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prisms, melting at 195'5 ; on oxidation with potassium perman-
ganate, it yields dibenzidenediamidobenzoic acid, (C 6 H 5 .CH=N) 2 .
C 6 H 3 CO 2 H. The hydrochloride, C 21 H 18 N 2 .C1H, crystallizes from
hot dilute hydrochloric acid in long needles.

When it is heated with ethyl iodide, it is converted into the
iodide, C 21 H 18 N 2 .C 2 H 5 I, which crystallizes in thick prisms, and, on
treatment with silver oxide, yields the corresponding hydroxide,
which remains behind after evaporation of the solution as a
strongly alkaline, oily liquid. 3

Dibenzidenemetadiamidotohcene crystallizes from a mixture of
ether and alcohol in small lustrous tablets, melting at 122 128.
It does not combine with acids, but when heated to 140 150
for a considerable time, it is converted into a base, which Schifi
considers to be amarine. 4

Benzidenephenyldiamine, C 6 H 5 .CH(NH 2 )NH(C 6 H 5 ). When
benzonitril, C 6 H 5 .CN, is heated with aniline hydrochloride to
220 240, phenylbenzenylamidine 5 is formed, and this is con-
verted into the diamine by the action of zinc and dilute acetic
acid :

\NH.C 6 H 5

It is very soluble in all solvents, with the exception of water
and separates from dilute alcohol in indistinct crystals, melting at

Ladenburg, J5er. Dcutsch. Chem. Ges. xi. 599.

Calm, ibid. xvii. 2938.

Ibid. x. 1126 ; xi. 591, 1648.

Ann. Chem. Pharm. cxl. 98.

Bernthsen, Ann. Chem. Pharm. clxxxiv. 348.


114'5 115. At a higher temperature it distils without decom-
position, and on heating with chloroform and alcoholic potash
yields the smell of the carbamines.

Benzidencphenylamine hydrochloride, C 13 H 14 N 2 .C1H, crystallizes
from water in thick prisms, melting at 223 224'5. 1

Benzidenc-acetamide, C 6 H 5 .CH(NH.C 2 H 3 O) 2 , is formed by
heating benzaldehyde with acetamide, and crystallizes from hot
water in fine silky needles. 2

Benzidene urethane, C 6 H 5 .CH(NH.CO.OC 2 H 5 ) 2 , is formed when
hydrochloric acid is added to a mixture of benzaldehyde and
ethyl carbamate. It separates from alcohol as a silky crystalline
mass, which melts at 171, and can be sublimed. 3

Benzidene ure'ides are formed by heating benzaldehyde with
urea, and are split up again into these substances by boiling
with water. 4

y NH.CO.NH 2

Benzidenedi-ureide, C C H 5 .CH/ , fine needles.



C 6 H 5 .CH/ , white powder.

Benzidenetri-ureide, ;>N CO NIL

C 6 H 5 .CH<

\NH.CO.NH 2 .

C 6 H 5 .CH<


Benzidenetetra-ure'ide, C H 5 .CH\ , white powder.


C (! H,.CH


2091 Orlhochlorobenzaldehyde, C 6 H 4 C1.CHO. By the action of
phosphorus pentachloride on salicylaldehyde, C 6 H 4 (OH)CHO,
orthochlorobenzidene chloride, C 6 H 4 C1.CHC1 2 , is obtained as an

1 Bernthsen and Scymanski, Ecr. Deulsch. Chcm. Ges. xiii. 917.

2 Itoth, Ann. Chcm. Pharm. cliv. 72.

3 Bischoff, Bcr. Deutsch. Chem. Gcs. vii. 634, 1082.

4 Schiff, Ann. Chcm. Pfuirm. cxl. 115 ; cxlviii. 330 ; cli. 892.


oily liquid, which boils at 227 230, and possesses a penetrating
smell and a sharp burning taste. When this compound is heated
with water to 170, the aldehyde is formed ; it is a liquid which
boils at 210, has a sharp smell and taste, and readily oxidizes in
the air to orthochlorobenzoic acid. It combines with acid sodium
sulphite. 1

