119 
caused by raindrops, and the vortex rings caused by a puff 
of water. The various ways in which these vortices move 
were also shown. But Professor Reynolds’ object in show- 
ing these experiments was to illustrate the importance of 
the method of study rather than from the intrinsic impor- 
tance of the results already obtained, which are not as yet 
sufficiently complete for publication. 
“ On the powerful Oxidising Action of Animal Charcoal 
upon Organic Matters as shown by the Analysis of the 
Drainage from a large heap of a Mixture of Night-soil and 
Animal Charcoal,” by William Thomson, F.RS., Edin. 
I had occasion some time ago to examine a sample of the 
fluid which had drained from a large heap of several thou- 
sands of tons of a mixture of Night-soil and Animal Char- 
coal which had lain for about one year or more, covered over 
with clay and pitch to prevent the rain from washing it 
away. This heap was about 7 or 8 feet in height, and the 
drainage from the whole which could be collected, did not 
amount to more than an average of about 12 gallons in 24 
hours. It exuded from the heap in minute streamlets which 
drained down its sides, and at no part of this immense col- 
lection of oxidising organic matter could the slightest 
unpleasant odour be detected. The liquid which drained 
away was mixed with a small amount of suspended matter, 
which however soon settled to the bottom, leaving a per- 
fectly colourless solution which was quite free from smell, 
but possessed a strong saline taste, and when treated with 
hydrochloric, sulphuric, or other acid it produced a copious 
effervescence. 
This liquid was submitted to a very careful analysis in 
the following manner. 
1. 50 c.c. of the liquid was evaporated to dryness in a 
tared platinum capsule and heated in an air bath at 220° Fah. 
till it ceased to lose weight, and its weight then noted. 
