142 TEMPERATURE OF THE WATER USED IN INFUSION. 
Society to dwell on the importance of these preparations, 
the attention which has been already bestowed upon them 
is a sufficient evidence that they are by no means disre- 
garded. 
I shall confine myself on this occasion to the considera- 
tion of the methods which have been recommended for the 
preparation of infusion of calumba. This infusion is in fre- 
quent use, and is one of those most difficult to preserve from 
undergoing decomposition. Many Pharmaceutists recom- 
mend that the water for the preparation of this infusion 
should be either cold, or considerably under the boiling 
temperature, and the cold infusion, by percolation has 
received the sanction of the Edinburgh College. I shall 
therefore endeavour, as briefly as possible, to state the result 
of some experiments I have made with reference to this 
infusion. 
An infusion of calumba made with cold water, after being 
allowed to stand the specified time, which is two hours, and 
then strained off, will be very bright and free from starch ; 
whilst on the other hand, if made with boiling water, it 
will contain a considerable quantity of starch, and will not 
be quite so bright. The latter difference is caused by very 
fine particles held in suspension, which gradually subside ; 
the difference between the two in strength and aroma ap- 
pears quite trifling and unimportant. 
If portions of the two infusions be kept under similar 
circumstances, that made with cold water will be observed 
to be several hours in advance of the other in the com- 
mencement and progress of decomposition ; and if it be 
warm summer weather, symptoms of incipient change will 
very rapidly appear, being indicated by a general cloudi- 
ness, and the accumulation of small particles of insoluble 
matter on the surface of the hitherto bright infusion, which 
gradually extend themselves throughout the entire fluid. 
The precise time at which this takes place, will of course 
depend much on the state of the weather. The change, 
when it becomes visible, in the infusion made with boiling 