Metachlordbenzaldehyde is formed when benzaldehyde is
chlorinated in presence of a dehydrating agent, such as sul-
phuric acid, zinc chloride, aluminium chloride, etc., and is a
liquid boiling at 210 213 . 2

It may also be obtained by heating a hydrochloric acid
solution of metamidobenzaldehyde and cuprous chloride to the
boiling-point and then gradually adding a solution of sodium
nitrite. 3

Parachlorobenzaldeliyrlc is obtained by boiling parachlorobenzyl
bromide with water and lead nitrate in an atmosphere of carbon
dioxide. It crystallizes in white tablets, melting at 47"5, which
are slightly soluble in cold, more readily in hot water, and readily
in alcohol ; it smells like benzaldehyde, readily oxidizes in the
air and unites with acid sodium sulphite to form a compound
which is only slightly soluble. 4

The product of the action of chlorine on benzidene chloride
in presence of iodine is a mixture of ortho- and para-chloro-
benzidene chlorides, which boils at 230 237 , 5 and was formerly
thought to be the pure para-compound. 6 When it is heated
with anhydrous oxalic acid, boiled with lead nitrate, or heated
to 170 with water, a mixture of the aldehydes is obtained,
boiling at 210 214; in the cold it smells like benzaldehyde,
but when heated has a very sharp, penetrating odour arid causes
a flow of tears. The same mixture is formed, together with ethyl
iodide, when benzyl ethyl ether is treated with chlorine in
presence of iodine : 7

C H 6 ,CH 2 .O.C 2 H 5 +ICl 3 =C 6 H 4 Cl.CHO-f-C 2 H 5 I-r-2HCl.

Lichlorobenzaldehyde, C 6 H 3 CL,CHO(C1 : Cl = 3 : 4). Beilstein
and Kuhlberg, by the action of chlorine on boiling dichloro-

1 Henry, Per. Dcutsch. Chcm. Gas. ii. 135.

2 Miiller, ibid, xviii. Kef. 6oO

3 Ibid, xviii. Rcf. b95.

< Jackson and White, ibid. xi. 10J2.

5 Anschiitz, Ann. Chc.m. Pharm. ccxxvi 19.

6 Beilstein and Kuhlberg, ibid, cxlvi. 327.

7 Sintenis, Bcr. Deutsch. Chem. Get. iv. 699.


toluene, obtained a dichlorobenzidene chloride,
which boils at 257, and is converted into the aldehyde by
heating with water to 200. It is soluble in boiling water, more
readily in alcohol, and crystallizes in fine needles, which melt at
68, volatilize in steam, and combine with acid sodium sulphite. 2
A compound, which is probably identical with this, is ob-
tained by the further chlorination of metachlorobenzaldehyde
in presence of a dehydrating agent, and is described as a liquid,
boiling at 240 243.*

a-Trichlorolenzaldehyde, CgH^Cl^OHO. The further chlori-
nation of a-trichlorotoluene yields a-trichlorobenzidene chloride,
C 6 H 2 C1 3 .CHC1 2 , which boils at 280 281, and solidifies be-
low in fine needles. 4 The aldehyde obtained by heating it
with water to 260 is insoluble in water, crystallizes in very
fine needles, which melt at 112 113, and is volatile with
steam. 5

fi Trichlorobenzaldehyde. The ft-trichlorol/enzidene chloride
obtained from /3-trichlorotoluene, melts at 84, boils at 280, and
yields the /3-trichlorobenzaldehyde which melts at 90 (Seelig).

