August 31,1872.] 
THE PHARMACEUTICAL JOURNAL AND TRANSACTIONS. 
1G3 
that Dohm recognized in water of hitter almonds the 
presence of prussic acid, discovered in 1782 by Scheele. 
Soon afterwards Gehlen and Schrader demonstrated 
that the above waters owed their remarkable physiolo¬ 
gical properties entirely to the presence of prussic acid, 
and in 1837 Liebig and Wohler proposed to substitute 
for these medicaments, always variable and uncertain 
in composition, solutions of prussic acid of known 
strength. 
In the second decade of our century the labours of 
Sertiimer resulted in a great progress in the same road. 
The study of the juice of various Papaveracea, known 
under the name of opium, led him to the discovery of 
morphine ; to this latter was afterwards added a group 
of opium bases, among which should be mentioned co¬ 
deine, discovered by Robiquet. The study of the Ru- 
biacece and Strychnacece gave results not less important. 
Pelletier and Caventou discovered quinine and cincho¬ 
nine in the cinchona bark and strychnine in the fruit of 
Strychnos Ni tx-vomica not to speak of other less impor¬ 
tant bases. In the place of opium, a complex substance, 
containing not less than six different alkaloids possessed 
of opposite properties; in the place of the powder or 
tincture of cinchona; in the place of the tincture 
or extract of nux-vomica ; in the place, in one word, of 
mechanical mixtures, as variable in their medical pro¬ 
perties as in their composition, the physician has now at 
his disposition morphine and codeine with their well 
crystallized salts, quinine and cinchonine, and finally 
strychnine and its salts,—chemical compounds of which 
the uniform action cannot be denied. Besides these the 
chemist has extracted from the Digitalis purpurea and 
Artemisia , their active principles, and the physician is 
thus enabled to substitute for the infusions and extracts 
of those plants digitaline and santonine, which are now 
obtained pure and well crystallized. 
Another investigation, no less important therapeuti¬ 
cally, has been that of the valerian root ( Valeriana offi¬ 
cinalis). It was found that its action was due to two 
different principles, oil of valerian and valerianic acid, 
both of which merit the attention of the chemist, and 
either of which is available for use by the physician. 
Eor the infusion of coffee or of tea, caffeine (theine) may 
now be substituted, and in the place of tincture of galls 
the physician may employ chemically pure tannic acid. 
But the researches of organic chemistry have not been 
confined to substances already recognized as medicines; 
there is scarcely a plant, flower or fruit which it has not 
searched for active principles. Chemists discovered vera- 
trine in the white hellebore ( Veratrum album), atropine 
in the belladonna ( Atropa belladonna) ; and quickly 
physicians utilized in the happiest manner the neurotic 
and febrifuge properties of the one, and the faculty of 
dilating the pupil possessed by the other. 
Soon the researches made in the domain of organic 
chemistry took a fresh direction; they were no longer 
limited to submitting animal and vegetable matter to 
the action of solvents like water, alcohol and ether, or 
exhausting them by bases or dilute acids, or, in one 
word, decomposing them into their immediate principles. 
The most energetic reagents; substances greedy for 
water, such as sulphuric and phosphoric acids; oxidi¬ 
zing agents of all degrees of intensity, from fuming 
nitric acid, chromic acid, oxide of .manganese and per¬ 
oxide of lead or to oxygen obtained by electrolysis, 
rendered active by means of platinum black; chlorine, 
bromine, iodine; ammonia, in the gaseous state or in 
solution; the hydrated alkalies, in concentrated solu¬ 
tion or even in a state of fusion,—all these bodies be¬ 
came the chemist’s new instruments of research. And 
it was no longer only upon the principles already formed 
in the animal or vegetable organism that Iris researches 
were made. 
In the presence of such powerful agents of decompo¬ 
sition, the primitive substances underwent more or less 
profound modifications, and these were the products of 
the decomposition of the elements of plants which the 
chemist had then in his hands. Here was an unexpected 
source of riches for the seekers. The same body, under 
the influence of different reagents, was found to undergo 
the most varied metamorphoses; and under different 
conditions of time, concentration and temperature, the 
same reagent produced upon the one body the most 
diverse modifications. Moreover, these products of decom¬ 
position of animal and vegetable substances were 
modified in their turn under the influence of chemical 
agents, until at last the successive substances led to 
the simplest combinations or even to the elements them¬ 
selves. Aided by this new method of investigation, 
organic chemistry suddenly took a development which 
for a time completely relegated inorganic chemistry to 
the second place. But at the same time that the field 
of research was so enlarged, the number qf. labourers 
increased, and from their active hands soon issued the 
incontestable treasury of facts upon which to-day 
organic chemistry rests. At first these treasures 
were in chaos and confusion; men whom chance favoured 
with a valuable discovery and those who saw long efforts 
crowned at last by success frequently knew not what to 
do with their riches. But soon the spirit of order took up 
the task of classifying the mass of materials;. it sought 
to test them and distinguish that which was important 
from that which was not, and to unite those which 
appeared analogous. When once order had taken the 
place of confusion, the eye was immediately arrested with 
admiration at the constitution of each substance, and at 
the marvellous bonds which connected all these bodies 
with each other. 
(To be continued.) 
THE AIMS AND INSTRUMENTS OF SCIENTIFIC 
THOUGHT.* 
BY PROFESSOR. CLIFFORD. 
It is my duty to speak to you for a short time about 
the aims and instruments of scientific thought. It may 
have occurred (and very naturally too) to such as have 
had the curiosity to read, the title of this lecture, that it 
must necessarily be a very dry and difficult subject, in¬ 
teresting to very few, intelligible to still fewer, and 
above all, utterly incapable of adequate treatment within 
the limits of a discourse like this. It is quite true that 
a complete setting forth of my subject would require a 
comprehensive treatise on logic, with incidental discus¬ 
sion of the main question of metaphysics; that it would 
deal with ideas demanding close study for their ap¬ 
prehension, and investigations requiring a peculiar taste 
to relish /them. It is not my intention to present you 
with such a treatise this evening. The British Associa¬ 
tion, like the world in general, contains, three classes ot 
persons. In the first place it contains scientific thinkers, 
that is to say, persons whose thoughts have very fre¬ 
quently the characters which I shall presently describe. 
Secondly, it contains persons , who are. engaged in work 
upon what are called scientific subjects, but 'who, in 
general, do not, and are not expected to think about 
the subjects in a scientific manner. Lastly, it contains 
persons who suppose that their work. and their 
thoughts are unscientific, but who would like to know 
something about the business of the other two classes 
aforesaid. Now, to any one w T ho, belonging to one o 
these classes, considers either of the other two,.it will 
be apparent that there is a certain gulf between him and 
them - that he does not quite understand them, nor 
they him; and that an opportunity for sympathvand 
comradeship is lost through this want of understanding. 
It is this gulf that I desire to bridge over, to the best 
of my power. That the scientific thinker may consider 
* Lecture delivered before the British Association at 
Brighton, Monday, August 19th, 1872. 
