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fluid contained so much arsenic. Now, to use Reinsch’s test it was almost 
impossible to obtain pure copper, and when he attempted to do it by galvanic 
aid, even then it was difficult, for sometimes the electricity carried over from 
one pole to the other not only the copper, but the arsenic with it. What 
was it that caused Reinsch’s test to supersede Marsh’s test ? Marsh’s 
test was said to be the most delicate test for arsenic. But it was so deli- 
cate as to be almost useless, because it depended on your dissolving in 
nascent hydrogen the arsenic of your suspected fluid. You had to get your 
nascent hydrogen from two materials, zinc and sulphuric acid, but when 
Marsh’s test was employed almost all the sulphuric acid of commerce con- 
tained arsenic, and so did almost all the zinc, and therefore you had to test 
your tests before you could proceed with your analysis. Reinsch’s test was 
adopted because it was supposed to get over that difficulty ; but now it is 
known that the chemist should have the same reason for suspecting that 
arsenic may be found in copper as well as in either sulphuric acid or zinc. 
This is an illustration to show that something more is required in attaining 
scientific facts than even the most careful and accurate power of observation. 
That, no doubt, is a great intellectual power, but at the same time I agree 
with one of Mr. Row’s observations, that the men who devote themselves most 
assiduously to the mere observation of minute facts in nature are scarcely 
ever, from the habits they acquire, good general reasoners on general grounds 
The eye can be readily adapted by training to the most minute observa- 
tion, and may easily become more skilled and adapted to observe objects. 
The eye is a most wonderful instrument, from the power of adaptability 
which it possesses, and which enables the savages and Arabs to have long 
sight, while it gives to others who have to examine minute objects an almost 
microscopic vision. But that microscopic sight leads frequently to a microscopic 
structure of the mind. Most of the objections raised against Revelation come 
from those microscopic observers, and I think that matter was very wisely 
and forcibly brought before the world in what I think the most valuable 
of all Dr. Whewell’s works, his Bridgewater Treatise on Astronomy, where 
he traced the difference between the sceptical mind of Laplace and the 
believing mind of Newton. Laplace’s analytical powers were of the 
highest order ; he was a trained manipulator of analytical formulae. 
Laplace was a man whose mind was trained to the manipulation of mathe- 
matical formulae and the interpretation of mathematical symbols. Whewell 
showed that that had contracted his mind, and prevented broad general 
views. His was the case of a mere inductive mind ; but Newton’s was a 
deductive mind. He was a man who put together what had been arrived 
at by the process of deduction, and strove to bind it up into a general truth ; 
and Whewell showed that there was this difference between the two, that 
where the one mind became highly sceptical, the other became highly capable 
of belief. The more we investigate the matter the more we shall find that 
faith is an element quite as much required by the mathematician or the phy- 
sicist or the philosopher, as it is required by the theologian. I agree with 
Mr. Reddie in thinking that the illustration of the great antiquity of man 
