PREFACE TO FORMER EDITION. 



THIS book was originally compiled as a handbook for prac- 

 tical work in Physiological Chemistry at University College, 

 London, since no single text or class book covered the 

 complete course, or treated Physiological Chemistry as part 

 of the subject of organic Chemistry, or even as an in- 

 dependent subject. 



The present book must still be regarded mainly as a 

 compilation. It represents an attempt to give to the worker 

 a nearly complete statement of the whole subject. Each 

 section has a short explanatory summary of the essential 

 points, so as to connect the various sections together. The 

 essential points are illustrated by the practical experiments, 

 which are printed in different type. 



The illustrations are also compiled from various sources. 

 These are mentioned underneath each figure. The illustra- 

 tions of apparatus not so mentioned have been drawn from 

 my own sketches. For those of the osazone crystals, haemin, 

 and tyrosine, I am indebted to Miss V. G. Sheffield, who 

 has also kindly helped in reading the proof sheets. 



In most physiological chemistry laboratories the strengths 

 of the reagents employed are very various, e.g. dilute acetic 

 acid may be i per cent., or 2 per cent, or 5 per cent., or even 

 10 per cent. In order that all workers may employ a reagent 

 of standard concentration, a list of reagents has been carefully 

 drawn up and is appended. 



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