574 Annals New York Academy of Sciences 



by nonbasic cyclic nitrogen compounds. These compounds are slightly more 

 polar than alkanes and are more concentrated in the carbon tetrachloride 

 eluate (table 5) than in the »-heptane eluate (table 4). In table 4, the 

 peaks at .v = —6 and — 7, C^ = 16 are larger than those of homologous ions 

 at C^ 13, this suggests that the nitrogen ions may have obscured the "peak- 

 ings" at X = —6 and — 7, Ci^ = 16 which are generally observed in the mass 

 spectra of the terrestrial alkanes. "Peakings" at x = +1, C^ = 21 in 

 tables 4 and 5 have an odd mass number and also are suggestive of nitrogen 

 compounds. "Peakings" in the 19 to 25 carbon number ranges of the x = 0, 

 — 2, and —4 columns which appear in tables 4, 5, or 7 are uncommon in 

 sedimental hydrocarbon spectra but are present in the mass spectrum of the 

 saturated hydrocarbons from oysters.'^^ Neither crude oil nor sedimental 

 organic contaminants are probable sources of the mono-, di-, and tricyclo- 

 alkanes which form the ions producing the latter peakings. Nevertheless, 

 differences in the carbon numbers at which the "peakings" maxima occur in 

 the various columns of tables 4, 5, and 7 as well as the alternate high or low 

 values of odd and even C ^ "parent ions" in table 5 may be more suggestive 

 of a biological product than of an abiotically formed mixture that is thermo- 

 dynamically at equilibrium. 



Contamination 



Carbonaceous chondrites are friable, seemingly porous stones. Olivine, a 

 mineral that forms at temperatures above 400° C. is present in the Murray 

 but apparently not in the Orgueil stone. Associated minerals in the Orgueil 

 suggest that it may have formed in an environment resembling an organic rich 

 saline environment on Earth,'- and the compositions of the extractable car- 

 bonaceous fractions of the Murray and Orgueil, also, are indicative of marine 

 type sedimentary deposits. Although the compositions and the intimate 

 associations of the mineral and carbonaceous materials in carbonaceous 

 chondrites are not incongruous with a marine ecology, meteorites are likely to 

 be contaminated by terrestrial substances. It is important to consider the 

 most probable contaminants and the effect that they may have upon the 

 composition of the carbon constituents of meteorites. 



All meteorites accepted as carbonaceous chondrites were observed during 

 their fall to Earth. Many of the carbonaceous chondrite fragments that have 

 been collected are partially coated with a heat altered layer. Charred crusts 

 were apparently formed on the lead surfaces of the meteorites when these 

 areas were heated to incandescence on entry into Earth's atmosphere. 



In transit to Earth carbonaceous chondrites break-up. Boato's- measure- 

 ments show that meteoritic waters released at temperatures above 180° C. 

 apparently have not been exchanged with terrestrial waters. Carbonaceous 

 chondrites give off sizeable quantities of water at temperatures in excess of 

 180° C.,* and additional evidence has been presented'- that these meteorites 

 did retain substances in space which normally boil below 180° C. The volatile 

 constituents of carbonaceous chondrites suggest that they have restricted the 

 egress of gases to the vacuum of space. Perhaps, the interiors of these frag- 

 ments are less accessible than their porous structures may indicate, but re- 

 gardless of the permeabilities of carbonaceous chondrites, their fall was over 