Tetrachlorolcnzidene chloride, C 6 HC1 4 .CHC1 2 , has been prepared
from tetrachloro toluene ; it is a liquid, which boils at 305 306,
and is decomposed by water at 250. The aldehyde thus formed
has not been further investigated. 6

Pentachloro'benzid.ene chloride, C 6 C1 5 .CHC1 2 , is formed by the
continued action of chlorine on benzidene chloride in presence
of iodine and finally of antimony chloride. It crystallizes from
alcobol in long flat plates, melts at 109, boils at 334, and is not
attacked by water even at 300 . 7

Ortlwbromolenzaldehyde, C 6 H 4 JBr.CHO, has been prepared by
boiling orthobromobenzyl bromide with water and lead nitrate ;
it is a heavy, oily liquid, which oxidizes very rapidly in the air. 8

Metabromolenzaldehyde, C 6 H 4 Br.CHO, is a liquid which does
not solidify in a freezing mixture (Jackson and White), boils
at 233 236, and may be prepared by the b.romination of
benzaldehyde in presence of a dehydrating agent (Miiller).

Parabromobenzaldehyde, C 6 H 4 Br.CHO, crystallizes in long
white needles, melting at 57.

Ann. Chfm. Pharm. cl. 291. 2 Ibid. clii. 228.

Her. Dcutsch. Chem. Ges. Kef. xviii. 25.

Ann. Chem. Pharm. cl. 299 ; SeeHg, Etr. Dculsch. Chem. Ges. xviii. 420.
Ibid. ; Aim. Chem. Pharm. clii. 238.

Ibid. cl. 3C3. 7 2bid. cl. 306.

Jackson and White, Amer. Chem. Juurn. iii. 32.


Para-iodobenzaldehijde, C 6 H 4 LCHO, also forms needles, melting
at 73 (Jackson and White).

2092 Orthanitrobenzaldehyde, C 6 H 4 (NO 2 )CHO, is formed in
small quantity, together with the m eta-compound, by the action
of a mixture of nitric and sulphuric acids on benzaldehyde. 1 It
may, however, be more readily prepared from orthonitrocinnamic
acid, C 6 H 4 (NO 2 )CH=CH.CO 2 H. When the ethyl ether of this
acid is dissolved in concentrated nitric acid and treated with sodium
nitrite, the temperature of the mixture not being allowed to rise
more than a few degrees, a compound is formed which contains
a nitric acid residue in the side chain. The mixture is poured,
after having stood for some hours, into water, and the oil which
separates out distilled in steam, sodium carbonate being added
from time to time ; the distillate consists of water and pure
orthonitrobenzaldehyde. 2 It can be still more conveniently
prepared by oxidizing orthonitrocinnamic acid with potassium
permanganate in alkaline solution (Friedliinder and Henriques).
The solution must be cooled with ice and shaken up with
benzene at short intervals in order to remove the aldehyde from
the further action of the oxidizing agent. The benzene solution
is then evaporated, the aldehyde remaining behind. 3

It is readily soluble in alcohol, slightly in water, and crystal-
lizes in long, light yellow needles, melting at 46, which smell
like benzaldehyde in the cold, but give off a penetrating vapour
when heated.

It forms a readily soluble compound with acid sodium sulphite,
which crystallizes in small, lustrous plates ; concentrated caustic
soda solution decomposes it completely into orthonitrobenzyl
alcohol and orthonitrobenzoic acid. When a little water and
caustic soda are added to its solution in acetone, indigotin,
G 16 H 10 N 2 O 2 , the colouring matter of indigo, separates out after
a short time. 4

Orthonitrobenzaldoximc, C H 4 (NO 2 )CH.NOH. Gabriel and
Meyer, by the action of hydrochloric acid and amyl nitrite on
amidorthonitrophenylacetic acid, obtained a diazo-compound :

NH 2 .C 6 H 3 (N02)CH 2 .CO 2 H + 2NO 2 H + HC1 =

C1N NC 6 H 3 (N0 2 )CH 2 NO + CO 2 + 3H 2 O.

