed the analogy between silicic and carbonic
acids. These ideas do not appear to have attracted the attention
they merited, because they were too far in advance of those re-
ceived at the time, and those who have since taken them up
have doubtless been unintentionally unjust in not quoting their
author.

Ebelmen employed the atomic weight for silicium as estab-
lished by Dumas, and wrote the formula of silicic ether,

SiO,C4HjO, (8i=7, 0=8, C=6, H=l).
This is the most simple expression for the result of his analysis,
but his formula is not in accordance with that of Dumas for
silicic acid ; for in order to correspond with it, silicic ether should
be written SiO, C^H, ^0, as if it contained two atoms of ethyl.§
Indeed Ebelmen's formula implies a hypothesis quite distinct
from that, founded on the vapor-density of chlorid of silicium,
for, to use the nomenclature of the present day, the first formula
represents silicium as monoatomic, and the second as diatomic.

Gmelinll wrote the chlorid of silicium and silica SiOL and
SiO, (Si=14, 01=85*5, 0=8), and these formulae were adopted
by tne greater number of chemists, and they found a new argu-

* Eflsai 8ur 1a Th^rie det proportionB Ohimiques, p. 184; Paris, 1819.

!Ann. de Chim. et Phys., m, zxziii, 867 ; 1826.
Ann. de Chim. et Phys., [2 J, lii, 118 ; 1888. We will add that in this memoir
Mr. Gandin i^ves the definition of atom and molecule which is received at the pres-
ent day. And we are happy in being* able to render justice to «n acute inteilect,
whose penetration has not been sufficiently recognized.

?Ann. de Chim. et Phys., [8], zvi. 141 ; 1846.
Handbach der Cfaemie, li, 889; Heid^beig, 1844.

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Frudd and Crafit on the EVwrs of Silicic Acid. IfiT

ment in their favor in the brilliant researches of Marignac on
the isomorphism of fiuosilicates, flaotitanates, and flnoetannates.*

When the progress of organic chemistry forced the chemists,
after Gerhardt, to double the atomic weights of oxygen and car-
bon, leaving that of hydrogen =1, which was nothing else than
returning to the old relations of Berzelius and Dumas, the ques*
tion arose, whether silica ought to be written

Sie (Si=14, e=16) or SiO, (Si=28).

Gerhardt answered the question implicitly in favor of the
latter formula, when he wrote silicic etnerf 4(SiO), 4(C^H,0),
and without doubt his only motive for retaining the atomic
weight of Ebelmen (81=7) was the same, which prevented him
from chan^ng those of carbon and oxygen in his work on or-

Snic chemistry. In order to have been consistent with his own
Boretic views, he need only have gone back to the formula of
Oaudin. Odlingj: has done this, and writes silica ^iG,, and
considers ^H^O^ as the normal hydrate of silicic acid, to which
the ethers correspond.

Odling, as well as Gerhardt and Gaudin before him, have de-
duced these formulae from the consideration of the vapor-density
of the chlorid of silicium and of silicic ether. This must \>q
regarded as an important argument in their favor, and to deny
its value it woi^ld oe necessary to forget the admirable order in-
troduced by Gerhardt in the classification of organic compounds
in the place of the confusion which reigned before the vapor-
density was employed as a criterion to determine the molecular
weight of compounds. It would be necessary, also, to ignore
the important results obtained by various chemists, particularly
by Wurtz§ and Gannizzaro,|| in the fixation of molecular weights
according to the same law.

Nevertheless we must remember that the ideas of A vogadro
and Ampere are nothing more than a physical hypothesis ; and
although this hypothesis has been fruitful in accurate conclu-
sions, even from the stand-point of a chemist, it must yield
before purely chemical considerations in the determination of
the relative weights of atoms and molecules. This conviction
haa led us to study the organic compounds of silicium in the
hope of obtaininff results which would enable us to resolve, on
entirely chemiciu grounds, the question of the true atomic
weight of silicium, and we must also admit, with the hope of con-
firming by our research the conclusions drawn from the law of
Ampere.

* Ann. dea Mines, [6], xv, 221. f 'I^it^ de Chimie Oi^^anique, ii, 86S.

