303 boussingatjlt’s reseakches on the action oe foliage. 
profitable market for that which they incur an expense now to be rid of, disposing of it 
for manure or any casual purpose. For our fast passenger steamers the oil will be a 
boon of the greatest value, and our sharp-witted companies will doubtless try its mettle. 
For our men-of-war it will, in unpeaceful times, be an imperative necessity, and we may 
be sure that our new G-overnment will neglect no important means of providing for the 
supremacy of the British navy. 
Whatever further experiments may be probably undertaken before oil is adopted by 
the Admiralty, sufficient at least has been done, and under such superintendence that 
the results can neither be doubted nor disputed, to prove that there is a fuel capable of 
superseding coal for steam and mechanical purposes, that it has been practically tried 
and applied, and which only awaits the demand to come into the market at economic 
prices. 
BOUSSINGxVULT’S EESEAECPIES ON THE ACTION OF FOLIAGE. 
A full abstract of the first part of these investigations, communicated to the French 
Academy of Sciences, is given in the ‘ Comptes Eendus,’ vol. lx. No. 18 (May, 1865). 
Theodore Saussure had long ago ascertained that, while plants prosper and decompose 
carbonic acid gas in an atmosphere containing as much as one-twelfth or even one-eighth 
part of that gas, they proinpTy perish in unmixed carbonic acid, apparently without 
decomposing any of it. Boussingault made his experiments in a better form, upon 
leaves only, avoiding all complication of the action of the roots or other parts of the 
plant. His results are:— 
1 . That leaves exposed to sunshine in pure carbonic acid do not decompose this gas at 
all, or only with extreme slowness. 
2 . But in a mixture with atmospheric air, they decom.pose carbonic acid rapidly. The 
oxygen of the atmospheric air, however, appears to play no part. 
3. Leaves decompose carbonic acid in sunshine as readily when this gas is mixed with 
nitrogen or with hydrogen. 
Although this decomposition of carbonic acid by green foliage must be a case of dis¬ 
sociation,—a separation of carbon from oxygen,—yet Boussingault recognizes an analogy 
here with an opposite phenomenon, viz. with the slow combustion of phosphorus at the 
ordinary temperature. Phosphorus in pure oxygen emits no light, does not sensibly 
undergo combustion, but does so in a mixture of oxygen with atmospheric air, or with 
nitrogen, hydrogen, or carbonic acid. The analogy may even be carried further. For 
while a stick of phosphorus is not phosphorescent in pure oxygen at ordinary or in¬ 
creased pressure, it becomes so in rarified oxygen. And Boussingault equally ascertained 
that leaves which exerted no sensible action upon pure carbonic acid at ordinary pres¬ 
sure’ decomposed it, with the liberation of oxygen gas, under diminished pressure. That 
is, rarefaction and mixture with an inert gas act alike in mechanically separating the 
atoms, whether of carbonic acid as in the one case, or of oxygen as in the other, so as to 
determine the action either of combination or of dissociation. 
In a continuation of these investigations (‘Comptes Eendus,’ vol. Ixi. Sept. 25, 1865), 
Boussingault shows that carbonic oxide, whether pure or diluted, is not decomposable by 
foliage, and that this iuertness^of green foliage upon carbonic oxide goes to confirm the 
opinion maintained in his ‘ Economie Eurale,’ that leaves simultaneously decompose 
carbonic acid and water, COo, HO = CO, II, O 2 ; the O 2 being liberated, CO,H expresses 
the relation under which carbon is united with the elements of water in cellulose, starch, 
sugar, etc., i.e. in the important principles elaborated by the leaves, the composition of 
which is represented by carbon and water. He goes on to prove that a leaf which has 
been decomposing carbonic acid and water all day long is capable of doing the same 
work the next day, if not allowed to dry, but the losing of a certain amount of water 
annihilates this faculty, and irremediably destroys the life of the cells of a leaf, vegetable 
life in this state being far less tenacious than that of some of the lower animals {Tardi- 
grades, Notipes, etc.), which bear wonderful desiccation. 
The third instalment of the investigation is given in Nos. 16 and 17 of the same 
volume (Oct. 16 and 23, 1865). It appears that detached leaves, kept in shade for many 
days, with the cut end of the petiole in water to prevent desiccation, preserve the power 