1 Rudolph, Ber. Deutsch. Chcm. Ges. xiit. 310,

2 Friedland-T and Henriques, ibid. xiv. 2301.

3 Einhorr,, ibid. xvii. 119.

4 Bacycr and Drewsen, ibid. xv. 2857.


On heating with alcohol, this is converted into nitroso-
metliylnitrobenzene, C 6 H 4 (NO 2 )CH 2 NO, this being decomposed by
oxidation with formation of nitrogen monoxide and orthonitro-
benzaldehyde, which was first prepared pure by this method. 1

This substance was subsequently recognised as orthonitrobenzal-
doxime and prepared from the aldehyde and hydroxylamine. 2
It crystallizes from hot water in hair-like needles, which melt
at 95, have a sweet taste, and form a yellow solution in alkalis.
Its methyl ether, C 6 H 4 (NO 2 )CH.NOCH 3 , is formed by heating
it to 100 with caustic potash, methyl alcohol and methyl iodide ;
it is only slightly soluble in water, readily in alcohol, and
crystallizes in silky needles, melting at 58.

Metanitrobcnzaldeliyde, C 6 H 4 (N0 2 )CHO, was first obtained by
Bertagnini by the action of a mixture of nitric and sulphuric
acids on benzaldehyde. 3 In order to prepare it, 1 part of the
latter is dissolved in a mixture of 5 volumes of fuming nitric
acid with 10 volumes of sulphuric acid, the temperature being
kept below 15. The nitro-compound is precipitated by water,
washed and re-crystallized from dilute alcohol. 4 It forms lustrous
white needles, melting at 58, 5 smells like benzaldehyde when
cold, but gives off a penetrating vapour when heated, and
combines with the acid sulphites of the alkalis (Bertagnini), as
well as with acid aniline sulphite 6 to form crystalline compounds.

Mctanitrobenzidcnc chloride, C 6 H 4 (NO 2 )CHC1 2 , is obtained by
the action of phosphorus pentachloride on the aldehyde ; it
crystallizes from alcohol in needles or small thin plates, melting
at 65. 7

Metanitrobenzidene bromide, C H 4 (N0 2 )CHBr 2 , is formed by
heating the aldehyde with bromine to 140, and crystallizes in
microscopic tablets, melting at 101 102 . 8

Metanitrobenzaldoxime, C 6 H 4 (N0 2 )CH.NOH, was first obtained
from metanitro-amidophenylacetic acid and was called nitroso-
m ethylinetanitrobenzene?

It is readily formed by the combination of hydroxylamine

Her. Deutsch. Chem. Gcs. xiv. 832, 2332.
Gabriel, ibid. xv. 3057.
Ann. Chcm. P/iann. Ixxix. 260.

Widmao, ficr. Deutsch. Ghsm. Ges. xiii. 678 ; see also Frie41aiider and
iriques, ibid. xiv. 2801.
Lippmaim and Hawliczek, ibid. ix. 1463.
SchifT, Ann. Chcm. Pharm. cxcv. 301.
Widman, Bcr. Deutsch. Chem. Ges. xiii. 676.
WachendoriF, Ann. Chem. Pharm. clxxxv. 266.
Gabriel, Bcr. Deutsch. Chnn. Gcs. xv. 834.

L 2


with metanitrobenzaldehyde, 1 and crystallizes from water in long,
flat needles, melting at 118 119. Its methyl ether also forms
flat needles and melts at 63 63'5.

Trinitrohydrobenzamide, N 2 (CH.C 6 H 4 .NO 2 ) 3 , is formed by the
action of ammonia on metanitrobenzaldehyde; it is insoluble in
water and ether, and only slightly soluble in boiling alcohol, from
which it separates out in flocks consisting of very thin needles.
When it is heated to 125 or boiled with dilute caustic potash
solution, it is converted into the isomeric trinitro-amarine, which
forms warty crystals and has a feeble alkaline reaction. Its salts
are difficultly soluble and have a very bitter taste (Bertagnini).

