Xv. a Study of Some Biochemical

A CHARACTERISTC of biochemistry is its great heritage of colour tests which have been devised to meet the demand for means of identifying substances of complex or unknown constitution where the more exact methods of pure organic chemistry were of no avail. Some of these biochemical tests are of a degree of delicacy and specificity almost comparable to biological reactions; but, owing to the difficulties of micro-analysis, the mechanisms of many of these tests are as yet imperfectly understood. This is not a practical disadvantage as long as the specific nature of the test is asured, but occasionally doubtful cases arise when the knowledge of the rationale of a reaction is essential, and it was from experience of such cases that I was led to investigate some of the well-known colour tests, laying stress on the nature and limiting conditions of the test apart from the chemistry of the substances involved in it.