Yaw, . " 7
vies} Negative Bonds, and Rule for Balancing Equations. 51
oY SO —_———
one molecule of each shows how many molecules* of the
other must be taken, the words each and other referring
respectively to oxidising and reducing agents. A few
equations will illustrate :—
2HNO3+3H;8503;=3H,80,+2NO+H,0.
The nitrogen in HNO, has five bonds, and in NO it has
two, losing three, therefore three molecules of H,S0; must
be taken. The sulphur in H,S803 has four bonds, and in
H,S80, it has six, gaining two, therefore two molecules of
HNO; must be taken. Again,—
35n+4HNO;3;=38n0,4+4NO}2H,0.
The Sn gains four bonds (free elements having no bonds),
hence four molecules of HNO; must be taken, and the
N of HNO; losing three bonds, three of Sn must be taken,
65b+ 10H NO; =35b;05 + 10NO +10H,0.
Here the rule calls for three of Sb and five of HNO;,, but
since the produ& Sb,Os cannot be written with an odd
number of atoms of antimony, we must double the amount
of each, and instead of three and five take six and ten.
3H:8+-HNO;=3H,S0,-+8NO+4H,0. .
Here the sulphur in H,S has —2 (minus two) bonds, and
in H,80, it has +6, so it has gained eight bonds; hence
we must take eight molecules of HNO;, and we take
three of H,$, because the nitrogen loses three bonds.
35b283+28HNO3=38b,05+9H,S0,+28NO+5H,0,
In this equation both the sulphur and the antimony of
Sb,O5 are oxidised ; each atom of sulphur gains eight
bonds (as explained above), and the three atoms will gain
twenty-four bonds. Each atom of the antimony gains
two bonds, the two atoms gaining four bonds. These
added to the twenty-four bonds gained by the sulphur,
make twenty-eight (that is, one molecule of Sb,S; gains
twenty-eight bonds); hence we must take twenty-eight
molecules of HNO, also three of Sb,S3, because -the
nitrogen of the HNO; loses three bonds. :
HIO;3+3H,503=3H,S0,+ HI.
In this the rule calls for two HIOg and six of H,S0;, but
we take one and three, which are "in the same proportion.
The rule gives relative quantities only.
3Pb+246HNO;=3Pb(NO;),4+NO+4H,0. :
Here the rule requires two of HNO;, and shows that exactly
 two are reduced to NO; but in order to make a solu.
sion of lead nitrate six more must be added, which are not
reduced.
3NaH,PO,4-7HNO, =3NaNO;+ 3H3PO,4-4NO+2H,0
Here the phosphorus gains four bonds, and four of HNO;
are reduced to NO ; but three more are required to liberate
the hypo-phosphorus acid from 3NaH,PO,, hence we take
seven in all.

‘THE CHEMICAL NEWS.

NEGATIVE BONDS, AND RULE FOR BALANCING
EQUATIONS.
By OTIS COE JOHNSON.

ProF. HuGo SCHWANERT, in hisnew ¢ Lehrbuch der Pharmaceutischen
 Chemie,” gives a rule for the constru@ion of
chemical equations, His method depends upon algebraical
principles, as does also that of James Bottomley, read
before the Manchester Philosophical Seciety, February 19,
1877, and given in the CuemicaL NEws, vol. xxxvii., p, 110,
My method is a chemical one, and is derived directly
from principles of oxidation. It is founded upon a system
of negative bonds. I here use the term bond in a’sense
partially new, which can better be understood by the
illustrations that follow than by any definition which can
be framed.
By the bonds of an element is meant the amount of oxidation
 it has sustained, or a bond is the measuring unit of
oxidation. The terms positive and negative are used not
in an ele&rical but in a stritly numerical sense. The
bonds of an element may always be ascertained with cersainty
 by one of the following rules :—
(1.) Free elements have no bonds, and may be represented
 by zero, written thus—CI° or C1,°, Ba®, Al°, &c.
(2.) Hydrogen in combination has always ane bond, and
it is positive, written thus, H*, . |
(3) Oxygen in combination has two bonds, always
minus, written thus, O01, :
(4.) The bonds of the metals in combination are usually
plus. The most prominent exceptions are their combinations
 with hydrogen, Sb" | +111 Ag—IIpf+1IT,
(5.) The sum of the bonds of any compound is always
zero. Thus, HE N*TVO;=VI=0, that is, the H has one
positive bond, the N five positive bonds, and each atom
of O has two negative bonds, and the three atoms have
six negative bonds: six positive bonds added to six nega.
tive equals zero. In the same way, H!Cl+tVQ—Vi=o
Hts tVI0, ~VHr=0, Hyp tVp,-vin=o,
Ba¥ 0," WH, FH=0 Fe, 05 Hg tVi=0,
Bal! H, HWP, XQ Xvi=0
(6.) Acid radicals are always negative, HI +VQ,™VI=0
or H I (105) ~=0°, Pb,VIP,tXQ,—)Vi=0

’
or PbYI(PO,) ~Vi=0
The bonds of the radicals being equal to the number of
atoms of hydrogen with which it is capable of combining.
An oxidising agent is one that can increase the number
of bonds of some other substance; hence oxidation of one
substance must involve the reduction of some other. The
number of bonds gained by one are lost by the other. The
real bonds are transferred from the oxidising to the re
ducing agent. Thus in the equation—
2PbCrO4+5Zn+16HCl=2Pb+ Cr,Cls+ 5ZnCl,+8H,0,
it can be proven that the ten bonds lost by the lead chromate
 are transferred to the zinc.
From these principles is derived a rule for writing equations,
 by which every equation involving oxidation may be
balanced almost at a glance, if we know the products
formed. The rule is :—The number of bonds changed in

AsH;+6AgN0O;4-3H,0 =6Ag+H;3A50;+6HNO;.
The arsenic in AsHgz has minus three (—3) bonds, and in
H3AsO3 it has plus three (+3); the gain is six, therefore
ake six of AgNO;.
3KNO3+8Al+5KOH +2H,0 =3NH;+4K,AL0,.
The nitrogen in NHj has —3 bonds, having lost eight,
therefore take eight of Al; and as the Al gains three, take
:hree molecules of KNO;.
This article will be foliowed by another showing the use
of the rule in organic chemistry,
University of Michigan.
July 4. 1880.

—— ©

Carbazol.—C. Graebe.—The author describes the preparation
 of carbazol and potassium carbazol, and gives an
account of the derivatives methyl-carbazol, ethyl-carbazol,
sthyl-carbazoline, acetyl-carbazoline, tetra-nitro-carbazol,
and the chlorine derivatives.—Liebig’s Aunalen. 202. 2.

* As this definition of bond is a new and provisional one, possibly
the adoption of a new ferm might be less objectionable than the use
of new definitions for the established term, bond, as a character ir
quantivalence.

* In case of free elements, to avoid complexity, atoms are renresented
 as molecules.