tints of the ordinary kinds. They show too that the 
substances accompanying the cellulose (whether clothing 
the fibres, or contained in their interior) are the same 
with this variety of cotton as with all those previously 
examined. 
An Improved Method for preparing Marsh Gas,” by C. 
SCHORLEMMEE, F.RS. 
Everyone who ever had to prepare soda-lime knows that 
the preparation of this substance is a troublesome as well 
as a laborious process. Chemists will therefore hail with 
pleasure a paper “ On the Determination of Nitrogen,” by 
S. W. Johuson {Liebig's Ann., 169, 69). He has found 
that in using the method of Varrentrapp and Will, soda-lime 
may be replaced by an intimate mixture, of about equal 
weights, of anhydrous sodium carbonate and dry slaked 
lime. It occurred to me that such a mixture might also be 
employed instead of soda-lime in the preparation of marsh- 
gas, and I found that by heating an intimate mixture of 
anhydrous sodium acetate with more than twice its weight 
of lime and sodium carbonate, a very regular and quiet 
evolution of marsh gas took place. The gas, thus obtained, 
always contains some acetone, which is easily removed by 
shaking it with water, or, better still, with a solution of 
acid sodium sulphite. 
MICROSCOPICAL AND NATURAL HISTORY SECTION. 
October 13th, 1873. 
Professor W. C. Williamson, President of the Section, 
in the Chair* 
The President delivered the following address : 
It being the wish of your Council that I should open our 
