Cellulose 



In regard to the time factor, or duration of exposure to the 

 acid required to give the maximum number, this was in all cases 

 controlled by observation. Thus with the acid HNO 3 .^H 2 O 

 (1-488 sp.gr.), after 48 hours the product was still blued by 

 iodine, and gave 161 c.c. NO ; whereas after 62 hours' ex- 

 posure the iodine reaction was not obtainable, and the maximum 

 number (1657 c.c. NO) was obtained. At the slightly lower 

 gravity 1-483, an exposure of 120 hours was necessary. At the 

 still lower gravity when the cotton (nitrate) passes into solution, 

 the maximum is very rapidly attained (5 minutes). 



The highest nitrate obtained as above, with nitric acid only, 

 is somewhat lower than when sulphuric acid is present. Under 

 these latter conditions the author regards the highest nitrate 

 obtainable as C 24 H 18 (NO. J H) 11 O 9 . 



THERMAL CONSTANTS. By calorimetric observation on the 



