120 
THE RESEARCHES OF AVOGRABO. 
repulsion, nor that of attraction, with all their 
modifications, is sufficient, according to re- 
searches hitherto made, to explain life. Already 
it has been more than once attempted to 
deduce life from the laws of mechanics, phy- 
sics, and of chemistry. This error has been 
committed by the physiologists and physi- 
cians of the iatromathematic and iatrocliemi- 
cal schools. In every age distinguished natu- 
ralists discovered this error and opposed it. 
The difficulty of explaining the manifesta- 
tions of activity of living bodies by the laws 
of other natural powers, probably depends 
on the imperfect knowledge which is possessed 
concerning natural phenomena in general ; 
but so long as we cannot succeed in account* 
ing for them in this manner, we are authorized 
in attributing them provisionally to powers 
of a particular species. 
(To ie continued.) 
ON THE RELATION OF THE SPECI- 
FIC HEAT OF BODIES TO THEIR 
ATOMIC WEIGHTS. 
This paper is intended to convey a con- 
densed view of the researches of Avogrado, 
an Italian philospher, as related in two 
separate memoirs.^ 
It may be proper to observe that in a pre- 
vious paper,'!' from the consideration of the 
affinity between the density and specific heat 
of bodies, he had established the formula 
m 
d — — where the density of the ductile metals, 
as 
is simply proportional to the mass of the atom 
divided by the cube of its affinity for heat, or 
affinitary number as it may be termed; a repre- 
sents the quantity which corresponds with the 
cube of the distanceof the centres oftheatoms, 
thatis tosay,thisdistanceis simply proportional 
to the affinity of each substance for heat, 
the mass of the atom not entering into its 
determination. 
The affinitary number is obtained by divid- 
ing the atomic weight of a body by that 
of potassium, which is considered unity : 
thus, the affinitary number of gold will be 
,|:^=2'5. or, as Avogrado makes, 
5 073. Then m=5 073, d=22-18 and d=r^s 
the 
affinity of gold for heat. 
M. Avogrado, by his experiments on the 
specific heat of bodies, has confirmed the 
accuracy of the law deduced by Dulongand 
Petit, from their researches, that the specific 
heat of the atom of a compound gas is expressed 
by the square root of the whole, or fractional 
* Ann. de Chim. et de Physique, t. Iv. and 
Ivii. 
+ Memorie della Reale Accademia delle 
Scienae di Torino, xxx. 91. 
number of the atoms of the simple gases, by f 
whose combination the cornpoundatom is formed. 
He has, however, been more particular in ; 
his expression of the law, which, according - 
to him, is of the following import : the specific 
heat of an atom of a compound body is equal ;l 
to the square root of the whole, or fractional ; 
number, expressing the atoms or portions of '< 
atoms which, by their combination, from the i 
atom of the compound body, whether in the ■ 
solid or liquid state, adopting as unity thespe- r 
cific heat of some simple body in the same state. ! 
This rule, however, is not easily applied to ' 
solids and liquids, because the atoms and j, 
volumes of gases are equivalent ; whereas, in 
the former classes, it is a question requiring 1 
much investigation to resolve, what is the ' 
composition of the compound atom in the ' 
solid or liquid state. For the composition, 
according to theoretical considerations, is often 
different from what it is in the gaseous or i 
vaporific state. Impressed with a desire of ' 
dealing up this difficulty, Avogrado was led l! 
into the discussion of the subject of the atomic 
weight of bodies, and has considered it proper 
to reduce the numbers attached to them by the , 
Continental chemists to one-half. These new 
numbers being deduced from the consideration ? 
of the specific heat, he has termed them ther- i 
mic atoms. The numbers were ascertained by ' 
means of an instrument of simple construction. 1 
The vessel in which the substance to be ; 
experimented on was placed, consisted of a i 
cylinder of thin brass, with a flat upper edge. i 
To this is applied a brass plate, pierced with 
three holes in its circumference, to enable 
three screws to pass which rise on the edge of 
the vessel, and are tightened from above by 
nuts, so that by interposing between the plate 
and the edge of the vessel a portion of oil 
skin, the access of water and external air is 
completely prevented. This vessel is con- 
tained in a large 'one, also made of brass, 
intended to hold adeterminate quantity of water 
at the temperature of the atmosphere, in 
which is placed a small mercurial thermo- 
meter with a brass scale, and covered bulb, 
which is completely immersed in water. 
To ascertain the specific heat, the small 
vessel was filled with the substance in powder, 
if it was a solid, and the weight noted. The 
vessel was then closed with the brass plate, 
and was kept in a vessel full of boiling water, 
until it was concluded that it, as well as its 
contents, had acquired all the heat which 
could be communicated to it by boiling water. 
The temperature of the air ; that of the 
water contained in the interior vessel of the 
apparatus, and that indicated by the thermo- 
meter which was plunged into it were marked ; 
the small vessel was then rapidly reinoved 
from the vessel of boiling water, by means 
of a pair of pincers, and placed in the exte- 
rior vessel. This being done, the temperature 
indicated by the thermometer of this vessel 
was marked every minute. This tempera- 
ture increased at first rapidly, then slowly, 
and generally reached its maximum in eight 
or ten minutes. It is obvious that this 
method would be a very easy one for deter- 
mining the specific heat of bodies, if it did not 
