Mr. Teschemacher on Gun-Cotton. 259 



strong acids were in contact with the cotton about two mi- 

 nuteSj and after squeezing well, the cotton was washed in 

 water to free it from the acid : the quantity of water used w'as 

 5000 grs. 



The strong acid squeezed out of the cotton weighed 113| 

 grs. (No. 2), leaving 374 grs. of acid (No. 3) to be accounted 

 for, to make up the original quantity used. The cotton thus 

 prepared was perfectly dried in the air over a water-bath, and 

 was found to weigh 79 grs., being an increase of 32-40 grs. on 

 the cotton used, equal to an increase of 69^ grs. upon every 

 100 grs. of cotton in its original state. 



To ascertain whether the cotton would absorb anything 

 more, I steeped 25 grs. of the above cotton, after it had been 

 washed and dried, in fresh acid (No. 1), but no increase of 

 weight took place. I also steeped a fresh portion of cotton for 

 three minutes in the same quantity of fresh acid (No. 1) ; it 

 weighed after washing and drying 78 grs. ; a third portion 

 was steeped for four minutes in one-third more acid than in 

 the previous experiments, it Aveighed after washing 79 grs. ; 

 so that it appeared that the cotton had taken up its maximum 

 from the acid by the first immersion. 



As these 32*40 grs. increase of weight were clearly derived 

 from the 4872 g^'^* o' the mixed acids, I made the following 

 experiments to ascertain what alteration the acids had under- 

 gone. 



I neutralized 100 grs. by weight of the original acid (No. 1) 

 by carbonate of soda, and found that it required 52"80 grs. of 

 soda for that purpose. I found likewise that to neutralize 

 the 113| grs. of strong acid (No. 2) separated from the cotton, 

 required 58*52 grs. of soda, and that the remaining 374 grs. 

 of acid to be accounted for, contained in the washings, required 

 170*30 grs. of soda for neutralization, making together 228*82 

 grs. of soda required to neutralize the 48 7|^ grs. of acids No. 

 2 and 3, used for acting upon the cotton ; therefore, if 100 

 grs. of the original mixed acids (No. 1) required 52*80 grs. of 

 soda as above for neutralization, 487| grs. would requii*e (if 

 not acted upon by the cotton) 257*36 grs. of soda; it how- 

 ever only required 22882 grs. as above. The difference, 28*54 

 grs. of soda, is therefore equal to the acid which disappeared, 

 or was taken up by the immersion of 4G*60 grs. of cotton in 

 the mixed acids. To ascertain whether a portion of each of 

 the mixed acids, or only one of them, was taken up by the 

 cotton, I added to the solution of the 100 grs. of mixed acids 

 (No. 1) (neutralized by the soda) chloride of barium, and ob^ 

 tained a precipitate weighing 126 grs. of sulphate of barytes. 



1 also, in the same manner, precipitated from the solution 

 T2 



