D

ILLINOIS

UNIVERSITY OF ILLINOIS AT URBANA-CHAMPAIGN

PRODUCTION NOTE

University of Illinois at
Urbana-Champaign Library
Brittle Books Project, 2015.COPYRIGHT NOTIFICATION

In Public Domain.
Published prior to 1923.

This digital copy was made from the printed version held
by the University of Illinois at Urbana-Champaign.
It was made in compliance with copyright law.

Prepared for the Brittle Books Project, Main Library,
University of Illinois at Urbana-Champaign
by

Northern Micrographics
Brookhaven Bindery
La Crosse, Wisconsin

2015THE BOOK

op the

BALANCE OF WISDOM.

AN ESSAY ON DETERMINATIONS OF SPECIFIC
GRAVITY BY THE ARABIANS OF
THE XIITH CENTURY.

Read before the N. Y. Academy of Science
May 29th, 1876,

by

H. CABBINGTON BOLTON, Ph.D.

Reprinted from the American Chemist, May1 1876.

NEW YORK:

JOHN F. TROW & SON, PRINTERS AND BOOKBINDERS,
205-213 East Twelfth Stkeet.

1876.NOTES ON THE EARLY LITERATURE OF
CHEMISTRY.

BY H. CAKRINGTON BOLTON, PH.D.

vn.

THE BOOK OF THE BALANCE OF WISDOM.

^ Head before the New Yorh Academy of Sciences May
Z	29, 1876.

3	.	. ■ .

* So rapid are the strides made by science in this
£ progressive age, and so boundless is its range, that
those who view its career from without find great dif-
v . iiculty in following its diverse and intricate pathways,
jf1 while those who have secured a footing within the
^ mysterious domain and are free to journey on the
^ same road are often quite unable to keep pace with
its fleet movements and would fain retire from the
unequal contest. It is not surprising, then, that those
actually contributing to the advancement of science,
H. pressing eagerly upward and onward, should neglect
to look back upon the labors of those who precede

4	them, and should sometimes lose sight of the obliga-
^ tions which science owes to forgotten generations.

2*7 Could the wisdom of the world concealed in the
| silent unwritten history of past ages be divulged
*5 by a miracle of revelation, how startling and inter-
esting would be the wonderful disclosure! Imagina-
- tion fails to conceive of the possible social and scien-
tific status of the present era, had the named and the
unnamed " lost arts " been preserved through all time,
. and had the experience of the human race been unin-
^ teiTuptedly handed down to the existing generation,
csi The legitimate feeling of exultation and satisfaction
. ' enjoyed by oriental scholars when years of painstaking

b 3,751

4

research amid the musty records of the past are at
length rewarded by a literary and historical discovery
of importance, seems to ns comparable to the pleasur-
able excitement experienced by the scientists whose
investigations of nature are crowned by the determi-
nation of a new species, or the establishment of a new
law. In this respect, the Egyptologist and the Natu-
ralist, the student of ancient history and the student
of modern chemistry, have a common purpose, each in
his own sphere seeking the truth.

Original investigations in the field of history are,
however, vouchsafed only to those profound linguists
whose erudition and skill in deciphering semi-oblit-
erated cryptographs have been the fruit of a lifetime's
laborious study ; and these absorbed in their study of
the ancient, too often neglect to compare the wisdom
of early times with the progress of modern scientific
truths, and fail to appreciate the points most valuable
to the student of science. Hence the history of science
yet remains to be written.

This suggestion may be met with references to the
works of the savans who, especially in the preceding
century, devoted much to the elaboration of historical
treatises in their several departments of science ; but
these are few in number, and as we believe merely
sketch the outlines, the details of which will yet be
supplied by some mighty genius at once a linguist, an
archaeologist and a scientist.

Meanwhile, in default of the erudition which alone
allows of critical examination of monumental inscrip-
tions, papyri, and original manuscripts, the humble
searcher after knowledge must be content to study
available translations, notes, and criticisms provided
by oriental scholars, and to bring into prominence
such materials as his imperfect powers can command.

Bearing in mind the great obligations whicfr the
exact sciences owe to the Arabian philosophers of the
middle ages, it Is not 'surprising that such of their5

works as are made available by the translations of
linguists, afford abundant and rich sources of infor-
mation to the student of the History of Science. The
work named at the beginning of this article forms a
remarkable contribution to the early history of the
determination of specific gravities^ This "Book of
the Balance of Wisdom " is an Arabic treatise on the
water-balance, written in the twelfth century, for an
account of which the historian of science is indebted
to the chevalier N. Khanikoff, sometime Russian Con-
sul General at Tabriz, an important city of northern
Persia. Mr. Khanikoff having obtained access, in
some manner not explained, to a manuscript copy of
the Arabic work, translated into the French language
copious extracts, and prepared an analysis of its con-
tents; these data, together with a transcript of the
original Arabic version, he communicated to the
American Oriental Society. The Society's Committee
of Publication, in preparing the Russian Consul's work
for their Journal, translated his notes into English, re-
translated the Arabic extracts, and added their own
valuable comments. The completed article is found
in the sixth volume of the Journal of the American
Oriental Society, pp. 1 to 128, published in 1859.

The Book of the Balance of Wisdom treats exclu-
sively of the balance and of the results attainable by
this instrument which has given to modern science so
many beautiful discoveries. Its exposition of the
principles of the centres of gravity, of researches into
the specific gravity of metals, precious stones and
liquids, shows these Orientals to have attained to ex*
peri mentation, a step in the progressive knowledge of
physical truths entirely unknown to the ancients. Be-
fore offering such citations from this work as may
seem necessary to establish this proposition, we will
endeavor to answer two questions which naturally
suggest themselves to our readers. What is the date
-of the original manuscript, and who was its Author?6

most happily both queries admit of satisfactory replies,
based on internal evidence.