Paranitrobenzaldehyde, C 6 H 4 (NO 2 )CHO, is prepared by boiling
10 parts of paranitrobenzyl chloride with 60 parts of water, 14
parts of lead nitrate, and 10 parts of nitric acid of sp. gr. 1'3,
for several hours. If the solution be more dilute, nitrobenzyl
alcohol is formed instead of the aldehyde. The product is shaken
out with ether and the aldehyde separated by means of acid
sodium sulphite. 2

Paranitrobenzaldehyde may also be readily obtained by the
oxidation of paranitrocinnamic acid. 3 It crystallizes from hot
water in thin prisms, often an inch in length, which melt at
100, have a characteristic smell, and do not volatilize readily
in steam. Its compound with acid sodium sulphite is readily
soluble in water and crystallizes in small iridescent plates.
It is not attacked to an appreciable extent by boiling nitric
acid, which must not, however, be too concentrated, but is
quantitatively converted into parahydroxybenzoic acid by
chromic acid. 4

When it is heated with aniline hydrochloride and zinc
chloride, paranitrodiamidotriphenylmethane, CH(C 6 H 4 .NH 2 ) 2
C 6 H 4 .N0 2 , is formed, which on reduction yields paraleucaniline,
CH(C 6 H 4 ."NH 2 ) 3 . It is oxidized by mercuric oxide to pararosani-
line, C(OH)(C 6 H 4 .NH 2 ) 3 (Fischer and Greiff).

Paranitrobenzidene chloride, C 6 H 4 (N0 2 )CH01 2 , is formed by
the action of phosphorus pentachloride on pnranitrobenzalde-
hyde ; it crystallizes from alcohol in short, well-formed prisms,
melting at 46. 5

Paranitrobenzidene bromide, C 6 H 4 (NO2)CHBr 2 , is formed by

Gabriel, Ber. Dcnd-ch. Chem. Ges. xv. 3061.

0. Fischer and Greiff, ibid. xiii. 669.

Baeyer, ibid. xiv. 2317 ; Friedlander, ibid. xiv. 2577 ; Basler, ibid, xvi 2714.

0. Fischer, ibid. xiv. 2525.

Zimmermann and M filler, ibid, xviii. 996.


heating paranitrotoluene with bromine to 140, and crystallizes
from alcohol in needles or small rectangular plates, melting at
82 82-5 . 1

Both compounds are converted into pararosaniline when
heated with aniline. 2

Paranitrobenzaldoxime, C 6 H 4 (N0 2 )CH=N.OH, crystallizes
from hot water in long needles, melting at 128'5. s

2093 Orthamidobenzaldehyde, C 6 H 4 (NH 2 )CHO, was first ob-
tained by Gabriel in small quantities by oxidizing orthamido-
benzaldoxime with an acid solution of ferric chloride. 4 Fried-
lander and Henriques found that orthonitrobenzaldehyde is
converted by the action of tin and acetic acid into anthranil, 5
C 7 H 5 NO, a compound which stands to anthranilic acid or
orthamidobenzoic acid in the same relation as lactimide to
a-amidopropionic acid (Part II. p. 159). This is converted
into Orthamidobenzaldehyde by heating with ferrous sulphate
and ammonia : 6


4 <; |

2H = C 6 H
) \CHO.

The latter can also be obtained directly in the same way from
orthonitrobenzaldehyde. 7 It is very soluble in alcohol, less
readily in water, forming a yellow solution, and crystallizes in
lustrous plates, which are volatile with steam, their vapour
possessing a penetrating smell resembling that of an indigo vat.
It melts at 39 40, and solidifies on cooling In a crystalline
mass; at a higher temperature a portion distils without de-
composition, while the remainder is converted into a dark
yellow, resinous mass. It can be heated with caustic soda
solution or ammonia without undergoing any change ; dilute
mineral acids, however, readily convert it into an amorphous
condensation product. When it is heated with acetic anhydride,
acetylorthamidobenzaldehyde, C 6 H 4 (NH.C 2 H 3 O)CHO, is formed ;
it crystallizes from hot water in long white needles, melting at
70 71.

