V O L U M E 21, NO. 8, A U G U S T 1 9 4 9 nearly all cases, tellurium alone, tellurium compounds, and combinations of tellurium with ferrous sulfate or copper sulfate gave low results. Of the selenium catalysts, selenium alone, or with ferrous sulfate or copper sulfate, was satisfactory. Sodium selerlite and gave slightly loR-er results in cases. It may be concluded that tellurium is not generally suitable as a catslvst for the Kjelt1,thl digestion.
1013 LITERATURE CITED
Bradstreet, R.B,, CHEY., 4 s k L , ED., 12, Gj7 (1940). (2) Davisson, B. S.,J . Ind. Eng. Chem., 11, 466 (1919). (3) Gresin, Yu. D., F a r m . Zhur., 1937, S o . 2 . 104-9 (4) Illaiionov, V. V., and Soloveva. N. A . , Z . anal. Chcm., 100 328-43 (1936).
R E G L I V E DJ u l y 12, 194%
Simplified Gas Microanalyzer C L i R E N C E N. STOVER, J R . , WILLIAM S. PARTRIDGE,
AND
WARRER M. GARRISON1
L'niversity of Vyorning, Larumie, Fyo.
LTHOUGII the Saunders-Taylor method ( 1 , 2 ) for the micro-
A analysis of gas is rapid and accurate. it has certain discidvantages. The custom-built multiway stopcock around which the apparatus is designed is relatively espensive and inconvenient to obtain. Likewise, the design of the combustion chamber requires an undue amount of care to prevent overheating the grease on the ground joint through which the chamber is connected to the apparatus. The desirable features of the method can be retained in a simplified form which is easily fnhricatrcl from standard stopcocks and ground joints.
0
to the tungsten electrodes. \Vith this design the filament could he operated as long as required without cooling the ground joint, which was lubricated with Bpiezon X. In a typical analysis the reaction tube was evacuated through D and volume F was evacuated through one side of stopcock G. The other arm of G was connected to a reservoir of gas to be analyzed. During the evacuation the mercury level in .V was kept below the mark a t H by applying vacuum through stopcock L a t J . When the pressure in F was 10-5 mm. or Iomer, a sample of gas was added through G . The mercury level was raised to I by cautiously opening L to the atmosphere. The difference in height of the mercury menisci a t I and in manometer 31 was a measure of the gas in volume 7'. Stopcock C was then rotated and the gas was forced into the appropriate reaction tube by raising the mercury level. After a period of time determined by experiment, the mercury was lowered to H and C mas closed. The gas was then compressed again to I and the manometer was read. The difference between the two manometer readings after correction for residual gas in the reaction tube was a measure of the volume change in the reaction tube used. The residual gas correction was calculated from the volume ratio of A and F ; for the apparatus shown this value was 0.00441 or 0.417&
A representative analysis of a four-component determinate misture is given in Table I. The gases in these samples were purified by the techniques outlined by Saunders and Taylor ( 2 ) . The modified analyzer is easier to build and more readily kept in operation than previous designs, I n general, the analytical difficulties encountered by Saunders and Taylor are still present.
h
Table I.
Analysis of a Standard Sample Taken, Mm.
Found, hlm.
17.1
32.4
17.3 17.1 32.8 32.0
CHI
68.2
GHs
14.7
68.5 68.1
Component H2 CO
Figure 1. Diagram of 3Iicronnalyzer
The 1-inni. capillary two-n-ay stopcock, C, replaced the multiway stopcock in the original Saunders-Taylor design. The stopcock plug and reaction tubes, A , were evacuated througll D ,which was connected to high vacuuni. Gas to be analyzed was passed irito A by rotating the plug 180". Tubes holding reagents for various determinations had 10/30 ground joints and were interchangeable at B. These tubes were similar to those used by Saunders and Taylor. The reaction tube shown was used for combustions and was a modification of the origin:tl design. The two leads were 1-mm. tungsten and the filanierit was made from three turns of platinum wire spot-n-eldcd 1
Present addresb, University of California. Berkeley, Calif.
14.0 11.8
IIowerer, the small empirical correction used h y them in cn1c.ulnting carbon dioside contractions can be neglected if not more than l C % escess osygen v a s added to the hydrocarbon fraction prior to combustion. This correction, the need for n-hich they attributed to stabilization of ozone on t,he walls of the n-atercooled combustion tube, apparently may be neglected, if, RS in the present design, the combustion tube is air-cooled and can, as a result, attain a higher wall temperature during combustion. LITERATURE CITED
(1) Garrison, W. hl., and Burton, hZ., J . Chem. Phys., 10, 730-9 11942)). ( 2 ) Saunders, K. W., 2nd Taylor, H. h.,Ihid.,9, 616-26 (1941). RECEIIE D July 23, 1048.