The dedication of the work proves it to have been
composed at the court of the Saljuke Sultan Sanjar
who reigned oyer a large part of the ancient Caliphate
of Bagdad from a.d. 1117 to 1157. In this introduc-
tion, the author appeals to this potentate in the follow-
ing fulsome expressions of homage characteristic of the
Orientals:

44 Most magnificent Sultan, the exalted Shah of
Shahs, the king of subject nations, the chief of the
Sultans of the world, the Sultan of God's earth ....
the shelter of Islamism and of Muslims, the arm of
victorious power . . . . Prince of Believers—may
' God perpetuate his reign and double his power! For
his felicity is the illuminating sun of the world, and
his justice its vivifying breath."

And immediately following this passage, occurs
mention of the date:

" I sought assistance from his beams of light irra-
diating all quarters of the world, and was thereby
guided to the extent of my power of accomplishment
in this work, and composed a Book on the Balance of
Wisdom for his high treasury, during the months of
the year 515 of the Hegira of our Elect Prophet Mo-
hammed—may the benedictions of God rest upon him
and his family, and may he have peace!"

This proves the treatise to have been written in the
years 1121-1122 a.d. At this period of the world's
history we find Arab philosophers cultivating litera-
ture and science, while the rest of Europe was just
emerging from intellectual darkness. The religious
world had scarce recovered from the intense excite-
ment aroused by Peter the Hermit and his followers,
who led the tumultuous rabble 600,000 strong towards
the Holy City; and priests, knights and peasants were
preparing with frantic zeal for a Second Crusade.
Aboard and H6loise were names which afforded end-
less discussions in the cloister and on the hearth.
Science was at a low ebb, a century elapsed before7

Albert lis Magnus and Roger Bacon exerted their in-
fluence ; and scholastic philosophy, attaining its lof-
tiest height, swayed the intellects of the age.

The authorship of the Book of the Balance of Wis-
dom is easily determined by the fortunate circumstance
that the author names himself several times, ''but in
so modest a manner as scarcely to attract attention;
instead of heralding himself at once, in his first words,
after the usual expressions of religious faith, as Arab
authors are wont to do, he begins his treatise by dis-
coursing on the general idea of the balance " and then
simply remarks: " Says al-Khazini, after speaTcing of the
balance in general," and proceeds to enumerate the
advantages of the balance which he is about to des-
cribe. Two other passages in the extracts furnished
by Mr. Khanikoff satisfy the Oriental scholars who
have examined them that the author is this self-
named al-Khazini.

Attempts to identify al-Khazini with individuals
of historical fame have given rise to differences of
opinion, but the weight of evidence is in favor of re-
garding him as the same with Alhazen the Arab opti-
cian and physiologist.

Alhazen seems to have been a native of Persia and
to have resided in Spain and Egypt, but of his biog-
raphy little is known. He is especially distinguished
for his demonstration of the theory of vision, showing
that the rays of light are reflected from external ob-
jects to the eye and do not issue forth from, the eye to
impinge on external things, as up to his time had been
taught.

This explanation, moreover, was not based on mere
hypothesis, but was the result of anatomical investiga-
tions as well as of mathematical discussions.

Alhazen also explained the astronomical refraction
of light, its dependence on the variation of the density
of the media traversed, and its influence in producing
the phenomenon of twilight. In the discussion of all8

these problems he evinced true scientific greatness. He
favored the theory of the progressive development of
animal forms, anticipating a doctrine but newly obtain-
ing acceptance. Dr. J. W. Draper,* who has been our
guide in this connection, says of Alhazen: Though
more than seven centuries part him from our times, the
physiologists of this age may accept him as their com-
peer."

The name al-Khazini signifies "related to the treas-
urer," which accords with his statement that the work
was composed for the royal treasury.

The Book of the Balance of Wisdom begins with a
dedication to God " the compassionate, the merciful,"
and a pious statement of the author's religious faith.
An introduction, divided into eight sections, then fol-
lows ; in the first section, the advantages and uses of
the Balance are enumerated in this language:

" These advantages are: 1, exactness in weighing;
this balance shows variations to the extent of a mithkal, j-
or of a grain, although the entire weight is a thousand
mithkals, provided the maker has a delicate hand,
attends to the minute details of the mechanism, and
understands it; 2, that it distinguishes pure metal
from its counterfeit, each being recognized by itself
without any refining; 3, that it leads to a knowledge
of the constituents of a metallic body without separ-
ation one from another............; 4, that it shows

the superiority in weight of one of two metals over
the other in water, when their weight in air is the same,
and reversely............; 5, that it makes the sub-
stance of the thing weighed to be known by its weight

............; 6............; 7, the gain above ail

others-that it enables one to know what is a gen-
uine precious stone, such as a hyacinth, or ruby,
or emerald, or fine pearl; for it truly discriminates

* Hist. Int. Devel. Europe, page 360.

t We cannot here undertake to discuss the ancient Arabic system of
weights, but merely state that while authorities differ, Mr. Khanikoff,
after a careful examination and comparison of modern and ancient
standards of weight in Georgia,'Daghistan and elsewhere, ^where Arabic
customs have suffered little change, assigns to the mithkal the value of
4.5 grammes. The mithkal, according to Abu-r-Raihan (quoted below)
equals 6 daniks; 1 danik=4 tassujs; 1 tassuj=4 grains; and 1 grain
=4 barley-corns.9

between these and tlieir imitations or similitudes in
color, made to deceive."

Then follows the theory of the water balance; and in
the fourth section some account of its early history
and the well-known narrative of King Hiero's crown.