Orlhamidobenzaldoxime, C 6 H 4 (NH 2 )CH=N.OH, is formed by

1 "Wachendorff, Ann. Chcm. Pharm. clxxxv. 268.

2 Zimmermanu and Miiller, Bcr. Dcutsch. Ghem. Ges. xvii. 2936.
8 Gabriel and Herzberg, ibid. xvi. 2000.

4 Ber. Deutsch. Chem. Ges. xv. 2004.

5 Ibid. xv. 2105.

6 Friedlander, ibid. xv. 2572.

7 Friedlander and Gohring, ibid. xvii. 456.


the reduction of the corresponding nitro-compound with am-
monium sulphide, and crystallizes from hot water in long, flat,
lustrous needles, melting at 132 133 . 1

Metamidobenzaldehyde, C 6 H 4 (NH 2 )CHO, is obtained by re-
ducing metanitrobenzaldehyde with ammonia and ferrous
sulphate, and distilling the product with steam ; it is a yellow,
oily liquid, which solidifies at low temperatures and yields
amorphous condensation products with even greater readiness
than the ortho-compound (Friedlander and Gohring).

Metamidobenzaldoxime, C 6 H 4 (NH 2 )CH=N.OH, is formed
when a solution of metanitrobenzaldoxime in caustic soda is
added to a hot solution of ferrous sulphate saturated with
ammonia, the blue-black ferrous hydroxide being converted
into brown ferric hydroxide. The filtrate is rendered faintly
acid with hydrochloric acid, treated with ammonia and then
extracted with ether; the residue left on evaporation of the
ethereal extract consists of metamidobenzaldoxime, which
crystallizes from hot benzene in fine, snow-white needles, melt-
ing at 88. Oxidation with an acid solution of ferric chloride
yields an amorphous, yellow oxidation product of metamido-
benzaldehyde. 2

Paramidobenzaldehyde, C 6 H 4 (NH 2 )CHO, has been obtained as
a decomposition product of its aldoxime ; it crystallizes from
water in small, indented plates, which melt at 69'5 71 '5, but
soon change into a modification insoluble in water and melting
at a higher temperature. When heated with acetic anhydride
and sodium acetate, it is converted into acctylparamidobenzalde-
hyde, C 6 H 4 (NH.C 2 H 3 O)CHO, which crystallizes from hot water
in long, lustrous needles, melting at 155.

Paramidobenzaldoxime, C 6 H 4 (NH 2 )CH=:N.OH, is formed by
the action of ammonium sulphide on paranitrobenzaldoxime,
and crystallizes from hot water in yellow tablets, melting at
124. It dissolves in an excess of hydrochloric acid, forming a
solution which soon deposits dark red needles with a blue re-
flection, while hydroxylamine remains in solution. Caustic soda
decomposes the red compound, paramidobenzaldehyde or its con
densation products being set free. 3

Dimclhylparamidobenzaldehyde, C C H 4 .N(CH 3 ) 2 CHO. When
zinc chloride is allowed to act on a mixture of chloral hydrate

1 Gabriel and Mayer, Bar. Dcutsch. Chcm. Ges. xiv. 2338.

2 Gabriel, ibid. xvi. 1997.

2 Gabriel and Herzbcrg, ibid. xvi. 2000,


mid dimethylaniline, dimethylamidophenylhydroxytrichlorethane
is formed, and is decomposed by caustic potash with formation of
dimethylparamidobenzaldehyde and chloroform or decomposition
products of these :


C H/ = C 6 H/ +CHCL,

\N(CH 3 ) 2 X N(CH 3 ) 2

The new compound crystallizes in small plates, which melt at
73, readily dissolve in alcohol and hot water, and are volatile
vith steam. 1


