"It is useful in this sense to make a clear distinction between the conception of an element as a separate homogenous substance and as a material but invisible part of a compound."

"I have achieved neither fame nor wealth, but I have learned to know the human heart."

"The spirit of scientific inquiry must be cultivated in all children."

"The edifice of science not only requires material, but also a plan. Without the material, the plan alone is but a castle in the air—a mere possibility; whilst the material without a plan is but useles…"

"I consider it my duty to be useful to my country."