" It is said that the [Greek] philosophers wTere first led
to think of setting up this balance and moved thereto
by the book of Menelaus * addressed to Domitian, in
which he says: 4 O King, there wTas brought one day
to Hiero, King of Sicily, a crown of great price, pre-
sented to him on the part of several provinces, which
was strongly made and of solid workmanship. Now
it occurred to Hiero that this crown was not of pure
gold, but alloyed with some silver ; so he inquired in-
to the matter of the crown, and clearly made out that
it was composed of gold and silver together. Pie
therefore wished to ascertain the proportion of each
metal contained in it, while at the same time, he was
averse to breaking the crown on account of its solid
workmanship. So he questioned the geometricians
and mechanicians on the subject, but no one sufficient-
ly skilled was found among them, except Archimedes
the geometrician, one of the courtiers of Hiero. Ac-
cordingly he devised a piece of mechanism which, by
delicate contrivance, enabled him to inform King
Hiero how much gold and how much silver was in
the crown, while yet it retained its form. This was
before the time of Alexander. Afterwards Menelaus
[himself] thought about the water-balance and brought
out certain universal arithmetical methods to be applied
to it; and there exists a treatise by him on the subject.
It wTas then four hundred years after Alexander."

Al-Khazini takes pains in this sketch of the early
history of specific gravity, to establish dates by ref-
erence to cotemporaneous individuals, but his chro-
nology is evidently at fault. The Hiero alluded to is
Hiero II., who died 216 B.C., while Alexander the
Great lived more than a century earlier (356 B.c.—
323 B.C.)

This Arabic version of the anecdote of Hiero's

* A celebrated mathematician who lived in the reign of Trojan, 98—
117 a.d., and author of a treatise on Spherical Geometry.10

crown lacks the piquancy ancl interest of the narrative
as originally given by Vitruvius, and is moreover not
an accurate transcription; the words " devised a piece
of mechanism " convey the impression that Archime-
des constructed some peculiar form of apparatus with
which to solve the problem. Indeed this story, famil-
iar as it is, is not unfrequently erroneously related,
even as al-Khazini himself has done, and compilers of
text books of natural philosophy, content to copy from
each other instead of seeking the original sources,
transmit the errors of detail.

These reflections are in part suggested by a singular
construction given to the narrative in a recent and
really excellent text-book on the History of Natural
Science, in which the authoress commits the remarka-
ble anachronism of representing (in a woodcut) the
crown and the metallic masses suspended - in water
from spi'iiig-balances of modern appearance and con-
struction.

To dispel any lingering ideas of this character we
here revive the passage in Vitruvius,* " De Architect
tara," the original source of the narrative, and in
which it appears that the " greatest geometer of an-
tiquity " arrived at his results by a comparison of
unequal volumes of water obtained by displacement,
and not by direct weighings in that liquid.

44 Book IX. Chapter 3. Of the method of detedt-
ing silver when mixed with gold."

" Though Archimedes discovered many curious mat-
ters which evince great intelligence, that which I am
about to mention is the most extraordinary. Hiero,
when he obtained the royal power in Syracuse, hav-
ing, on the fortunate turn of his affairs, decreed a vo-
tive crown of gold to be placed in a certain temple to
the immortal gods, commanded it to be made of great

* Marcus Vitruvius Pollio, a distinguished Roman architect and
author, served as military engineer under Julius Caesar in Africa,
B.C. 46. His work, "De Architectural1 (written in his old age),
comprising ten books, is the only ancient treatise on the subject ex-
tant. Of Vitruvius1 biography very little is known.11

value, and assigned an appropriate weight of gold to
the manufacturer. He, in due time, presented the
work to the King, beautifully wrought, and the weight
appeared to correspond with that of the gold which
had been assigned for it. But a report having been
circulated that some of the gold had been abstracted,
and that the deficiency thus caused had been supplied
with silver, Hiero was indignant at the fraud, and
unacquainted with the method by which the theft
might be detected, requested Archimedes would un-
dertake to give it his attention.

" Charged with this commission, he, by chance, went
to a bath, and being in the vessel, perceived that as
his body became immersed, the water ran out of the
vessel. Whence, catching at the method to be adopted
for the solution of the proposition, he immediately
followed it up, leaped out of the vessel in joy, and
returning home naked, cried out with a loud voice
that he had found that of. which he was in search, for,
he continued exclaiming in Greek, dvprjua (I have found
it out).

"After this he is said to have taken two masses, each
of a weight equal to that of the crown, one of them
of gold and the other of silver. Having prepared
them he filled a large vase with water up to the brim,
wherein he placed the mass of silver, which caused as
much water to run out as was equal to the bulk thereof.
The mass being then taken out, he poured in by meas-
ure as much water as was required to fill the vase once
more to the brim. By these means he found what
quantity of water was equal to a certain weight of
silver. He then placed the mass of gold in the ves-
sel, and on taking it out, found that the water which
ran over was lessened, because the magnitude of the
gold mass was smaller than that containing the same
weight of silver.

4 4 After again filling the vase by measure, he put the
crown itself in, and discovered that more water ran
over than with the mass of gold, that was equal to it
in weight; and thus from the superfluous quantity of
water carried over the brim by the immersion of the
crown, more than that displaced by the mass, he
found by calculation, the quantity of silver mixed
with the gold and made manifest the fraud of the
manufacturer." *

* The Architecture of Marcus Vitruvius Pollio, in ten books. Trans
lated from the Latin by Joseph Grwilt, London, 1826, pp. 264, 265.12

Continuing the sketch of the history of the water-
balance given by al-Khazini in the fourth section of
the Introduction, we find references to several Arabian
philosophers, among them the celebrated physician
Avicenna (Ibn Bina) who " distinguished [the compo-
nents of] a compound scientifically and exactly," and
Abu-r-Raihan 44 who took observations on the relations
of [different] metallic bodies and precious stones, one
to another, as indicated by this balance."

