The brown substance P, obtained from filtrate A by evaporation and
extracting the residue with hot water, was suspended in warm water and
dilute sulphuric was added. A white precipitate was formed and a strong
fatty acid odor was developed. After the mixture had been heated for
some hours on the water bath a small portion was made alkaline and it
reduced Fehling solution. The main solution was filtered and the
precipitate supposed to be a fatty acid was saved. The filtrate was
neutralized with barium carbonate, filtered, evaporated, freed from
caramel, and the solution then gave the tests mentioned above for
rhamnose.
A portion of the precipitate supposed to be a fatty acid was ignited in
a porcelain spoon. It fused, carbonized, and burned. The remainder was
heated with alcoholic potash and reprecipitated with hydrochloric acid.
The precipitate was washed and heated with alcohol. Part of it
dissolved. The insoluble part was found to be a lead compound. On
boiling it with hydrochloric acid and cooling, lead chloride
crystallized out. This was confirmed by dissolving the lead chloride in
hot water and precipitating as lead sulphide. These experiments were not
carried farther on account of the small quantity of material, but they
show that the gummy substance obtained from filtrate A contained
rhamnose (either as a lead compound of free sugar or as a lead compound
of a rhamnoside), and also, most probably, the lead compound of an
organic acid.[44]