1 Pbiloeophical Magazine, zviii, 368.
I Le9ons de Philoaophie Cbimique; Paris, 1864.
I Santo di on Cono di Filoeofia Chimica; Piea, 1868.
Am. Joub. Sci.~Sbcoivd Sxbies, Vol. XLIII^o. 12a— March, 18S7.
21 ^



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158 Friedel and Crafts on the Ethers of Silicic Acid.

We believe that we have suooeeded in demonstratiiig that the
most simple formulae possible for silicic acid and the normal
silicic ether are SiOj and Sij^K^^HjO), and in consequence,
that the true atomic weight of silicium is 28.

Silicate of ethyl* — We chose as point of departure fdr our re-
search the silicic ether, discovered and studied by Ebelmen. In
regard to this body we have little to add to the facts recorded
by him. The ether was prepared as recommended by him, tak-
ing care to use absolute alcohol, and to add it in small quantities
at a time to the chlorid of silicium. When the alcohol is per-
fectly anhydrous, the quantity of ether obtained is almost equal
to the theoretical ; however, a small quantity of chlorid of sili-
cium is always carried off by the hydrochloric acid gas which



Silicic ether, purified by repeated distillation, boils at 165®'5.
We determined its density at 0"^ C. =0-9676. Ebelmen gives
the density at 20° C. =0-933. The moisture of the air trans-
forms it rapidly into a solid body, silicic acid ; a piece of which,
after being kept three years, l)ecame hard enough to scratch
glass. Notwithstanding its decomposability by moisture, the
ether remains unaltered for some time under water, and when it
is distilled with water, only traces of silica remain behind in the
vessel. These facts must be attributed to its nearly complete
insolubility in water, for aoueous alcohol transforms it immedi-
ately into a polysilicate, as Ebelmen has already observed. All
the water contained in the alcohol does not react immediately
upon the ether, for when it is heated during a long time in a
closed tube with aqueous alcohol, a larger quantity of polysili-
cate is obtained than when the two liquids are merely distilled
together.

Assigning, like Gerhardt and Odling, the formula Si, 4(€,H50)
to silicic ether, we are naturally led to think that it would be
possible to replace one-auarter of the ethyl and oxygen (O^HjOJ
by chlorine ; as in the diethylic lactic ether an atom of peroxya
of ethyl (€21150) can be replaced by chlorine with formation
of chlorolactate of ethyl.

Diethylic lactic ether. Normal allirate of cthjl.



Chlorolactate of eihyL Mooochlorbydrlne of aUlcIo ether.

€3H^e)^ Si )r.

€,H, j^^ 3(€,H,)^^^3



In case of silicic ether, we ought to be able to go further, and
not only replace one but several atoms of peroxyd of ethyl by
chlorine, and obtain the bodies

• Th* atomic weighU #ed are 9i=28, 0=16, €=12, H=l.

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Riedel and Crafts on the Ethers of Silicic Acid. 169

DiehtarbTdrlae of •ilieic ctbar. Tricblorhrdrine of ■iUeic ether.

01, CI3 ,

Mcnochlorhydrine of silicic ether. — This ether was obtained by
heating in a sealed tube during one hour at 150^ C. three mole*
coles of normal silicic ether with one molecule of chlorid of
silicium. The reaction is

*^^*+^(4(€,H,) [ ^*) = * 3(€,H,) p» I .

On distilling the contents of the tube we noticed that there
was no free chlorid of silicium remaining. The liquid com-
meooed to boil at 146^ and almost the whole product passed
between ISS^'-IBO^. After several fractionated aistillations, we
analyzed the product boiling at ISS^'T-IST^.

L Substance weighed, - ^ 0*3785 gr.

ee,, .... 0-5006 "

H^O, .... 0-2645 "

Q. SubstoDce, weight, - * 1*4646 *"

AgCI, .... 1*0650 «

SiOg, . . • . 0*4365 "

We will also give here the result of an analysis of monochlor*
hydrine preparSl by the action of chlorid of acetyl on silicio
ether, and boiling ISS^-IST*".

ni. Substance, weight, - - 0*2190 gr.

e%, .... 0*2936 **

H^e, - • . - 0*1626 "







I.


a


IIL


Theory.


c


ss:


36*06




36*65


86*27


H


:=


. 7*46




7*74


7*66


Si


^^




13*96




14*10


CI


2SI




1811




17*88



The determination of silicium and chlorine was made bv de<-
composing the body in a flask with an alcoholic solution of am-
monia, distilling the alcohol and heating the flask in order to
render the silica easy to wash upon a filter. The chlorine was
determined in the nitrate from the silica. The alcohol carries
over with it on distillation a little NH^Cl, and it must be care*
folly condensed and evaporated slowly and the residue added to
the filtrate from the silica.