Al-Khazini also states that the instrument in ques-
tion was called " the Physical Balance " by Moham-
med Bin Zakariya of Rai, and it was named i ' the
Balance of Wisdom," by the u eminent teacher Abu-
Hatim al-Muzaifar Bin Ismail of Isfazar."

Abu-r-Raihan alluded to above is often quoted by
al-Khazini and deserves our attention. He was a
distinguished Arabian astronomer born about 970,
and died 1038 a.d. He was a member of the Society of
Savans founded in the capital of Kharizm, and of
which the eminent physician Avicenna was a shining
light. He was the author of a number of works on
astronomy, cosmography and physics, one of which
entitled "The Book of the Best Things for the Know-
ledge of Mineral Substances," and contained in the
Ayin-Akbari, or Institutes of the Emperor Akbar,
treats of the specific gravity of bodies and of hydro-
static methods for determining them. It is this work
to which al-Khazini refers. A review of Abu-r-Raihan's
treatise has been published by M. J. J. Clement-Mul-
let, under the title, " Recherches sur l'Histoire Nat-
urelle et la Physique chez'les Arabes." * Since this
Arabic manuscript is probably the most ancient work
extant which systematically treats of specific gravities,
we make another digression and give a brief synopsis
of its contents.

It contains theoretical explanations of the origin

* Journal Asiatique. SerieV.,Vol. xi., p. 879.13

and formation of mineral bodies founded on the views
of the Greeks, and particularly on those of Aristotle-
According to these views, the variety of the weights
of bodies depends upon the dry and the moist exhal-
ation from them; air and water are the elements of
these vapors, air giving the lightness and water the
heaviness. The author then proceeds to describe
methods for determining the specific gravity of bod-
ies in the following words :

'' Scientific men determine by means of water the
measure of these differences in weights. They pre-
pare a vessel filled with water in which they introduce
100 mithkals of each of the metals; the quantity of
water thrown out by each gives the difference in vol-
ume and weight, that one which displaces the largest
bulk of water has consequently the largest volume
but the least density, and that one which displaces the
least water is the heaviest."

* Abu-r-Raihan gives in tabular form the specific
gravity of nineteen substances, nine of which are min-
erals and nine are stones. In the following table we
annex the values assigned by modern authorities,
showing the remarkable accuracy, in most instances,
of, the early determinations .

TABLE OF SPECIFIC GKAVITIE8.

Abu-r-Raihan.

....19.05
....13.58
....11.33
..10.35

Modern Authorities.

Gold...,
Mercury,
Lead...
Silver...
Bronze.,
Copper.
Brass...
Iron
Tin.....

8.82
8.70
8.57

7.74
7.3t

19.30
13.568
11.346
10.52

7.79
7.29
3.99
8.90
3.52
2.73
2.75
2.90
2.61

8.05 to 8.95
8.78

8.58

Sapphire......

Oriental Ruby,

Ruby.........

Emerald......

Pearl.........

Lapis Lazuli..

Cornelian.....

Amber (?).....

Rock crystal..

2.56

3.58
3.85
2.75
2.69
2.60

2.53
2.50

3.97

1.08 (?)
2.5814

In tlie third lecture of the Book of the Balance of

Wisdom al-Khazini describes a form of specific
gravity flask which he calls the "conical instrument
of Abu-r-Raihan " and to whom he apparently ascribes
the invention. A mere inspection of the accompany-
ing cut, a fac-simile of that in the original manuscript,
together with the explanations (also from the original),
suffices to show its nature and the method of using it.

The author remarks that "the instrument is very
difficult to manage, since very often the water remains
suspended in the lateral tube, dropping from it little
by little into the scale of the balance*" This passage
shows that Abu-r-Raihan had noticed capillary attrac- ■
tion; it is also certain that he understood that the size
of the neck of the instrument alfected the delicacy of
the determinations, for he says he would have it " made
narrower than the little finger but for the difficulty of
removing through a smaller tube the bodies immersed
in the water."

Al-Khazini's work is made up of eight lectures,
each lecture includes several chapters and each chapter
has several sections; to give the table of contents
entire would undesirably lengthen this article, and we
prefer to quote Al-Kliazini's own summary of his
treatise as contained in the sixth section of the intro-
duction.



Place of the pan (of the balance)

Tube in the form of a water pipe.

Handle of the instrument.
Mouth of the instrument.

Neck of the Instrument.
Perforation.15

" I have divided tlie book into three parts: 1.
General and fundamental topics, such as heaviness
and lightness; centres of gravity; the proportion of
the submergence of ships in water; diversity of the
causes of weight; mechanism of the balance and the
steelyard; mode of weighing with it in air and in
liquids; the instrument for measuring liquids, in order
to ascertain which is the lighter and which is the
heavier of two, without resort to counterpoises; know-
ledge of the relations between different metals and
precious stones in respect to [given] volume; sayings
of ancient and modern philosophers with regard to the
water balance and their intimations on the subject.
This part includes four lectures of the book in their
order. II. Mechanism of the balance of wisdom;
trial of it; fixing upon it of [the points indicating] the
specific gravities of metals and precious stones ; adop-
tion of counterpoises suited to it; application of it to
the verification of metals and distinguishing of one
from another [in a compound], without melting or
refining, in a manner applicable to all balances; recog-
nition of precious stones and distinction of the gen-
uine from their imitations or similitudes in color.
There are here added chapters on exchange and the
mint, in connection wTitli the mode of proceeding, in
general, as to things saleable and legal tenders. This
part embraces three lectures. III. Novelties and
elegant contiivances in the way of balances such as:
the balance for weighing dirhams and dinars without
resort to counterpoises; the balance for leveling the
earth to the plane of the horizon; the balance known
as the 1 even balance' which weighs from a grain to
a thousand dirhams or dinars by means of three
pomegranate counterpoises; and the hour-balance,
which makes known the passing hours, whether of the
night or of the day, and their fractions in minutes
and seconds, and the exact correspondence therewith
of the ascendant star and fractions of a degree. This
part is in one lecture."

