91 
Mr. W. Brande’s Chemical Researches, &c, 
very slight discoloration occasioned by the addition of infusion 
of galls to a solution of the colouring matter, under circum- 
stances most favourable to the action of that delicate test of 
iron, first led me to doubt the inferences of those able che- 
mists, and subsequent experiments upon the combinations to 
which they allude, tended to confirm ray suspicion, and in- 
duced me to give up no inconsiderable portion of the time 
which has elapsed since the last meeting of this Society, to 
the present investigation. 
An examination of the chyle and of lymph, in order to 
compare their composition with that of the blood, formed an 
important part of this inquiry, especially as those fluids have 
not hitherto been submitted to any accurate analysis, on ac- 
count of the difficulty of procuring them in sufficient quantities, 
and in a state of purity. Whilst engaged in assisting Mr. 
Home in his physiological researches, several opportunities 
occurred of collecting the contents of the thoracic duct under 
various circumstances, and in different animals ; on other oc- 
casions Mr. Brodie has kindly furnished me with the mate- 
rials for experiment. 
SECTION II. 
On the Composition of Chyle * 
The contents of the thoracic duct are subject to much varia- 
tion. About four hours after an animal has taken food, pro- 
vided digestion has not been interrupted, the fluid in the duct 
may be regarded as pure chyle ; it is seen entering by the 
lacteals in considerable abundance, and is of an uniform white- 
Ns 
