A well-known physician of the sixteenth century, Johann Meckenbach, claimed, in 1548, to have discovered the process of producing oil of amber. Although Meckenbach was not entitled to the credit he claimed, as the experiment had already been successfully made, he gained great repute by this means, and when he communicated to Duke Albrecht of Prussia the secret of his process, the rulers of other lands overwhelmed the duke with requests for a supply of the precious remedy. Ferdinand, Archduke of Austria, sent a special messenger the long journey to Berlin, twice in a year, for a few flasks of the oil, which was regarded as a cure for many diseases.[115] The oil of amber—_oleum succini_ of the Pharmacopœia—has maintained its repute as a cure for various affections up to the present day. In some forms of gout and rheumatism it relieves the inflammation and pain in the joints; and its antispasmodic action makes it a valuable remedy in cases of asthma, whooping-cough, hysteria, bronchitis, and infantile convulsions.[116] An early version of the strange tale that ships were attracted by masses of rocks, or even mountains of loadstone, is given by Palladius (c. 367–c. 431 A.D.). He relates that the loadstone was produced on a group of islands called the Maniolæ, which were on the route to Taprobane (Ceylon), and continues, “if any ship constructed with iron nails approached these islands they were drawn by the power of the loadstone and their course was arrested. For this reason those voyaging to Taprobane use ships especially put together with wooden pegs.” Probably the legend arose from the fact that wood was often used in the case of vessels trading in this region, because iron was scarce and expensive. This is the view of Procopius, who found the same story still current in the sixth century.[117] It has been noted as a curious fact that none of the ancient writers who treat of the loadstone recognized that the attractive energy exerted by this substance on iron was also exerted by iron upon the loadstone; on the contrary, they constructed many ingenious hypotheses to explain why this was not the case.[118] The strange fancy that in the presence of a diamond a piece of loadstone was robbed of its attractive force, must have arisen from an observation of the well-known electric properties of the first-named stone, and from the idea that the much more valuable stone should have the greater power. Here, as in many other cases, we see how little interest was taken in actual experiment by ancient writers, a pre-conceived idea of the eternal fitness of things being the main criterion.