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saturated with these liquors, the excess expressed out, and 
then dried gently, and aged for 24 hours ; afterwards well 
washed in lukewarm water and dried. A portion of each 
parcel was then treated with dilute hydrochloric acid, some 
of the original stock of New Orleans cotton being placed in 
the same acid, and going through the same treatments. The 
mordants being dissolved out, the cotton was well washed to 
free it from the acid, dried, and its strength ascertained with 
the following results : — 
New Orleans Cotton not mordanted, 10 ex- 
periments 143*9 grs. 
Ditto mordanted with iron, 10 experiments... 96*8 grs. 
Ditto mordanted with alumina, 10 experiments 94* 1 grs. 
A very notable diminution of strength has occurred in the 
mordanted parcels. 
Gun cotton. The only undeniable chemical compound 
which cotton forms with other elements, without undergoing 
conspicuous physical change, is in gun cotton. A sample of 
New Orleans was treated with equal volumes of concentrated 
sulphuric and nitric acids ; it increased in weight 66 per cent, 
burned well, and was soluble in alconolised ether. Twenty 
hairs being measured gave a mean length of 0*997 inch; twenty 
hairs before treating gave a mean length of 0'996 inch. The 
difference 0*001 being within the range of error, it may be 
said not to have changed in length. The strength of 10 
hairs was taken, and gave a mean of 85*4 grs. The 
mean strength of 19 hairs before treatment being 138*1, 
there has been a considerable diminution of strength. This 
may not be true of all kinds of gun cotton. 
Mercerised Cotton. It is very well known that cotton cloth 
treated with concentrated solution of caustic soda shrinks in 
