On the Perspiration alleged to take place in Plants. 243 
to that produced by treating peroxide of manganese with alcohol 
and diluted sulphuric acid. On distillation of either of these 
mixtures, and subsequent rectification over muriate of lime, to 
keep down any undecomposed alcohol, an ethereous liquid is pro- 
duced, with an acid taste, and a penetrating smell like that of 
acetic ether, which on mixture with water separate into two 
strata, one of sulphuric ether, and the other of oil of wine. 
When alcohol is distilled with sulphuric acid, and the addition 
either of chromic acid or of peroxide of manganese, it appears to 
undergo the same alteration as with sulphuric acid alone: sul- 
phuric ether and oil of wine are formed by means of the oxygen 
of the chromic acid, or of the oxide of manganese. The sul- 
phuric remains unchanged, but its presence is necessary to deter- 
mine the decomposition of the alcohol, and the partial disoxy- 
genation of the chromic acid, or of the oxide of manganese, by 
reason of its affinity with the oxides of chrome or of manganese. 
It should be remarked that Scheele had already observed, that 
in leaving together for some days a mixture of peroxide of man- 
ganese, sulphuric acid, and alcohol, and then distilling with a 
gentle heat, the alcohel passes over with a strong odour much 
resembling that of nitrous ether. M. Dobreiner has also re- 
marked a similar odour in a mixture of chromate of potash, sul- 
phuric acid, and alcohol, which he seems to attribute to a pecu- 
liar kind of ether produced by the action of chromic acid on the 
alcohol. 
LIII. On the Perspiration alleged to take place in Plants. By 
Mrs. Acnus JBBetson, 
To Dr. Tilloch. 
Sir, — Do plants perspire, or do they not? A careful exami- 
nation enables me to say that no such property can be discovered 
to attach to plants. 
When J first collected the many subjects I intended publishing 
on Botany, I divided the various parts into separate laws taken 
from the dissection of the vegetable in general. I thought Na- 
ture herself (as I proceeded progressively) seemed to arrange 
them thus: Mine was no hurried work, but one which has 
taken above tweuty years to regulate, and is perfectly original, 
though entitled Botany. When I first introduced my dissections 
in Nicholson’s Journal, near fourteen years past, I dissected a 
flower and corolla to show the curious manner in which a sort of 
flower or pattern was to be viewed when the various layers of 
the petal were seen together. 1 have not forgotten the joke that 
Hh2 was 
