148 Natural-Historical Collections. 
And now he applies the same appellation to an earth, which he has discovered in 
thorite, and which possesses many properties resembling the old thorina, though 
the two earths are not identical. 
The new earth, thorina, possesses the following properties: It is colourless, 
infusible, after being strongly ignited it is insoluble in the acids, except the sul- 
phuric acid; nor does it become soluble on being heated with alkaline sub- 
stances. It is insoluble in caustic alkalies, but is dissolved by their carbonates. 
The solution heated gives a precipitate of thorina, which is redissolved on the 
temperature being lowered. ‘The salts of thorina have a pure astringent taste. 
A concentrated solution of the sulphate of thorina, when boiled, coagulates into 
a thick pulp, but is re-dissolved in cold water. This property forms the most 
prominent character of the new earth. Like the salts of cerium, it is precipitated 
by sulphate of potash, with which a solution of it is saturated. The precipitate 
is a double salt and soluble in pure water. Like yttria it is precipitated by the 
cyanuret of iron and potassium. 
On the Change in the Colours of the Flowers of the Hibiscus mutabilis.— 
The changing Hibiscus has received this name, on account of the remarkable and 
periodical variations which the colour of the flowers present. White in the morn- 
ing, they become more or less red or carnation-coloured towards the middle of the 
day, and terminate in a rose colour when the sun is set. This fact has been long 
known, but we were totally ignorant of the cause. The following observation may 
assist to discover it, and give some useful ideas on the coloration of flowers. ~ 
Mr. Ramond de la Sagra remarked, in the Botanic Garden of Havanna, of 
which he is the director, that, on the 19th October 1828, this flower remained 
white all day, and did not commence to redden till the next day, towards noon. 
On consulting the meteorological tables, which he kept with care, he found that 
on this very day, the 19th October, the temperature did not rise above 19° C. 
whilst ordinarily it was at least 30°, at the period of inflorescence of this plant. 
It would appear then that the temperature holds a place of some importance in 
the coloration of certain flowers. The experiments of Mr. Macaire have taught, 
that it seems to be connected with different degrees of oxigenation of the chromule, 
or colouring matter, contained in the parenchyma. . Is this oxigenation altogether, 
or in part, determined by the temperature ? Can the colour of certain petals be- 
modified by variations of heat ? These questions require experiments.—Ann. 
de Sciences, &c. No. XV. 
*,* We have been requested to insert the following correction respecting the 
original discoverer of the Crassina ovata, one of the new shells, described by 
Captain Brown, in our last Number, p. 12. 
_. © The Crassina ovata was discovered by W. Nicol, Esq. Lecturer on Natural 
Philosophy, Edinburgh, among gravel on the shores of the Gair Loch, about two 
miles from its entrance. Dead specimens were also found by him on the beaches 
of the Clyde, near the mouth of the Gair Loch.” 
