Pittsburg dispatch. [volume] (Pittsburg [Pa.]) 1880-1923, 1890-10-11
PRODUCT OF BRAINS.
Continued from Ninth Page.

|
combustion tube. Careful experiments show
| that the sulphate of silver washing tube is a
| complete protection against hydrochloric acid,
and the metallic silver In the tube was relied
| on for protection against free chlorine, or
| other chlorine compounds. The time OF max.
| ing a combustion was about an hour and a
| quarter; Is to 20 minutes being taken to heat
| the oxide of copper. about half an hour for the
burning and 25 to 30 minutes for the air aspira.
| tion Blair's apparatus is substantially the
| same rs the above. His purifying train follow.
| ing the combustion tube contains a tube OF
anhydrous sulphate of copper OF pumlce stone.
| This tube Is always freshly filled.
DUDLEY's HARD WORK AT IT.
Dudley began his study of this problem of
the release of the carbon by quite an amount
of preliminary study on the. reliability of his
apparatus and method of making combustions.
A number of notifications were tried. but
finally the apparatus and method previously
described under the heading, "Dudley's Appa-
rotus and Method" were settled upon, and this
apparatus and method were checked up by the
following determinations: Into an ordinary
glass combustion tube some % grams OF the
well-known combustion mixture of chromate
of lead and bichromate of potash were placed,
taking care that the material did not reach to
at each end by asbestos plugs previously ig.
nited. The tube was then placed Ill the fur
mace a combustion made in the regular way,
the position of the material, not reaching to
formly heaIed
This combustion was simply a blank to elimi-
nate any possible error due to impurities In the
combustion mixture. A small increase in
weight in the absorption apparatus was found,
and second blank gave exactly the same re-
suits. As this solution of double chloride will
he referred to hereafter. we will say that it was
made in Dudey's laboratory by obtaining from
the market commercial chloride of copper and
commercial chloride of ammonium, and dis
solving these in water and mixing them in the
For dnuh In nln1 iAn fai
ing one molecule each of the two salts. A
small amount of free ammonia was added.
enough to cause perceptible separation of
hydrated oxide of copper. The solution was
then allowed to settle, and always filtered
through previously lgnited asbestos before
uslng
CONCLUSIONS OF THE ANALYSTS.
The conclusions here presented are not those
of the committee in their official capacity.
They are the views Professionally held by the
members whose work is given above. The
combustion of carbon in porcelain tube in a
stream of purified oxygen, when the precau-
tions indicated are used. gives sensibly ac-
curate results. If the carbon contains chlorine
it is desirable to use coil of metallic silver in
the combustion tube, and it is apparently also
essential to use some solution of silver, prefer
ably the sulphate, in the purifying train. The
chronic acid method is capable of burning all
the carbon used. If this carbon also contains
oxidant in the purifying train, preferably
pyrogallic acid with oxalate of potash; also
liquid silver absorbent must follow the de-
oxdIzing tube. Under these conditions this
method gives seusibly accurate results. The
most important discovery made by the commit
tee in this work pertains to the variable action
of the double chloride solutions. This appar-
emily throws doubts on the reliability of all
carbon determinations previously made by this
re-agenr, since they show variations on the
same steel lying between l.0l6 and Ll5O.
CARBON AFFECTED BY CHLORIDE.
When the degree of acidity is kept constant,
the apparent quantity of carbon found is af-
fected by the mode of preparation of the double
chloride by its age, and by the number of
times it has been crystallized A carbon sponge
derived from a double chloride solution does
not appear to lose any carbon by drying at
temperature under 1000 c., but loses if the heat
is higher. The problems now before the COM
mittee. as suggested by the above results, are:
The determination of carbon IN steel by some
direct process not involving the use of double
chloride; the direct combustion of finely divided
metal in oxygen or chronic acid is one of
these. or by fusion in a mixture of bi-sulphate
and bichromate of potash. The determlna-
tion, if possible, whether a neutral or aka
line double chloride liquid may not dissolve a
portion Of the carbonaceous residuum, and thus
lead to results which are too low. The deter
mination whether the addition of acid simply
prevents this tendency. or whether the use of
acid may not favor the separation of pre-
existing organic matter i'll the liquid, and its
retention by the carbon sponge, thus leading to
results which are too high. The investigation
of the cause of the influence of repeated
crystallizations of the double chloride on the
apparent quantity of carbon.
Finally, 1t is to be presumed that many, If not
all of the above points. have attracted the
tenton of other analysts; and the committee
will be glad to learn of the results and expert
ence of others along these lines.
Prof. Lunge followed with short address
in which he commended the work Of the
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