SEPTEMBER 29, 1899.] 
More than twenty years earlier Berzelius 
had said: ‘“‘The application of whatis known 
regarding the combination of the elements 
in inorganic nature, to the critical exami- 
nation of their compounds in organic, is the 
key by which we may hope to arrive at 
true ideas with respect to the composition 
of organic substances.’? Bunsen followed 
up this idea, showing that the so-called 
alkarsin, As,(CH,), was a radical, but a 
compound radical, being made up of arsenic 
an inorganic element combined with hydro- 
carbon radicals which are organic. This 
work of Bunsen’s, though of course far less 
reaching in importance than Wohler’s then 
recent synthesis of urea, was far more dif- 
ficult and dangerous, not only than this, 
but also than Liebig and Wobhler’s investi- 
gations of the benzoyl radical and Gay- 
Lussac’s study of the cyanogen radical. 
This work of these four chemists established 
for the time being the ‘radical theory’ 
which indeed was to be soon overthrown, 
but was later to reappear as a part of our 
theory of to-day. 
At the time Bunsen was carrying on his 
researches on organic compounds of arsenic, 
he was beginning that series of investiga- 
tions on the gases in the iron furnace, which 
culminated in the report presented to the 
British Association in 1845 by himself and 
Lord Playfair, on the ‘ Gases evolved from 
iron furnaces, with reference to the theory 
of smelting of iron.’ While the utilization of 
the waste gases of the iron furnace for fuel 
had been attempted at a much earlier date, 
it was not till the work of Bunsen, alone 
and with Playfair, that the enormous waste 
in these gases was impressed upon iron- 
masters; so that Bunsen can be said to 
have largely contributed to this great source 
of economy in the modern furnace. In 
other directions also these investigations 
bore practical fruit. 
The study of furnace gases had demanded 
methods of gas-analysis which at that time 
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449 
did not exist. Perfecting the old, origi- 
nating new, Bunsen built up a system of 
methods of gas analysis which have re- 
mained the foundation of those subsequently 
used ; indeed he has been called the founder 
of this branch of analytical chemistry. 
In this connection should be mentioned 
the Bunsen burner, now universally used 
in chemical laboratories, and almost as ex- 
tensively outside, asin the Welsbach light. 
The principle of mixing a proper amount of 
air with a combustible gas and burning it 
from an open tube is very simple—after it is 
known, but it was unknown until discoy- 
ered by Bunsen. 
In 1841 and 1842 Bunsen published his 
experiments on the use of carbon in the 
place of the more expensive platinum in the 
Grove battery. The outcome of this work 
was the Bunsen battery, which has been 
one of the most useful as well as the cheap- 
est of all batteries, and which may be said 
to have refused to yield supremacy until 
displaced with all other batteries by the 
dynamo. 
Having a powerful source of electricity 
at his disposal, he re-investigated the 
methods by which nearly fifty years before 
Davy had been the fortunate discoverer of 
so many new elements. Bunsen improved 
these methods, and made in connection 
with Matthiessen, the first thorough study 
of lithium, which had been discovered by 
Arfvedson in 1817, and for the first time 
the metal was isolated by him. 
All through this period and for many 
years later he took great interest in min- 
eralogical chemistry, especially in the 
chemistry of rock formation. In 1847 he 
visited Iceland, and soon. after published a 
number of papers on the chemical geology of 
that island and also on the theory of geysers. 
A series of investigations carried out 
with Sir Henry Roscoe, on photo-chemistry, 
laid the foundations of actinometry. The 
work of Daguerre and his followers had 
