Chemistry, Ixvii 
of the corn poppy, &c. but they are of so miscellaneous a nature, 
that I must satisfy myself with referring the reader to the paper 
itself. (Phil. Trans. 1818, p. 110.) 
What is-called sap green is the inspissated juice of the berries 
of the buckthorn, ripe or half ripe. It differs entirely from the 
green matter of vegetables in general, being: soluble in water, 
and being rendered yellow by alkalies, of which it is a very 
sensible test... Acids render it red. 
I may here notice Dr, Clarke’s experiments, to demonstrate 
that iron constitutes the colouring matter of the red. rose. 
(See Annals of Philosophy, xii. 196 296.) I have no doubt that 
Dr. Clarke extracted iron from the petals of the rose. Indeed 
I saw a small globule of iron which he had actually extracted ; 
but a little consideration will be sufficient to convince us that the 
red colour of the rose cannot be ascribed to iron. The changes 
produced upon the colour of the rose by acids and alkalies, and 
the very fugitive nature of that colour, are quite inconsistent 
with the idea that the colour is owing to iron. ™ 
5.: Morphia.—Sertiirner has been generally considered as the 
_ discoverer of morphia. There can be no doubt that he first drew 
the attention of chemists to it, and gave it a degree of importance 
which it did not possess before, by showing that it possessed the 
properties of an alkali, But Vauquelin has shown, in a satisfac- 
tory manner, that the substance itselfhad been obtained by Seguin, 
and that most of its properties had been described by him many 
years ago in a paper communicated to the. Institute in 1804; 
but not published till it made its appearance in the Annales de 
Chim,.in December, 1814. In that: paper Seguin showed that 
the alkalies precipitated a white matter from infusion of opium, 
which was -soluble in hot water and in alcohol, which, crys- 
tallized in: prisms, and. dissolved in acids, ‘but was not capable of 
combining with any alkaline body. These properties, so far as 
they go, belong to morphia, and serve to: characterise it. We 
must admit, therefore, that Seguin first, discovered: morphia; 
-but it is to. Sertiirner that we owe the first ideas respecting its 
alkaline nature.—(See Ann, de Chim. et Phys. ix. 282.) bs 
_. 6. Camphor.—This substance melts at 349°, and boils when 
heated to the temperature of 299°,.as we are informed by Gay- 
Lussac. It-is purified by mixing it with some quicklime, put- 
ting the mixture: into a glass. shaped somewhat. like a. phial, 
melting it, causing it to boil slowly, and keeping the upper part 
of the vessel at such a temperature that the camphor becomes 
-solid, but retains a temperature not much under that at which 
it fuses. This high temperature is requisite, m order to give 
camphor that semitransparency which it is required to have by 
those that purchase it. Gay-Lussac has proposed as an im- 
provement, in this troublesome and expensive process, to distil 
it in a retort like a liquid, and to condense it in globular copper 
receivers. This method would be much more rapid and less ex- 
e2 
