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investigations have been made to assume a tendency, the very 
opposite of that which this Society has been established to 
promote. Such investigations have often been made to 
assume a tendency either to pantheism or to materialism, 
and it is much, to be regretted that tbat should have been 
the case. Stili I believe that whatever arguments, based 
on scientific truth, may be urged in favour of pantheism or 
of materialism, they may always, on close examination, be 
found to have a weak point, and to be untenable. I will 
give you an illustration of that. I remember very well a 
lecture, delivered at the recent meeting of the British 
Association at Dundee, by an eminent philosopher, on the 
subject of matter and force, which afforded a good example 
of the truth that the suppressio veri is very often closely 
aljied to the suggestio falsi. The argument made use of 
was this : An experiment was shown, in which, by the 
action of acetate of lead upon zinc, what we know as 
the zinc or lead tree was formed. The molecules of lead 
are released from the acetic acid by those of zinc, and are 
gradually deposited, and being deposited in that gradual 
manner, they attach themselves one to the other in certain 
definite directions, according to the nature of the molecular 
attraction, which exists between particle and particle of that 
particular kind of matter. They undergo crystallization, and 
you have the lead formed into thin crystalline laminae. The 
same thing may take place in a solution of silver, with differ- 
ently formed crystalline laminae ; and it results simply from 
the molecules of a particular substance being allowed gra- 
dually to agglomerate together, and to take up that position 
which their polar attraction for each other may indicate, and 
which will be different with different substances. If they are 
thrown together suddenly, without being allowed to take up 
their successive positions, then no crystallization at all, or 
imperfect crystallization, takes place. This constitutes the 
difference between loaf-sugar and sugar-candy. In loaf-sugar 
the crystallization takes place very rapidly, but in sugar- 
candy the formation takes place gradually, as the water 
evaporates, and the particles of sugar have time to take up 
that position which their nature dictates, and growth takes 
place. The crystallizations of the lead tree in the lecture I 
referred to were compared to fern-leaves, and they certainly 
have a very leaf-like appearance. The lecturer went on to say 
that just as the molecules of lead and silver form crystals 
under these circumstances, like beautiful leaves, so the union 
of carbon, from the carbonic acid of the atmosphere and other 
sources, and hydrogen, forms certain matter under the influ- 
