i879m 
Notices of Books . 
125 
has been done during these twenty years, gives an importance 
to this new volume which is far greater than that usually to be 
attached to the re-issue of such a volume. Of this mass of 
work, here so ably recorded, a very large portion is due to the 
adtive and untiring personal investigations of the author himself. 
Few men have studied more deeply than Dr. Thudichum the 
chemistry of the urine in health and in disease, and his results 
in this field of investigation alone, apart from his masterly re- 
marks on the chemistry of the bile and his still later discoveries 
in connection with the chemistry of the brain, claim and secure 
for him the foremost rank among contemporary workers in 
science. 
What is especially valuable in the book, in addition to the 
mere record of fadts, is what may be termed its historical aspedt. 
To each substance of importance the author devotes a special 
chapter, and gives at the beginning of each a summary of its 
history, so that from the date of its discovery we are enabled to 
follow its development at the hands of the various chemists who 
have given it their attention. It may be said, in fadt, that the 
author, not content with mere history, has repeated all experi- 
ments of any importance relating to his subjedt, — a method of 
procedure which enables him, in his critical remarks, to confirm 
or condemn with an authority not to be lightly gainsaid. As a 
special illustration of this the exhaustive chapters on Urea and 
Uric Acid may be cited. 
A special chapter is devoted to Xanthine. This substance, 
first discovered by Marcet in 1819 in a calculus, was further 
discovered by Liebig and Wohler, and shown by Strahl and 
Lieberkiihn in 1848 to be a normal ingredient of urine. Ten 
years later (1858) Thudichum showed it to be a normal ingre- 
dient of the human liver. Its now extensively studied properties 
are graphically detailed, and its relation to hypoxanthine and 
guanine clearly pourtrayed. Its preparation by the phospho- 
molybdic process is of great value. By this process Thudichum 
obtains Kreatinine as such, and also two new bodies — Reducine 
and Urochrome. To these and similar bodies he applies the 
term “ alkaloid ” in a wider sense than is usually accepted. 
Reducine is a characteristic type of a remarkable class of bodies 
occurring also in the brain, and possesses, like these, in addition 
to its basic properties, co-existent acid properties, pointing to 
the probability of its being an amido-acid with marked basic 
tendencies. 
The fact that hypoxanthine, a pathological ingredient of urine, 
occurs naturally in the brain of man and ox, though vaguely 
indicated by Muller, was first experimentally demonstrated by 
Thudichum. Guanine, although not occurring in urine, also re- 
ceives special attention, on account of its chemical relations to 
the uric acid group. 
Under Kreatinine, an undoubted ingredient of urine, we have 
