18 REPORT—1863, 
(which had previously been dried in the air) were suspended in a capacious 
and well-ventilated drying-chamber, the temperature of which was main- 
tained, for the above period, at not less than 49° C, They were then trans- 
ferred, while in the chamber, to stoneware jars with tightly closing lids 
(the same as were used for keeping the cotton immersed in acid), and were 
allowed to become perfectly cold in these before submission to treatment 
with acid. 
The vessels which were found most suitable for use in treating the 
cotton with the acid were large and rather deep stoneware pans: one, 
provided with an iron lid, contained the quantity of mixed acids required 
for the treatment of a certain number of skeins; a second, which was fitted 
with a perforated ledge of iron, and was surrounded by cold water, served 
for the treatment of the cotton, which was conducted as follows :—a propo- 
tion of the acid haying been transferred to the second pan, two skeins were 
thoroughly immersed in it, and stirred about for two or three minutes ; 
when saturated with acid they were raised upon the shelf ard pressed 
together with the paddle, so as to allow the superfluous acid to flow off; the 
quantity of acid absorbed by these skeins was replaced in the pan by an 
addition of fresh acid, and further skeins were immersed, those which had 
drained being transferred to a jar while tke freshly immersed ones were 
soaking, In this way the operation of immersion was continued until the 
whole of the skeins to be treated at one time had been transferred to tue 
jars, six of the large yarn or nine of the fine being introduced into one of 
these. 
The skeins were pressed down in the jars by means of the paddle, and 
sufficient acid was added just to cover the cotton completely. The jars were 
then closed and placed into vessels containing water, in a cool building, 
where they remained for forty-eight hours. 
It was found an important precaution to keep the vessel in which the 
cotton was first immersed surrounded with water, especially in the warm 
season during which these experiments have been conducted, as the evo- 
lution of heat during the first action of the acids upon the cotton is con- 
siderable. The contents of the jars to which the gun-cotton was transferred 
were not found to become heated to any important extent, even wien not 
surrounded by water. The proportion of acid to cotton said to be contained 
in the jars, as the process is carried out at Hirtenberg, is that of ten to one ; 
but it was found necessary, in order to cover the cotton completely as di- 
rected, to employ at least fifteen parts of acid to one of cotton, This pro- 
portion would doubtless be much diminished if means were employed for 
compressing the cotton in the jars more highly than was the case in these 
experiments. 
The precaution of adding a fresh supply of the acids to that which remains 
in the immersing-vessel after the withdrawal of each quantity of cotton 
treated, was proved by experiment to be of the greatest importance in 
securing the uniformity of the product. In one of the first operations, 
no fresh quantity of acid was added before immersing the skeins treated 
last. In other respects these skeins were submitted to precisely the same 
treatment as the remainder (2. ¢. an additional quantity of acid was added 
to them in the jar, they were allowed to remain for forty-eight hours, &c.). 
When examined synthetically, they furnished at least one-half per cent. 
more cotton than the skeins first treated in the same operation; and when 
fired in the proof-mortar, a decidedly lower range was obtained with the 
cotton last treated. 