The monochlorhydrine of silicic ether is a colorless liquid,
which does not fume in the air, but is rapidly decomposed by
moisture or by water with evolution of HGl. It reacts easilv
OQ alcohol ; HCl is given off and normal silicic ether is formea.
It bums with a ^reen flame due to chlorine and with a smoke
composed of silicic acid.



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160 Friedel and Crafts on the Ethers of Silicic Acid.

Its density at 0^ compared with that of water at the same
temperature =*1'0483. Its vapor density was found to be 7'06.
The theory of a condensation to two vols, requires 6*87.

The data for the determination are :

Difference between two weights of bulb, 1*1975 gr.

Temperature of the balance, - - 12^

" oilbath, - - 230^

Height of barometer, .... 762*8 mm.

Capacity of bulb, .... S23 cc.

Air remaining in bulb, - - - . 2 cc.

We obtained the same chlorhydrine by heating for about one
hour at 170^-180° one molecule of chlorid of acetyl with one
molecule of silicic ether. The products of the reaction are acetic
ether and the monochlorhydrine, and the reaction may be repre-
sented by the equation :

CI

40 grams of silicic ether, heated with 24 grams of chlorid of
acetyl, ^ve 25 grams of acetic ether, nearly pure, and boiling at
75^-80°. The theory reauires 27 grams. Almost the whole of
Che remainder of the product passed at 155^-158^.

The experiment was undertaken with the object of obtaining
an aceto-silicate of ethyl^ supposing that the reaction would take
place according to the equation :

but no traee of such a body was formed.

The monochlorhydrine of silicic ether is also formed when
the ether is heated with the perchlorid of phosphorus ; there is
formation of a small quantity of oxychlorid of phosphorus and
•of other more volatile compounds containing phosphorus. A
Jarge quantity of chlorid of ethyl is given off. The product ob-
tained in this reaction and boiling at 155'^-158^ was used to pre-
pare the triethylic mono-amylic silicic ether. See below.

2%e dkhhrhydrine of siUcic ether is obtained by a reaction
analogous to that which gives monochlorhydrine, by heating
together one molecule of silicic ether and one molecule of ohlo-
rid of silicium.

I CI,

It can also be prepared by heating monochlorhydrine with
the chlorid of silicium.



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Friedel and Crafts on the Ethers of Silicic Acid. 161



SiCI^+2



3(€;



Si



,H.)}^»



■i



= 3



2(€,



CI,



The reaction takes place somewhat less, readily than the one
which gives rise to the monochlorhydrine, and it is necessary to
heat the sealed tubes longer and to separate the product by a
larger number of fractionated distillations. While manipulating
the chlorhydrines the utmost care must be taken to prevent ex-
posure to the moisture of the atmosphere, which decomposes
them the more readily the more chlorine they contain. The
vases containing the aifferent products were always kept in a
glass jar, which bad the bottom covered with sulphuric acid and
a gkss cover fitting air-tight.

The dichlorhydrine boils at ISBMSS*". Analyses gave :



IL



m.



C,
H,
CI,

Si,

The vapor-density is 6-76 ; theory 6-545. Data :

IHffereDce of 2 wt8. of bulb, 0-8695 gr.

Temperature of balance, - 22^

** " oil-bath, - 213* Air thermometer 211 <*-5

Height of barometer, - 766-9 ram.

Capacity of bulb, - - 229-6 cc.
Air remaiuiug in bulb, - 0*3 cc.

The density at 0^ of the dichlorhydrine is 1*144. This body
resembles the monochlorhydrine in all its physical properties.

The irkhlorhydrine of sUicic ether is obtained by heating for
several hours at 160^, either the silicic ether or the two preced-
ing chlorhydrines, with an excess of chlorid of silicium, and
senarating the products by a large number of fractionated dis-
tillations. The precautions that were taken to keep the other
chlorhydrines firom contact with moisture are still more neces-
aary in the case of the trichlorhydrine. It boils at lOSMOS"*.
Analyses gave :



Substance, weight, -


-


0-3480 gr.