In the seventh chapter, which treats of the "Mechan-
ism of the Instrument for measuring Liquids____and

Application of it according to the philosopher Pappus
the Greek," we find a description of a hydrometer." The length of this
instrument, which is
cylindrical in shape,
measures half a
hand-cubit; and the
breadth is equal to
that of two fingers,
or less. It is made
of brass, is hollow,
not solid, and the
lighter particles of
brass are carefully
turned off by the
lathe. It has two
bases, at its two ends,
resembling two light
drum-skins, each fit-
ted to the end, care-
fully, with the most
exact workmanship;
and on the inner
plane of one of the
two bases is a piece
of tin, carefully fitted
to that plane by the
lathe, shaped like a
funnel, the base of
which is the drum-
skin itself. The in-
strument being thus
made, when put into
liquid in a reservoir
or vessel, it stands
upon it in an erect
position and does
not incline anyway."

The author then
describes at length,
the manner of gradu-
ating the instrument,
the 'decimal system
being employed
throughout. He re-
marks that the
weight of the funnel
shaped piece of tin
must be varied ac-
cording to the den-17

sity of the water assumed as a standard." Tables
of the specific gravities corresponding to the marks
on the instrument accompany the detailed account
of its application.

The annexed figure of the hydrometer of Pappus
(page 16) does not give a very clear idea of the
iostium,ent, and is intended to show chiefly the
manner of constructing and graduating it; the details
given in the manuscript are so minute, however, that
it is evident Pappus' instrument resembled closely
that of Gay-Lussac. It was, however, provided with
two scales, one with its numbers increasing upwards to
indicate the volume submerged in liquids of different
density; the other with its numbers increasing down-
wards, to. show the specific gravities corresponding
to those submerged volumes.

The above-mentioned Pappus was an eminent Greek
geometer of Alexandria, who flourished about 380 or
400 a.d. Consequently he was a cotemporary of
Synesius of Cyrene (378-430 a.d.), in one of whose
letters occurs what is ordinarily regarded as the first
recorded mention of the hydrometer. It is certainly
most interesting to find that al-Khazini's description
of Pappus' instrument corresponds very closely with
the statements of Synesius, a coincidence not observed
by previous writers.

Synesius, l< the good bishop of Ptolemais," writing
to his instructress,* the fair pagan philosopher and
mathematician, the ill-fated Hypatia, and being de-
sirous of trying the winesf he is using, says:

"My health is so delicate that I need a hydroscope,
and I beg you to have one made for me of copper. It
is a tube cylindrical in shape and of the form and size
of a pipe: on its length it bears a straight line crossed
by small lines, by means of which we determine the
weight of waters. One end is terminated by a cone,

* Not in a letter of Hypatia to Syne&ius, as Hoefer has it in his Hist.
Physique, Paris 1872, 12mo.

t Draper, Hist. Int. Bevel, Er,roy>e.18

arranged in such a manner that the tube and the cone
have the same base. This instrument is called baryl-
lion. If you place it in water, point downwards, it
stands erect and the divisions that cross the vertical
line can be easily counted, and by this means the den-
sity of water is determined.*

Hoefer, the French Historian of Chemistry, in relating
this statement remarks that none of the commentators
of the Letters of Synesius were able to explain the
nature of this instrument until the mathematician
Fermat, in answer to Castelli's request, communicated
his view, correctly apprehending the principles and
uses of the instrument described. This was in 1628,
and now we learn that the Arabian philosophers five
centuries earlier were perfectly familiar with the iden-
tical instrument mentioned by Synesius.

Al-Khazini describes several forms of balances at
great length, giving details of construction and em-
ployment. One of these balances he ascribes to Ar-
chimedes ; and he professes to quote the particulars re-
specting it from Menelaus, without however giving the
title of the latter's work.

Another balance described by our author is that of
Muliammed Bin Zakariya of Rai; it-differs from that

* Synesius Opera. Ep^t. XV. Lutetia, 1012, 4to, p. 174.

BALANCE OF ARCHIMEDES.

a.	Bowl for gold .

b.	Bowl for silver.

c.	Movable weight.19

of Archimedes by tlie introduction of the needle,
called by the Arabs the " tongue.1' and by the substi-
tution of a movable suspended bowl for the movable
weight.

Finally, in the fifth lecture, he gives a minute descrip-
tion of the Balance of Wisdom according to Abu-
Hatim al-Muzaffar Bin Ismail of Isfazar. " He begins
by remarking, that the balance being an instrument of
precision, like astronomical instruments, such as the
astrolabe and the zijassafaih, its whole workmanship
should be carefully attended to, He next describes
the beam, the front piece, the two 'cheeks' between
which the 4 tongue' moves, and the tongue itself." He
gives the length of the beam as four bazaar cubits
(two meters) and remarks that 4'length of the beam
influences the sensibility of the instrument; " it is con-
structed of iron or bronze. The balance is provided
with five bowls or pans, made of very thin plates of
bronze, three of which have the form of hemispheres
(see engraving, page 20), one of which is spherical
and the remaining one, destined to be plunged into
water, is finished with a conical bottom. Two of these
bowls bore the name of the 44 aerial" and were perma-
nently attached to the beam; another pan was mova-
ble on the right arm of the beam ; and the bowl intend-
ed to be immersed in water was fastened underneath
the aerial bowl of the left arm; this bowl bore the
name of the "aquatic" and the spherical bowl was
named the " winged."

