738 REPORT—1896. 
In these two experiments the following figures were found for the quantity of 
gas not absorbed by magnesium : — 
I It 
c.c. c.c. 
Volume of the nitrogen before the absorption by 
1172 1918 
magnesium . $ 4 : = : : : 
Volume of the collected gas (hydrogen, traces of 
nitrogen and argon) 5 : c ; 95°6 28°2 
Volume of the dry cleaned gas (argon) . : 13°0 23°9 
Volume per cent. of gas not absorbed compared with 
the original quantity of nitrogen ‘ . ; iki 1:24 
Volume per cent. compared with the original volume 
of gas . : : ; 1-04 1:16 
The gas thus cleaned was put into Pliicker’s tubes at the glass technical Insti- 
tute of Menes Goetze in Leipzig. 
The examination of the gas by spectral analysis was made by Professors Eder 
and Valenta with their concave grating. 
The result of this examination was.an absolute conformity of the spectrum of 
the gas isolated by the author with Lord Rayleigh’s normal spectrum of argon 
determined by Eder. 
The author concluded by expressing the great pleasure he had in making this 
communication upon argon in the land of its birth, and in the presence of one of its 
distinguished discoverers. 
3. The Manufacture of Chlorine by means of Nitric Acid. 
By Dr. F. Hurter. 
4, Low Temperature Research. By Professor J. Dewar, F.R.S. 
5. Report on Electrolytic Analysis.—See Reports, p. 244. 
6. A Modified Form of Schrotter’s Apparatus for the Determination of 
Carbonic Anhydride. By Cuartes A. Koun, Ph.D., B.Sc. 
Of the many forms of apparatus for the estimation of carbonic anhydride by 
loss, that devised by Schrétter is probably most widely in use. Compared with 
other forms, it is certainly more handy than Bunsen’s apparatus, although the 
latter is more accurate, since it contains an absorption tube charged with dehy- 
drated copper sulphate on pumice in addition to calcium chloride. In a modified 
Bunsen apparatus described by A. Christomanos (‘ Ber.,’ 1894, 27, 2748), the drying 
tube is replaced by a small wash bottle containing concentrated sulphuric acid ; 
the advantages of the latter over calcium chloride as a drying agent are pointed 
out. But this modified form suffers from the same disadvantage as the ordinary 
Schrétter apparatus in not making any special provision for the absorption of 
hydrochloric acid gas which is evolved whenever hydrochloric acid is employed in 
the decomposition of a carbonate. This is a well-recognised source of error, and it 
is customary to attach a tube charged with dehydrated copper sulphate on pumice 
to the sulphuric acid bulb of the ordinary Schrétter apparatus in order to effect 
the complete absorption of the hydrochloric acid gas. With this addition, very 
reliable results can be obtained, but the method of attachment of the additional 
tube is always more or less clumsy. The object of the present modification is to 
overcome this, and the new form has two additional advantages. The apparatus 
is more stable, and the copper sulphate tube can be easily turned through any 
angle, so as to attach the indiarubber tubing for drawing air through the 
apparatus, after heating to drive out the carbonic anhydride and allowing to cool. 
The pumice containing the dehydrated copper sulphate is held in place by a plug 
of glass wool, and the ground glass stopper below it keeps well in its place if 