€e,, ....
H,4, ....


.


0-3270 -


-


0-1676 **


SubetaDce, weight, .


-


0-7006 •*


AgCl. ....


-


10685 •*


Substance, weight, -


-


0-3260"


9ie„ ....


-


0-1000 "


!. II.


m.


Theory.


26-62


....


25-39


5-36


....


6-29


37-64


• • • •


37-56


•«.. .•••


14-35


14-81



I. Substance, weight, -
H,4, - - -



0-3995 gr.
01976 "
0-1040 "



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162 Friedel and Crafts on the Ethers of Silicic Add.

II. Substance, weight, ... - 0*5945 gr.
AgCI, 1-4190 "

III. (Boil, point =104*^-106^.) Substence, wt., 0-4285 "

€02» 0-2100 "

HaO, . * 01070 "

IV. Substance remaining in the bnlb after the

determination of the vapor-density,

weight, 0-6465 "

SiOa, - 01790 "

I n. III. IV. Theory.

C, 13-46 13-62 13-41

H, 2-89 2-80 2-78

CI, 6907 69-83

Si, 15-27 16-58

Tlie vapor-density =6*878; theory 6'216.

Difference between two weights of bulb, - 0-9317 gr.
Temperature of the balance, . - - 22^-5

" " oil-bath, - - - 163*>-6

Barometric pressure, ... - 766-6 mm.

Capacity of bulb, 231-5 cc

No air remaining.

The density at 0° =1-291.*

The boiling points of the above compounds, in which a por-
tion of the atoms of the peroxyd of ethyl are replaced by chlo-
rine, represent a series, in which the secondary differences are
nearly constant. ^

Silicate of ethyl, - - 165*'-6 j.o.e

Monochlorhydrine, - - 167 ^a H'^'S

•Dichlorhydrine, - . - 137 ^, 13

Trichlorhydrine, - - 104 ^^ 12

Chlorid of silicium, - 69

THethylic monoamylic silicic ether, — The monochlorhydrine
served to prepare this mixed ether, which is nothing else than
a normal ethylic silicate, in which one atom of ethyl is replaced
by amyl. To obtain it, it is saflficient to bring together a mole-
cule of monochlorhydrine and one of amylic alcohol. The re-
action takes place immediately with evolution of HCl.

The liquid commenced to distil at 205^, and almost all passed
below 280°. The greater part boiled at 216°-225°. The analy-
sis of different products gave —

* The density of chlorid of silicium at the same temperature we determined
=1-622.



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L


a


UL


IV.


V.


Theory.


52-74




62-73




63-78


52-80


10-13




10-38




10-76


10-40




10-80




11-40




11-20



Friedel and Crafts on the Ethers of Silicic Acid, 163

L (BoiliDg point 216''-226''.) Substance, wt^ 0-2875 gr.

€02, - 0-6660 "

H^e, - 0-2620 "

II (Boiling point 223^-230'^.) Substance, wt, 0-7015 "

SiOa, - 0-1626 **

IIL (216^-220°.) Substance, wt, 02215 "

€02, - 0-4280 "

H^O, - 0-2070 " "

IV. (216**-220^) Substance, wt, 0-3845 "

SiO^, - 0-0940 **

Another preparation where an excess of amjlic alcohol had
been employed —

V. (214*-220°-) Substonce, wt^ 0-3796 gr.

eOa, - 0-7480 "

Hj,e, - 0-3640 «

L a UL

C,
B,
Si,

Analysis number v, and those of products boiling above 280^,
indicated the presence of a mixed ether, containing more amyl
than the one we sought to obtain. This fact awakened our at-
tention, and induced us to make some researches on the action
of alcohols upon the ethers of acids, which showed us that an
alcohol can act directly upon an ether and that an interchange
of the two radicals takes place;* thus when an excess of amylic
alcohol is employed, it acts upon the triethylic mono-amylic
silicic ether and an ether containing more amy! is formed.

