Although the latter part of the last century, and the first half of the present, have been very remarkable for the number of distinguished men who have flourished during that period, in almost every branch of knowledge; yet neither the bar nor the senate, neither literature nor any of the sciences, can boast of greater men, nor lay claim to more positive improvement, than Chemistry.
If we only consider that interval between the discovery of oxygen by Priestley, in 1774, and the conclusion of Sir Humphrey Davy's labours, Chemistry almost seems like a new science; and it continues to advance with such rapidity, and is daily opening out so many new questions, that the most accomplished chemist of one year is never sure how much he may have to learn the next; nor, unless he reasons with great caution, how much he may have to _un_learn.
To a physiologist, who requires assistance _from all branches of science_, Chemistry must always be an interesting study. When we lay aside all speculations as to what is the abstract nature of Life, and study that which is the proper object of philosophy—that to which it seems the faculties of man are limited—namely, the _laws_ in obedience to which the phenomena in nature occur; and apply the knowledge thus obtained to the occurrences which take place in the human body; we soon discover that, whatever the abstraction "Life" may be, we live proximately, in virtue of certain changes in various forms of matter; as food, air, the various constituents of our bodies, &c.; and that these consist of multiplied separations and rearrangements of their respective elements, which it is the special province of Chemistry to examine.
If we investigate the changes of the living, or the structure of the dead, with these objects,—we shall be in no danger of perverting Chemistry to purposes to which it is inapplicable. When, however, we proceed a step further, and seek to give a _chemical expression_ to various uses and relations of different parts of the body, the greatest caution is required.
In the first place, in a machinery which is a practical application of a great _many_ sciences, it is to the last degree improbable that they can be expressed by any _one_.