MISCELLANY. 
315 
Determination of the Causticity of the Soda Salts of Commerce. By M. 
Barriswil. — Having had occasion to examine, with M. S. Riess ; alka- 
limetrically, some samples of commercial soda, we employed, in order 
to determine the caustic alkali, a new process of great accuracy, which, 
although demanding somewhat more time than the ordinary process, 
is so readily executed that it may be recommended to manufacturers, 
and in some cases it might certainly be employed with advantage in 
analytical investigations of the laboratory. 
This process is founded on two chemical reactions, both well known, 
viz: — 
1. When an excess of chloride of barium is poured into a solution 
of carbonate of soda, the filtered liquid is not rendered turbid by car- 
bonic acid. 
2. When the least quantity of alkali is added to a perfectly neutral 
solution of chloride of barium, the filtered liquid is rendered turbid by 
carbonic acid. 
The process of analysis consists in determining the amount of barytes 
eliminated from the chloride of barium by the caustic alkali contained 
in the soda salt. For this purpose, 10 grms. of the soda to be assayed 
aie dissolved in water, and to the solution one of 25 grms. of perfectly 
neutral chloride of barium, that is to say, an excess, added to it. It is 
now filtered, the filtrate washed, and a current of carbonic acid passed 
into the filtered liquid, which is then heated to boiling ; the precipitate 
collected, washed and weighed. 1 equiv. of carbonate of barytes cor- 
responds to 1 equiv. of caustic soda. This process, which we have 
frequently employed, has enabled us to detect less than 1 per cent, of 
caustic alkali in a soda salt, and to convince ourselves that certain 
samples, which were said to contain from 1 to 2 per cent, of free alkali, 
contained not the least trace. These samples were very rich sodas of 
remarkable purity • submitted to the alkalimetric test by Gay-Lussac's 
method, they saturated 58| measures of the test-liquor, according to 
which they should contain 99 per cent, of pure and dry carbonate of 
soda. Astonished to meet in a commercial product, made on so large 
a scale, so remarkable a purity, we verified with chemically pure car- 
bonate of soda our alkalimetric liquid, which had however been made 
with the greatest care. It required exactly 59^ divisions of the tube 
for 3-185 grms. of the soda salt. With nitrate of silver and chloride of 
barium, we obtained scarcely perceptible precipitates in the solution 
of soda previously saturated with nitric acid. One single crystalliza- 
tion removed the last traces of impurity. — Chem. Gaz.from Jour, de Pharm. 
New and economical process for preparing oxide of Carbon. — By M. 
Filhoi,.— In the memoir which he published a short time ago on lactic 
acid, M, Pelouze noticed the following reaction as being very curious. 
