582 



SCIENCE 



[N. S. Vol. LIII. No. 1382 



cal determinations and yields a logical conventional 

 form for expressing the whole analysis of the brine. 

 The vapor density of technical phosgene: A. F. 

 0. Germann and Vernon Jersey. A 75 gm. 

 sample of technical phosgene was distilled from a 

 large cylinder of the liquefied gas, obtained from 

 the Chemical Warfare Service through Dr. Goss. 

 Pure phosgene has a vapor tension at 0° C. of 

 about 552 mm.; the sample taken showed a vapor 

 tension dn excess of one atmosphere at — 80° C, 

 that is, in a bath of solid carbon dioxide and 

 acetone. The sample was subjected to fractional 

 distillation in a vacuum until the vapor tension at 

 0° C. was approximately correct. Following this, 

 three fracbional distillations alternated with three 

 determinations of the vapor density of the gas, un- 

 tU five groups of three determinations each had 

 been obtained for the vapor density, and the nearly 

 pure gas had been fractionally distilled 15 times. 



Average of 1st group of densities 4.4708 



" " 2d " " " 4.5060 



" " 3d " " " 4.5216 



" " 4th " " " 4.5244 



" " 5th " " " 4.5263 



The values given are in grams per liter at 

 standard conditions, uncorrected for the compres- 

 sibOity of the gas and for the contraction of the 

 globes when evacuated. Technical phosgene is 

 very impure. The principal impurities are very 

 volatile and of relatively low molecular weight, 

 probably carbon dioxide ajid hydrogen chloride re- 

 sulting from hydrolysis. Eepeated fractional dis- 

 tillation yields a product whose density tends 

 toward a maximum value, probably the value for 

 pure phosgene. 



The cryosoopy of boron trifluoride solutions: V. 

 Systems with methyl ether and with methyl chlo- 

 ride: A. F. O. Germann and Marion Cleaveland. 

 Gasselin prepared the compound BFs.(CH3):0 by 

 mixing the gases; he obtained a liquid boiling at 

 126° C. This compound has been prepared from 

 liquid boron trifluoride and liquid methyl ether 

 in the course of the determination of the melting 

 point curve of solutions of the two substances. 

 The curve shows a eutectie at 3 per cent. BF, 

 (molecular percentages) and a maximum at 50 

 per cent. The vapor tensions of solutions contain- 

 ing from 60 per cent, to 90 per cent. BF3 were so 

 high, that the form of apparatus used was inade- 

 quate. The form of the curve so far as determined 

 seems to indicate the existence of a second com- 

 pound in this interval. Methyl chloride was pre- 

 pared from salt, sulfuric acid and wood alcohol; 

 was purified by repeated fractional distillations; 



and gave the usual indications of a pure substance, 

 such as constant freezing point for the first and 

 last fractions of the liquid. The melting point 

 curve with BF3 shows two maxima, at 15 per cent. 

 BF3, and at 33 per cent. BFj, and an angular 

 point in the curve at 50 per cent. The form of 

 the maxima at 15 per cent, is identical with that 

 at 50 per cent, for methyl ether; the mixture 

 yields about 15 per cent, of the total volume of a 

 liquid, whose freezing and boiling points are 

 identical with those of BF3. (CH3)20. The logical 

 inference is that methyl chloride as prepared con- 

 tains methyl ether as an impurity, and that this 

 impurity yields a constant boiling mixture. It 

 would seem that boron trifluoride might be used 

 as a test for the presence of methyl ether in 

 methyl chloride; the same test might be extended 

 to the homologues. The interpretation of the other 

 maxima mentioned must await the completion of 

 further work on the purity of methyl chloride. 



The cryoscopy of phosgene solutions: I. Sys- 

 tem with chlorine: A. F. O. Germann and V. 

 Jersey. The melting point curve of solutions of 

 phosgene and chlorine was determined. The curve 

 is very complex. There is a eutectie at 25 per 

 cent, (molecular percentages) chlorine; and an- 

 gular points in the curve at 6 per cent., 11 per 

 cent., 50 per cent., 63 per cent., 75 per cent, and 

 91 per cent, chlorine. The following compounds, 

 which dissociate at the melting point, are indi- 

 cated: 16COa,.CL; SCOa^.CL; COCL.Cl-; 

 3COa=.5Cl,; COClj.sa,; and COCL.lOCl,. The 

 second of these, chlorine octaphosgenate, is particu- 

 larly interesting, as corresponding with the octa- 

 hydrate of chlorine. The affinity of chlorine for 

 phosgene, and the instability of the eompoimds 

 would seem to offer an explanation of the mech- 

 anism of certain phases of the catalysis of carbon 

 monoxide and chlorine by means of charcoal sat- 

 urated with chlorine. If we assume a layer of 

 chlorine molecules on the surface of the charcoal, 

 the high concentration of chlorine thus obtained 

 might be supposed in the presence of carbon mon- 

 oxide to shift the equilibrium in the direction of 

 one of the chlorine-phosgene complexes, which 

 promptly decomposes because of its instability, 

 leaving the surface film of chlorine for further 

 action. It would be desirable to determine the 

 melting point curve of carbon monoxide and chlo- 

 rine solutions, to clear up some of the points in- 

 volved in this reaction. 



Charles L. Parsons, 



Secretary 



