82 
EEPOBT— 1847 . 
form, &c., and adds the following description of the process he has Mowed iitbe 
few experiments which be has yet tried: — 
“ It is to be rolled out on a smooth surface in sheets of anv convenient sizesiit- 
able to the object to be taken, and varying in thickness according to the size. Fa 
small objects, such as ibutfc exhibited, from the V^th to it|th of as inch isilat 
enough. Ilie sheet is dipped fur a luument or two iuio dtiiliiiy watir, and piasd 
warm upon the object, upon the surface of which It is to be carefully pTmauli 
the filler point or a convenient elastic pad, so os to ensope its dose ud naikm 
adaptation. In moulding soft objects, it is of coarse necessary that theytluild 
K sa elasticity or resiliency, os is the ease with llWog or recently dead »a«i 
*. The gutta {)ercUa docs not seem to be applicable to take moulds ftoo mj 
fragile bodies, such as many fossils, which would not bear the reiiuiiite pressottaot 
^init of the removal of the mould when rigid without risk. The moetdflicatvdi- 
ject* however and slender projections, if tirm enough in the original, D»y i» 
plaster cast be removed without any difficulty %\hcn the latter is softened 1 )T»o* 
meutary immersion in hot water.” 
On Friday, at 3 o’clock, after the sectional meetings were coocludcd, Dr.Duii®! 
gave a lecture at the Botanic Garden in explanation of the researches he had b«* 
carrj'ing on there at various times on subjects connected with Vegetable fhyswloff 
and Agricultural Chemistry, and of the Apparatus by means of which they ^ 
conducted. 
He first clctuilcd the experiments, instituted by him prior to the year ls36, “til* 
action of the different rays of tlie spectrum upon growing plants, dettreno'^^r 
traitsnntting light through coloured glasses, the effect of which glasses upon tw 
sunbeam had been first determined. 
It apjumred from the results obtained, that the value of the ray in stunul»fii?f 
functions td plantawas in proportion toils illuminating rather thantoitsliealii?'’^ 
Its cbeniical influence, a cmiclasion at that time opposed to the experinjenb of 
nobler, but since fully confirmed by other observers. The functions aoinflfW'** 
•were,— ^ 
I ** 'Iccompoaition of carbonic acid and the consequent evolution of osyp®) 
iu hie experiments witli more or less nitrogen. 
I'toduction of the greun colour of tbu leaves. 
I be expanding or unfolding of the leaves, and the existence of that eicitflMitr 
whwh lielongs to the sensitive plant. 
«yoltttion of water from the leaves. 
5. The absorption of the same by the roots. 
ilie second traio of experimente carried on within the garden related toilieF®' 
purtioQ between the amount t»|' oxygen expired by the leaves of plants durins-'*®- 
f'r carbuoic acid emitted from all parts of a plant ot 
PI? cuDcluikd dial the balance was in favour of 
^ ‘^^'titrary, bad inferred from Ids experiments, that the 
rt cr exceed toe former in its influence upon the atmosphere, 
fined Sn rl'l? construction, in which the 
rnnr-.^«i T/ ‘^'"'enrions. and in -whicli poruens of * 
I i r withdrawn for examination, Br. DsobrtT 
^ed^ ui satisfying himself that the air of the jar contained a greater 
plant was confined within it,proniW« ‘- 
luwped healthy. There wa*. it is true, an oscillation in the proportion J 
gas was examined by day or by night, bat the absorpM^ 
*^i^‘l''*cngagcnicntof carbonic acid during the latter 
fomjc cvnlutioD of oxygen and the disappearance of carbonic acid dw"5 
explained the nature of the agricultural experimeBts 
cert Garden, for the 
cesfllve ^ happen if a piece of ground wns planted for a 
of nnuliLf. tui ^ Bamc crop, and what difference there would be in _ 
in 3 tatic(>«aiii',ii,.,i continued in the same throughout, manure being 
11 • The results of this inquiry, which were stated in tabl®s<i*P®* 
