And again: “I am constrained to believe that there is the Stone which makes Gold, and which makes Silver; because I have at distinct turns, made projection with my hand, of one grain of the Powder, upon some thousand grains of hot Quick-silver; and the buisiness succeeded in the Fire, even as Books do promise; a Circle of many People standing by, together with a tickling Admiration of us all. . . . He who first gave me the Gold-making Powder, had likewise also, at least as much of it, as might be sufficient for changing two hundred thousand Pounds of Gold: . . . For he gave me perhaps half a grain of that Powder, and nine ounces and three quarters of Quick-silver were thereby transchanged: But that Gold, a strange man [a stranger], being a Friend of one evenings acquaintance, gave me.”[86] [86] J. B. VAN HELMONT: _The Tree of Life_ (see _Oriatrike_ or _Van Helmont’s Workes_, p. 807). [Illustration: PLATE 13. _To face page 84_]] The Testimony of Helvetius. § =63.= =John Frederick Helvetius= (see plate 13), an eminent doctor of medicine, and physician to the Prince of Orange, published at the Hague in 1667 the following remarkable account of a transmutation he claimed to have effected. Certain points of resemblance between this account and that of van Helmont (_e.g._, in each case the Stone is described as a glassy substance of a pale yellow colour) are worth noticing: “On the 27 December, 1666, in the forenoon, there came to my house a certain man, who was a complete stranger to me, but of an honest, grave countenance, and an authoritative mien, clothed in a simple garb like that of a Memnonite. . . .