The Chemical Constitution of the Tubercle Bacillus

Abstract

1. Dried tubercle bacilli extracted with hot solutions of spirit, alcohol, alcohol-ether, Aronson's mixture, yield large percentages of fatty substances. 2. On filtering the boiling extracts a white acid-fast precipitate deposits on cooling. 3. The filtrates on evaporation can be saponified by soda, and on subsequent agitation with ether and water two extracts can be obtained —an ethereal and a watery extract. 4. The ethereal extract contains fat which is not acid-fast. 5. By saponifying the dried ethereal extract with alcoholic potash and decomposing the resulting soaps with sulphuric acid a mixture of fatty acids is obtained containing probably oleic, isocetinic and myristinic acids. None of these are acid-fast. 6. The watery extract (soap) on decomposition yielded a fatty acid with a melting point corresponding to lauric acid. 7. The filtrates also yield lipochromes to which the cultures of tubercle bacillus owe their colour. 8. The white acid-fast precipitate obtained by the original extraction can be saponified, but with great difficulty. 9. By prolonged boiling with alcoholic potash the acid-fast precipitate is decomposed and results in the deposition of an acid-fast snow-white flaky powder, and a non-acid-fast filtrate of fatty acids. 10. The chemical examination of the white flaky powder shows it to be an alcohol. 11. Acid- and alcohol-fastness of the tubercle bacillus is due to the presence of an alcohol.