We cannot here enter upon a more detailed exami-
nation of this portion of al-Khazini's treatise; suffice
it to say, he speaks of the mode of adjusting the bal-
ance and of its application to the examination of
metals and of precious stones. Al-Khazini distinctly
states that in taking the specific gravity of bodies he
employed " a determined sort of water similar in den-
sity to the Vater ol the Jaihun of Khuwarazm," and
further that "we made all our comparisons in oneBALANCE OF WISDOM. On^-third the ste of original drawing.)

a. Means of Suspension. /. Air-bowl.	i. Winged-bowl.	I. Pomegranate counterpoise,,

c.	Tongue.	g. Second air-bowl.	Movable bowl.	m. Rings of suspension.

d.	Two cheeks.	h. Water-bowl.	k. Basin.21

single comer of the earth, namely in Jurjaniyah [a city]

of Khuwarazm......and early in the autumnal

season of the year.1' The "Jaihun" is the modern
river Oxus, and " Khuwarazm" corresponds to the
modern province of Khiva.

The editor, Mr. Khanikoff, calls special attention to
the following passages, which he considers the most
remarkable in the whole treatise:

"When a heavy body of whatever substance is
transferred from a rarer to a denser air it becomes
lighter in weight, from a denser to a rarer air it be-
comes heavier." (Lect. I. Chap. v. § 1.)

" Air-weight cjpes not apparently vary, although
there is actual variation, owing to difference of at-
mospheres. As regards its water-weight, a body
visibly changes, according to the difference between
waters of [different] regions, wells and reservoirs, in
respect to rarity and density, together with the inci-
dental difference due to the variety of seasons and
uses. So then the water of some determined region
and known city is selected, and we observe upon the
water weight of the body, noting exactly what it is,
relatively to the weight of one hundred mithkals; and
we refer [all] operations to that [result as a standard,]
and keep it in mind against the time when we are
called upon to perform them, if the Supreme God so
wills. In winter one must operate with tepid, not very
cold water, on account of the inspissation and opposi-
tion tc gravity of the latter, in consequence of which
the water-weight of the body [weighed in it] comes
out less than it is found to be in summer. This is the
reason why the water-bowl settles down when the
water has just the right degree of coldness, and is in
slow motion, while in case it is hot and moving
quickly, or of a lower temperature, yet warmer than
it should be, the bowl does not settle down as when
the water is tepid. The temperature of water is plainly
indicated, 'both in winter and summer ; let these particu-
lars therefore be kept in mind." (Lect. Y. Chap. vi.

§ 5.)

An examination of these extracts compels a belief
that the Arabian philosophers of the twelfth century
knew the air to have weight, though they never
applied the means they had discovered of measuring22

it. The sentence in italics leads to the conjecture that
they also had some means of determining the tem-
perature of water; possibly a form of aerometer was
the instrument employed, and they were thus enabled
to recognize the fact that the density of water increases
in proportion to its coldness.

Al-KhazlnFs work contains several tables of the
specific gravities of substances determined either by
the Balance of Wisdom or by the hydrometer of Pap-
pus. In these tables are enumerated fifty substances,
nme of which are metals, ten precious stones, thirteen
materials of which models were made, and eighteen
liquids. The smallness of the list is not surprising, for
most of the substances contained in modern lists of
specific gravities were entirely unknown to the Ara-
bians ; the exactness of the results obtained is marvel-
lous, when we take into consideration the coarseness of
their means of graduating instruments and the back-
ward state of the mechanical arts at that period.

The first table comprises the specific gravities of
seven metals and two alloys; the results interpreted
into our system, together with the values assigned by
modern authorities * are found below. For sake of
comparison, we also annex the figures obtained by
Abu-r-Raihan, from whom it is believed al-Khazini
quotes; the slight discrepancies are largely due to
different methods of calculation adopted by Clement-
Mullet and Khanikoff.

Al-Khazini's First Table of Specific Gravities.

Substances. Al-Khazini. Abu-r-Raihan. Modern Authorities.

Gold [cast]... 19.05......19.05.......... 19.30

Mercury......13.56......13.58..........13.59

Lead........11.32......11.33..........11.34

Silver.......10.30......10.35..........10.52

Bronze ...... 8.82...... 8.82... .8.05 to 8.95

* Cf. Prof. F. W. Clarke's Tables of Specific Gravities, etc. in Constants
of Nature, Part I. Smithsonian Miscellaneous Collections, 1873, 8vo.23

Copper......	8.66....	.. 8.70......	.... 8.78
Brass.......	8.57....	,8.57......	_____ 8.58
Iron (forged).	7.74....	... 7.74.	7.79
Tin .........	7.32...,	. .. 7.31......	.... 7.29

It is.interesting to learn that the Arabian physicists
fully appreciated the necessity of operating on pure
materials and the advantages of averaging the results
of many determinations.

Thus, al-Khazini says he purified gold by melting it
five times, after which it melted with difficulty, solidi-
fied rapidly, and left hardly any trace upon the touch-
stone : and, after ten trials to obtain the weight of the
volume of water displaced by different weights of the
gold, he found, for a hundred mithkals of gold,
weights varying from 5 mithkals 1 danik and 1 tassuj
to 5 mithkals 2 daniks; as mean weight he adopts 5
mithkals 1 danik 2 tassujs, which by calculation yields
the figures in the preceding table.

Likewise mercury was purified by passing it repeat-
edly through many folds of linen cloth. In writing
of mercury, he remarks that it is not, properly speaking
a metal, but it is " the mother of the metals, as sulphur
is their father." This view of the nature of mercury
was prevalent among Arabian Chemists, and is found
in the writings of Geber (or Djafar) who lived four
centuries earlier. Geber writes of mercury: " it is also
(as some say) the matter of metals with sulphur,1' *
and he does not place it in the same class with metals
which he defines as " extensible under the hammer,"
a property not possessed by mercury under ordinary
conditions.