2094 The products formed by the dry distillation of gum ben-
zoin 2 are mentioned in writings which date back as far as the
sixteenth century. Hieronymus Rosello, who, under the name
of Alexius Pedemontanus, published a work, De Secretis, in the
year 1557, mentions in it the butter of benzoin, and Libavius
in his Alcliymia, written in 1595, says that when laser* vel
Icnzoin is distilled, water comes over first, followed by a thick
oil, " ultima exit instar mannae, gummi." Blaise de Vigenere,
whose TraitS defcu ct du sel, appeared after his death in 1608,
says that with a strong fire " infinies petitcs aiyuilles ct fila-
ments" appear, which must be soon removed because they
would otherwise melt like marrow (moelle). About the same
period, Turquet de Mayerne in his Pharmacopoea teaches how to
obtain flowers of benzoin from the residue by subliming it in an

1 Roessneck, Bcr. Dcutech. Chcm. Gcs. xviii. 1516 ; xix. 365.

2 This resin is obtained by means of incisions in the bark of Styrax Benzoin, a
tree indigenous to Java and Sumatra. It is sent into tHe European market from
the latter island, and this was formerly the only source from which it could be
obtained. A highly valued variety is now sent from Siam, but nothing further is
known as to its origin. It was formerly counted as one of the costly spices. It
is first mentioned by Ibn Batuta, who travelled in the East about the years 1325
1349, and describes it under the name of Luban Jawi (incense of Java). The
latter word was then the name of Sumatra, and the Arabs designated by it the
whole archipelago, as well as the products obtained from it. The Arabic name
gradually became corrupted into banjawi, benjui, benzui, rjenzoe, benzoin, and in
English also benjamin or gum benjamin, which is now the name in general
commercial use (Kliiekiger and Hanbury, Pkarmacographia, 2nd cd. p. 403).

3 Laser is the name of a Persian and Indian product on which a tax was
imposed at the Roman customs-house in Alexandria during the second century of
our era. Some suppose that it was asa foetida, while benzoe was also called
asa dulcis.


earthen vessel to which a cap of paper has been adapted, or by
heating it mixed with sand in a retort, and since that time
flores benzoes have been an ordinary pharmaceutical prepara-
tion. A solution of the resin in alcohol was also in use ; mixed
with lead acetate it was employed as a choice cosmetic under
the names of magisterium lenzoe* or lac virginis. Ehrenfried
Hagendorn, a physician of Gorlitz, in 1671 found in this a salt
which was identical with flowers of benzoin, both in smell and
taste. Lemery in 1675 also remarked on the acid nature of
this substance, saying, " les fleurs de lenjoin ont une acidiU
fort agrdable" a fact which was further proved by the researches
of Scheele, who showed, in 1775, that the flowers of benzoin could
be more economically obtained by digesting the resin with
slaked Hme and water for some hours, boiling and adding
hydrochloric acid to the filtrate; finally, Lichtenstein in 1782
conclusively proved that they are an acid.

The correct composition of benzoic acid was determined in
1832 by Liebig and Wohler, 1 who showed that it is a compound
of the radical benzoyl, C 7 H 6 (p. 89). Mitscherlich, on the
other hand, showed in 1834 that it is decomposed into carbon
dioxide and benzol on heating with milk of lime, and looked
upon it as a carbonic acid derivative of benzol ,' Liebig opposed
this view, as he considered the benzol to be merely a product of
the destruction of the benzoic acid ; the latter compound can,
however, as was shown somewhat later, be readily prepared
synthetically from carbon dioxide and benzol, and we can
therefore look upon it as carbonic acid, CO(OH) 2 , in which one
hydroxyl has been replaced by phenyl, or as a compound of
phenyl with carboxyl. The latter supposition corresponds to
that of Berzelius, according to which, benzoic acid is oxalic acid
copulated with phenyl, oxalic acid being dicarboxyl.
Many varieties of benzoin contain cinnamic acid 2 in addition
to benzoic acid and frequently only the former. 3 Both these
acids occur, either free or in the form of ethereal salts, together
with other aromatic compounds, in Tolu balsam (p. 3), Peru

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