Triethyl monoamyl silicic ether is a colorless, somewhat oily
liquid, with a feeble odor like that of all amylic compounds.
It is not entirely decomposed by treatment with an alooholio
flolntion of ammonia, and it is necessary to employ a solution of
caustic soda in alcohol to make the determination of silica.
Ebelmen made the same observation in regard to the silicate of
amyl. Density at 0°=0-926.

The mixed ether on distillation, even in vacuo, has a tenden-
C7 to decompose witJi formation of diamylic diethylic ether, and
doubtless at the same time of normal ethylic silicic ether. A
product which had been prepared from the monochlorhydrine
without an excess of amylic alcohol, after several distillations at
lOOMlO®, under a pressure =3-5 millemeters of mercury, had a
compoeilion between that of the mono- and the di-aigylic mixed
ether.

Substance, weight, - - 0-2806 gr.
€0-, - - - . 0-5640 **
HaO, .... 0-2750 «

* This Journal, z1, 84.

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164 Friedel and CrafU on the Ethers of Silicic Acid.

I. Si,8(€,H,),{€,H,,)e4. Si,2(€,H.),2(€,H,,)e^.
C, 54-88 52-80 67-63

H, 10-91 10-40 10-96

Diethylic diamylic silicic ether was prepared in the same way
as the preceding by treating the dichlornydrine with amylic al-
cohol. The portion boiling at 245°-250° was analyzed.

I. Substance, weight, - - - - 0-2115 gr.

€e«, 0-4496 "

H,e, 0-2095 "

n. SubftUnce, weight, .... 0-8980 ''

SiOa, 0-0780 "

L n. Theory.

C, 57-89 ^ 57-53

n, 10-99 10-96

Si, 9*15 9-59

The density at 0°=0-9150. '

Monoeihylic triamyUc silicic ether was obtained in the same way
as the preceding with the trichlorhydrine and amylic alcohol.
It boils at 280'*-285^.

I. Substance, weight, .... 0*2410 gr.

€0., 0-5350 "

H^e, 0-2425 "

IL Substance, weight, 0-4820 "

SiOj, 0-0875 "

I. II. Theory. Si€iyH380^.

C, 60-51 6108

H, 11-18 11-37

Si, 8-47 8*38

This ether resembles in its properties the silicate of amyl. The
density at 0''=0-913.

All these mixed ethers can only be prepared from the pare
chlorhydrines, as they are decomposed on distillation, and there-
fore cannot be purified in that way.

PdysiliccUes of ethyl — ^Ebelmen describes, besides the normal
silicate, two others, the one containing twice as much silicic acid,
and the other four times as much, and calls them bisilicate and
quachrisilicate of ethyl.

He obtained the bisilicate, to which he giyes the formula
2SiO, C^H^O (Si=7, C=6, 0=8, H=l),
by treating the chlorid of silicium with alcohol containing one
equivalents (16 per cent) of water. One equivalent of alcohol
was added to two equivalents of chlorid.

To quote his memoir, " when the product is distilled, the tem-
perature of the liquid, contained in the retort, rises from 160**
to 350^ without a considerable quantity of the product distilling.



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Friedel and Crafts on the Ethers of Silicic Add. 165

At this moment the mercury thermometer is taken away, the
receiver is changed, and on continuing to heat, soon an abundant
colorless product passes. * * * The liquid, distilled above
860^, was rectified with a thermometer placed in the i^tort ; a
very small quantity of a product, which distilled below 850°,
was collected by itself, then the thermometer was removed, and
the distillation continued, and in a few instants almost the whole
contents of the retort passed over into the receiver. It did not
appear doubtful to me, that a body, which distills with so great
rapidity could be other than a definite product, having a fixed
boiling point near 860°." According to Ebelmen the bisilicate
can also be obtained by adding to the protosilicate alcohol, con-
taining the requisite quantitv of water.

As for the quadrisilicate, he says that it is obtained by adding
a little aqueous alcohol to the bisilicate, and remains in the re-
tort after the distillation of the latter. It appears to be decom-
posed into bisilicate and silica at a temperature a little above that
at which the bisilicate distills. The existence of these two ethers,
if we give th^m the formulae

Si I r, 2Si ) ^ I 2Si ) £.

accords perfectly with what is known of the formation of con-
densed l)odies. Wurtz* has observed the formation of poly-



Online LibraryJohn AlmonThe American journal of science and arts → online text (page 19 of 102)