This section is from the book "Materia Medica And Therapeutics Inorganic Substances", by Charles D. F. Phillips. Also available from Amazon: Materia medica and therapeutics.
Salts of gold are readily decomposed by organic substances, and they coagulate albumen, but when the soluble chlorides are given internally they become absorbed to some extent, probably in the intestine, as oxides combined with albumen. When rubbed upon the gums and tongue, according to an old-fashioned method of administration, they are also absorbed, but are liable to cause much local irritation. Neither metallic gold nor the oxides can be absorbed (although poisoning by gold leaf is said to be an aristocratic method of suicide in China), nor is an ointment containing either these or the chlorides likely to produce any effect through the skin.
Elimination occurs through the liver, the intestinal canal, and the kidneys, but is very slow (Husemann): the urine is colored yellow during the process. Rabuteau maintains that the elimination of gold is never complete, some of the metal being reduced and deposited, especially in the epithelial and nerve-tissues; for on examining these parts in the body of a rat that had died after taking 15 gr. of gold chloride in fourteen days, he found the contour of epithelium from the intestinal tract to be very strongly marked, as by nitrate of silver, and the axis-cylinder of the nerve-tubules to be colored slightly green; he considers that this deposition of the metal explains why gold seems more active than mercury, for having nearly the same atomic weight and specific heat, their properties should (according to the analogies of other substances as observed by him) be also very similar, were it not that the gold is less completely eliminated (Op. cit.). We must remark, however, upon this point, that though mercury may, as a rule, be more readily eliminated than gold, yet it has also often been found deposited in bone, liver, and other parts of the body, long after its administration.
The chloride of gold has an irritant and caustic effect, and stains the skin of a yellow color, which becomes violet, and later black, from reduction of the metal.