22 REPORT—1868. 
cess of manufacture. It was found, moreover, that the cotton yarn obtained 
in this experiment was very decidedly weaker (7. ¢. could sustain only consi- 
derably less strain) than the ordinary product—a result which must be ascribed 
to the greater predominance of sulphuric acid in the mixture which has been 
once used. 
Experiments with this mixture and the finer yarn, furnished a different re- 
sult to the foregoing. The products corresponded closely in composition to 
the theoretical result attained by the original or first employment of the acids. 
The rotting or weakening effect noticed above was much less apparent in these 
products than in the case of coarse yarn. 
It would appear from these results that the mechanical condition of the 
cotton (7. ¢. the thickness of the yarn) exerts an important influence upon the 
nature of the product furnished by the once-used acid. Further operations 
are in progress in which this acid is employed; and the explosive effects of 
the resulting products will be carefully compared with those of the material 
obtained in the ordinary way. 
(19) 3. No systematic artillery experiments or others illustrative of the ex- 
plosive effects of gun-cotton prepared at Waltham Abbey have as yet been in- 
stituted, beyond a few trials of small charges in the mortar employed at the 
Gunpowder Works for purposes of proof. Even these results, however, as far 
as they go, are possessed of considerable interest, as demonstrating some of 
the most important points of difference between gun-cotton and gunpowder, 
when used in cannon, and as illustrating to some extent the value of the simple 
mechanical means devised by Baron Lenk for regulating the explosive action 
of the gun-cotton. 
A quantity of the coarse roving, corresponding in weight to one-third of the 
proof-charge of gunpowder, was wound round a conical wooden plug, with the 
application only of a slight strain (equal to two ounces). The range obtained 
by this charge, or cartridge, was fully equal to that furnished by a full-proof 
charge of Enfield-rifle powder. The same weight of gun-cotton, wound upon 
a cone of the same dimensions, but kept during the winding under a strain of 
one pound, gave a range which was materially shorter than that furnished by 
the loosely wound charge, but quite equal to the average proof range (or three 
times the weight) of ordinary cannon-powder. Results agreeing with the 
above, and in very good accordance with each other, were obtained in frequent 
repetitions of those experiments. 
The variation in composition of exceptional or special products, such as have 
been referred to in the preceding, manifested themselves in a corresponding 
variation in the range obtained with them, when tried under the same condi- 
tions as the ordinary products. Thus the skeins which in one particular 
operation had, as above described, been immersed finally, without addition 
of fresh acid, and which furnished synthetically a somewhat high proportion 
of cotton, did not yield so long a range as the ordinary products, nor as the 
first skeins obtained in the same operation. Again, the coarse yarn which 
had been treated with acid already once used, when wound into cartridges 
with a strain of two ounces on the yarn, did not furnish as long ranges as the 
ordinary products wound under a strain of one pound; and when made into 
cartridges under the latter conditions, the ranges it furnished were very con- 
siderably below the average results obtained with the ordinary product. 
The absence of any appreciable residue in the mortar, and of any but the 
most trifling amount of smoke, only noticeable if watched for, were, it is hardly 
necessary to say, novel and important features in these few proof experiments. 
- (20) 4. Some observations made during the drying, and in the preservation 
ee Oe re 