In this conception of al-Khazini we find moreover
the germs of the doctrine of the transmutation of
metals, the basis of that alchemical pseudo-science
which subsequently acquired such a wonderful in-
fluence over the human race. For if metals have

* Geber, Sum of Perfection, Book I, Part III. Chap 6.24

mercury for a mother and sulphur for a father, they
are not simple substances, and if compounds, they are
capable of artificial preparation and mutual transfor-
mation. This is, however, not the only passage con-
taining allusions to a belief in transmutation, though
no mention occurs of any practical attempts to effect
it; the following extract clearly refers to the com-
pound nature of metals.

" When the common people hear from natural philos-
ophers that gold is the most equal of bodies, and the
one which has attained to perfection of maturity, at
the goal of competition in respect to equilibrium, they
firmly believe that it is something which lias gradu-
ally come to that perfection by passing through the
forms of all [other metallic] bodies, so that its gold
nature was originally lead, afterwards became tin,
then brass, then silver, and finally reached the perfec-
tion of gold."

Writing of the precious metals, al-Khazini dis-
courses in a philosophical spirit on their universal ap-
preciation, in the following language:

" 4 Men prize these metals,' says Abu-r-Raihan, .'only
because under the action of fire they admit of being
made into conveniences for them, Such as vessels more
durable than others, instruments of agriculture, weap-
ons of war, and other things which no one can dispense
with, who is set to possess himself of the good things
of life and is desirous of the adornments of wealth.'
But if besides the rarity of the occurrence of gold, its
durability and the little appearance of moisture upon
it, whether moisture of water or humidity of the earth,
or of its being cracked or calcined by any fire, and
consumed together; with its ready yielding to the
stamp, which prevents counterfeiters from passing
off something else for it, and lastly the beauty, of its
aspect—if there is not [besides all these characteristics]
some inexplicable peculiarity pertaining to gold, why
is the little infant delighted with it, and why does he
stretch himself out from his bed in order to seize upon
it? And why is the young child lured thereby to
cease from weeping, although he knows no value that
it has, nor by it supplies any want? And why do all
people in the world make it the ground of being at25

peace one with another, not drawing their swords to
fight, though at the sacrifice of the powers of body
and soul, of family connections, children, ground
possessions, and everything, with even a superfluity of
renunciation for the sake of acquiring that; and yet
are ever longing for the third stream * to stuff their
bellies with the dust ? "

This passage is a sample of the simplicity of much
of the Book of the Balance of Wisdom; and, occurring
in the midst of the purely scientific demonstrations and
data, is peculiarly refreshing; the author's testimony
to that inexplicable peculiarity of gold which renders
it the special object of avarice, leads us to conjecture
that had he lived in modern times he would have
proved a warm champion of " hard money " doctrines.

The second table of specific gravities contains the
determinations of various precious stones; it is not
possible in every case to identify the stones, and
hence some uncertainty obtains with regard to the
values :

Substances.	Specific Gravities.

	Al-Khazini.	Modern Authorities.
Celestial Hyacinth_______	8.96*	4.83
Red Hyacinth.........	. .3.85f	3.99
[Ruby] of Badakhshan.,	3.58	-
Emerald.....,........	. 2.75	2.68 to 2.77
Lapis Lazuli.........	2.69	2.9
Fine Pearl............	2.60	2.68
Cornelian.............	2.56	2.62
	, , 2.56	2.69
Onyx and Crystal......	.2.50	2.63 % to 2.88 §
Pharaoh's glass.........	2.49	2.45 | to 3.44**

Substances.	Specific Gravities.

Al-Khazini gives detailed accounts of these pre-

Al-Khazini gives detailed accounts of these pre-

♦Alluding, say the editors, to the traditional saying of the Arabians:
" If the son of Adam were to possess two flowing rivers of gold and
silver, doubtless he would desire a third."

* Oriental sapphire.	§ Roek crystal 2.68 to 2.88.

t Oriental ruby.	|i English mirror glass.

X Onyx 2.63 to 2.81.	** English flint glass.

226

eious stones, of \#iich we quote a few brief extracts.
He says: "Emerald and chrysolite are interchangeable
names, whether applied to one and the same thing, or
to two things of which one has no real existence," a
passage which shows that mineralogical terminology
was afflicted with superfluous synonyms at an early
day. Of the cornelian he says: " Men have long tired
of the cornelian, so that it has ceased to be used as a
stone for seal-rings; even for the hands of common
people, to say nothing of the great." Of the " fine
pearl," he writes: " The pearl is not a stone at all, but
only the bone of an animal, and not homogeneous in
its parts." "Coral," he writes, "is a plant, though
petrified like the Jew's stone and the sea-crab." He
is aware that " glass is not the product of a mine,
but, on the contrary, kindred to stones, or sand, or
alkali," and he states that he has included it in the
above list, " because it resembles crystal."

The third table comprises " the materials of models
and patterns formed by goldsmiths, and woods of well
known trees." Interpreting the Arabic weights as
before, we have the following table:

Substances.	Specific Gravities.

	Al-Khazini.	Modem Authorities.
Clay of Siminjan____	.......1.99.	clay 1.068 to 2.63
Pure salt...........	.......2.19	2.068 to 2.17
Saline earth........	.......1.11	
Sandarach.....______	.......0.71	1.05 to 1.09
Amber.............	.......0.85	1.06 to 1.08
Enamel............	. .______8.93	
Pitch ..... .........	.......1.04	1.07
Wax__________ _____	.......0.95	0.96
Ivory..............	.......1.64	1.82
Ebony .............	.......1.13	1.18
Pearl shell.........	....... 2.4&	2.64
Bakkam wood......		1.03
Willow wood.......	... ...0.40	0.58

Substances.	Specific Gravities.27

The last table embraces a number of liquids.

