69b 
THE PHARMACEUTICAL JOURNAL AND TRANSACTIONS. 
[March 1, 1873. 
The Essays of Scheele were translated into English, 
and published in the year 1786, by Dr. Beddoes, whose 
name is connected with the establishment of the Medical 
Pneumatic Institution, in Bristol, where, with the assist¬ 
ance of the young Humphry Davy, experiments were 
made on the cure of diseases by the aid of “ factitious 
airs” or gases, nitrous oxide amongst the number. 
Dr. Beddoes relates in his preface the origin of the 
compliment, a paraphrase of which was afterwards 
spoken of Davy, which in its first application was so 
deservedly paid to Scheele. It was observed to him, he 
says, “ by a near relation of Bergmann, that the greatest 
of Bergmann's discoveries was the discovery of Scheele." 
It was then pointed out by the lecturer that great as 
the memory of Scheele actually is, and lasting as it must 
be, he receives credit for only a part of his work. A 
man of extremely retiring disposition, he sometimes 
omitted to publish his work till some time had elapsed, 
and other experimenters had gone over the same ground. 
This was the case with his treatise on ‘Air and Fire,’ in 
which is announced the independent discovery of both 
oxygen and nitrogen. 
The lecturer then proceeded to give a rapid sketch of 
the theories which had been maintained up to Scheele’s 
time, with reference to the phenomena of combustion 
and the nature of fire. 
The ancients and even the alchemists regarded fire as 
an element or simple substance. In the act of burning, a 
thing was supposed to lose something, the escape of 
which was assumed to give rise to the appearances ordi¬ 
narily attendant upon combustion. 
Many of the metals were known to become converted, 
by exposure to heat in the air, into calxes. According to 
the views current at that time the metals were supposed 
to be compounds of these calxes, with a hypothetical 
element called sulphur, or inflammable earth, which, 
during the calcination, was believed to escape from 
them. 
This idea is stated clearly in the following passage 
from Scheele’s “essay on Air and Fire.’ “Iron con¬ 
sists of an earth sui generis , united with a certain quan¬ 
tity of phlogiston, and a certain quantity of heat: all 
metals agree in that point: the difference is in their 
earths, which, according to their nature, have absorbed 
either more or less phlogiston.” 
Every different kind of combustible substance was 
supposed to contain an inflammable constituent peculiar 
to itself. 
At the beginning of the last century this idea was 
modified in an important respect by the celebrated 
Stahl, whose theory of phlogiston , though necessarily 
-abandoned at the foundation of modern chemistry by 
Lavoisier, will always be remembered with respect. The 
leading idea of the theory was the existence of a uni¬ 
versal element of combustibility, the presence of which 
in a substance rendered it capable of burning. 
It is remarkable that throughout the progress of these 
ideas, developed so slowly, two circumstances insepa¬ 
rable from all ordinary cases of combustion whether slow 
or rapid had been systematically ignored. 
These were the facts that, on the one hand, the pre¬ 
sence of air is necessary for combustion, and on the other 
that metals when calcined in the air increase in weight. 
The results of these experiments had been confirmed 
by men so able and eminent as Robert Boyle and others, 
but the facts had remained unnoticed or were disposed 
of by superficial explanations. 
This was the state of matters when Scheele commenced 
his experiments on “Air and Fire,” about 1774. In 
his essay on this subject, a translation of which, by J. 
R. Forster, LL.D., is bound up in the volume belonging 
to.the library of the Pharmaceutical Society together 
with the rest of his essays, Scheele demonstrated the 
existence in air of two kinds of elastic fluids, of which 
one was completely absorbed by burning- phosphorus, by 
solution of liver of sulphur, by alkaline sulphites, by 
turpentine, and all such oils as will dry in the air and 
may be changed into a resinous substance; also by 
moistened iron filings, and by many other substances. 
In all these cases a kind of air is left in which “ neither 
a candle will burn nor any spark be visible.” And 
“this air which is unserviceable for the fiery phenomenon, 
and which makes (as he stated erroneously) about two- 
thirds of common air, he called “ corrupted or foul air” 
(nitrogen).” The other constituent of air which in the 
experiment with the phosphorus is absorbed by it, 
Scheele called “ empyreal air,” and obtained in a state of 
purity by several processes. 
In the course of his experiments with this kind of air 
he observed and described correctly not only all the 
ordinary properties of oxygen gas, but was careful to 
note that it was entirely absorbed by phosphorus and 
those other substances which he had employed in the 
analysis of atmospheric air. 
“ Therefore these experiments prove that empyreal air 
is that kind of air by means of which fire burns in com¬ 
mon air, and it is in common air mixed with a kind of 
air which has not the least attraction of the inflam¬ 
mable ; and it is owing to this that some hindrance is made 
to rapid and violent conflagration; and most certainly 
if all the air consisted of empyreal air, the water would 
be of little service for extinguishing of fires.” 
One of the earliest of Scheele’s essays was on ‘ Fluor 
Mineral and its Acid.’ His attention had doubtless 
been attracted to this subject, “ on account of the beau¬ 
tiful phosphoric light which this stone yields in a dark 
place when it has been heated. But its constituent 
parts are as yet little known.” An observation which, 
notwithstanding the numerous experiments since made 
in the hope of isolating fluorine, is scarcely less true at 
the present day than it was in 1771. Scheele’s first ex¬ 
periments upon the action of acids on fluor were made in 
glass retorts, and the consequent formation of white 
silicious earth in the water which he had placed in the 
receiver, together with the corrosion of the glass, caused 
him much perplexity, and led him not unnaturally into 
some serious errors. 
Another very early essay was that on Manganese, or, 
‘Magnesia Vitrariorum,’ published in 1774. 
It has already been pointed out how, in the course of 
trying the effect of vitriolic acid upon this mineral, 
Scheele discovered pure emp3 T real air or oxygen. When 
he came to use muriatic acid, he made the discovery of 
another gaseous element scarcely less important in the 
eyes of the chemist. This substance was called, by 
Scheele, “ dephlogisticated muriatic acid,” in accordance 
with the views current in his day ; and did not receive 
the name chlorine till many years afterwards, when 
its character as an element was established by Sir H. 
Davy. 
The leading properties of chlorine are described quite 
correctly in Scheele’s memoir, and were experimentally 
illustrated by the lecturer. One of its most striking 
peculiarities, which was of course unknown to Scheele, is 
its power of uniting with hydrogen gas, regenerating 
the muriatic acid from which it was obtained. Under 
the influence of light of sufficient intensity and especially 
of the more refrangible violet rays of the spectrum, this 
combination is effected so rapidly that explosion ensues. 
It is interesting to note that although Scheele was not 
acquainted with this particular instance of chemical 
action promoted by the agency of light, he was the first 
to observe and explain the photographic action of sun¬ 
light. For having exposed luna cornua to the sun, he 
found that a black powder was formed and muriatic acid 
generated. “ Hence it follows that the blackness which 
the luna cornua acquires from the sun’s light is silver by 
reduction.” 
One discovery of Scheele’s will always be associated, at 
any rate, in the minds of pharmacists, with the memory 
of the illustrious Swede. The discovery of prussic or 
hydrocyanic acid was the result of some excellent and 
