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BOSTON JOURNAL OF CHEMISTR 
Volume XX1\' 
CONTENTS. 
Familiar Science. — James Prescott Joule . . i 
The Periodic System i 
Scientific Recreations 2 
15rief Studies in Biology 3 
Fauna and Flora of Primitive and Recent 
Periods 3 
Scientific Brevities 4 
Practical Che.mistry and the Art.s. — The 
English Channel Bridge ....... 5 
A Novel Elevator 5 
Transparencies in Prussian Blue .... 5 
The Scientific Knowledge of the Ancient 
Greeks and Romans 6 
Eikonogen, a New Photographic Developer . 6 
Industrial Memoranda 7 
The Out-Door World. — Original Observa- 
tions S 
Gleanings 8 
Editorial. — Fluorescence 9 
The British Association at Newcastle ... 10 
Meteorology for November. 1889, with Review 
of the Autumn 11 
Astronomical Phenomena for January, 1890 12 
{.^lestions and Answers iz 
Literary Notes 12 
Medicine and Pharmacy.- — Is Crime a Dis- 
ease? I'J 
We Eat Too Much 13 
Monthly Summary of Medical Progress . . 14 
An Experiment in Color-Blindness .... 15 
On the Dilution of Cow's Milk in Infant 
Feeding 15 
The Stomach-Brush 15 
Hair-Balls from the Stomach 16 
Formyl Amidophenol Ether 16 
The Nutmeg in Medicine 16 
Medical Memoranda 16 
Publishers' Column 16 
Fan^iliar Scierjce. 
JAMES PRESCOTT JOULE. 
One of the most distingiii.shecl scienti.sts ol" 
the present century died at Sale, near Man- 
chester, England, on the i ith of last October. 
James Prescott Joule was born at Salford, 
near Manchester, in the year 18 r8. His 
health was so delicate that he was not sent to 
school, but received his first elementary edu- 
cation from his mother. At the age of fifteen 
he commenced his scientific studies, under the 
tuition of the eminent chemist, Dalton, the 
discoverer of the atomic weights, who was at 
that time President of the Manchester Literary 
and Philosophical Society. Under the direc- 
tion of his instructor he made some more or 
less important investigations upon the consti- 
tution of gases and vapors, and the effect upon 
them of heat, but his first personal researches 
were made in 183S upon the subject of mag- 
netism. In 1840 he discovered the principle 
of magnetic saturation, or the limit beyond 
which it is impossible to increase the power 
of a magnet. 
AlK)ut this time he suggested an electric 
BOSTON, JANUARY, 1890. 
Number i. 
unit to express the power of the current. As 
the molecular weight of water was at that 
time considered to be nine, he proposed to use 
as unit of quantity that amount of electricity 
which would decompose nine grains of water. 
Although this unit has never been accepted, 
an international congress of electricians has 
recently given his name to a practical unit of 
electric work, based on the modern system of 
electric measurements. The ampere, which 
now replaces Joule's proposed unit, is the 
current which will deposit .0014888 grammes 
of silver in one .second. 
Joule's gi'eatest fame, however, is due to his 
demonstration of the great principles of the 
conservation of energ)-, and the mechanical 
equivalent of heat. Count Rumford, in the 
last century, experimented upon the develop- 
ment of heat by the friction produced in 
very first, and at once became a firm supporter 
of Joule's theories, and was a co-worker with 
him for many years. 
This discovery of the connection between 
the great forces of Nature was an epoch in 
scientific history, and was to physics, what 
the discovery of oxygen and the true nature 
of combustion was to chemistry. His other 
work alone would have given Joule a high 
rank in the scientific world, but it has been 
almost completely overshadowed by this great 
physical and mathematical generalization, 
which he was the first to formulate in defi- 
nite terms. 
The accompanying portrait is reproduced 
from La Nature' 
boring a cannon, and in August, 1843, at a 
meeting of the British Association, at Cork, 
Joule, after referring to Rumford's researches, 
stated that he was "convinced that, by the 
will of the Creator, the great principles of 
Nature are indestructible ; each time that a 
mechanical force is exerted in any way, an 
equivalent quantity of heat is always pro- 
duced." 
At this day, when the doctrine of the con- 
servation of force is undisputed, and is one of 
the corner stones of science, it seems strange 
that the new theory was by no means unani- 
mously accepted by the leading scientists of 
the day. Even Faraday was not convinced 
of its truth for several years, and Miller and 
Graham likewi.se doubted it at first ; but Sir 
William Thomson comprehended the truth 
and importance of tlie generalization from the 
THE PERIODIC SYSTEM. 
Every elementary body combines with 
others in definite proportions by weight 
which are unchangeable. Hydrogen, which 
combines in the smallest proportion of all, is 
taken as unity, and its combining number, 
or atomic weight, is considered as r. Oxy- 
gen has an atomic weight of 16, and never 
combines with hydrogen except in that pro- 
portion, or a multiple of it. Thus in water, 
one atom of oxygen with a weight of 16 is 
combined with two atoms of hydrogen with 
a weight of 2, giving the proportion of 2 to 
16. Another compound of hydrogen -and 
o.xygen, known as peroxide of hydrogen, 
contains two atoms of hydrogen and two of 
oxygen, giving the proportions 2 to 32. The 
element carbon has an atomic weight of 12, 
and unites with four atoms of hydrogen to 
form marsh gas, which contains four parts by 
weight of hydrogen to twelve of carbon. 
Oxvgen and carbon unite to form carbonic 
acid gas, which contains one atom of carbon 
with a weight of 12, united to two atoms of 
oxygen weighing 32. These proportional or 
atomic weights with which all elements com- 
bine with one another, are determined by 
direct analysis, and are always fixed and 
invariable. 
Now if we arrange the elements in certain 
horizontal and vertical lines, so as to form a 
table, commencing with lithium with its atomic 
weight of 7, and ending with uranium with a 
weight of 240, we obtain a most remarkable 
result. We find that in this table, the ele-. 
ments form themselves into groups of those 
which most closely resemble each other in 
other chemical and physical characteristics 
besides their atomic weights, The alkaline 
