218 
ME. ABEL’S KESEARCHES ON GUN-COTTON. 
Experiment 113. — Two other specimens, weighing 44 and 34 grms., were exposed day 
and night in a hot-air chamber, to a temperature ranging between 35° and 50°. The 
specimens were weighed periodically, in an air-dry condition. After the lapse of ten 
■weeks one sample had lost 1T8 per cent., and the other T56 per cent. 
In conducting these quantitative experiments, it was observed that the exposure of 
gun-cotton for a protracted period to a moderately elevated temperature had the effect 
of reducing the hygroscopic power of the fibre, so that upon exposure of gun-cotton 
which had been thus heated to the atmosphere, the maximum proportion of moisture 
absorbed by it was very notably lower than that contained in the original sample. The 
actual loss sustained by the above samples, which were always weighed after exposure 
to air for definite periods, was therefore somewhat less than indicated by the numbers 
given. 
Part III.— INFLUENCE EXERTED UPON THE STABILITY OF GUN-COTTON BY SPECIAL 
MODES OF PREPARING AND PRESERVING IT. 
I. Reduction of gun-cotton fibre to a fine state of division . — Abundant proofs have 
been obtained that the long-continued washing and the treatment with an alkaline, liquid 
to which gun-cotton is submitted, do not completely separate from it products of the 
partial oxidation of organic impurities retained by the cotton up to the time of its con- 
version. This is unquestionably due in great measure to the tubular structure of the 
fibre. If the impurities were merely upon the surface of the fibre, their perfect removal 
by the action of solvents should be accomplished without difficulty, but it does not appear 
that even long- continued digestion of gun-cotton in alcohol has the effect of completely 
freeing it of the impurities soluble in that liquid which are locked within the fibre. 
The action of a warm or cold alkaline liquid upon the material might perhaps eventually 
result in the complete removal of these bodies, but the loss of product and destructive 
effect upon the fibre, resulting from any other than a brief digestion in a very dilute 
alkaline bath, are too considerable to admit of such a treatment. The following expe- 
riments may be quoted in illustration of this. 
Experiment 114. — A quantity of gun-cotton which had already been submitted to the 
usual purification with water and a hot alkaline bath, was boiled for ten minutes in a 
solution of potassic carbonate of the strength usually employed (of specific gravity 1*02). 
By this treatment the material sustained a loss of 3-7 per cent., the bath having assumed 
an amber colour. Upon being again boiled for twenty minutes in the same alkaline 
bath, which thereby became considerably deepened in colour, the sample sustained a 
further loss of 12 - 09 per cent. The strength of the fibre had been considerably reduced 
by this treatment. 
Experiment 115. — 6 '5 grms. of gun-cotton and 0 - 4 grm. of sodic carbonate were placed 
together with 50 cub. centims. of water in a flask to which a vertical condenser was 
attached, and were heated to 100° for twelve hours. The alkali was then found to have 
become nearly neutralized, and the dark brown liquid contained sodic nitrate in abun- 