Substances.	Specific Gravities.

Al-Khazini. Modern Authorities.

Sweetwater.................1.	1.

Hot water......................958	.959

Ice.......................... .965	.916 to .926

Sea water............ .......1.041	1.028 to 1.04

Water of Indian melon........1.016

Salt water [saturated solution].. 1.144	1.205

Water of cucumber...........1.017

Water of common melon.......1.0B0

Wine vinegar................ 1.027

Wine....................... 1.022	1.013

Oil of sesame.................915	.992 to 1.038

Olive oil........... ..........920	.917 to .919

Cow's milk..................1.110	1.029 to 1.040

Hen's egg...................1.035	1.09

Honey....................... 1.406	1.450

Blood of men in good health. .1.033	1.053

Warm human urine...........1.018 )	1 01t

Cold human urine............ .1.025 \	'

The temperatures at which the determinations of
the "hot water" and " sweet water n were made are
not known; the difference of density observed, viz.,
0.04166, approximates that between water at 3.9°C. and
100°C., which according to modern physicists is equal
to 0.04044.

The high specific gravity of cow's milk is note-
worthy and may have led al-Khazini and others into
lactometrical controversy.

Besides these contributions to the knowledge of
specific gravities, al-Khazini devotes some attention to
certain subjects not closely connected with the main
theme. In the third lecture he attempts to calculate the
quantity of gold which would compose a sphere equal
to the globe of the earth, and arrives at a number of
mithkals which requires for expression twenty-nine
digits.28

In the same lecture he takes up the problem of the
chess-board, of which he supposes the squares to be
filled with dirhams, each square containing twice the
number in the preceeding; he finds the total number
of dirhams to be 18,446,744,073,709,551,615. He then
applies himself to ascertaining the dimensions of the
treasury In which the treasure should be deposited,
and finally quotes the lines of an Arabian poet which
fix the time in which one might spend this sum at
200,000,000,000,000,000 years.

In the last lecture he describes the methods of ap-
plying the balance to leveling and to the measuring
of time—of this portion Mr. Khanikoff gives the fol-
lowing concise exposition:

" The balance level consists of a long lever, to the
two ends of which were attached two fine silken cords,
turning on an axis fixed at a point a little above its
centre of gravity, and suspended between two sight-
pieces of wood, graduated. At the moment when
the lever became horizontal, the cords were drawn in a
horizontal direction, without deranging its equilibrium,
and the divisions of the scales of the sight-pieces corres-
ponding to the points where the cords touched them,
were noted. For leveling plane surfaces, use was
made of a pyramid with an equilateral triangular base,
and hollow and open to the light, from the summit
of which hung a thread ending with a heavy point.
The base of the pvramitl thus arranged was applied
to the plane which was to be leveled, and earned over
this plane in all directions. Wherever the plane
ceased to be horizontal the joint deviated from the
centre of the base.

" The balance-clock consisted of a long lever
suspended similarly to the balance-level. To one of
its arms was attached a reservoir of water, which, by
means of a small hole perforated on the bottom of it,
emptied itself in twenty-four hours. This reservoir,
being filled with water, was poised by weights attached
to the other arm of the lever, and in proportion as the
water flowed from it, the arm bearing it was lifted,
the weights on the other arm slid down, and by their
distance from the centre of suspension indicated the
time which had elapsed."29

Further analysis of the contents of this extraor-
dinary work is incompatible with our reader's patience,
and jet many points of interest demand at least a
passing notice; these may, however, be embodied in a
summary of the principal propositions contained in
this treatise, and the recapitulation may serve to jus-
tify in some measure this Contribution to the Early
History of Chemical Physics.

1.	The Book of the Balance of Wisdom shows the
Arabian philosophers of the twelfth century to have
entertained advanced views regarding attraction.
They recognized gravity as a force, and attributed to
it a direction towards the centre of the earth; they
also knew that it diminishes with the distance, but
they erroneously supposed this diminution to be in the
direct ratio of the distance and not as its square.

2.	They were acquainted with the connection be-
tween the weight of the atmosphere and its increasing
density, since mention is made of the loss of weight of
a body weighed in a denser atmosphere.

8. They understood the theory of centre of gravity,
and applied it to the investigation and construction
of balance, and steelyards.

4.	They made frequent use of the hydrometer,
which they inherited from antiquity, and possibly they
employed this instrument as a thermometer for dis-
tinguishing by variations of density the different tem-
peratures of liquids.

5.	They observed the action of capillary attraction.

6.	They compiled full and accurate tables of the
specific gravities of most of the solids and liquids with
which they were acquainted.

7.	Their system of philosophy was founded on ex-
periment and observation.

In conclusion, we quote the following appropriate
remarks from M. KhanikofTs introduction:

" The history of the sciences presents to us an in-
contestable fact of deep significance: the rediscov-30

ery in modern times of truths laboriously estab-
lished of old; and this fact is of itself enough to
indicate the necessity of searching carefully in the
scientific heritage of the past after all that it may be
able to furnish us for the increase of our actual know-
ledge ; for a double discovery, necessarily requiring
a double effort of human intellect, is an evident waste
of that creative force which causes the advance of
humanity in the glorious path of civilization."

School of Mines, Columbia College,

New Yobk, May, 1876.This book is a preservation facsimile produced for
the University of Illinois, Urbana-Champaign.
It is made in compliance with copyright law
and produced on acid-free archival
!	60# book weight paper

which meets the requirements of
ANSI/NISO Z39.48-1992 (permanence of paper).

Preservation facsimile printing and binding
by

Northern Micrographics
Brookhaven Bindery
La Crosse, Wisconsin
2015