294 
INFLUENCE OF CLIMATE ON VEGETATION. 
immense quantities. Mr. Ruffin, U. S., told us long ago, that the reduced vegetable masses 
in America were quite inert until regenerated by shell marl ; and therefore, he lamented 
the local absence of mineral chalk and limestone ; he approached the truth practically, but 
failed to establish a clear and indisputable theory. 
Having assumed new ground, upon the convincing arguments of Mr. Rowlandson, and 
on various occasions endeavoured to show that the chief object of liming is, or ought to be, 
the fixation of humic acid in a soil which is supersaturated with that inimitable produce of 
organic decay ; it is now proper to request the attention of the young aspiring horticulturist 
to one or more simple processes, the result of which must, I imagine, be conclusive. In 
the first place, let him provide himself with three phials, containing an ounce or two of 
caustic potassa, caustic soda, each in solution, and pure liquor of ammonia. In three cups 
put a portion of brown heath-mould, old decayed wood, or black spit dung ; on each pour 
as much boiling rain-water as will quite cover the soil ; colour, more or less deep, will be 
extracted from all, but this colour will be made greatly deeper, by adding some drops of 
either of the three forenamed alkalies. The operator should vary the application till he 
satisfy himself on every point, and then note down the observed effects. The liquor from 
each cup should be pressed off through linen, and passed into separate tumblers or wine- 
glasses, and when clear, the intensity of the colour will demonstrate the specific solvent 
power of the particular alkali that has been used. Thus, there will be three distinct 
humates, one of potassa, one of soda, and the third of ammonia ; all proving the important 
fact, that the three alkalies dissolve humic matter, and hold it in solution. In this stage 
of the processes, add a small teaspoonful of finely powdered quicklime to every glass, and 
stir the contents several times ; after which, permit the separated matter to subside, when 
it will be seen that the colour has been discharged, and a flocky, brown sediment formed in 
considerable quantity ; clear lime-water will also produce similar results. 
Finally, as a converse, let the experiment with the three humous earths be varied, only 
substituting powdered lime, or strong lime-water, for the three alkalies, and it will appear 
that no colour is extracted, that it has been attracted and fixed, being deposited as an in- 
soluble humate of lime. The more the experiments are varied the better ; knowledge will 
be gained at every step, and proof conclusive will be established that lime acts as a 
corrector, and that its attractive afiinity for redundant humid matter is paramount. 
The compounds of Lime must be deferred till the next number. 
INFLUENCE OF CLIMATE ON VEGETATION. 
By Mr. Moore. 
Meyer's table printed at p. 203, shows theoretically how the surface of the earth may be 
divided into zones from the equator to the poles, and into regions from the sea-level to the 
mountain-tops, in such a way, that these latitudinal and altitudinal divisions may be seen 
to bear respectively a certain relation to each other, the decrement of temperature in the 
two series being singularly parallel. Temperature, it is to be understood, is made 
prominent in these observations, not as being the only important element of climate, but 
as constituting the most ready index to those climatic conditions which principally affect 
the life and development of plants. This scheme of Meyer's points in a right direction, 
though, for the practical purposes of cultivation, it is too rigidly formal ; the zones and 
regions being strictly confined within parallelisms of latitude and altitude. 
The division of the surface of the globe on the basis of isothermal lines, seems, however, 
to admit of practical application as a means of assisting in the grouping of cultivated 
exotic plants into sections or divisions, which shall convey a more just and complete idea 
of their requirements in respect to artificial temperature, than is the case with the old 
groups to which the lumping terms of " stove " and '* greenhouse " have so long been 
applied. In stretching out such a division, we are, as already observed, merely following 
the practice of intelligent cultivators who have long since found that two structures— two 
