130 REPORT—1857. 
which takes place resembles the so-called butyric acid fermentation. Thus, 
when the gases which are evolved from the surface of the steeping vats are 
collected, which is most conveniently effected by filling the receivers with 
the flax water and supporting them over the surface of the liquid, the 
mixture of gases obtained, when transferred to the mercurial trough, and 
examined by the introduction of pellets of potash, explosion of the residue 
with oxygen, &c., according to Bunsen’s excellent methods, was found, in 
numerous trials, to afford merely carbonic acid, hydrogen, and nitrogen. In 
no case could traces of carbonic oxide, carburetted hydrogen, nor of sul- 
phuretted hydrogen be detected. The absence of sulphuretted hydrogen 
was carefully ascertained by the employment of various methods; not the 
least indication of its presence could be detected, though papers moistened 
with acetate of lead were exposed to the gases evolved during the entire 
progress of the fermentation. This fact is important, as it has been asserted 
that the disagreeable odour of the flax-pool depended upon the copious evo- 
lution of sulphuretted hydrogen; and its presence in the gases evolved has 
been reported by a French chemist, though upon insufficient evidence, 
afforded by the examination of flax-water, conveyed in bottles from remote 
parts of the country to Paris. The production of a large amount of sul- 
phuretted hydrogen has been urged as a serious objection to the adoption of 
Schenck’s hot-water process. 
The corrected composition of 100 volumes of the mixed gases evolved 
from the fermenting vats was found to be as follows :— 
Carbonic acid .<,scs.s5c0ssee Fee san gaees Sees eee 
ETVOYOPEN Cevcccsccvewseoccecestg hoe 44°30 
INGGMOU EM ae tantecwaenwesesa sae aateg ani scese 33°41 
100-00 
At the Belfast meeting of the Association, it was stated by the Reporter 
that, during the fermentation, a very considerable amount of butyric acid was 
produced. Since that period, the experiments have been repeated on a con- 
siderable scale, and it has been found that, though, when the fermentation 
has fairly commenced, after the straw has been about twenty-four hours 
immersed, the distillate from the fermenting liquid contains formic acid and 
butyric acid; yet, as the process continues, and especially towards its con- 
clusion, the formic acid almost entirely disappears, and the butyric acid de- 
creases in amount, and is replaced by valerianic acid. In some cases, indeed, 
the distillate, towards the conclusion of the period of steeping, afforded nearly 
pure valerianic acid. 
Report of the Committee on the Magnetic Survey of Great Britain. 
By Major-General SaBine. 
Tue author gave a brief review of the important researches connected with 
the magnetism of the globe by MM. Kreil and Lamont, on the Continent of 
Europe, Dr. Bache and others in America, and by our own observers in 
various parts of the earth. He adverted to the Magnetic Survey of the British 
Islands, executed at the request of the British Association in 1837 and 1838, 
published in the ‘ Reports’ for 1838, as the first national work of this descrip- 
tion which had been executed in any country, and to the similar works 
since completed in Austria and Bavaria, at the expense of the Governments 
of those countries, in proof of the value of the example. It is on such 
